The UV Luminosity Function at 6 < z < 10 from the Hubble Frontier Fields

NASA Astrophysics Data System (ADS)

Livermore, Rachael C.; Finkelstein, Steven L.; Lotz, Jennifer M.

2017-01-01

The Hubble Frontier Fields program has obtained deep optical and near-infrared Hubble Space Telescope imaging of six galaxy clusters and associated parallel fields. The depth of the imaging (m_AB ~ 29) means we can identify faint galaxies at z > 6, and those in the cluster fields also benefit from magnification due to strong gravitational lensing that allows us to reach intrinsic absolute magnitudes of M_UV ~ -12.5 at z ~ 6. Here, we present the UV luminosity functions at 6 < z < 10 from the complete Hubble Frontier Fields data, revealing a steep faint-end slope that extends to the limits of the data. The lack of any apparent turnover in the luminosity functions means that faint galaxies in the early Universe may have provided sufficient ionizing radiation to sustain reionization.

Wide Field Imaging of the Hubble Deep Field-South Region III: Catalog

NASA Technical Reports Server (NTRS)

Palunas, Povilas; Collins, Nicholas R.; Gardner, Jonathan P.; Hill, Robert S.; Malumuth, Eliot M.; Rhodes, Jason; Teplitz, Harry I.; Woodgate, Bruce E.

2002-01-01

We present 1/2 square degree uBVRI imaging around the Hubble Deep Field - South. These data have been used in earlier papers to examine the QSO population and the evolution of the correlation function in the region around the HDF-S. The images were obtained with the Big Throughput Camera at CTIO in September 1998. The images reach 5 sigma limits of u approx. 24.4, B approx. 25.6, V approx. 25.3, R approx. 24.9 and I approx. 23.9. We present a catalog of approx. 22,000 galaxies. We also present number-magnitude counts and a comparison with other observations of the same field. The data presented here are available over the world wide web.

Studying Galaxy Formation with the Hubble, Spitzer and James Webb Space Telescopes

NASA Technical Reports Server (NTRS)

Gardner, Jonathan P.

2007-01-01

The deepest optical to infrared observations of the universe include the Hubble Deep Fields, the Great Observatories Origins Deep Survey and the recent Hubble Ultra-Deep Field. Galaxies are seen in these surveys at redshifts 2x3, less than 1 Gyr after the Big Bang, at the end of a period when light from the galaxies has reionized Hydrogen in the inter-galactic medium. These observations, combined with theoretical understanding, indicate that the first stars and galaxies formed at z>lO, beyond the reach of the Hubble and Spitzer Space Telescopes. To observe the first galaxies, NASA is planning the James Webb Space Telescope (JWST), a large (6.5m), cold (<50K), infrared-optimized observatory to be launched early in the next decade into orbit around the second Earth- Sun Lagrange point. JWST will have four instruments: The Near-Infrared Camera, the Near-Infrared multi-object Spectrograph, and the Tunable Filter Imager will cover the wavelength range 0.6 to 5 microns, while the Mid-Infrared Instrument will do both imaging and spectroscopy from 5 to 28.5 microns. In addition to JWST's ability to study the formation and evolution of galaxies, I will also briefly review its expected contributions to studies of the formation of stars and planetary systems.

Studying Galaxy Formation with the Hubble, Spitzer and James Webb Space Telescopes

NASA Technical Reports Server (NTRS)

Gardner, Jonathan F.; Barbier, L. M.; Barthelmy, S. D.; Cummings, J. R.; Fenimore, E. E.; Gehrels, N.; Hullinger, D. D.; Markwardt, C. B.; Palmer, D. M.; Parsons, A. M.;

Studying Galaxy Formation with the Hubble, Spitzer and James Webb Space Telescopes

NASA Technical Reports Server (NTRS)

Gardner, Jonathan P.

2007-01-01

The deepest optical to infrared observations of the universe include the Hubble Deep Fields, the Great Observatories Origins Deep Survey and the recent Hubble Ultra-Deep Field. Galaxies are seen in these surveys at redshifts z>6, less than 1 Gyr after the Big Bang, at the end of a period when light from the galaxies has reionized Hydrogen in the inter-galactic medium. These observations, combined with theoretical understanding, indicate that the first stars and galaxies formed at z>10, beyond the reach of the Hubble and Spitzer Space Telescopes. To observe the first galaxies, NASA is planning the James Webb Space Telescope (JWST), a large (6.5m), cold (<50K), infrared-optimized observatory to be launched early in the next decade into orbit around the second Earth- Sun Lagrange point. JWST will have four instruments: The Near-Infrared Camera, the Near-Infrared multi-object Spectrograph, and the Tunable Filter Imager will cover the wavelength range 0.6 to 5 microns, while the Mid-Infrared Instrument will do both imaging and spectroscopy from 5 to 28.5 microns. In addition to JWST's ability to study the formation and evolution of galaxies, I will also briefly review its expected contributions to studies of the formation of stars and planetary systems.

Young Galaxy Candidates in the Hubble Frontier Fields. IV. MACS J1149.5+2223

NASA Astrophysics Data System (ADS)

Zheng, Wei; Zitrin, Adi; Infante, Leopoldo; Laporte, Nicolas; Huang, Xingxing; Moustakas, John; Ford, Holland C.; Shu, Xinwen; Wang, Junxian; Diego, Jose M.; Bauer, Franz E.; Troncoso Iribarren, Paulina; Broadhurst, Tom; Molino, Alberto

2017-02-01

We search for high-redshift dropout galaxies behind the Hubble Frontier Fields (HFF) galaxy cluster MACS J1149.5+2223, a powerful cosmic lens that has revealed a number of unique objects in its field. Using the deep images from the Hubble and Spitzer space telescopes, we find 11 galaxies at z > 7 in the MACS J1149.5+2223 cluster field, and 11 in its parallel field. The high-redshift nature of the bright z ≃ 9.6 galaxy MACS1149-JD, previously reported by Zheng et al., is further supported by non-detection in the extremely deep optical images from the HFF campaign. With the new photometry, the best photometric redshift solution for MACS1149-JD reduces slightly to z = 9.44 ± 0.12. The young galaxy has an estimated stellar mass of (7+/- 2)× {10}8 {M}⊙ , and was formed at z={13.2}-1.6+1.9 when the universe was ≈300 Myr old. Data available for the first four HFF clusters have already enabled us to find faint galaxies to an intrinsic magnitude of {M}{UV}≃ -15.5, approximately a factor of 10 deeper than the parallel fields.

A MULTIWAVELENGTH STUDY OF TADPOLE GALAXIES IN THE HUBBLE ULTRA DEEP FIELD

DOE Office of Scientific and Technical Information (OSTI.GOV)

Straughn, Amber N.; Eufrasio, Rafael T.; Gardner, Jonathan P.

2015-12-01

Multiwavelength data are essential in order to provide a complete picture of galaxy evolution and to inform studies of galaxies’ morphological properties across cosmic time. Here we present the results of a multiwavelength investigation of the morphologies of “tadpole” galaxies at intermediate redshift (0.314 < z < 3.175) in the Hubble Ultra Deep Field. These galaxies were previously selected from deep Hubble Space Telescope (HST) F775W data based on their distinct asymmetric knot-plus-tail morphologies. Here we use deep Wide Field Camera 3 near-infrared imaging in addition to the HST optical data in order to study the rest-frame UV/optical morphologies ofmore » these galaxies across the redshift range 0.3 < z < 3.2. This study reveals that the majority of these galaxies do retain their general asymmetric morphology in the rest-frame optical over this redshift range, if not the distinct “tadpole” shape. The average stellar mass of tadpole galaxies is lower than that of field galaxies, with the effect being slightly greater at higher redshift within the errors. Estimated from spectral energy distribution fits, the average age of tadpole galaxies is younger than that of field galaxies in the lower-redshift bin, and the average metallicity is lower (whereas the specific star formation rate for tadpoles is roughly the same as field galaxies across the redshift range probed here). These average effects combined support the conclusion that this subset of galaxies is in an active phase of assembly, either late-stage merging or cold gas accretion causing localized clumpy star formation.« less

Studying Galaxy Formation with the Hubble, Spitzer and James Webb Space Telescopes

NASA Technical Reports Server (NTRS)

Gardner, Jonathan P.

2009-01-01

The deepest optical to infrared observations of the universe include the Hubble Deep Fields, the Great Observatories Origins Deep Survey and the recent Hubble Ultra-Deep Field. Galaxies are seen in these surveys at redshifts z greater than 6, less than 1 Gyr after the Big Bang, at the end of a period when light from the galaxies has reionized Hydrogen in the inter-galactic medium. These observations, combined with theoretical understanding, indicate that the first stars and galaxies formed at z greater than 10, beyond the reach of the Hubble and Spitzer Space Telescopes. To observe the first galaxies, NASA is planning the James Webb Space Telescope (JWST), a large (6.5m), cold (less than 50K), infrared-optimized observatory to be launched early in the next decade into orbit around the second Earth-Sun Lagrange point. JWST will have four instruments: The Near-Infrared Camera, the Near-Infrared multi-object Spectrograph, and the Tunable Filter Imager will cover the wavelength range 0.6 to 5 microns, while the Mid-Infrared Instrument will do both imaging and spectroscopy from 5 to 28.5 microns. In addition to JWST's ability to study the formation and evolution of galaxies, I will also briefly review its expected contributions to studies of the formation of stars and planetary systems, and discuss recent progress in constructing the observatory.

The MUSE Hubble Ultra Deep Field Survey. IX. Evolution of galaxy merger fraction since z ≈ 6

NASA Astrophysics Data System (ADS)

Ventou, E.; Contini, T.; Bouché, N.; Epinat, B.; Brinchmann, J.; Bacon, R.; Inami, H.; Lam, D.; Drake, A.; Garel, T.; Michel-Dansac, L.; Pello, R.; Steinmetz, M.; Weilbacher, P. M.; Wisotzki, L.; Carollo, M.

2017-11-01

We provide, for the first time, robust observational constraints on the galaxy major merger fraction up to z ≈ 6 using spectroscopic close pair counts. Deep Multi Unit Spectroscopic Explorer (MUSE) observations in the Hubble Ultra Deep Field (HUDF) and Hubble Deep Field South (HDF-S) are used to identify 113 secure close pairs of galaxies among a parent sample of 1801 galaxies spread over a large redshift range (0.2 < z < 6) and stellar masses (107-1011 M⊙), thus probing about 12 Gyr of galaxy evolution. Stellar masses are estimated from spectral energy distribution (SED) fitting over the extensive UV-to-NIR HST photometry available in these deep Hubble fields, adding Spitzer IRAC bands to better constrain masses for high-redshift (z ⩾ 3) galaxies. These stellar masses are used to isolate a sample of 54 major close pairs with a galaxy mass ratio limit of 1:6. Among this sample, 23 pairs are identified at high redshift (z ⩾ 3) through their Lyα emission. The sample of major close pairs is divided into five redshift intervals in order to probe the evolution of the merger fraction with cosmic time. Our estimates are in very good agreement with previous close pair counts with a constant increase of the merger fraction up to z ≈ 3 where it reaches a maximum of 20%. At higher redshift, we show that the fraction slowly decreases down to about 10% at z ≈ 6. The sample is further divided into two ranges of stellar masses using either a constant separation limit of 109.5 M⊙ or the median value of stellar mass computed in each redshift bin. Overall, the major close pair fraction for low-mass and massive galaxies follows the same trend. These new, homogeneous, and robust estimates of the major merger fraction since z ≈ 6 are in good agreement with recent predictions of cosmological numerical simulations. Based on observations made with ESO telescopes at the La Silla-Paranal Observatory under programmes 094.A-0289(B), 095.A-0010(A), 096.A-0045(A) and 096.A-0045(B).

MUSE deep-fields: the Ly α luminosity function in the Hubble Deep Field-South at 2.91 < z < 6.64

NASA Astrophysics Data System (ADS)

Drake, Alyssa B.; Guiderdoni, Bruno; Blaizot, Jérémy; Wisotzki, Lutz; Herenz, Edmund Christian; Garel, Thibault; Richard, Johan; Bacon, Roland; Bina, David; Cantalupo, Sebastiano; Contini, Thierry; den Brok, Mark; Hashimoto, Takuya; Marino, Raffaella Anna; Pelló, Roser; Schaye, Joop; Schmidt, Kasper B.

2017-10-01

We present the first estimate of the Ly α luminosity function using blind spectroscopy from the Multi Unit Spectroscopic Explorer, MUSE, in the Hubble Deep Field-South. Using automatic source-detection software, we assemble a homogeneously detected sample of 59 Ly α emitters covering a flux range of -18.0 < log10 (F) < -16.3 (erg s-1 cm-2), corresponding to luminosities of 41.4 < log10 (L) < 42.8 (erg s-1). As recent studies have shown, Ly α fluxes can be underestimated by a factor of 2 or more via traditional methods, and so we undertake a careful assessment of each object's Ly α flux using a curve-of-growth analysis to account for extended emission. We describe our self-consistent method for determining the completeness of the sample, and present an estimate of the global Ly α luminosity function between redshifts 2.91 < z < 6.64 using the 1/Vmax estimator. We find that the luminosity function is higher than many number densities reported in the literature by a factor of 2-3, although our result is consistent at the 1σ level with most of these studies. Our observed luminosity function is also in good agreement with predictions from semi-analytic models, and shows no evidence for strong evolution between the high- and low-redshift halves of the data. We demonstrate that one's approach to Ly α flux estimation does alter the observed luminosity function, and caution that accurate flux assessments will be crucial in measurements of the faint-end slope. This is a pilot study for the Ly α luminosity function in the MUSE deep-fields, to be built on with data from the Hubble Ultra Deep Field that will increase the size of our sample by almost a factor of 10.

The Great Observatories Origins Deep Survey (GOODS): Overview and Status

NASA Astrophysics Data System (ADS)

Hook, R. N.; GOODS Team

2002-12-01

GOODS is a very large project to gather deep imaging data and spectroscopic followup of two fields, the Hubble Deep Field North (HDF-N) and the Chandra Deep Field South (CDF-S), with both space and ground-based instruments to create an extensive multiwavelength public data set for community research on the distant Universe. GOODS includes a SIRTF Legacy Program (PI: Mark Dickinson) and a Hubble Treasury Program of ACS imaging (PI: Mauro Giavalisco). The ACS imaging was also optimized for the detection of high-z supernovae which are being followed up by a further target of opportunity Hubble GO Program (PI: Adam Riess). The bulk of the CDF-S ground-based data presently available comes from an ESO Large Programme (PI: Catherine Cesarsky) which includes both deep imaging and multi-object followup spectroscopy. This is currently complemented in the South by additional CTIO imaging. Currently available HDF-N ground-based data forming part of GOODS includes NOAO imaging. Although the SIRTF part of the survey will not begin until later in the year the ACS imaging is well advanced and there is also a huge body of complementary ground-based imaging and some follow-up spectroscopy which is already publicly available. We summarize the current status of GOODS and give an overview of the data products currently available and present the timescales for the future. Many early science results from the survey are presented in other GOODS papers at this meeting. Support for the HST GOODS program presented here and in companion abstracts was provided by NASA thorugh grant number GO-9425 from the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Incorporated, under NASA contract NAS5-26555.

The intense starburst HDF 850.1 in a galaxy overdensity at z ≈ 5.2 in the Hubble Deep Field.

PubMed

Walter, Fabian; Decarli, Roberto; Carilli, Chris; Bertoldi, Frank; Cox, Pierre; Da Cunha, Elisabete; Daddi, Emanuele; Dickinson, Mark; Downes, Dennis; Elbaz, David; Ellis, Richard; Hodge, Jacqueline; Neri, Roberto; Riechers, Dominik A; Weiss, Axel; Bell, Eric; Dannerbauer, Helmut; Krips, Melanie; Krumholz, Mark; Lentati, Lindley; Maiolino, Roberto; Menten, Karl; Rix, Hans-Walter; Robertson, Brant; Spinrad, Hyron; Stark, Dan P; Stern, Daniel

2012-06-13

The Hubble Deep Field provides one of the deepest multiwavelength views of the distant Universe and has led to the detection of thousands of galaxies seen throughout cosmic time. An early map of the Hubble Deep Field at a wavelength of 850 micrometres, which is sensitive to dust emission powered by star formation, revealed the brightest source in the field, dubbed HDF 850.1 (ref. 2). For more than a decade, and despite significant efforts, no counterpart was found at shorter wavelengths, and it was not possible to determine its redshift, size or mass. Here we report a redshift of z = 5.183 for HDF 850.1, from a millimetre-wave molecular line scan. This places HDF 850.1 in a galaxy overdensity at z ≈ 5.2, corresponding to a cosmic age of only 1.1 billion years after the Big Bang. This redshift is significantly higher than earlier estimates and higher than those of most of the hundreds of submillimetre-bright galaxies identified so far. The source has a star-formation rate of 850 solar masses per year and is spatially resolved on scales of 5 kiloparsecs, with an implied dynamical mass of about 1.3 × 10(11) solar masses, a significant fraction of which is present in the form of molecular gas. Despite our accurate determination of redshift and position, a counterpart emitting starlight remains elusive.

My Most Memorable AAS Meeting, or How Stephen Hawking's Chauffeur and Chubby Wise's Fiddle Are Related to the Hubble Deep Field (At Least In My Mind and Experience!)

NASA Astrophysics Data System (ADS)

Lucas, R. A.

1999-05-01

Sometimes, in the most extraordinary conditions and times, strange things happen which remind us of just how small a world we really inhabit, and how so many varied things may suddenly be juxtaposed in our lives, and in the lives of others. My most memorable AAS meeting involves not only the meeting but events while getting there. It was January 1996, and we had just finished our observations and initial data reduction of the Hubble Deep Field, the members of the HDF working group doggedly coming in to the STScI by various means over the December holidays and the New Year, in the midst of several blizzards which even closed STScI for a number of days. Not surprisingly, work on the HDF AAS presentations was ongoing until the last minute, until people left snowy Baltimore for sunny San Antonio. My street was plowed for the first time in a week a few hours before my 6AM flight, so after digging out my car, with no time for sleep, between 3AM and 6AM on the morning I left, I soon discovered my own surprising connections between Stephen Hawking's chauffeur, Chubby Wise's fiddle, and the Hubble Deep Field. I'll elaborate in this paper if you're curious!

Deep Keck u-Band Imaging of the Hubble Ultra Deep Field: A Catalog of z ~ 3 Lyman Break Galaxies

NASA Astrophysics Data System (ADS)

Rafelski, Marc; Wolfe, Arthur M.; Cooke, Jeff; Chen, Hsiao-Wen; Armandroff, Taft E.; Wirth, Gregory D.

2009-10-01

We present a sample of 407 z ~ 3 Lyman break galaxies (LBGs) to a limiting isophotal u-band magnitude of 27.6 mag in the Hubble Ultra Deep Field. The LBGs are selected using a combination of photometric redshifts and the u-band drop-out technique enabled by the introduction of an extremely deep u-band image obtained with the Keck I telescope and the blue channel of the Low Resolution Imaging Spectrometer. The Keck u-band image, totaling 9 hr of integration time, has a 1σ depth of 30.7 mag arcsec-2, making it one of the most sensitive u-band images ever obtained. The u-band image also substantially improves the accuracy of photometric redshift measurements of ~50% of the z ~ 3 LBGs, significantly reducing the traditional degeneracy of colors between z ~ 3 and z ~ 0.2 galaxies. This sample provides the most sensitive, high-resolution multi-filter imaging of reliably identified z ~ 3 LBGs for morphological studies of galaxy formation and evolution and the star formation efficiency of gas at high redshift.

Dark-ages reionization and galaxy formation simulation-XI. Clustering and halo masses of high redshift galaxies

NASA Astrophysics Data System (ADS)

Park, Jaehong; Kim, Han-Seek; Liu, Chuanwu; Trenti, Michele; Duffy, Alan R.; Geil, Paul M.; Mutch, Simon J.; Poole, Gregory B.; Mesinger, Andrei; Wyithe, J. Stuart B.

2017-12-01

We investigate the clustering properties of Lyman-break galaxies (LBGs) at z ∼ 6 - 8. Using the semi-analytical model MERAXES constructed as part of the dark-ages reionization and galaxy-formation observables from numerical simulation (DRAGONS) project, we predict the angular correlation function (ACF) of LBGs at z ∼ 6 - 8. Overall, we find that the predicted ACFs are in good agreement with recent measurements at z ∼ 6 and z ∼ 7.2 from observations consisting of the Hubble eXtreme Deep Field, the Hubble Ultra Deep Field and cosmic sssembly near-infrared deep extragalactic legacy survey field. We confirm the dependence of clustering on luminosity, with more massive dark matter haloes hosting brighter galaxies, remains valid at high redshift. The predicted galaxy bias at fixed luminosity is found to increase with redshift, in agreement with observations. We find that LBGs of magnitude MAB(1600) < -19.4 at 6 ≲ z ≲ 8 reside in dark matter haloes of mean mass ∼1011.0-1011.5 M⊙, and this dark matter halo mass does not evolve significantly during reionisation.

Ultra-deep K S-band Imaging of the Hubble Frontier Fields

NASA Astrophysics Data System (ADS)

Brammer, Gabriel B.; Marchesini, Danilo; Labbé, Ivo; Spitler, Lee; Lange-Vagle, Daniel; Barker, Elizbeth A.; Tanaka, Masayuki; Fontana, Adriano; Galametz, Audrey; Ferré-Mateu, Anna; Kodama, Tadayuki; Lundgren, Britt; Martis, Nicholas; Muzzin, Adam; Stefanon, Mauro; Toft, Sune; van der Wel, Arjen; Vulcani, Benedetta; Whitaker, Katherine E.

2016-09-01

We present an overview of the “KIFF” project, which provides ultra-deep K s -band imaging of all six of the Hubble Frontier Fields clusters, Abell 2744, MACS-0416, Abell S1063, Abell 370, MACS-0717, and MACS-1149. All of these fields have recently been observed with large allocations of Directors’ Discretionary Time with the Hubble and Spitzer telescopes, covering 0.4\\lt λ \\lt 1.6 μ {{m}} and 3.6-4.5 μ {{m}}, respectively. VLT/HAWK-I integrations of the first four fields reach 5σ limiting depths of {K}s˜ 26.0 (AB, point sources) and have excellent image quality (FWHM ˜ 0.″4). The MACS-0717 and MACS-1149 fields are observable from the northern hemisphere, and shorter Keck/MOSFIRE integrations on those fields reach limiting depths of K s = 25.5 and 25.1, with a seeing FWHM of ˜ 0.″4 and 0\\buildrel{\\prime\\prime}\\over{.} 5. In all cases the K s -band mosaics cover the primary cluster and parallel HST/ACS+WFC3 fields. The total area of the K s -band coverage is 490 arcmin2. The K s -band at 2.2 μ {{m}} crucially fills the gap between the reddest HST filter (1.6 μ {{m}} ˜ H band) and the IRAC 3.6 μ {{m}} passband. While reaching the full depths of the space-based imaging is not currently feasible from the ground, the deep K s -band images provide important constraints on both the redshifts and the stellar population properties of galaxies extending well below the characteristic stellar mass across most of the age of the universe, down to and including the redshifts of the targeted galaxy clusters (z≲ 0.5). Reduced, aligned mosaics of all six survey fields are provided.

The Far-Field Hubble Constant

NASA Astrophysics Data System (ADS)

Lauer, Tod

1995-07-01

We request deep, near-IR (F814W) WFPC2 images of five nearby Brightest Cluster Galaxies (BCG) to calibrate the BCG Hubble diagram by the Surface Brightness Fluctuation (SBF) method. Lauer & Postman (1992) show that the BCG Hubble diagram measured out to 15,000 km s^-1 is highly linear. Calibration of the Hubble diagram zeropoint by SBF will thus yield an accurate far-field measure of H_0 based on the entire volume within 15,000 km s^-1, thus circumventing any strong biases caused by local peculiar velocity fields. This method of reaching the far field is contrasted with those using distance ratios between Virgo and Coma, or any other limited sample of clusters. HST is required as the ground-based SBF method is limited to <3,000 km s^-1. The high spatial resolution of HST allows precise measurement of the SBF signal at large distances, and allows easy recognition of globular clusters, background galaxies, and dust clouds in the BCG images that must be removed prior to SBF detection. The proposing team developed the SBF method, the first BCG Hubble diagram based on a full-sky, volume-limited BCG sample, played major roles in the calibration of WFPC and WFPC2, and are conducting observations of local galaxies that will validate the SBF zeropoint (through GTO programs). This work uses the SBF method to tie both the Cepheid and Local Group giant-branch distances generated by HST to the large scale Hubble flow, which is most accurately traced by BCGs.

Star Formation in Distant Red Galaxies: Spitzer Observations in the Hubble Deep Field-South

NASA Astrophysics Data System (ADS)

Webb, Tracy M. A.; van Dokkum, Pieter; Egami, Eiichi; Fazio, Giovanni; Franx, Marijn; Gawiser, Eric; Herrera, David; Huang, Jiasheng; Labbé, Ivo; Lira, Paulina; Marchesini, Danilo; Maza, José; Quadri, Ryan; Rudnick, Gregory; van der Werf, Paul

2006-01-01

We present Spitzer 24 μm imaging of 1.5~40 μJy and conclude that the bulk of the DRG population is dusty active galaxies. A mid-infrared (MIR) color analysis with IRAC data suggests that the MIR fluxes are not dominated by buried AGNs, and we interpret the high detection rate as evidence for a high average star formation rate of =130+/-30 Msolar yr-1. From this, we infer that DRGs are important contributors to the cosmic star formation rate density at z~2, at a level of ~0.02 Msolar yr-1 Mpc-3 to our completeness limit of KAB=22.9 mag.

HFF-DeepSpace Photometric Catalogs of the 12 Hubble Frontier Fields, Clusters, and Parallels: Photometry, Photometric Redshifts, and Stellar Masses

NASA Astrophysics Data System (ADS)

Shipley, Heath V.; Lange-Vagle, Daniel; Marchesini, Danilo; Brammer, Gabriel B.; Ferrarese, Laura; Stefanon, Mauro; Kado-Fong, Erin; Whitaker, Katherine E.; Oesch, Pascal A.; Feinstein, Adina D.; Labbé, Ivo; Lundgren, Britt; Martis, Nicholas; Muzzin, Adam; Nedkova, Kalina; Skelton, Rosalind; van der Wel, Arjen

2018-03-01

We present Hubble multi-wavelength photometric catalogs, including (up to) 17 filters with the Advanced Camera for Surveys and Wide Field Camera 3 from the ultra-violet to near-infrared for the Hubble Frontier Fields and associated parallels. We have constructed homogeneous photometric catalogs for all six clusters and their parallels. To further expand these data catalogs, we have added ultra-deep K S -band imaging at 2.2 μm from the Very Large Telescope HAWK-I and Keck-I MOSFIRE instruments. We also add post-cryogenic Spitzer imaging at 3.6 and 4.5 μm with the Infrared Array Camera (IRAC), as well as archival IRAC 5.8 and 8.0 μm imaging when available. We introduce the public release of the multi-wavelength (0.2–8 μm) photometric catalogs, and we describe the unique steps applied for the construction of these catalogs. Particular emphasis is given to the source detection band, the contamination of light from the bright cluster galaxies (bCGs), and intra-cluster light (ICL). In addition to the photometric catalogs, we provide catalogs of photometric redshifts and stellar population properties. Furthermore, this includes all the images used in the construction of the catalogs, including the combined models of bCGs and ICL, the residual images, segmentation maps, and more. These catalogs are a robust data set of the Hubble Frontier Fields and will be an important aid in designing future surveys, as well as planning follow-up programs with current and future observatories to answer key questions remaining about first light, reionization, the assembly of galaxies, and many more topics, most notably by identifying high-redshift sources to target.

Evolution Of The Galaxy Major Merger Rate Since Z 6 In The Muse Hubble Ultra Deep Field Survey.

NASA Astrophysics Data System (ADS)

Ventou, E.; Contini, T.; MUSE-GTO Collaboration

2017-06-01

Over the past two decades, strong evidence that galaxies have undergone a significant evolution over cosmic time were found. Do galaxy mergers, one of the main driving mechanisms behind the growth of galaxies, played a key role in their evolution at significant look-back time? Due to the difficulty to identify these violent interactions between galaxies at high redshifts, the major merger rate, involving two galaxies of similar masses, was constrained so far up to redshift z 3, from previous studies of spectrocopic pair counts. Thanks to MUSE, which is perfectly suited to identify close pairs of galaxies with secure spectroscopic redshifts, we are now able to extend such studies up to z 6. I will present the results obtained from deep (10-30h) MUSE observations in the Hubble Ultra Deep Field. We provide the first constraints on the galaxy major merger evolution over 12 Gyrs (0.2 < z < 6) and over a broad range of stellar masses, showing that there is a flattening of the major merger rate evolution at very high redshift.

Completing the Legacy of Hubble's Wide/Deep Fields: An Aligned Complete Dataset of 1220 Orbits on the GOODS-N/CANDELS-N Region

NASA Astrophysics Data System (ADS)

Illingworth, Garth

2017-08-01

The GOODS-N/CANDELS-N region is second only to the GOODS-S/ECDF-S region in the extent of its HST and Spitzer coverage, making it a remarkable science resource. Yet of 1220 orbits of ACS and WFC3/IR imaging from 27 programs on the GOODS-N region, fully 42% of the total, about 520 orbits of imaging data from 22 programs, remains unavailable in MAST as a high-level science data product (HLSP). The GOODS-N region dataset is a key Legacy field ( 3 Msec from HST, 6 Msec from Spitzer, and 2 Msec from Chandra). We propose to deliver, with catalogs, HST ACS and WFC3/IR HLSPs to MAST for all 1220 orbits of GOODS-N data. We will also deliver HLSPs for the EGS, UDS and the COSMOS CANDELS regions, including new data not included to date. These four HLSPs, 2300 orbits of HST data ( 75% of a HST Cycle ), will add substantially to (1) our understanding of the build-up of galaxies to z 6 in the first Gyr during reionization, (2) the development of galaxies over the subsequent Gyr to the peak of the star formation rate in the universe at z 2-3, and (3) the transition at z<2 of early star-forming galaxies to the full splendor of the Hubble sequence. We can do this major AR Legacy program, having submitted a HLSP of ALL 2442 orbits of HST data on the GOODS- S region (>950 orbits new). The total volume of data in the GOODS-S Hubble Legacy Field (HLF-GOODS-S) is 5.8 Msec in 7211 exposures ( 70% of a HST cycle). The HLF-GOODS-S includes 4 new deep areas akin to the HUDF/XDF. The four proposed NEW Hubble Legacy Field datasets will complement the Frontier Field datasets and our recent HLF-GOODS-S and HUDF/XDF HLSP submissions. They will be cornerstones of Hubble's Legacy as the JWST era dawns.

Space Science

NASA Image and Video Library

2002-04-01

This picture of the galaxy UGC 10214 was was taken by the Advanced Camera for Surveys (ACS), which was installed aboard the Hubble Space Telescope (HST) in March 2002 during HST Servicing Mission 3B (STS-109 mission). Dubbed the "Tadpole," this spiral galaxy is unlike the textbook images of stately galaxies. Its distorted shape was caused by a small interloper, a very blue, compact galaxy visible in the upper left corner of the more massive Tadpole. The Tadpole resides about 420 million light-years away in the constellation Draco. Seen shining through the Tadpole's disk, the tiny intruder is likely a hit-and-run galaxy that is now leaving the scene of the accident. Strong gravitational forces from the interaction created the long tail of debris, consisting of stars and gas that stretch our more than 280,000 light-years. The galactic carnage and torrent of star birth are playing out against a spectacular backdrop: a "wallpaper pattern" of 6,000 galaxies. These galaxies represent twice the number of those discovered in the legendary Hubble Deep Field, the orbiting observatory's "deepest" view of the heavens, taken in 1995 by the Wide Field and planetary camera 2. The ACS picture, however, was taken in one-twelfth of the time it took to observe the original HST Deep Field. In blue light, ACS sees even fainter objects than were seen in the "deep field." The galaxies in the ACS picture, like those in the deep field, stretch back to nearly the begirning of time. Credit: NASA, H. Ford (JHU), G. Illingworth (USCS/LO), M. Clampin (STScI), G. Hartig (STScI), the ACS Science Team, and ESA.

The MUSE Hubble Ultra Deep Field Survey. II. Spectroscopic redshifts and comparisons to color selections of high-redshift galaxies

NASA Astrophysics Data System (ADS)

Inami, H.; Bacon, R.; Brinchmann, J.; Richard, J.; Contini, T.; Conseil, S.; Hamer, S.; Akhlaghi, M.; Bouché, N.; Clément, B.; Desprez, G.; Drake, A. B.; Hashimoto, T.; Leclercq, F.; Maseda, M.; Michel-Dansac, L.; Paalvast, M.; Tresse, L.; Ventou, E.; Kollatschny, W.; Boogaard, L. A.; Finley, H.; Marino, R. A.; Schaye, J.; Wisotzki, L.

2017-11-01

We have conducted a two-layered spectroscopic survey (1' × 1' ultra deep and 3' × 3' deep regions) in the Hubble Ultra Deep Field (HUDF) with the Multi Unit Spectroscopic Explorer (MUSE). The combination of a large field of view, high sensitivity, and wide wavelength coverage provides an order of magnitude improvement in spectroscopically confirmed redshifts in the HUDF; i.e., 1206 secure spectroscopic redshifts for Hubble Space Telescope (HST) continuum selected objects, which corresponds to 15% of the total (7904). The redshift distribution extends well beyond z> 3 and to HST/F775W magnitudes as faint as ≈ 30 mag (AB, 1σ). In addition, 132 secure redshifts were obtained for sources with no HST counterparts that were discovered in the MUSE data cubes by a blind search for emission-line features. In total, we present 1338 high quality redshifts, which is a factor of eight increase compared with the previously known spectroscopic redshifts in the same field. We assessed redshifts mainly with the spectral features [O II] at z< 1.5 (473 objects) and Lyα at 2.9

SELFI: an object-based, Bayesian method for faint emission line source detection in MUSE deep field data cubes

NASA Astrophysics Data System (ADS)

Meillier, Céline; Chatelain, Florent; Michel, Olivier; Bacon, Roland; Piqueras, Laure; Bacher, Raphael; Ayasso, Hacheme

2016-04-01

We present SELFI, the Source Emission Line FInder, a new Bayesian method optimized for detection of faint galaxies in Multi Unit Spectroscopic Explorer (MUSE) deep fields. MUSE is the new panoramic integral field spectrograph at the Very Large Telescope (VLT) that has unique capabilities for spectroscopic investigation of the deep sky. It has provided data cubes with 324 million voxels over a single 1 arcmin2 field of view. To address the challenge of faint-galaxy detection in these large data cubes, we developed a new method that processes 3D data either for modeling or for estimation and extraction of source configurations. This object-based approach yields a natural sparse representation of the sources in massive data fields, such as MUSE data cubes. In the Bayesian framework, the parameters that describe the observed sources are considered random variables. The Bayesian model leads to a general and robust algorithm where the parameters are estimated in a fully data-driven way. This detection algorithm was applied to the MUSE observation of Hubble Deep Field-South. With 27 h total integration time, these observations provide a catalog of 189 sources of various categories and with secured redshift. The algorithm retrieved 91% of the galaxies with only 9% false detection. This method also allowed the discovery of three new Lyα emitters and one [OII] emitter, all without any Hubble Space Telescope counterpart. We analyzed the reasons for failure for some targets, and found that the most important limitation of the method is when faint sources are located in the vicinity of bright spatially resolved galaxies that cannot be approximated by the Sérsic elliptical profile. The software and its documentation are available on the MUSE science web service (muse-vlt.eu/science).

The MUSE Hubble Ultra Deep Field Survey. V. Spatially resolved stellar kinematics of galaxies at redshift 0.2 ≲ z ≲ 0.8

NASA Astrophysics Data System (ADS)

Guérou, Adrien; Krajnović, Davor; Epinat, Benoit; Contini, Thierry; Emsellem, Eric; Bouché, Nicolas; Bacon, Roland; Michel-Dansac, Leo; Richard, Johan; Weilbacher, Peter M.; Schaye, Joop; Marino, Raffaella Anna; den Brok, Mark; Erroz-Ferrer, Santiago

2017-11-01

We present spatially resolved stellar kinematic maps, for the first time, for a sample of 17 intermediate redshift galaxies (0.2 ≲ z ≲ 0.8). We used deep MUSE/VLT integral field spectroscopic observations in the Hubble Deep Field South (HDFS) and Hubble Ultra Deep Field (HUDF), resulting from ≈30 h integration time per field, each covering 1' × 1' field of view, with ≈ 0.̋65 spatial resolution. We selected all galaxies brighter than 25 mag in the I band and for which the stellar continuum is detected over an area that is at least two times larger than the spatial resolution. The resulting sample contains mostly late-type disk, main-sequence star-forming galaxies with 108.5 M⊙ ≲ M∗ ≲ 1010.5 M⊙. Using a full-spectrum fitting technique, we derive two-dimensional maps of the stellar and gas kinematics, including the radial velocity V and velocity dispersion σ. We find that most galaxies in the sample are consistent with having rotating stellar disks with roughly constant velocity dispersions and that the second order velocity moments Vrms = √V2+σ2 of the gas and stars, a scaling proxy for the galaxy gravitational potential, compare well to each other. These spatially resolved observations of the stellar kinematics of intermediate redshift galaxies suggest that the regular stellar kinematics of disk galaxies that is observed in the local Universe was already in place 4-7 Gyr ago and that their gas kinematics traces the gravitational potential of the galaxy, thus is not dominated by shocks and turbulent motions. Finally, we build dynamical axisymmetric Jeans models constrained by the derived stellar kinematics for two specific galaxies and derive their dynamical masses. These are in good agreement (within 25%) with those derived from simple exponential disk models based on the gas kinematics. The obtained mass-to-light ratios hint towards dark matter dominated systems within a few effective radii. Based on observations made with ESO telescopes at the La Silla-Paranal Observatory under programmes 094.A-0289(B), 095.A-0010(A), 096.A-0045(A) and 096.A-0045(B).

The Hubble Deep UV Legacy Survey (HDUV): Survey Overview and First Results

NASA Astrophysics Data System (ADS)

Oesch, Pascal; Montes, Mireia; HDUV Survey Team

2015-08-01

Deep HST imaging has shown that the overall star formation density and UV light density at z>3 is dominated by faint, blue galaxies. Remarkably, very little is known about the equivalent galaxy population at lower redshifts. Understanding how these galaxies evolve across the epoch of peak cosmic star-formation is key to a complete picture of galaxy evolution. Here, we present a new HST WFC3/UVIS program, the Hubble Deep UV (HDUV) legacy survey. The HDUV is a 132 orbit program to obtain deep imaging in two filters (F275W and F336W) over the two CANDELS Deep fields. We will cover ~100 arcmin2, reaching down to 27.5-28.0 mag at 5 sigma. By directly sampling the rest-frame far-UV at z>~0.5, this will provide a unique legacy dataset with exquisite HST multi-wavelength imaging as well as ancillary HST grism NIR spectroscopy for a detailed study of faint, star-forming galaxies at z~0.5-2. The HDUV will enable a wealth of research by the community, which includes tracing the evolution of the FUV luminosity function over the peak of the star formation rate density from z~3 down to z~0.5, measuring the physical properties of sub-L* galaxies, and characterizing resolved stellar populations to decipher the build-up of the Hubble sequence from sub-galactic clumps. This poster provides an overview of the HDUV survey and presents the reduced data products and catalogs which will be released to the community.

SPECTROSCOPIC CONFIRMATION OF FAINT LYMAN BREAK GALAXIES NEAR REDSHIFT FIVE IN THE HUBBLE ULTRA DEEP FIELD

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rhoads, James E.; Malhotra, Sangeeta; Cohen, Seth

We present the faintest spectroscopically confirmed sample of z {approx} 5 Lyman break galaxies (LBGs) to date. The sample is based on slitless grism spectra of the Hubble Ultra Deep Field region from the Grism ACS Program for Extragalactic Science (GRAPES) and Probing Evolution and Reionization Spectroscopically (PEARS) projects, using the G800L grism on the Hubble Space Telescope Advanced Camera for Surveys. We report here confirmations of 39 galaxies, preselected as candidate LBGs using photometric selection criteria. We compare a 'traditional' V-dropout selection, based on the work of Giavalisco et al., to a more liberal one (with V - imore » > 0.9), and find that the traditional criteria are about 64% complete and 81% reliable. We also study the Ly{alpha} emission properties of our sample. We find that Ly{alpha} emission is detected in {approx}1/4 of the sample, and that the liberal V-dropout color selection includes {approx}55% of previously published line-selected Ly{alpha} sources. Finally, we examine our stacked two-dimensional spectra. We demonstrate that strong, spatially extended ({approx}1'') Ly{alpha} emission is not a generic property of these LBGs, but that a modest extension of the Ly{alpha} photosphere (compared to the starlight) may be present in those galaxies with prominent Ly{alpha} emission.« less

Hubble Captures Detailed Image of Uranus Atmosphere

NASA Image and Video Library

1998-08-02

NASA Hubble Space Telescope peered deep into Uranus atmosphere to see clear and hazy layers created by a mixture of gases. Using infrared filters, Hubble captured detailed features of three layers of Uranus atmosphere.

Selections from 2017: Hubble Survey Explores Distant Galaxies

NASA Astrophysics Data System (ADS)

Kohler, Susanna

2017-12-01

Editors note:In these last two weeks of 2017, well be looking at a few selections that we havent yet discussed on AAS Nova from among the most-downloaded paperspublished in AAS journals this year. The usual posting schedule will resume in January.CANDELS Multi-Wavelength Catalogs: Source Identification and Photometry in the CANDELS COSMOSSurvey FieldPublished January2017Main takeaway:A publication led byHooshang Nayyeri(UC Irvine and UC Riverside) early this year details acatalog of sources built using the Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey(CANDELS), a survey carried out by cameras on board the Hubble Space Telescope. The catalogliststhe properties of 38,000 distant galaxies visiblewithin the COSMOS field, a two-square-degree equatorial field explored in depthto answer cosmological questions.Why its interesting:Illustration showing the three-dimensional map of the dark matter distribution in theCOSMOS field. [Adapted from NASA/ESA/R. Massey(California Institute of Technology)]The depth and resolution of the CANDELS observations areuseful for addressingseveral major science goals, including the following:Studying the most distant objects in the universe at the epoch of reionization in the cosmic dawn.Understanding galaxy formation and evolution during the peak epoch of star formation in the cosmic high noon.Studying star formation from deep ultravioletobservations and studying cosmology from supernova observations.Why CANDELS is a major endeavor:CANDELS isthe largest multi-cycle treasury program ever approved on the Hubble Space Telescope using over 900 orbits between 2010 and 2013 withtwo cameras on board the spacecraftto study galaxy formation and evolution throughout cosmic time. The CANDELS images are all publicly available, and the new catalogrepresents an enormous source of information about distant objectsin our universe.CitationH. Nayyeri et al 2017 ApJS 228 7. doi:10.3847/1538-4365/228/1/7

VizieR Online Data Catalog: Redshifts of 65 CANDELS supernovae (Rodney+, 2014)

NASA Astrophysics Data System (ADS)

Rodney, S. A.; Riess, A. G.; Strolger, L.-G.; Dahlen, T.; Graur, O.; Casertano, S.; Dickinson, M. E.; Ferguson, H. C.; Garnavich, P.; Hayden, B.; Jha, S. W.; Jones, D. O.; Kirshner, R. P.; Koekemoer, A. M.; McCully, C.; Mobasher, B.; Patel, B.; Weiner, B. J.; Cenko, S. B.; Clubb, K. I.; Cooper, M.; Filippenko, A. V.; Frederiksen, T. F.; Hjorth, J.; Leibundgut, B.; Matheson, T.; Nayyeri, H.; Penner, K.; Trump, J.; Silverman, J. M.; U, V.; Azalee Bostroem, K.; Challis, P.; Rajan, A.; Wolff, S.; Faber, S. M.; Grogin, N. A.; Kocevski, D.

2015-01-01

In this paper we present a measurement of the Type Ia supernova explosion rate as a function of redshift (SNR(z)) from a sample of 65 supernovae discovered in the Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey (CANDELS) supernova program. This supernova survey is a joint operation of two Hubble Space Telescope (HST) Multi-Cycle Treasury (MCT) programs: CANDELS (PIs: Faber and Ferguson; Grogin et al., 2011ApJS..197...35G; Koekemoer et al., 2011ApJS..197...36K), and the Cluster Lensing and Supernovae search with Hubble (CLASH; PI: Postman; Postman et al. 2012, cat. J/ApJS/199/25). The supernova discovery and follow-up for both programs were allocated to the HST MCT supernova program (PI: Riess). The results presented here are based on the full five fields and ~0.25deg2 of the CANDELS program, observed from 2010 to 2013. A companion paper presents the SN Ia rates from the CLASH sample (Graur et al., 2014ApJ...783...28G). A composite analysis that combines the CANDELS+CLASH supernova sample and revisits past HST surveys will be presented in a future paper. The three-year CANDELS program was designed to probe galaxy evolution out to z~8 with deep infrared and optical imaging of five well-studied extragalactic fields: GOODS-S, GOODS-N (the Great Observatories Origins Deep Survey South and North; Giavalisco et al. 2004, cat. II/261), COSMOS (the Cosmic Evolution Survey, Scoville et al., 2007ApJS..172....1S; Koekemoer et al., 2007ApJS..172..196K), UDS (the UKIDSS Ultra Deep Survey; Lawrence et al. 2007, cat. II/314; Cirasuolo et al., 2007MNRAS.380..585C), EGS (the Extended Groth Strip; Davis et al. 2007, cat. III/248). As described fully in Grogin et al. (2011ApJS..197...35G), the CANDELS program includes both "wide" and "deep" fields. The wide component of CANDELS comprises the COSMOS, UDS, and EGS fields, plus one-third of the GOODS-S field and one half of the GOODS-N field--a total survey area of 730 arcmin2. The "deep" component of CANDELS came from the central 67arcmin2 of each of the GOODS-S and GOODS-N fields. The CANDELS fields analyzed in this work are described in Table 1. (6 data files).

ALMA Spectroscopic Survey in the Hubble Ultra Deep Field: Survey Description

NASA Astrophysics Data System (ADS)

Walter, Fabian; Decarli, Roberto; Aravena, Manuel; Carilli, Chris; Bouwens, Rychard; da Cunha, Elisabete; Daddi, Emanuele; Ivison, R. J.; Riechers, Dominik; Smail, Ian; Swinbank, Mark; Weiss, Axel; Anguita, Timo; Assef, Roberto; Bacon, Roland; Bauer, Franz; Bell, Eric F.; Bertoldi, Frank; Chapman, Scott; Colina, Luis; Cortes, Paulo C.; Cox, Pierre; Dickinson, Mark; Elbaz, David; Gónzalez-López, Jorge; Ibar, Edo; Inami, Hanae; Infante, Leopoldo; Hodge, Jacqueline; Karim, Alex; Le Fevre, Olivier; Magnelli, Benjamin; Neri, Roberto; Oesch, Pascal; Ota, Kazuaki; Popping, Gergö; Rix, Hans-Walter; Sargent, Mark; Sheth, Kartik; van der Wel, Arjen; van der Werf, Paul; Wagg, Jeff

2016-12-01

We present the rationale for and the observational description of ASPECS: the ALMA SPECtroscopic Survey in the Hubble Ultra-Deep Field (UDF), the cosmological deep field that has the deepest multi-wavelength data available. Our overarching goal is to obtain an unbiased census of molecular gas and dust continuum emission in high-redshift (z > 0.5) galaxies. The ˜1‧ region covered within the UDF was chosen to overlap with the deepest available imaging from the Hubble Space Telescope. Our ALMA observations consist of full frequency scans in band 3 (84-115 GHz) and band 6 (212-272 GHz) at approximately uniform line sensitivity ({L}{CO}\\prime ˜ 2 × 109 K km s-1 pc2), and continuum noise levels of 3.8 μJy beam-1 and 12.7 μJy beam-1, respectively. The molecular surveys cover the different rotational transitions of the CO molecule, leading to essentially full redshift coverage. The [C II] emission line is also covered at redshifts 6.0\\lt z\\lt 8.0. We present a customized algorithm to identify line candidates in the molecular line scans and quantify our ability to recover artificial sources from our data. Based on whether multiple CO lines are detected, and whether optical spectroscopic redshifts as well as optical counterparts exist, we constrain the most likely line identification. We report 10 (11) CO line candidates in the 3 mm (1 mm) band, and our statistical analysis shows that <4 of these (in each band) are likely spurious. Less than one-third of the total CO flux in the low-J CO line candidates are from sources that are not associated with an optical/NIR counterpart. We also present continuum maps of both the band 3 and band 6 observations. The data presented here form the basis of a number of dedicated studies that are presented in subsequent papers.

The morphology of faint galaxies in Medium Deep Survey images using WFPC2

NASA Technical Reports Server (NTRS)

Griffiths, R. E.; Casertano, S.; Ratnatunga, K. U.; Neuschaefer, L. W.; Ellis, R. S.; Gilmore, G. F.; Glazebrook, K.; Santiago, B.; Huchra, J. P.; Windhorst, R. A.

1994-01-01

First results from Hubble Space Telescope (HST) Medium Deep Survey images taken with Wide Field/Planetary Camera-2 (WFPC2) demonstrate that galaxy classifications can be reliably performed to magnitudes I814 approximately less than 22.0 in the F815W band. Published spectroscopic surveys to this depth indicate a mean redshift of bar-z approximately 0.5. We have classified over 200 galaxies in nine WFPC2 fields according to a basic morphological scheme. The majority of these faint galaxies appear to be similar to regular Hubble-sequence examples observed at low redshift. To the precision of our classification scheme, the relative proportion of spheroidal and disk systems of normal appearance is as expected from nearby samples, indicating that the bulk of the local galaxy population was in place at half the Hubble time. However, the most intriguing result is the relatively high proportion (approximately 40%) of objects which are in some way anomalous, and which may be of relevance in understanding the origin of the familiar excess population of faint galaxies established by others. These diverse objects include apparently interacting pairs whose multiple structure is only revealed with HST's angular resolution, galaxies with superluminous star-forming regions, diffuse low surface brightness galaxies of various forms, and compact galaxies. These anomalous galaxies contribute a substantial fraction of the excess counts at our limiting magnitude, and may provide insights into the 'faint blue galaxy' problem.

A Sneak Peek at the JWST Era: Observing Galaxies Below the Hubble Limit with Gravitational Lensing

NASA Astrophysics Data System (ADS)

Livermore, Rachael C.

2016-01-01

The installation of WFC3 on the Hubble Space Telescope pushed the frontier of high-redshift galaxy studies to only 500 Myr after the Big Bang. However, observations in this epoch remain challenging and are limited to the brightest galaxies; the fainter sources believed to be responsible for reionizing the Universe remain beyond the grasp of Hubble. With gravitational lensing, however, we can benefit from the magnification of faint sources, which brings them within reach of today's telescopes. The Hubble Frontier Fields program is a deep survey of strongly lensing clusters observed in the optical and near-infrared. Unfortunately, detecting highly magnified, intrinsically faint galaxies in these fields has proved challenging due to the bright foregound cluster galaxies and intracluster light. We have developed a technique using wavelet decomposition to overcome these difficulties and detect galaxies at z~7 with intrinsic UV magnitudes as faint as MUV = -13. We present this method and the resulting luminosity functions, which support a steep faint-end slope extending out to the observational limits. Our method has uncovered hundreds of galaxies at z > 6 fainter than any that have been seen before, providing our first insight into the small galaxy population during the epoch of reionization and a preview of the capabilities of JWST.

VizieR Online Data Catalog: Ultradiffuse galaxies found in deep HST images of HFF (Lee+, 2017)

NASA Astrophysics Data System (ADS)

Lee, M. G.; Kang, J.; Lee, J. H.; Jang in, S.

2018-03-01

Abell S1063 and Abell 2744 are located at redshift z=0.348 and z=0.308, respectively, so their HST fields cover a relatively large fraction of each cluster. They are part of the target galaxy clusters in the Hubble Frontier Fields (HFF) Program, for which deep Hubble Space Telescope (HST) images are available (Lotz+ 2017ApJ...837...97L). We used ACS/F814W(I) and WFC3/F105W(Y) images for Abell S1063 and Abell 2744 in the HFF. The effective wavelengths of the F814W and F105W filters for the redshifts of Abell S1063 and Abell 2744 (6220 and 8030Å) correspond approximately to SDSS r' and Cousins I (or SDSS i') in the rest frame, respectively. Figure 1 display color images of the HST fields for Abell S1063 and Abell 2744. In this study we adopt the cosmological parameters H0=73km/s/Mpc, ΩM=0.27, and ΩΛ=0.73. For these parameters, luminosity distance moduli of Abell S1063 and Abell 2744 are (m-M)0=41.25 (d=1775Mpc) and 40.94 (d=1540Mpc), and angular diameter distances are 978 and 901Mpc, respectively. (5 data files).

Emission-Line Galaxies from the PEARS Hubble Ultra Deep Field: A 2-D Detection Method and First Results

NASA Technical Reports Server (NTRS)

Gardner, J. P.; Straughn, Amber N.; Meurer, Gerhardt R.; Pirzkal, Norbert; Cohen, Seth H.; Malhotra, Sangeeta; Rhoads, james; Windhorst, Rogier A.; Gardner, Jonathan P.; Hathi, Nimish P.;

The Hubble Space Telescope Medium Deep Survey with the Wide Field and Planetary Camera. 1: Methodology and results on the field near 3C 273

NASA Technical Reports Server (NTRS)

Griffiths, R. E.; Ratnatunga, K. U.; Neuschaefer, L. W.; Casertano, S.; Im, M.; Wyckoff, E. W.; Ellis, R. S.; Gilmore, G. F.; Elson, R. A. W.; Glazebrook, K.

1994-01-01

We present results from the Medium Deep Survey (MDS), a Key Project using the Hubble Space Telescope (HST). Wide Field Camera (WFC) images of random fields have been taken in 'parallel mode' with an effective resolution of 0.2 sec full width at half maximum (FWHM) in the V(F555W) and I(F785LP) filters. The exposures presented here were targeted on a field away from 3C 273, and resulted in approximately 5 hr integration time in each filter. Detailed morphological structure is seen in galaxy images with total integrated magnitudes down to V approximately = 22.5 and I approximately = 21.5. Parameters are estimated that best fit the observed galaxy images, and 143 objects are identified (including 23 stars) in the field to a fainter limiting magnitude of I approximately = 23.5. We outline the extragalactic goals of the HST Medium Deep Survey, summarize our basic data reduction procedures, and present number (magnitude) counts, a color-magnitude diagram for the field, surface brightness profiles for the brighter galaxies, and best-fit half-light radii for the fainter galaxies as a function of apparent magnitude. A median galaxy half-light radius of 0.4 sec is measured, and the distribution of galaxy sizes versus magnitude is presented. We observe an apparent deficit of galaxies with half-light radii between approximately 0.6 sec and 1.5 sec, with respect to standard no-evolution or mild evolution cosmological models. An apparent excess of compact objects (half-light radii approximately 0.1 sec) is also observed with respect to those models. Finally, we find a small excess in the number of faint galaxy pairs and groups with respect to a random low-redshift field sample.

Big World of Small Neutrinos

Science.gov Websites

electron neutrino, muon neutrino, or tau neutrino. The three different neutrinos are complemented by anti of the neutrinos we detect will look different (have a different flavor) compared to the time they Big World of Small Neutrinos Neutrinos will find you! Fig 1: Hubble image of the deep field

Building the Case for SNAP: Creation of Multi-Band, Simulated Images With Shapelets

NASA Technical Reports Server (NTRS)

Ferry, Matthew A.

2005-01-01

Dark energy has simultaneously been the most elusive and most important phenomenon in the shaping of the universe. A case for a proposed space-telescope called SNAP (SuperNova Acceleration Probe) is being built, a crucial component of which is image simulations. One method for this is "Shapelets," developed at Caltech. Shapelets form an orthonormal basis and are uniquely able to represent realistic space images and create new images based on real ones. Previously, simulations were created using the Hubble Deep Field (HDF) as a basis Set in one band. In this project, image simulations are created.using the 4 bands of the Hubble Ultra Deep Field (UDF) as a basis set. This provides a better basis for simulations because (1) the survey is deeper, (2) they have a higher resolution, and (3) this is a step closer to simulating the 9 bands of SNAP. Image simulations are achieved by detecting sources in the UDF, decomposing them into shapelets, tweaking their parameters in realistic ways, and recomposing them into new images. Morphological tests were also run to verify the realism of the simulations. They have a wide variety of uses, including the ability to create weak gravitational lensing simulations.

Constraints on z~10 Galaxies from the Deepest Hubble Space Telescope NICMOS Fields

NASA Astrophysics Data System (ADS)

Bouwens, R. J.; Illingworth, G. D.; Thompson, R. I.; Franx, M.

2005-05-01

We use all available fields with deep NICMOS imaging to search for J110-dropouts (H160,AB<~28) at z~10. Our primary data set for this search is the two J110+H160 NICMOS fields taken in parallel with the Advanced Camera for Surveys (ACS) Hubble Ultra Deep Field (UDF). The 5 σ limiting magnitudes were ~28.6 in J110 and ~28.5 in H160 (0.6" apertures). Several shallower fields were also used: J110+H160 NICMOS frames available over the Hubble Deep Field (HDF) North, the HDF-South NICMOS parallel, and the ACS UDF (with 5 σ limiting magnitudes in J110 and H160 ranging from 27.0 to 28.2). The primary selection criterion was (J110-H160)AB>1.8. Eleven such sources were found in all search fields using this criterion. Eight of these are clearly ruled out as credible z~10 sources, either as a result of detections (>2 σ) blueward of J110 or their colors redward of the break (H160-K~1.5) (redder than >~98% of lower redshift dropouts). The nature of the three remaining sources could not be determined from the data. This number appears consistent with the expected contamination from low-redshift interlopers. Analysis of the stacked images for the three candidates also suggests some contamination. Regardless of their true redshifts, the actual number of z~10 sources must be three or fewer. To assess the significance of these results, two lower redshift samples (a z~3.8 B-dropout and z~6 i-dropout sample) were projected to z~7-13 using a (1+z)-1 size scaling (for fixed luminosity). They were added to the image frames and the selection was repeated, giving 15.6 and 4.8 J110-dropouts, respectively. This suggests that to the limit of this probe (~0.3L*z=3), there has been evolution from z~3.8 and possibly from z~6. This is consistent with the strong evolution already noted at z~6 and z~7.5 relative to z~3-4. Even assuming that three sources from this probe are at z~10, the rest-frame continuum UV (~1500 Å) luminosity density at z~10 (integrated down to 0.3L*z=3) is just 0.19+0.13-0.09 times that at z~3.8 (or 0.19+0.15-0.10 times, including the small effect from cosmic variance). However, if none of our sources are at z~10, this ratio has a 1 σ upper limit of 0.07. Based on observations made with the NASA/ESA Hubble Space Telescope, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555.

CANDELS: The Cosmic Assembly Near-Infrared Deep Extragalactic Legacy Survey

NASA Technical Reports Server (NTRS)

Grogin, Norman A.; Koekemoer, anton M.; Faber, S. M.; Ferguson, Henry C.; Kocevski, Dale D.; Riess, Adam G.; Acquaviva, Viviana; Alexander, David M.; Almaini, Omar; Ashby, Matthew L. N.;

Lens models under the microscope: comparison of Hubble Frontier Field cluster magnification maps

NASA Astrophysics Data System (ADS)

Priewe, Jett; Williams, Liliya L. R.; Liesenborgs, Jori; Coe, Dan; Rodney, Steven A.

2017-02-01

Using the power of gravitational lensing magnification by massive galaxy clusters, the Hubble Frontier Fields provide deep views of six patches of the high-redshift Universe. The combination of deep Hubble imaging and exceptional lensing strength has revealed the greatest numbers of multiply-imaged galaxies available to constrain models of cluster mass distributions. However, even with O(100) images per cluster, the uncertainties associated with the reconstructions are not negligible. The goal of this paper is to show the diversity of model magnification predictions. We examine seven and nine mass models of Abell 2744 and MACS J0416, respectively, submitted to the Mikulski Archive for Space Telescopes for public distribution in 2015 September. The dispersion between model predictions increases from 30 per cent at common low magnifications (μ ˜ 2) to 70 per cent at rare high magnifications (μ ˜ 40). MACS J0416 exhibits smaller dispersions than Abell 2744 for 2 < μ < 10. We show that magnification maps based on different lens inversion techniques typically differ from each other by more than their quoted statistical errors. This suggests that some models underestimate the true uncertainties, which are primarily due to various lensing degeneracies. Though the exact mass sheet degeneracy is broken, its generalized counterpart is not broken at least in Abell 2744. Other local degeneracies are also present in both clusters. Our comparison of models is complementary to the comparison of reconstructions of known synthetic mass distributions. By focusing on observed clusters, we can identify those that are best constrained, and therefore provide the clearest view of the distant Universe.

The Hubble Deep UV Legacy Survey (HDUV)

NASA Astrophysics Data System (ADS)

Montes, Mireia; Oesch, Pascal

2015-08-01

Deep HST imaging has shown that the overall star formation density and UV light density at z>3 is dominated by faint, blue galaxies. Remarkably, very little is known about the equivalent galaxy population at lower redshifts. Understanding how these galaxies evolve across the epoch of peak cosmic star-formation is key to a complete picture of galaxy evolution. Here, we present a new HST WFC3/UVIS program, the Hubble Deep UV (HDUV) legacy survey. The HDUV is a 132 orbit program to obtain deep imaging in two filters (F275W and F336W) over the two CANDELS Deep fields. We will cover ~100 arcmin2 sampling the rest-frame far-UV at z>~0.5, this will provide a unique legacy dataset with exquisite HST multi-wavelength imaging as well as ancillary HST grism NIR spectroscopy for a detailed study of faint, star-forming galaxies at z~0.5-2. The HDUV will enable a wealth of research by the community, which includes tracing the evolution of the FUV luminosity function over the peak of the star formation rate density from z~3 down to z~0.5, measuring the physical properties of sub-L* galaxies, and characterizing resolved stellar populations to decipher the build-up of the Hubble sequence from sub-galactic clumps. This poster provides an overview of the HDUV survey and presents the reduced data products and catalogs which will be released to the community, reaching down to 27.5-28.0 mag at 5 sigma. By directly sampling the rest-frame far-UV at z>~0.5, this will provide a unique legacy dataset with exquisite HST multi-wavelength imaging as well as ancillary HST grism NIR spectroscopy for a detailed study of faint, star-forming galaxies at z~0.5-2. The HDUV will enable a wealth of research by the community, which includes tracing the evolution of the FUV luminosity function over the peak of the star formation rate density from z~3 down to z~0.5, measuring the physical properties of sub-L* galaxies, and characterizing resolved stellar populations to decipher the build-up of the Hubble sequence from sub-galactic clumps. This poster provides an overview of the HDUV survey and presents reduced data products and catalogs which will be released to the community.

Lyman-alpha fractions in the Hubble Ultra Deep Field at 4 < z < 6

NASA Astrophysics Data System (ADS)

Harish, Santosh; Malhotra, Sangeeta; Rhoads, James; Christensen, Lise; Tilvi, Vithal; Finkelstein, Steven; Pharo, John

2018-01-01

Lyman-alpha (Lya) emitting galaxies at high-redshifts serve as a good probe of neutral hydrogen in the intergalactic medium (IGM). Here we present measurements of the Lya fraction using a sample of Lyman-break galaxies (LBGs) between 4 < z < 6 with deep HST grism observations from the GRAPES/PEARS projects as well as spectroscopic observations from the MUSE integral-field spectrograph. The sample of LBGs at z~5 & 6 are spectroscopically confirmed with deep HST grism data from the GRAPES and PEARS projects. We also measure Lya fractions using a sample of photometrically-selected LBGs for the same redshift range. In addition, we study the EW distribution in relation to continuum and line luminosities, as well as the relation between photometric and spectroscopic redshift. We find that objects with higher EWs tend to have larger differences between photometric and spectroscopic redshifts.

SEDS: The Spitzer Extended Deep Survey. Survey Design, Photometry, and Deep IRAC Source Counts

NASA Technical Reports Server (NTRS)

Ashby, M. L. N.; Willner, S. P.; Fazio, G. G.; Huang, J.-S.; Arendt, A.; Barmby, P.; Barro, G; Bell, E. F.; Bouwens, R.; Cattaneo, A.;

Multi-Object Spectroscopy with MUSE

NASA Astrophysics Data System (ADS)

Kelz, A.; Kamann, S.; Urrutia, T.; Weilbacher, P.; Bacon, R.

2016-10-01

Since 2014, MUSE, the Multi-Unit Spectroscopic Explorer, is in operation at the ESO-VLT. It combines a superb spatial sampling with a large wavelength coverage. By design, MUSE is an integral-field instrument, but its field-of-view and large multiplex make it a powerful tool for multi-object spectroscopy too. Every data-cube consists of 90,000 image-sliced spectra and 3700 monochromatic images. In autumn 2014, the observing programs with MUSE have commenced, with targets ranging from distant galaxies in the Hubble Deep Field to local stellar populations, star formation regions and globular clusters. This paper provides a brief summary of the key features of the MUSE instrument and its complex data reduction software. Some selected examples are given, how multi-object spectroscopy for hundreds of continuum and emission-line objects can be obtained in wide, deep and crowded fields with MUSE, without the classical need for any target pre-selection.

The BUFFALO HST Survey

NASA Astrophysics Data System (ADS)

Steinhardt, Charles; Jauzac, Mathilde; Capak, Peter; Koekemoer, Anton; Oesch, Pascal; Richard, Johan; Sharon, Keren q.; BUFFALO

2018-01-01

Beyond Ultra-deep Frontier Fields And Legacy Observations (BUFFALO) is an astronomical survey built around the six Hubble Space Telescope (HST) Frontier Fields clusters designed to learn about early galactic assembly and clustering and prepare targets for observations with the James Webb Space Telescope. BUFFALO will place significant new constraints on how and when the most massive and luminous galaxies in the universe formed and how early galaxy formation is linked to dark matter assembly. The same data will also probe the temperature and cross section of dark matter in the massive Frontier Fields galaxy clusters, and tell us how the dark matter, cluster gas, and dynamics of the clusters influence the galaxies in and around them. These studies are possible because the Spitzer Space Telescope, Chandra X-ray Observatory, XMM-Newton, and ground based telescopes have already invested heavily in deep observations around the Frontier Fields, so that the addition of HST observations can yield significant new results.

Are Ultra-faint Galaxies at z = 6-8 Responsible for Cosmic Reionization? Combined Constraints from the Hubble Frontier Fields Clusters and Parallels

NASA Astrophysics Data System (ADS)

Atek, Hakim; Richard, Johan; Jauzac, Mathilde; Kneib, Jean-Paul; Natarajan, Priyamvada; Limousin, Marceau; Schaerer, Daniel; Jullo, Eric; Ebeling, Harald; Egami, Eiichi; Clement, Benjamin

2015-11-01

We use deep Hubble Space Telescope imaging of the Frontier Fields to accurately measure the galaxy rest-frame ultraviolet luminosity function (UV LF) in the redshift range z ˜ 6-8. We combine observations in three lensing clusters, A2744, MACS 0416, and MACS 0717, and their associated parallel fields to select high-redshift dropout candidates. We use the latest lensing models to estimate the flux magnification and the effective survey volume in combination with completeness simulations performed in the source plane. We report the detection of 227 galaxy candidates at z = 6-7 and 25 candidates at z ˜ 8. While the total survey area is about 4 arcmin2 in each parallel field, it drops to about 0.6-1 arcmin2 in the cluster core fields because of the strong lensing. We compute the UV LF at z ˜ 7 using the combined galaxy sample and perform Monte Carlo simulations to determine the best-fit Schechter parameters. We are able to reliably constrain the LF down to an absolute magnitude of MUV = -15.25, which corresponds to 0.005 L⋆. More importantly, we find that the faint-end slope remains steep down to this magnitude limit with α =-{2.04}-0.17+0.13. We find a characteristic magnitude of {M}\\star =-{20.89}-0.72+0.60 and log(ϕ⋆) = -{3.54}-0.45+0.48. Our results confirm the most recent results in deep blank fields but extend the LF measurements more than two magnitudes deeper. The UV LF at z ˜ 8 is not very well constrained below MUV = -18 owing to the small number statistics and incompleteness uncertainties. To assess the contribution of galaxies to cosmic reionization, we derive the UV luminosity density at z ˜ 7 by integrating the UV LF down to an observational limit of MUV = -15. We show that our determination of log(ρUV) = 26.2 ± 0.13 (erg s-1 Hz-1 Mpc-3) can be sufficient to maintain reionization with an escape fraction of ionizing radiation of fesc = 10%-15%. Future Hubble Frontier Fields observations will certainly improve the constraints on the UV LF at the epoch of reionization, paving the way to more ambitious programs using cosmic telescopes with the next generation of large aperture telescopes such as the James Webb Space Telescope and the European Extremely Large Telescope. Based on observations made with the NASA/ESA Hubble Space Telescope, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555. These observations are associated with programs 13495, 11386, 13389, and 11689. STScI is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555. The Hubble Frontier Fields data and the lens models were obtained from the Mikulski Archive for Space Telescopes (MAST). This work utilizes gravitational lensing models produced by PIs Ebeling, Merten, and Zitrin, funded as part of the HST Frontier Fields program conducted by STScI.

The GISMO two-millimeter deep field in GOODS-N

DOE Office of Scientific and Technical Information (OSTI.GOV)

Staguhn, Johannes G.; Kovács, Attila; Arendt, Richard G.

2014-07-20

We present deep continuum observations using the GISMO camera at a wavelength of 2 mm centered on the Hubble Deep Field in the GOODS-N field. These are the first deep field observations ever obtained at this wavelength. The 1σ sensitivity in the innermost ∼4' of the 7' diameter map is ∼135 μJy beam{sup –1}, a factor of three higher in flux/beam sensitivity than the deepest available SCUBA 850 μm observations, and almost a factor of four higher in flux/beam sensitivity than the combined MAMBO/AzTEC 1.2 mm observations of this region. Our source extraction algorithm identifies 12 sources directly, and anothermore » 3 through correlation with known sources at 1.2 mm and 850 μm. Five of the directly detected GISMO sources have counterparts in the MAMBO/AzTEC catalog, and four of those also have SCUBA counterparts. HDF850.1, one of the first blank-field detected submillimeter galaxies, is now detected at 2 mm. The median redshift of all sources with counterparts of known redshifts is z-tilde =2.91±0.94. Statistically, the detections are most likely real for five of the seven 2 mm sources without shorter wavelength counterparts, while the probability for none of them being real is negligible.« less

Hubble Captures Detailed Image of Uranus' Atmosphere

NASA Technical Reports Server (NTRS)

1996-01-01

Hubble Space Telescope has peered deep into Uranus' atmosphere to see clear and hazy layers created by a mixture of gases. Using infrared filters, Hubble captured detailed features of three layers of Uranus' atmosphere.

Hubble's images are different from the ones taken by the Voyager 2 spacecraft, which flew by Uranus 10 years ago. Those images - not taken in infrared light - showed a greenish-blue disk with very little detail.

The infrared image allows astronomers to probe the structure of Uranus' atmosphere, which consists of mostly hydrogen with traces of methane. The red around the planet's edge represents a very thin haze at a high altitude. The haze is so thin that it can only be seen by looking at the edges of the disk, and is similar to looking at the edge of a soap bubble. The yellow near the bottom of Uranus is another hazy layer. The deepest layer, the blue near the top of Uranus, shows a clearer atmosphere.

Image processing has been used to brighten the rings around Uranus so that astronomers can study their structure. In reality, the rings are as dark as black lava or charcoal.

This false color picture was assembled from several exposures taken July 3, 1995 by the Wide Field Planetary Camera-2.

The Wide Field/Planetary Camera 2 was developed by the Jet Propulsion Laboratory and managed by the Goddard Spaced Flight Center for NASA's Office of Space Science.

This image and other images and data received from the Hubble Space Telescope are posted on the World Wide Web on the Space Telescope Science Institute home page at URL http://oposite.stsci.edu/pubinfo/

Probing stellar mass build-up in galaxies at z=4-7 with CANDELS and S-CANDELS

NASA Astrophysics Data System (ADS)

Song, Mimi; Finkelstein, Steven L.; Ashby, Matthew; Merlin, Emiliano

2015-01-01

Over the last few years the advent of the Hubble Space Telescope (HST) Wide Field Camera 3 has enabled us to build statistically significant samples of galaxies out to z=8. We have subsequently witnessed remarkable progress in our understanding of galaxy evolution in the early universe. However, our understanding of the galaxy stellar mass growth in this era has been limited due to the lack of rest-frame optical data at a comparable depth as the HST data. Here we present results on the galaxy stellar mass function at z=4-7 from a sample of ~7500 galaxies over an area of ~280 square arcmin in the CANDELS GOODS-South and North fields, as well as the Hubble Ultra Deep Field. Utilizing deep IRAC data from the S-CANDELS and IUDF10 programs to robustly constrain the stellar masses of galaxies in our sample, we measure the stellar-mass to rest-frame ultraviolet (UV) luminosity trends in each of our redshift bins. We convolve these trends with recent measurements of the rest-frame ultraviolet luminosity function to derive the stellar mass functions. Contrary to initial studies at these redshifts, we find steeper low-mass-end slopes (-1.6 at z=4, and -2.0 at z=7), similar to recent simulations. Our results provide the most accurate estimates to date of the cosmic stellar mass density over the first two billion years after the Big Bang.

History of Hubble Space Telescope (HST)

NASA Image and Video Library

1995-12-01

This deepest-ever view of the universe unveils myriad galaxies back to the begirning of time. Several hundred, never-before-seen, galaxies are visible in this view of the universe, called Hubble Deep Field (HDF). Besides the classical spiral and elliptical shaped galaxies, there is a bewildering variety of other galaxy shapes and colors that are important clues to understanding the evolution of the universe. Some of the galaxies may have formed less than one-billion years after the Big Bang. The image was assembled from many separate exposures with the Wide Field/Planetary Camera 2 (WF/PC2), for ten consecutive days between December 18, 1995 and December 28, 1995. This true-color view was assembled from separate images taken with blue, red, and infrared light. By combining these separate images into a single color picture, astronomers will be able to infer, at least statistically, the distance, age, and composition of galaxies in the field. Blue objects contain young stars and/or are relatively close, while redder objects contain older stellar populations and/or are farther away.

Hubble Space Telescope Medium Deep Survey. 2: Deconvolution of Wide Field Camera field galaxy images in the 13 hour + 43 deg field

NASA Technical Reports Server (NTRS)

Windhorst, R. A.; Schmidtke, P. C.; Pascarelle, S. M.; Gordon, J. M.; Griffiths, R. E.; Ratnatunga, K. U.; Neuschaefer, L. W.; Ellis, R. S.; Gilmore, G.; Glazebrook, K.

1994-01-01

We present isophotal profiles of six faint field galaxies from some of the first deep images taken for the Hubble Space Telescope (HST) Medium Deep Survey (MDS). These have redshifts in the range z = 0.126 to 0.402. The images were taken with the Wide Field Camera (WFC) in `parallel mode' and deconvolved with the Lucy method using as the point-spread function nearby stars in the image stack. The WFC deconvolutions have a dynamic range of 16 to 20 dB (4 to 5 mag) and an effective resolution approximately less than 0.2 sec (FWHM). The multiorbit HST images allow us to trace the morphology, light profiles, and color gradients of faint field galaxies down to V approximately equal to 22 to 23 mag at sub-kpc resolution, since the redshift range covered is z = 0.1 to 0.4. The goals of the MDS are to study the sub-kpc scale morphology, light profiles, and color gradients for a large samole of faint field galaxies down to V approximately equal to 23 mag, and to trace the fraction of early to late-type galaxies as function of cosmic time. In this paper we study the brighter MDS galaxies in the 13 hour + 43 deg MDS field in detail, and investigate to what extent model fits with pure exponential disks or a(exp 1/4) bulges are justified at V approximately less than 22 mag. Four of the six field galaxies have light profiles that indicate (small) inner bulges following r(exp 1/4) laws down to 0.2 sec resolution, plus a dominant surrounding exponential disk with little or no color gradients. Two occur in a group at z = 0.401, two are barred spiral galaxies at z = 0.179 and z = 0.302, and two are rather subluminous (and edge-on) disk galaxies at z = 0.126 and z = 0.179. Our deep MDS images can detect galaxies down to V, I approximately less than 25 to 26 mag, and demonstrate the impressive potential of HST--even with its pre-refurbished optics--to resolve morphological details in galaxies at cosmologically significant distances (v approximately less than 23 mag). Since the median redshift of these galaxies is approximately less than 0.4, the HST resolution allows us to study sub kpc size scales at the galaxy, which cannot be done with stable images over wide fields from the best ground-based sites.

Measuring Cosmic Expansion and Large Scale Structure with Destiny

NASA Technical Reports Server (NTRS)

Benford, Dominic J.; Lauer, Tod R.

2007-01-01

Destiny is a simple, direct, low cost mission to determine the properties of dark energy by obtaining a cosmologically deep supernova (SN) type Ia Hubble diagram and by measuring the large-scale mass power spectrum over time. Its science instrument is a 1.65m space telescope, featuring a near-infrared survey camera/spectrometer with a large field of view. During its first two years, Destiny will detect, observe, and characterize 23000 SN Ia events over the redshift interval 0.4lo00 square degrees to measure the large-scale mass power spectrum. The combination of surveys is much more powerful than either technique on its own, and will have over an order of magnitude greater sensitivity than will be provided by ongoing ground-based projects.

Astronomers Set a New Galaxy Distance Record

NASA Image and Video Library

2015-05-06

This is a Hubble Space Telescope image of the farthest spectroscopically confirmed galaxy observed to date (inset). It was identified in this Hubble image of a field of galaxies in the CANDELS survey (Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey). NASA’s Spitzer Space Telescope also observed the unique galaxy. The W. M. Keck Observatory was used to obtain a spectroscopic redshift (z=7.7), extending the previous redshift record. Measurements of the stretching of light, or redshift, give the most reliable distances to other galaxies. This source is thus currently the most distant confirmed galaxy known, and it appears to also be one of the brightest and most massive sources at that time. The galaxy existed over 13 billion years ago. The near-infrared light image of the galaxy (inset) has been colored blue as suggestive of its young, and hence very blue, stars. The CANDELS field is a combination of visible-light and near-infrared exposures. Credits: NASA, ESA, P. Oesch (Yale U.)

HUBBLE'S TOP TEN GRAVITATIONAL LENSES

NASA Technical Reports Server (NTRS)

2002-01-01

The NASA Hubble Space Telescope serendipitous survey of the sky has uncovered exotic patterns, rings, arcs and crosses that are all optical mirages produced by a gravitational lens, nature's equivalent of having giant magnifying glass in space. Shown are the top 10 lens candidates uncovered in the deepest 100 Hubble fields. Hubble's sensitivity and high resolution allow it to see faint and distant lenses that cannot be detected with ground-based telescopes whose images are blurred by Earth's atmosphere. [Top Left] - HST 01248+0351 is a lensed pair on either side of the edge-on disk lensing galaxy. [Top Center] - HST 01247+0352 is another pair of bluer lensed source images around the red spherical elliptical lensing galaxy. Two much fainter images can be seen near the detection limit which might make this a quadruple system. [Top Right] - HST 15433+5352 is a very good lens candidate with a bluer lensed source in the form of an extended arc about the redder elliptical lensing galaxy. [Middle Far Left] - HST 16302+8230 could be an 'Einstein ring' and the most intriguing lens candidate. It has been nicknamed the 'the London Underground' since it resembles that logo. [Middle Near Left] - HST 14176+5226 is the first, and brightest lens system discovered in 1995 with the Hubble telescope. This lens candidate has now been confirmed spectroscopically using large ground-based telescopes. The elliptical lensing galaxy is located 7 billion light-years away, and the lensed quasar is about 11 billion light-years distant. [Middle Near Right] - HST 12531-2914 is the second quadruple lens candidate discovered with Hubble. It is similar to the first, but appears smaller and fainter. [Middle Far Right] - HST 14164+5215 is a pair of bluish lensed images symmetrically placed around a brighter, redder galaxy. [Bottom Left] - HST 16309+8230 is an edge-on disk-like galaxy (blue arc) which has been significantly distorted by the redder lensing elliptical galaxy. [Bottom Center] - HST 12368+6212 is a blue arc in the Hubble Deep Field (HDF). [Bottom Right] - HST 18078+4600 is a blue arc caused by the gravitational potential of a small group of 4 galaxies. Credit: Kavan Ratnatunga (Carnegie Mellon Univ.) and NASA

The MUSE Hubble Ultra Deep Field Survey. X. Lyα equivalent widths at 2.9 < z < 6.6

NASA Astrophysics Data System (ADS)

Hashimoto, T.; Garel, T.; Guiderdoni, B.; Drake, A. B.; Bacon, R.; Blaizot, J.; Richard, J.; Leclercq, F.; Inami, H.; Verhamme, A.; Bouwens, R.; Brinchmann, J.; Cantalupo, S.; Carollo, M.; Caruana, J.; Herenz, E. C.; Kerutt, J.; Marino, R. A.; Mitchell, P.; Schaye, J.

2017-11-01

We present rest-frame Lyα equivalent widths (EW0) of 417 Lyα emitters (LAEs) detected with Multi Unit Spectroscopic Explorer (MUSE) on the Very Large Telescope (VLT) at 2.9 200 Å above 1σ uncertainties. Two of these 12 LAEs show signatures of merger or AGN activity: the weak Civλ1549 emission line. For the remaining 10 very large EW0 LAEs, we find that the EW0 values can be reproduced by young stellar ages (< 100 Myr) and low metallicities (≲ 0.02 Z⊙). Otherwise, at least part of the Lyα emission in these LAEs needs to arise from anisotropic radiative transfer effects, fluorescence by hidden AGN or quasi-stellar object activity, or gravitational cooling.

The Chandra Deep Field-North Survey and the cosmic X-ray background.

PubMed

Brandt, W Nielsen; Alexander, David M; Bauer, Franz E; Hornschemeier, Ann E

2002-09-15

Chandra has performed a 1.4 Ms survey centred on the Hubble Deep Field-North (HDF-N), probing the X-ray Universe 55-550 times deeper than was possible with pre-Chandra missions. We describe the detected point and extended X-ray sources and discuss their overall multi-wavelength (optical, infrared, submillimetre and radio) properties. Special attention is paid to the HDF-N X-ray sources, luminous infrared starburst galaxies, optically faint X-ray sources and high-to-extreme redshift active galactic nuclei. We also describe how stacking analyses have been used to probe the average X-ray-emission properties of normal and starburst galaxies at cosmologically interesting distances. Finally, we discuss plans to extend the survey and argue that a 5-10 Ms Chandra survey would lay key groundwork for future missions such as XEUS and Generation-X.

The Local Group: the ultimate deep field

NASA Astrophysics Data System (ADS)

Boylan-Kolchin, Michael; Weisz, Daniel R.; Bullock, James S.; Cooper, Michael C.

2016-10-01

Near-field cosmology - using detailed observations of the Local Group and its environs to study wide-ranging questions in galaxy formation and dark matter physics - has become a mature and rich field over the past decade. There are lingering concerns, however, that the relatively small size of the present-day Local Group (˜2 Mpc diameter) imposes insurmountable sample-variance uncertainties, limiting its broader utility. We consider the region spanned by the Local Group's progenitors at earlier times and show that it reaches 3 arcmin ≈ 7 comoving Mpc in linear size (a volume of ≈350 Mpc3) at z = 7. This size at early cosmic epochs is large enough to be representative in terms of the matter density and counts of dark matter haloes with Mvir(z = 7) ≲ 2 × 109 M⊙. The Local Group's stellar fossil record traces the cosmic evolution of galaxies with 103 ≲ M⋆(z = 0)/M⊙ ≲ 109 (reaching M1500 > -9 at z ˜ 7) over a region that is comparable to or larger than the Hubble Ultra-Deep Field (HUDF) for the entire history of the Universe. In the JWST era, resolved stellar populations will probe regions larger than the HUDF and any deep JWST fields, further enhancing the value of near-field cosmology.

The Hubble Frontier Fields: Engaging Multiple Audiences in Exploring the Cosmic Frontier

NASA Astrophysics Data System (ADS)

Lawton, Brandon L.; Smith, Denise A.; Summers, Frank; Ryer, Holly; Slivinski, Carolyn; Lotz, Jennifer M.

2017-06-01

The Hubble Frontier Fields is a multi-cycle program of six deep-field observations of strong-lensing galaxy clusters taken in parallel with six deep “blank fields.” The three-year long collaborative program began in late 2013 and is led by observations from NASA’s Great Observatories. The observations, now complete, allow astronomers to look deeper into the universe than ever before, and potentially uncover galaxies that are as much as 100 times fainter than what the telescopes can typically observe. The Frontier Fields science program is ideal for informing audiences about scientific advances and topics in STEM. The study of galaxy properties, statistics, optics, and Einstein’s theory of general relativity naturally leverages off of the science returns of the Frontier Fields program. As a result, the Space Telescope Science Institute’s Office of Public Outreach (OPO) has engaged multiple audiences over the past three years to follow the progress of the Frontier Fields.For over two decades, the STScI outreach program has sought to bring the wonders of the universe to the public and engage audiences in the adventure of scientific discovery. In addition, we are leveraging the reach of the new NASA’s Universe of Learning education program to bring the science of the Frontier Fields to informal education audiences. The main underpinnings of the STScI outreach program and the Universe of Learning education program are scientist-educator development teams, partnerships, and an embedded program evaluation component. OPO is leveraging the infrastructure of these education and outreach programs to bring the Frontier Fields science program to the education community and the public in a cost-effective way.This talk will feature highlights over the past three years of the program. We will highlight OPO’s strategies and infrastructure that allows for the quick delivery of groundbreaking science to the education community and public.

HUBBLE CAPTURES DETAILED IMAGE OF URANUS' ATMOSPHERE

NASA Technical Reports Server (NTRS)

2002-01-01

Hubble Space Telescope has peered deep into Uranus' atmosphere to see clear and hazy layers created by a mixture of gases. Using infrared filters, Hubble captured detailed features of three layers of Uranus' atmosphere. Hubble's images are different from the ones taken by the Voyager 2 spacecraft, which flew by Uranus 10 years ago. Those images - not taken in infrared light - showed a greenish-blue disk with very little detail. The infrared image allows astronomers to probe the structure of Uranus' atmosphere, which consists of mostly hydrogen with traces of methane. The red around the planet's edge represents a very thin haze at a high altitude. The haze is so thin that it can only be seen by looking at the edges of the disk, and is similar to looking at the edge of a soap bubble. The yellow near the bottom of Uranus is another hazy layer. The deepest layer, the blue near the top of Uranus, shows a clearer atmosphere. Image processing has been used to brighten the rings around Uranus so that astronomers can study their structure. In reality, the rings are as dark as black lava or charcoal. This false color picture was assembled from several exposures taken July 3, 1995 by the Wide Field Planetary Camera-2. CREDIT: Erich Karkoschka (University of Arizona Lunar and Planetary Lab) and NASA

The Great Observatories Origins Deep Survey

NASA Astrophysics Data System (ADS)

Dickinson, Mark

2008-05-01

Observing the formation and evolution of ordinary galaxies at early cosmic times requires data at many wavelengths in order to recognize, separate and analyze the many physical processes which shape galaxies' history, including the growth of large scale structure, gravitational interactions, star formation, and active nuclei. Extremely deep data, covering an adequately large volume, are needed to detect ordinary galaxies in sufficient numbers at such great distances. The Great Observatories Origins Deep Survey (GOODS) was designed for this purpose as an anthology of deep field observing programs that span the electromagnetic spectrum. GOODS targets two fields, one in each hemisphere. Some of the deepest and most extensive imaging and spectroscopic surveys have been carried out in the GOODS fields, using nearly every major space- and ground-based observatory. Many of these data have been taken as part of large, public surveys (including several Hubble Treasury, Spitzer Legacy, and ESO Large Programs), which have produced large data sets that are widely used by the astronomical community. I will review the history of the GOODS program, highlighting results on the formation and early growth of galaxies and their active nuclei. I will also describe new and upcoming observations, such as the GOODS Herschel Key Program, which will continue to fill out our portrait of galaxies in the young universe.

Lyman Break Galaxies in the Hubble Ultra Deep Field through Deep U-Band Imaging

NASA Astrophysics Data System (ADS)

Rafelski, Marc; Wolfe, A. M.; Cooke, J.; Chen, H. W.; Armandroff, T. E.; Wirth, G. D.

2009-12-01

We introduce an extremely deep U-band image taken of the Hubble Ultra Deep Field (HUDF), with a one sigma depth of 30.7 mag arcsec-2 and a detection limiting magnitude of 28 mag arcsec-2. The observations were carried out on the Keck I telescope using the LRIS-B detector. The U-band image substantially improves the accuracy of photometric redshift measurements of faint galaxies in the HUDF at z=[2.5,3.5]. The U-band for these galaxies is attenuated by lyman limit absorption, allowing for more reliable selections of candidate Lyman Break Galaxies (LBGs) than from photometric redshifts without U-band. We present a reliable sample of 300 LBGs at z=[2.5,3.5] in the HUDF. Accurate redshifts of faint galaxies at z=[2.5,3.5] are needed to obtain empirical constraints on the star formation efficiency of neutral gas at high redshift. Wolfe & Chen (2006) showed that the star formation rate (SFR) density in damped Ly-alpha absorption systems (DLAs) at z=[2.5,3.5] is significantly lower than predicted by the Kennicutt-Schmidt law for nearby galaxies. One caveat to this result that we wish to test is whether LBGs are embedded in DLAs. If in-situ star formation is occurring in DLAs, we would see it as extended low surface brightness emission around LBGs. We shall use the more accurate photometric redshifts to create a sample of LBGs around which we will look for extended emission in the more sensitive and higher resolution HUDF images. The absence of extended emission would put limits on the SFR density of DLAs associated with LBGs at high redshift. On the other hand, detection of faint emission on scales large compared to the bright LBG cores would indicate the presence of in situ star formation in those DLAs. Such gas would presumably fuel the higher star formation rates present in the LBG cores.

A deep ALMA image of the Hubble Ultra Deep Field

NASA Astrophysics Data System (ADS)

Dunlop, J. S.; McLure, R. J.; Biggs, A. D.; Geach, J. E.; Michałowski, M. J.; Ivison, R. J.; Rujopakarn, W.; van Kampen, E.; Kirkpatrick, A.; Pope, A.; Scott, D.; Swinbank, A. M.; Targett, T. A.; Aretxaga, I.; Austermann, J. E.; Best, P. N.; Bruce, V. A.; Chapin, E. L.; Charlot, S.; Cirasuolo, M.; Coppin, K.; Ellis, R. S.; Finkelstein, S. L.; Hayward, C. C.; Hughes, D. H.; Ibar, E.; Jagannathan, P.; Khochfar, S.; Koprowski, M. P.; Narayanan, D.; Nyland, K.; Papovich, C.; Peacock, J. A.; Rieke, G. H.; Robertson, B.; Vernstrom, T.; Werf, P. P. van der; Wilson, G. W.; Yun, M.

2017-04-01

We present the results of the first, deep Atacama Large Millimeter Array (ALMA) imaging covering the full ≃4.5 arcmin2 of the Hubble Ultra Deep Field (HUDF) imaged with Wide Field Camera 3/IR on HST. Using a 45-pointing mosaic, we have obtained a homogeneous 1.3-mm image reaching σ1.3 ≃ 35 μJy, at a resolution of ≃0.7 arcsec. From an initial list of ≃50 > 3.5σ peaks, a rigorous analysis confirms 16 sources with S1.3 > 120 μJy. All of these have secure galaxy counterparts with robust redshifts ( = 2.15). Due to the unparalleled supporting data, the physical properties of the ALMA sources are well constrained, including their stellar masses (M*) and UV+FIR star formation rates (SFR). Our results show that stellar mass is the best predictor of SFR in the high-redshift Universe; indeed at z ≥ 2 our ALMA sample contains seven of the nine galaxies in the HUDF with M* ≥ 2 × 1010 M⊙, and we detect only one galaxy at z > 3.5, reflecting the rapid drop-off of high-mass galaxies with increasing redshift. The detections, coupled with stacking, allow us to probe the redshift/mass distribution of the 1.3-mm background down to S1.3 ≃ 10 μJy. We find strong evidence for a steep star-forming 'main sequence' at z ≃ 2, with SFR ∝M* and a mean specific SFR ≃ 2.2 Gyr-1. Moreover, we find that ≃85 per cent of total star formation at z ≃ 2 is enshrouded in dust, with ≃65 per cent of all star formation at this epoch occurring in high-mass galaxies (M* > 2 × 1010 M⊙), for which the average obscured:unobscured SF ratio is ≃200. Finally, we revisit the cosmic evolution of SFR density; we find this peaks at z ≃ 2.5, and that the star-forming Universe transits from primarily unobscured to primarily obscured at z ≃ 4.

Identification of Active Galactic Nuclei through HST optical variability in the GOODS South field

NASA Astrophysics Data System (ADS)

Pouliasis, Ektoras; Georgantopoulos; Bonanos, A.; HCV Team

2016-08-01

This work aims to identify AGN in the GOODS South deep field through optical variability. This method can easily identify low-luminosity AGN. In particular, we use images in the z-band obtained from the Hubble Space Telescope with the ACS/WFC camera over 5 epochs separated by ~45 days. Aperture photometry has been performed using SExtractor to extract the lightcurves. Several variability indices, such as the median absolute deviation, excess variance, and sigma were applied to automatically identify the variable sources. After removing artifacts, stars and supernovae from the variable selected sample and keeping only those sources with known photometric or spectroscopic redshift, the optical variability was compared to variability in other wavelengths (X-rays, mid-IR, radio). This multi-wavelength study provides important constraints on the structure and the properties of the AGN and their relation to their hosts. This work is a part of the validation of the Hubble Catalog of Variables (HCV) project, which has been launched at the National Observatory of Athens by ESA, and aims to identify all sources (pointlike and extended) showing variability, based on the Hubble Source Catalog (HSC, Whitmore et al. 2015). The HSC version 1 was released in February 2015 and includes 80 million sources imaged with the WFPC2, ACS/WFC, WFC3/UVIS and WFC3/IR cameras.

A Guided Inquiry on Hubble Plots and the Big Bang

ERIC Educational Resources Information Center

Forringer, Ted

2014-01-01

In our science for non-science majors course "21st Century Physics," we investigate modern "Hubble plots" (plots of velocity versus distance for deep space objects) in order to discuss the Big Bang, dark matter, and dark energy. There are two potential challenges that our students face when encountering these topics for the…

Mass Modeling of Frontier Fields Cluster MACS J1149.5+2223 Using Strong and Weak Lensing

NASA Astrophysics Data System (ADS)

Finney, Emily Quinn; Bradač, Maruša; Huang, Kuang-Han; Hoag, Austin; Morishita, Takahiro; Schrabback, Tim; Treu, Tommaso; Borello Schmidt, Kasper; Lemaux, Brian C.; Wang, Xin; Mason, Charlotte

2018-05-01

We present a gravitational-lensing model of MACS J1149.5+2223 using ultra-deep Hubble Frontier Fields imaging data and spectroscopic redshifts from HST grism and Very Large Telescope (VLT)/MUSE spectroscopic data. We create total mass maps using 38 multiple images (13 sources) and 608 weak-lensing galaxies, as well as 100 multiple images of 31 star-forming regions in the galaxy that hosts supernova Refsdal. We find good agreement with a range of recent models within the HST field of view. We present a map of the ratio of projected stellar mass to total mass (f ⋆) and find that the stellar mass fraction for this cluster peaks on the primary BCG. Averaging within a radius of 0.3 Mpc, we obtain a value of < {f}\\star > ={0.012}-0.003+0.004, consistent with other recent results for this ratio in cluster environments, though with a large global error (up to δf ⋆ = 0.005) primarily due to the choice of IMF. We compare values of f ⋆ and measures of star formation efficiency for this cluster to other Hubble Frontier Fields clusters studied in the literature, finding that MACS1149 has a higher stellar mass fraction than these other clusters but a star formation efficiency typical of massive clusters.

ALMA Spectroscopic Survey in the Hubble Ultra Deep Field: CO Luminosity Functions and the Evolution of the Cosmic Density of Molecular Gas

NASA Astrophysics Data System (ADS)

Decarli, Roberto; Walter, Fabian; Aravena, Manuel; Carilli, Chris; Bouwens, Rychard; da Cunha, Elisabete; Daddi, Emanuele; Ivison, R. J.; Popping, Gergö; Riechers, Dominik; Smail, Ian R.; Swinbank, Mark; Weiss, Axel; Anguita, Timo; Assef, Roberto J.; Bauer, Franz E.; Bell, Eric F.; Bertoldi, Frank; Chapman, Scott; Colina, Luis; Cortes, Paulo C.; Cox, Pierre; Dickinson, Mark; Elbaz, David; Gónzalez-López, Jorge; Ibar, Edo; Infante, Leopoldo; Hodge, Jacqueline; Karim, Alex; Le Fevre, Olivier; Magnelli, Benjamin; Neri, Roberto; Oesch, Pascal; Ota, Kazuaki; Rix, Hans-Walter; Sargent, Mark; Sheth, Kartik; van der Wel, Arjen; van der Werf, Paul; Wagg, Jeff

2016-12-01

In this paper we use ASPECS, the ALMA Spectroscopic Survey in the Hubble Ultra Deep Field in band 3 and band 6, to place blind constraints on the CO luminosity function and the evolution of the cosmic molecular gas density as a function of redshift up to z ˜ 4.5. This study is based on galaxies that have been selected solely through their CO emission and not through any other property. In all of the redshift bins the ASPECS measurements reach the predicted “knee” of the CO luminosity function (around 5 × 109 K km s-1 pc2). We find clear evidence of an evolution in the CO luminosity function with respect to z ˜ 0, with more CO-luminous galaxies present at z ˜ 2. The observed galaxies at z ˜ 2 also appear more gas-rich than predicted by recent semi-analytical models. The comoving cosmic molecular gas density within galaxies as a function of redshift shows a drop by a factor of 3-10 from z ˜ 2 to z ˜ 0 (with significant error bars), and possibly a decline at z > 3. This trend is similar to the observed evolution of the cosmic star formation rate density. The latter therefore appears to be at least partly driven by the increased availability of molecular gas reservoirs at the peak of cosmic star formation (z ˜ 2).

HUBBLE'S DEEPEST VIEW OF THE UNIVERSE

NASA Technical Reports Server (NTRS)

2002-01-01

[Left] A NASA Hubble Space Telescope view of the faintest galaxies ever seen in the universe, taken in infrared light with the Near Infrared Camera and Multi-Object Spectrometer (NICMOS). The picture contains over 300 galaxies having spiral, elliptical and irregular shapes. Though most of these galaxies were first seen in 1995 when Hubble was used to take a visible-light deep exposure of the same field, NICMOS uncovers many new objects. Most of these objects are too small and faint to be apparent in the full field NICMOS view. Some of the reddest and faintest of the newly detected objects may be over 12 billion light-years away, as derived from a standard model of the universe. However, a powerful new generation of telescopes will be needed to confirm the suspected distances of these objects. The field of view is 2 million light-years across, at its maximum. Yet, on a cosmic scale, it represents only a thin pencil beam look across the universe. The area of sky is merely 1/100th the apparent diameter on the full moon. [Right] Two close-up NICMOS views of candidate objects which may be over 12 billion light-years away. Each candidate is centered in the frame. The reddish color may mean all of the starlight has been stretched to infrared wavelengths by the universe's expansion. Alternative explanations are that the objects are closer to us, but the light has been reddened by dust scattering. A new generation of telescopes will be needed to make follow-up observations capable of establishing true distance. The image was taken in January 1998 and required an exposure time of 36 hours to detect objects down to 30th magnitude. Hubble was aimed in the direction of the constellation Ursa Major, in a region just above the handle of the Big Dipper. The color corresponds to blue (0.45 microns), green (1.1 microns) and red (1.6 microns). Credit: Rodger I. Thompson (University of Arizona), and NASA

PHOTOMETRIC REDSHIFTS IN THE HAWAII-HUBBLE DEEP FIELD-NORTH (H-HDF-N)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yang, G.; Xue, Y. Q.; Kong, X.

2015-01-01

We derive photometric redshifts (z {sub phot}) for sources in the entire (∼0.4 deg{sup 2}) Hawaii-Hubble Deep Field-North (H-HDF-N) field with the EAzY code, based on point-spread-function-matched photometry of 15 broad bands from the ultraviolet (U band) to mid-infrared (IRAC 4.5 μm). Our catalog consists of a total of 131,678 sources. We evaluate the z {sub phot} quality by comparing z {sub phot} with spectroscopic redshifts (z {sub spec}) when available, and find a value of normalized median absolute deviation σ{sub NMAD} = 0.029 and an outlier fraction of 5.5% (outliers are defined as sources having |z{sub phot} – z{sub spec} |/(1more » + z{sub spec} ) > 0.15) for non-X-ray sources. More specifically, we obtain σ{sub NMAD} = 0.024 with 2.7% outliers for sources brighter than R = 23 mag, σ{sub NMAD} = 0.035 with 7.4% outliers for sources fainter than R = 23 mag, σ{sub NMAD} = 0.026 with 3.9% outliers for sources having z < 1, and σ{sub NMAD} = 0.034 with 9.0% outliers for sources having z > 1. Our z {sub phot} quality shows an overall improvement over an earlier z {sub phot} work that focused only on the central H-HDF-N area. We also classify each object as a star or galaxy through template spectral energy distribution fitting and complementary morphological parameterization, resulting in 4959 stars and 126,719 galaxies. Furthermore, we match our catalog with the 2 Ms Chandra Deep Field-North main X-ray catalog. For the 462 matched non-stellar X-ray sources (281 having z {sub spec}), we improve their z {sub phot} quality by adding three additional active galactic nucleus templates, achieving σ{sub NMAD} = 0.035 and an outlier fraction of 12.5%. We make our catalog publicly available presenting both photometry and z {sub phot}, and provide guidance on how to make use of our catalog.« less

Deep learning for studies of galaxy morphology

NASA Astrophysics Data System (ADS)

Tuccillo, D.; Huertas-Company, M.; Decencière, E.; Velasco-Forero, S.

2017-06-01

Establishing accurate morphological measurements of galaxies in a reasonable amount of time for future big-data surveys such as EUCLID, the Large Synoptic Survey Telescope or the Wide Field Infrared Survey Telescope is a challenge. Because of its high level of abstraction with little human intervention, deep learning appears to be a promising approach. Deep learning is a rapidly growing discipline that models high-level patterns in data as complex multilayered networks. In this work we test the ability of deep convolutional networks to provide parametric properties of Hubble Space Telescope like galaxies (half-light radii, Sérsic indices, total flux etc..). We simulate a set of galaxies including point spread function and realistic noise from the CANDELS survey and try to recover the main galaxy parameters using deep-learning. We compare the results with the ones obtained with the commonly used profile fitting based software GALFIT. This way showing that with our method we obtain results at least equally good as the ones obtained with GALFIT but, once trained, with a factor 5 hundred time faster.

A TYPE Ia SUPERNOVA AT REDSHIFT 1.55 IN HUBBLE SPACE TELESCOPE INFRARED OBSERVATIONS FROM CANDELS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rodney, Steven A.; Riess, Adam G.; Jones, David O.

2012-02-10

We report the discovery of a Type Ia supernova (SN Ia) at redshift z = 1.55 with the infrared detector of the Wide Field Camera 3 (WFC3-IR) on the Hubble Space Telescope (HST). This object was discovered in CANDELS imaging data of the Hubble Ultra Deep Field and followed as part of the CANDELS+CLASH Supernova project, comprising the SN search components from those two HST multi-cycle treasury programs. This is the highest redshift SN Ia with direct spectroscopic evidence for classification. It is also the first SN Ia at z > 1 found and followed in the infrared, providing amore » full light curve in rest-frame optical bands. The classification and redshift are securely defined from a combination of multi-band and multi-epoch photometry of the SN, ground-based spectroscopy of the host galaxy, and WFC3-IR grism spectroscopy of both the SN and host. This object is the first of a projected sample at z > 1.5 that will be discovered by the CANDELS and CLASH programs. The full CANDELS+CLASH SN Ia sample will enable unique tests for evolutionary effects that could arise due to differences in SN Ia progenitor systems as a function of redshift. This high-z sample will also allow measurement of the SN Ia rate out to z Almost-Equal-To 2, providing a complementary constraint on SN Ia progenitor models.« less

Listening to galaxies tuning at z ~ 2.5-3.0: The first strikes of the Hubble fork

NASA Astrophysics Data System (ADS)

Talia, M.; Cimatti, A.; Mignoli, M.; Pozzetti, L.; Renzini, A.; Kurk, J.; Halliday, C.

2014-02-01

Aims: We investigate the morphological properties of 494 galaxies selected from the Galaxy Mass Assembly ultra-deep Spectroscopic Survey (GMASS) at z > 1, primarily in their optical rest frame, using Hubble Space Telescope (HST) infrared images, from the Cosmic Assembly Near-IR Deep Extragalactic Legacy Survey (CANDELS). Methods: The morphological analysis of Wield Field Camera (WFC3) H160 band images was performed using two different methods: a visual classification identifying traditional Hubble types, and a quantitative analysis using parameters that describe structural properties, such as the concentration of light and the rotational asymmetry. The two classifications are compared. We then analysed how apparent morphologies correlate with the physical properties of galaxies. Results: The fractions of both elliptical and disk galaxies decrease between redshifts z ~ 1 to z ~ 3, while at z > 3 the galaxy population is dominated by irregular galaxies. The quantitative morphological analysis shows that, at 1 < z < 3, morphological parameters are not as effective in distinguishing the different morphological Hubble types as they are at low redshift. No significant morphological k-correction was found to be required for the Hubble type classification, with some exceptions. In general, different morphological types occupy the two peaks of the (U - B)rest colour bimodality of galaxies: most irregulars occupy the blue peak, while ellipticals are mainly found in the red peak, though with some level of contamination. Disks are more evenly distributed than either irregulars and ellipticals. We find that the position of a galaxy in a UVJ diagram is related to its morphological type: the "quiescent" region of the plot is mainly occupied by ellipticals and, to a lesser extent, by disks. We find that only ~33% of all morphological ellipticals in our sample are red and passively evolving galaxies, a percentage that is consistent with previous results obtained at z < 1. Blue galaxies morphologically classified as ellipticals show a remarkable structural similarity to red ones. We search for correlations between our morphological and spectroscopic galaxy classifications. Almost all irregulars have a star-forming galaxy spectrum. In addition, the majority of disks show some sign of star-formation activity in their spectra, though in some cases their red continuum is indicative of old stellar populations. Finally, an elliptical morphology may be associated with either passively evolving or strongly star-forming galaxies. Conclusions: We propose that the Hubble sequence of galaxy morphologies takes shape at redshift 2.5 < z < 3. The fractions of both ellipticals and disks decrease with increasing lookback time at z > 1, such that at redshifts z = 2.5-2.7 and above, the Hubble types cannot be identified, and most galaxies are classified as irregular. Appendix A is available in electronic form at http://www.aanda.org

Understanding Supermassive Black Hole Growth Mechanisms in the SSA22 Protocluster

NASA Astrophysics Data System (ADS)

Bonine, Brett; Lehmer, Bret

2018-01-01

The SSA22 protocluster is a collection of galaxies at redshift z = 3.09, corresponding to a look back time of 11.6 billion years. Observations of the protocluster allow for the investigation of galaxy properties of such protocluster environments in the early universe, potentially giving insight into the formation and evolution of galaxy clusters visible in the local universe (e.g., the Coma Cluster). Compared to other field galaxies at a similar redshift, a larger fraction of galaxies in SSA22 have been found to possess active galactic nuclei (AGN). This enhanced AGN activity suggests a relationship between the environment within the cluster and the growth of supermassive black holes (SMBHs). I will clarify the role that the protocluster environment at z = 3.09 plays in enhancing the growth of SMBHs in the cluster. To accomplish this, we are analyzing recently obtained WFC3 F160W data from the Hubble Space Telescope (HST) in SSA22, and equivalent archival CANDELS data in the Hubble Deep Field-North, to compare the merger rates and stellar mass distributions of galaxies in the SSA22 protocluster and in the field. Our goal is to assess the relative role that mergers play in enhancing the SMBH growth observed in over-dense regions in the z = 3 Universe.

Type-Ia Supernova Rates to Redshift 2.4 from Clash: The Cluster Lensing and Supernova Survey with Hubble

NASA Technical Reports Server (NTRS)

Graur, O.; Rodney, S. A.; Maoz, D.; Riess, A. G.; Jha, S. W.; Postman, M.; Dahlen, T.; Holoien, T. W.-S.; McCully, C.; Patel, B.;

Type-Ia supernova rates to redshift 2.4 from clash: The cluster lensing and supernova survey with Hubble

DOE Office of Scientific and Technical Information (OSTI.GOV)

Graur, O.; Rodney, S. A.; Riess, A. G.

2014-03-01

We present the supernova (SN) sample and Type-Ia SN (SN Ia) rates from the Cluster Lensing And Supernova survey with Hubble (CLASH). Using the Advanced Camera for Surveys and the Wide Field Camera 3 on the Hubble Space Telescope (HST), we have imaged 25 galaxy-cluster fields and parallel fields of non-cluster galaxies. We report a sample of 27 SNe discovered in the parallel fields. Of these SNe, ∼13 are classified as SN Ia candidates, including four SN Ia candidates at redshifts z > 1.2. We measure volumetric SN Ia rates to redshift 1.8 and add the first upper limit onmore » the SN Ia rate in the range 1.8 < z < 2.4. The results are consistent with the rates measured by the HST/GOODS and Subaru Deep Field SN surveys. We model these results together with previous measurements at z < 1 from the literature. The best-fitting SN Ia delay-time distribution (DTD; the distribution of times that elapse between a short burst of star formation and subsequent SN Ia explosions) is a power law with an index of −1.00{sub −0.06(0.10)}{sup +0.06(0.09)} (statistical){sub −0.08}{sup +0.12} (systematic), where the statistical uncertainty is a result of the 68% and 95% (in parentheses) statistical uncertainties reported for the various SN Ia rates (from this work and from the literature), and the systematic uncertainty reflects the range of possible cosmic star-formation histories. We also test DTD models produced by an assortment of published binary population synthesis (BPS) simulations. The shapes of all BPS double-degenerate DTDs are consistent with the volumetric SN Ia measurements, when the DTD models are scaled up by factors of 3-9. In contrast, all BPS single-degenerate DTDs are ruled out by the measurements at >99% significance level.« less

Calibration of HST wide field camera for quantitative analysis of faint galaxy images

NASA Technical Reports Server (NTRS)

Ratnatunga, Kavan U.; Griffiths, Richard E.; Casertano, Stefano; Neuschaefer, Lyman W.; Wyckoff, Eric W.

1994-01-01

We present the methods adopted to optimize the calibration of images obtained with the Hubble Space Telescope (HST) Wide Field Camera (WFC) (1991-1993). Our main goal is to improve quantitative measurement of faint images, with special emphasis on the faint (I approximately 20-24 mag) stars and galaxies observed as a part of the Medium-Deep Survey. Several modifications to the standard calibration procedures have been introduced, including improved bias and dark images, and a new supersky flatfield obtained by combining a large number of relatively object-free Medium-Deep Survey exposures of random fields. The supersky flat has a pixel-to-pixel rms error of about 2.0% in F555W and of 2.4% in F785LP; large-scale variations are smaller than 1% rms. Overall, our modifications improve the quality of faint images with respect to the standard calibration by about a factor of five in photometric accuracy and about 0.3 mag in sensitivity, corresponding to about a factor of two in observing time. The relevant calibration images have been made available to the scientific community.

THE MULTIWAVELENGTH SURVEY BY YALE-CHILE (MUSYC): DEEP MEDIUM-BAND OPTICAL IMAGING AND HIGH-QUALITY 32-BAND PHOTOMETRIC REDSHIFTS IN THE ECDF-S

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cardamone, Carolin N.; Van Dokkum, Pieter G.; Urry, C. Megan

2010-08-15

We present deep optical 18-medium-band photometry from the Subaru telescope over the {approx}30' x 30' Extended Chandra Deep Field-South, as part of the Multiwavelength Survey by Yale-Chile (MUSYC). This field has a wealth of ground- and space-based ancillary data, and contains the GOODS-South field and the Hubble Ultra Deep Field. We combine the Subaru imaging with existing UBVRIzJHK and Spitzer IRAC images to create a uniform catalog. Detecting sources in the MUSYC 'BVR' image we find {approx}40,000 galaxies with R {sub AB} < 25.3, the median 5{sigma} limit of the 18 medium bands. Photometric redshifts are determined using the EAzYmore » code and compared to {approx}2000 spectroscopic redshifts in this field. The medium-band filters provide very accurate redshifts for the (bright) subset of galaxies with spectroscopic redshifts, particularly at 0.1 < z < 1.2 and at z {approx}> 3.5. For 0.1 < z < 1.2, we find a 1{sigma} scatter in {Delta}z/(1 + z) of 0.007, similar to results obtained with a similar filter set in the COSMOS field. As a demonstration of the data quality, we show that the red sequence and blue cloud can be cleanly identified in rest-frame color-magnitude diagrams at 0.1 < z < 1.2. We find that {approx}20% of the red sequence galaxies show evidence of dust emission at longer rest-frame wavelengths. The reduced images, photometric catalog, and photometric redshifts are provided through the public MUSYC Web site.« less

Galaxy-Galaxy Lensing in the Hubble Deep Field: The Halo Tully-Fisher Relation at Intermediate Redshift

NASA Astrophysics Data System (ADS)

Hudson, Michael J.; Gwyn, Stephen D. J.; Dahle, Håkon; Kaiser, Nick

1998-08-01

A tangential distortion of background source galaxies around foreground lens galaxies in the Hubble Deep Field is detected at the 99.3% confidence level. An important element of our analysis is the use of photometric redshifts to determine distances of lens and source galaxies and rest-frame B-band luminosities of the lens galaxies. The lens galaxy halos obey a Tully-Fisher relation between halo circular velocity and luminosity. The typical lens galaxy, at a redshift z = 0.6, has a circular velocity of 210 +/- 40 km s-1 at MB = -18.5, if q0 = 0.5. Control tests, in which lens and source positions and source ellipticities are randomized, confirm the significance level of the detection quoted above. Furthermore, a marginal signal is also detected from an independent, fainter sample of source galaxies without photometric redshifts. Potential systematic effects, such as contamination by aligned satellite galaxies, the distortion of source shapes by the light of the foreground galaxies, PSF anisotropies, and contributions from mass distributed on the scale of galaxy groups are shown to be negligible. A comparison of our result with the local Tully-Fisher relation indicates that intermediate-redshift galaxies are fainter than local spirals by 1.0 +/- 0.6 B mag at a fixed circular velocity. This is consistent with some spectroscopic studies of the rotation curves of intermediate-redshift galaxies. This result suggests that the strong increase in the global luminosity density with redshift is dominated by evolution in the galaxy number density.

TADPOLE GALAXIES IN THE HUBBLE ULTRA DEEP FIELD

DOE Office of Scientific and Technical Information (OSTI.GOV)

Elmegreen, Bruce G.; Elmegreen, Debra Meloy, E-mail: bge@watson.ibm.co, E-mail: elmegreen@vassar.ed

2010-10-20

Tadpole galaxies have a head-tail shape with a large clump of star formation at the head and a diffuse tail or streak of stars off to one side. We measured the head and tail masses, ages, surface brightnesses, and sizes for 66 tadpoles in the Hubble Ultra Deep Field (UDF) and looked at the distribution of neighbor densities and tadpole orientations with respect to neighbors. The heads have masses of 10{sup 7}-10{sup 8} M{sub sun} and photometric ages of {approx}0.1 Gyr for z {approx} 2. The tails have slightly larger masses than the heads and comparable or slightly older ages.more » The most obvious interpretation of tadpoles as young merger remnants is difficult to verify. They have no enhanced proximity to other resolved galaxies as a class, and the heads, typically <0.2 kpc in diameter, usually have no obvious double-core structure. Another possibility is ram pressure interaction between a gas-rich galaxy and a diffuse cosmological flow. Ram pressure can trigger star formation on one side of a galaxy disk, giving the tadpole shape when viewed edge-on. Ram pressure can also strip away gas from a galaxy and put it into a tail, which then forms new stars and gravitationally drags along old stars with it. Such an effect might have already been observed in the Virgo Cluster. Another possibility is that tadpoles are edge-on disks with large, off-center clumps. Analogous lop-sided star formation in UDF clump clusters is shown.« less

Dust attenuation in 2 < z < 3 star-forming galaxies from deep ALMA observations of the Hubble Ultra Deep Field

NASA Astrophysics Data System (ADS)

McLure, R. J.; Dunlop, J. S.; Cullen, F.; Bourne, N.; Best, P. N.; Khochfar, S.; Bowler, R. A. A.; Biggs, A. D.; Geach, J. E.; Scott, D.; Michałowski, M. J.; Rujopakarn, W.; van Kampen, E.; Kirkpatrick, A.; Pope, A.

2018-05-01

We present the results of a new study of the relationship between infrared excess (IRX ≡ LIR/LUV), ultraviolet (UV) spectral slope (β) and stellar mass at redshifts 2 < z < 3, based on a deep Atacama Large Millimeter Array (ALMA) 1.3-mm continuum mosaic of the Hubble Ultra Deep Field. Excluding the most heavily obscured sources, we use a stacking analysis to show that z ≃ 2.5 star-forming galaxies in the mass range 9.25≤ log (M_{\\ast }/M_{⊙}) ≤ 10.75 are fully consistent with the IRX-β relation expected for a relatively grey attenuation curve, similar to the commonly adopted Calzetti law. Based on a large, mass-complete sample of 2 ≤ z ≤ 3 star-forming galaxies drawn from multiple surveys, we proceed to derive a new empirical relationship between β and stellar mass, making it possible to predict UV attenuation (A1600) and IRX as a function of stellar mass, for any assumed attenuation law. Once again, we find that z ≃ 2.5 star-forming galaxies follow A1600-M* and IRX-M* relations consistent with a relatively grey attenuation law, and find no compelling evidence that star-forming galaxies at this epoch follow a reddening law as steep as the Small Magellanic Cloud (SMC) extinction curve. In fact, we use a simple simulation to demonstrate that previous determinations of the IRX-β relation may have been biased towards low values of IRX at red values of β, mimicking the signature expected for an SMC-like dust law. We show that this provides a plausible mechanism for reconciling apparently contradictory results in the literature and that, based on typical measurement uncertainties, stellar mass provides a cleaner prediction of UV attenuation than β. Although the situation at lower stellar masses remains uncertain, we conclude that for 2 < z < 3 star-forming galaxies with log (M_{\\ast }/M_{⊙}) ≥ 9.75, both the IRX-β and IRX-M* relations are well described by a Calzetti-like attenuation law.

The MUSE Hubble Ultra Deep Field Survey. VII. Fe II* emission in star-forming galaxies

NASA Astrophysics Data System (ADS)

Finley, Hayley; Bouché, Nicolas; Contini, Thierry; Paalvast, Mieke; Boogaard, Leindert; Maseda, Michael; Bacon, Roland; Blaizot, Jérémy; Brinchmann, Jarle; Epinat, Benoît; Feltre, Anna; Marino, Raffaella Anna; Muzahid, Sowgat; Richard, Johan; Schaye, Joop; Verhamme, Anne; Weilbacher, Peter M.; Wisotzki, Lutz

2017-11-01

Non-resonant Fe II* (λ2365, λ2396, λ2612, λ2626) emission can potentially trace galactic winds in emission and provide useful constraints to wind models. From the 3.15' × 3.15' mosaic of the Hubble Ultra Deep Field (UDF) obtained with the VLT/MUSE integral field spectrograph, we identify a statistical sample of 40 Fe II* emitters and 50 MgIII (λλ2796,2803) emitters from a sample of 271 [O II]λλ3726,3729 emitters with reliable redshifts from z = 0.85-1.50 down to 2 × 10-18 (3σ) ergs s-1 cm-2 (for [O II]), covering the M⋆ range from 108-1011 M⊙. The Fe II* and Mg II emitters follow the galaxy main sequence, but with a clear dichotomy. Galaxies with masses below 109 M⊙ and star formation rates (SFRs) of ≲ 1 M⊙ yr-1 have MgIII emission without accompanying Fe II* emission, whereas galaxies with masses above 1010 M⊙ and SFRs ≳ 10 M⊙ yr-1 have Fe II* emission without accompanying MgIII emission. Between these two regimes, galaxies have both MgIII and Fe II* emission, typically with MgIII P Cygni profiles. Indeed, the MgIII profile shows a progression along the main sequence from pure emission to P Cygni profiles to strong absorption, due to resonant trapping. Combining the deep MUSE data with HST ancillary information, we find that galaxies with pure MgIII emission profiles have lower SFR surface densities than those with either MgIII P Cygni profiles or Fe II* emission. These spectral signatures produced through continuum scattering and fluorescence, MgIII P Cygni profiles and Fe II* emission, are better candidates for tracing galactic outflows than pure MgIII emission, which may originate from HIII regions. We compare the absorption and emission rest-frame equivalent widths for pairs of FeIII transitions to predictions from outflow models and find that the observations consistently have less total re-emission than absorption, suggesting either dust extinction or non-isotropic outflow geometries.

Planets to Cosmology

NASA Astrophysics Data System (ADS)

Livio, Mario; Casertano, Stefano

2011-11-01

Preface; 1. Hubble's view of transiting planets D. Charbonneau; 2. Unsolved problems in star formation C. J. Clarke; 3. Star formation in clusters S. S. Larson; 4. HST abundance studies of low metallicity stars J. W. Truran, C. Sneden, F. Primas, J. J. Cowan and T. Beers; 5. Physical environments and feedback: HST studies of intense star-forming environments J. S. Gallagher, L. J. Smith and R. W. O'Connell; 6. Quasar hosts: growing up with monstrous middles K. K. McLeod; 7. Reverberation mapping of active galactic nuclei B. M. Peterson and K. Horne; 8. Feedback at high redshift A. E. Shapley; 9. The baryon content of the local intergalactic medium J. T. Stocke, J. M. Shull, and S. V. Penton; 10. Hot baryons in supercluster filaments E. D. Miller, R. A. Dupke and J. N. Bregman; 11. Galaxy assembly E. F. Bell; 12. Probing the reionization history of the Universe Z. Haiman; 13. Studying distant infrared-luminous galaxies with Spitzer and Hubble C. Papovich, E. Egami, E. Le Floc'h, P. Pérez-González, G. Rieke, J. Rigby, H. Dole and M. Reike; 14. Galaxies at z = g-i'-drop selection and the GLARE Project E. R. Stanway, K. Glazebrook, A. J. Bunker and the GLARE Consortium; 15. The Hubble Ultra Deep Field with NIMCOS R. I. Thompson, R. J. Bouwens and G. Illingworth.

Planets to Cosmology

NASA Astrophysics Data System (ADS)

Livio, Mario; Casertano, Stefano

2006-04-01

Preface; 1. Hubble's view of transiting planets D. Charbonneau; 2. Unsolved problems in star formation C. J. Clarke; 3. Star formation in clusters S. S. Larson; 4. HST abundance studies of low metallicity stars J. W. Truran, C. Sneden, F. Primas, J. J. Cowan and T. Beers; 5. Physical environments and feedback: HST studies of intense star-forming environments J. S. Gallagher, L. J. Smith and R. W. O'Connell; 6. Quasar hosts: growing up with monstrous middles K. K. McLeod; 7. Reverberation mapping of active galactic nuclei B. M. Peterson and K. Horne; 8. Feedback at high redshift A. E. Shapley; 9. The baryon content of the local intergalactic medium J. T. Stocke, J. M. Shull, and S. V. Penton; 10. Hot baryons in supercluster filaments E. D. Miller, R. A. Dupke and J. N. Bregman; 11. Galaxy assembly E. F. Bell; 12. Probing the reionization history of the Universe Z. Haiman; 13. Studying distant infrared-luminous galaxies with Spitzer and Hubble C. Papovich, E. Egami, E. Le Floc'h, P. Pérez-González, G. Rieke, J. Rigby, H. Dole and M. Reike; 14. Galaxies at z = g-i'-drop selection and the GLARE Project E. R. Stanway, K. Glazebrook, A. J. Bunker and the GLARE Consortium; 15. The Hubble Ultra Deep Field with NIMCOS R. I. Thompson, R. J. Bouwens and G. Illingworth.

Multi-Wavelength Diagnostics of Starbirth in Starbursts

NASA Astrophysics Data System (ADS)

Waller, William

2005-07-01

From the Orion Nebula to the Hubble Deep Field, starburst activity can be seen transforming galaxian clouds of gas into populous clusters of stars. The pyrotechnics and chemical enrichment associated with this activity have led to outcomes as ubiquitous as interstellar dust and as exquisite as life on Earth. In this talk, I will focus on the circumstances of star formation in the environmental context of ongoing starburst activity. I begin with the premises that (1) the formation of a single star takes time, (2) the formation of a populous cluster takes even more time, and (3) ``stuff'' happens in the interim. Hubble images of the Orion Nebula and Eagle Nebula show how hot stars can excavate neighboring clouds of gas and photoevaporate the star-forming cores that are exposed. Hubble observations of giant HII regions in M33 reveal a significant variation in the stellar populations, such that the most metal-rich HII regions contain the greatest proportions of the most massive stars. ISO and Spitzer observations of these same HII regions reveal corresponding variations in the nebular response. These multi-wavelength diagnostics of the stellar-nebular feedback in galaxian starbursts suggest a star-forming mechanism which is subject to photo-evaporative ablation -- an erosive process that is mediated by the metal abundance and corresponding amounts of protective dust in the starbursting environment.

Hubble Captures Celestial Fireworks Within the Large Magellanic Cloud

NASA Technical Reports Server (NTRS)

2000-01-01

This is a color Hubble Space Telescope (HST) heritage image of supernova remnant N49, a neighboring galaxy, that was taken with Hubble's Wide Field Planetary Camera 2. Color filters were used to sample light emitted by sulfur, oxygen, and hydrogen. The color image was superimposed on a black and white image of stars in the same field also taken with Hubble. Resembling a fireworks display, these delicate filaments are actually sheets of debris from a stellar explosion.

History of Hubble Space Telescope (HST)

NASA Image and Video Library

2000-07-01

This is a color Hubble Space Telescope (HST) heritage image of supernova remnant N49, a neighboring galaxy, that was taken with Hubble's Wide Field Planetary Camera 2. Color filters were used to sample light emitted by sulfur, oxygen, and hydrogen. The color image was superimposed on a black and white image of stars in the same field also taken with Hubble. Resembling a fireworks display, these delicate filaments are actually sheets of debris from a stellar explosion.

The star formation history of the Hubble sequence: spatially resolved colour distributions of intermediate-redshift galaxies in the Hubble Deep Field

NASA Astrophysics Data System (ADS)

Abraham, R. G.; Ellis, R. S.; Fabian, A. C.; Tanvir, N. R.; Glazebrook, K.

1999-03-01

We analyse the spatially resolved colours of distant galaxies of known redshift in the Hubble Deep Field, using a new technique based on matching resolved four-band colour data to the predictions of evolutionary synthesis models. Given some simplifying assumptions, we demonstrate how our technique is capable of probing the evolutionary history of high-redshift systems, noting the specific advantage of observing galaxies at an epoch closer to the time of their formation. We quantify the relative age, dispersion in age, on-going star formation rate and star formation history of distinct components. We explicitly test for the presence of dust and quantify its effect on our conclusions. To demonstrate the potential of the method, we study the spirals and ellipticals in the near-complete sample of 32 I_814<21.9 mag galaxies with z~0.5 studied by Bouwens, Broadhurst & Silk. The dispersion of the internal colours of a sample of 0.4

FAR-FLUNG GALAXY CLUSTERS MAY REVEAL FATE OF UNIVERSE

NASA Technical Reports Server (NTRS)

2002-01-01

A selection of NASA Hubble Space Telescope snapshots of huge galaxy clusters that lie far away and far back in time. These are selected from a catalog of 92 new clusters uncovered during a six-year Hubble observing program known as the Medium Deep Survey. If the distances and masses of the clusters are confirmed by ground based telescopes, the survey may hold clues to how galaxies quickly formed into massive large-scale structures after the big bang, and what that may mean for the eventual fate of the expanding universe. The images are each a combination of two exposures in yellow and deep red taken with Hubble's Wide Field and Planetary Camera 2. Each cluster's distance is inferred from the reddening of the starlight, which is due to the expansion of space. Astronomers assume these clusters all formed early in the history of the universe. HST133617-00529 (left) This collection of spiral and elliptical galaxies lies an estimated 4 to 6 billion light-years away. It is in the constellation of Virgo not far from the 3rd magnitude star Zeta Virginis. The brighter galaxies in this cluster have red magnitudes between 20 and 22 near the limit of the Palomar Sky Survey. The bright blue galaxy (upper left) is probably a foreground galaxy, and not a cluster member. The larger of the galaxies in the cluster are probably about the size of our Milky Way Galaxy. The diagonal line at lower right is an artificial satellite trail. HST002013+28366 (upper right) This cluster of galaxies lies in the constellation of Andromeda a few degrees from the star Alpheratz in the northeast corner of the constellation Pegasus. It is at an estimated distance of 4 billion light-years, which means the light we are seeing from the cluster is as it appeared when the universe was roughly 2/3 of its present age. HST035528+09435 (lower right) At an estimated distance of about 7 to 10 billion light-years (z=1), this is one of the farthest clusters in the Hubble sample. The cluster lies in the constellation of Taurus. Credit: K. Ratnatunga, R. Griffiths (Carnegie Mellon University); and NASA

Mothers of Invention: Hubble Engineers Push Robotic 'Evolution' to Save Telescope, Enable New Exploration

NASA Technical Reports Server (NTRS)

Morring, Frank, Jr.

2004-01-01

Robotic technology being developed out of necessity to keep the Hubble Space Telescope operating could also lead to new levels of man-machine team-work in deep-space exploration down the road-if it survives the near-term scramble for funding. Engineers here who have devoted their NASA careers to the concept of humans servicing the telescope in orbit are planning modifications to International Space Station (ISS) robots that would leave the humans on the ground. The work. forced by post-Columbia flight rules that killed a planned shuttle-servicing mission to Hubble, marks another step in the evolution of robot-partners for human space explorers. "Hubble has always been a pathfider for this agency," says Mike Weiss. Hubble deputy program manager technical. "When the space station was flown and assembled, Hubble was the pathfinder. not just for modularity, but for operations, for assembly techniques. Exploration is the next step. Things we're going to do on Hubble are going to be applied to exploration. It's not just putting a robot in space. It's operating a robot in space. It's adapting that robot to what needs to be done the next time you're up there."

NASA's Hubble Universe in 3-D

NASA Image and Video Library

2017-12-08

This image depicts a vast canyon of dust and gas in the Orion Nebula from a 3-D computer model based on observations by NASA's Hubble Space Telescope and created by science visualization specialists at the Space Telescope Science Institute (STScI) in Baltimore, Md. A 3-D visualization of this model takes viewers on an amazing four-minute voyage through the 15-light-year-wide canyon. Credit: NASA, G. Bacon, L. Frattare, Z. Levay, and F. Summers (STScI/AURA) Go here to learn more about Hubble 3D: www.nasa.gov/topics/universe/features/hubble_imax_premier... or www.imax.com/hubble/ Take an exhilarating ride through the Orion Nebula, a vast star-making factory 1,500 light-years away. Swoop through Orion's giant canyon of gas and dust. Fly past behemoth stars whose brilliant light illuminates and energizes the entire cloudy region. Zoom by dusty tadpole-shaped objects that are fledgling solar systems. This virtual space journey isn't the latest video game but one of several groundbreaking astronomy visualizations created by specialists at the Space Telescope Science Institute (STScI) in Baltimore, the science operations center for NASA's Hubble Space Telescope. The cinematic space odysseys are part of the new Imax film "Hubble 3D," which opens today at select Imax theaters worldwide. The 43-minute movie chronicles the 20-year life of Hubble and includes highlights from the May 2009 servicing mission to the Earth-orbiting observatory, with footage taken by the astronauts. The giant-screen film showcases some of Hubble's breathtaking iconic pictures, such as the Eagle Nebula's "Pillars of Creation," as well as stunning views taken by the newly installed Wide Field Camera 3. While Hubble pictures of celestial objects are awe-inspiring, they are flat 2-D photographs. For this film, those 2-D images have been converted into 3-D environments, giving the audience the impression they are space travelers taking a tour of Hubble's most popular targets. "A large-format movie is a truly immersive experience," says Frank Summers, an STScI astronomer and science visualization specialist who led the team that developed the movie visualizations. The team labored for nine months, working on four visualization sequences that comprise about 12 minutes of the movie. "Seeing these Hubble images in 3-D, you feel like you are flying through space and not just looking at picture postcards," Summers continued. "The spacescapes are all based on Hubble images and data, though some artistic license is necessary to produce the full depth of field needed for 3-D." The most ambitious sequence is a four-minute voyage through the Orion Nebula's gas-and-dust canyon, about 15 light-years across. During the ride, viewers will see bright and dark, gaseous clouds; thousands of stars, including a grouping of bright, hefty stars called the Trapezium; and embryonic planetary systems. The tour ends with a detailed look at a young circumstellar disk, which is much like the structure from which our solar system formed 4.5 billion years ago. Based on a Hubble image of Orion released in 2006, the visualization was a collaborative effort between science visualization specialists at STScI, including Greg Bacon, who sculpted the Orion Nebula digital model, with input from STScI astronomer Massimo Roberto; the National Center for Supercomputing Applications at the University of Illinois at Urbana-Champaign; and the Spitzer Science Center at the California Institute of Technology in Pasadena. For some of the sequences, STScI imaging specialists developed new techniques for transforming the 2-D Hubble images into 3-D. STScI image processing specialists Lisa Frattare and Zolt Levay, for example, created methods of splitting a giant gaseous pillar in the Carina Nebula into multiple layers to produce a 3-D effect, giving the structure depth. The Carina Nebula is a nursery for baby stars. Frattare painstakingly removed the thousands of stars in the image so that Levay could separate the gaseous layers on the isolated Carina pillar. Frattare then replaced the stars into both foreground and background layers to complete the 3-D model. For added effect, the same separation was done for both visible and infrared Hubble images, allowing the film to cross-fade between wavelength views in 3-D. In another sequence viewers fly into a field of 170,000 stars in the giant star cluster Omega Centauri. STScI astronomer Jay Anderson used his stellar database to create a synthetic star field in 3-D that matches recent razor-sharp Hubble photos. The film's final four-minute sequence takes viewers on a voyage from our Milky Way Galaxy past many of Hubble's best galaxy shots and deep into space. Some 15,000 galaxies from Hubble's deepest surveys stretch billions of light-years across the universe in a 3-D sequence created by STScI astronomers and visualizers. The view dissolves into a cobweb that traces the universe's large-scale structure, the backbone from which galaxies were born. In addition to creating visualizations, STScI's education group also provided guidance on the "Hubble 3D" Educator Guide, which includes standards-based lesson plans and activities about Hubble and its mission. Students will use the guide before or after seeing the movie. "The guide will enhance the movie experience for students and extend the movie into classrooms," says Bonnie Eisenhamer, STScI's Hubble Formal Education manager. The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency (ESA) and is managed by NASA’s Goddard Space Flight Center (GSFC) in Greenbelt, Md. The Space Telescope Science Institute (STScI) conducts Hubble science operations. The institute is operated for NASA by the Association of Universities for Research in Astronomy, Inc., Washington, D.C.

The Morphology of Passively Evolving Galaxies at Z-2 from HST/WFC3 in the Hubble Ultra Deep Field

NASA Technical Reports Server (NTRS)

Cassata, P.; Giavalisco, M.; Guo, Yicheng; Ferguson, H.; Koekemoer, A.; Renzini, A.; Fontana, A.; Salimbeni, S.; Dickinson, M.; Casertano, S.;

The MUSE Hubble Ultra Deep Field Survey. VI. The faint-end of the Lyα luminosity function at 2.91 < z < 6.64 and implications for reionisation

NASA Astrophysics Data System (ADS)

Drake, A. B.; Garel, T.; Wisotzki, L.; Leclercq, F.; Hashimoto, T.; Richard, J.; Bacon, R.; Blaizot, J.; Caruana, J.; Conseil, S.; Contini, T.; Guiderdoni, B.; Herenz, E. C.; Inami, H.; Lewis, J.; Mahler, G.; Marino, R. A.; Pello, R.; Schaye, J.; Verhamme, A.; Ventou, E.; Weilbacher, P. M.

2017-11-01

We present the deepest study to date of the Lyα luminosity function in a blank field using blind integral field spectroscopy from MUSE. We constructed a sample of 604 Lyα emitters (LAEs) across the redshift range 2.91 < z < 6.64 using automatic detection software in the Hubble Ultra Deep Field. The deep data cubes allowed us to calculate accurate total Lyα fluxes capturing low surface-brightness extended Lyα emission now known to be a generic property of high-redshift star-forming galaxies. We simulated realistic extended LAEs to fully characterise the selection function of our samples, and performed flux-recovery experiments to test and correct for bias in our determination of total Lyα fluxes. We find that an accurate completeness correction accounting for extended emission reveals a very steep faint-end slope of the luminosity function, α, down to luminosities of log10L erg s-1< 41.5, applying both the 1 /Vmax and maximum likelihood estimators. Splitting the sample into three broad redshift bins, we see the faint-end slope increasing from -2.03-0.07+ 1.42 at z ≈ 3.44 to -2.86-∞+0.76 at z ≈ 5.48, however no strong evolution is seen between the 68% confidence regions in L∗-α parameter space. Using the Lyα line flux as a proxy for star formation activity, and integrating the observed luminosity functions, we find that LAEs' contribution to the cosmic star formation rate density rises with redshift until it is comparable to that from continuum-selected samples by z ≈ 6. This implies that LAEs may contribute more to the star-formation activity of the early Universe than previously thought, as any additional intergalactic medium (IGM) correction would act to further boost the Lyα luminosities. Finally, assuming fiducial values for the escape of Lyα and LyC radiation, and the clumpiness of the IGM, we integrated the maximum likelihood luminosity function at 5.00

HUBBLE PINPOINTS WHITE DWARFS IN GLOBULAR CLUSTER

NASA Technical Reports Server (NTRS)

2002-01-01

Peering deep inside a cluster of several hundred thousand stars, NASA's Hubble Space Telescope uncovered the oldest burned-out stars in our Milky Way Galaxy. Located in the globular cluster M4, these small, dying stars - called white dwarfs - are giving astronomers a fresh reading on one of the biggest questions in astronomy: How old is the universe? The ancient white dwarfs in M4 are about 12 to 13 billion years old. After accounting for the time it took the cluster to form after the big bang, astronomers found that the age of the white dwarfs agrees with previous estimates for the universe's age. In the top panel, a ground-based observatory snapped a panoramic view of the entire cluster, which contains several hundred thousand stars within a volume of 10 to 30 light-years across. The Kitt Peak National Observatory's 0.9-meter telescope took this picture in March 1995. The box at left indicates the region observed by the Hubble telescope. The Hubble telescope studied a small region of the cluster. A section of that region is seen in the picture at bottom left. A sampling of an even smaller region is shown at bottom right. This region is only about one light-year across. In this smaller region, Hubble pinpointed a number of faint white dwarfs. The blue circles pinpoint the dwarfs. It took nearly eight days of exposure time over a 67-day period to find these extremely faint stars. Globular clusters are among the oldest clusters of stars in the universe. The faintest and coolest white dwarfs within globular clusters can yield a globular cluster's age. Earlier Hubble observations showed that the first stars formed less than 1 billion years after the universe's birth in the big bang. So, finding the oldest stars puts astronomers within arm's reach of the universe's age. M4 is 7,000 light-years away in the constellation Scorpius. Hubble's Wide Field and Planetary Camera 2 made the observations from January through April 2001. These optical observations were combined to create the above images. Spectral data were also taken. Credit for Hubble telescope photos: NASA and H. Richer (University of British Columbia) Credit for ground-based photo: NOAO/AURA/NSF

Evolution in the Continuum Morphological Properties of Ly alpha-Emitting Galaxies from Z=3.1 to Z=2.1

NASA Technical Reports Server (NTRS)

Bond, Nicholas A.; Gawiser, Eric; Guaita, Lucia; Padilla, Nelson; Gronwall, Chile Caryl; Ciardullo, Robin; Lai, Kamson

2011-01-01

We present a rest-frame ultraviolet morphological analysis of 108 z = 2.1 Lyman Alpha Emitters (LAEs) in the Extended Chandra Deep Field South (ECDF-S) and compare it to a similar sample of 171 LAEs at z = 3.1 . Using Hubble Space Telescope (HST) images taken as part of the Galaxy Evolution From Morphology and SEDs survey, Great Observatories Origins Deep Survey, and Hubble Ultradeep Field surveys, we measure the size and photometric component distributions, where photo- metric components are defined as distinct clumps of UV-continuum emission. At both redshifts, the majority of LAEs have observed half-light radii < 2 kpc, but the median half-light radius rises from 0.97 kpc at z = 3.1 to 1.41 kpc at z = 2.1. A similar evolution is seen in the sizes of individual rest-UV components, but there is no evidence for evolution in the number of mUlti-component systems. In the z = 2.1 LAE sample, we see clear correlations between the LAE size and other physical properties derived from its SED. LAEs are found to be larger for galaxies with larger stellar mass, larger star formation rate, and larger dust obscuration, but there is no evidence for a trend between equivalent width and half-light radius at either redshift. The presence of these correlations suggests that a wide range of objects are being selected by LAE surveys at that redshift, including a significant fraction of objects for which a massive and moderately extended population of old stars underlies the young starburst giving rise to the Lya emission.

ALMA SPECTROSCOPIC SURVEY IN THE HUBBLE ULTRA DEEP FIELD: CO LUMINOSITY FUNCTIONS AND THE EVOLUTION OF THE COSMIC DENSITY OF MOLECULAR GAS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Decarli, Roberto; Walter, Fabian; Aravena, Manuel

2016-12-10

In this paper we use ASPECS, the ALMA Spectroscopic Survey in the Hubble Ultra Deep Field in band 3 and band 6, to place blind constraints on the CO luminosity function and the evolution of the cosmic molecular gas density as a function of redshift up to z  ∼ 4.5. This study is based on galaxies that have been selected solely through their CO emission and not through any other property. In all of the redshift bins the ASPECS measurements reach the predicted “knee” of the CO luminosity function (around 5 × 10{sup 9} K km s{sup −1} pc{sup 2}). We find clear evidence ofmore » an evolution in the CO luminosity function with respect to z  ∼ 0, with more CO-luminous galaxies present at z  ∼ 2. The observed galaxies at z  ∼ 2 also appear more gas-rich than predicted by recent semi-analytical models. The comoving cosmic molecular gas density within galaxies as a function of redshift shows a drop by a factor of 3–10 from z  ∼ 2 to z  ∼ 0 (with significant error bars), and possibly a decline at z  > 3. This trend is similar to the observed evolution of the cosmic star formation rate density. The latter therefore appears to be at least partly driven by the increased availability of molecular gas reservoirs at the peak of cosmic star formation ( z  ∼ 2).« less

Star Formation at z = 2.481 in the Lensed Galaxy SDSS J1110+6459. II. What is Missed at the Normal Resolution of the Hubble Space Telescope?

NASA Astrophysics Data System (ADS)

Rigby, J. R.; Johnson, T. L.; Sharon, K.; Whitaker, K.; Gladders, M. D.; Florian, M.; Lotz, J.; Bayliss, M.; Wuyts, E.

2017-07-01

For lensed galaxy SGAS J111020.0+645950.8 at redshift z = 2.481, which is magnified by a factor of 28 ± 8, we analyze the morphology of star formation, as traced by rest-frame ultraviolet emission, in both the highly magnified source plane and simulations of how this galaxy would appear without lensing magnification. Were this galaxy not lensed, but rather drawn from a Hubble Space Telescope deep field, we would conclude that almost all its star formation arises from an exponential disk (Sérsic index of 1.0 ± 0.4) with an effective radius of {r}e=2.7+/- 0.3 {kpc} measured from two-dimensional fitting to F606W using Galfit, and {r}e=1.9+/- 0.1 {kpc} measured by fitting a radial profile to F606W elliptical isophotes. At the normal spatial resolution of the deep fields, there is no sign of clumpy star formation within SGAS J111020.0+645950.8. However, the enhanced spatial resolution enabled by gravitational lensing tells a very different story; much of the star formation arises in two dozen clumps with sizes of r = 30-50 pc spread across the 7 kpc length of the galaxy. The color and spatial distribution of the diffuse component suggests that still-smaller clumps are unresolved. Despite this clumpy, messy morphology, the radial profile is still well-characterized by an exponential profile. In this lensed galaxy, stars are forming in complexes with sizes well below 100 pc such sizes are wholly unexplored by surveys of galaxy evolution at 1< z< 3.

The structure of clusters of galaxies

NASA Astrophysics Data System (ADS)

Fox, David Charles

When infalling gas is accreted onto a cluster of galaxies, its kinetic energy is converted to thermal energy in a shock, heating the ions. Using a self-similar spherical model, we calculate the collisional heating of the electrons by the ions, and predict the electron and ion temperature profiles. While there are significant differences between the two, they occur at radii larger than currently observable, and too large to explain observed X-ray temperature declines in clusters. Numerical simulations by Navarro, Frenk, & White (1996) predict a universal dark matter density profile. We calculate the expected number of multiply-imaged background galaxies in the Hubble Deep Field due to foreground groups and clusters with this profile. Such groups are up to 1000 times less efficient at lensing than the standard singular isothermal spheres. However, with either profile, the expected number of galaxies lensed by groups in the Hubble Deep Field is at most one, consistent with the lack of clearly identified group lenses. X-ray and Sunyaev-Zel'dovich (SZ) effect observations can be combined to determine the distance to clusters of galaxies, provided the clusters are spherical. When applied to an aspherical cluster, this method gives an incorrect distance. We demonstrate a method for inferring the three-dimensional shape of a cluster and its correct distance from X-ray, SZ effect, and weak gravitational lensing observations, under the assumption of hydrostatic equilibrium. We apply this method to simple, analytic models of clusters, and to a numerically simulated cluster. Using artificial observations based on current X-ray and SZ effect instruments, we recover the true distance without detectable bias and with uncertainties of 4 percent.

The Hubble Space Telescope Frontier Fields Program

NASA Astrophysics Data System (ADS)

Koekemoer, Anton M.; Mack, Jennifer; Lotz, Jennifer M.; Borncamp, David; Khandrika, Harish G.; Lucas, Ray A.; Martlin, Catherine; Porterfield, Blair; Sunnquist, Ben; Anderson, Jay; Avila, Roberto J.; Barker, Elizabeth A.; Grogin, Norman A.; Gunning, Heather C.; Hilbert, Bryan; Ogaz, Sara; Robberto, Massimo; Sembach, Kenneth; Flanagan, Kathryn; Mountain, Matt

2017-08-01

The Hubble Space Telescope Frontier Fields program is a large Director's Discretionary program of 840 orbits, to obtain ultra-deep observations of six strong lensing clusters of galaxies, together with parallel deep blank fields, making use of the strong lensing amplification by these clusters of distant background galaxies to detect the faintest galaxies currently observable in the high-redshift universe. The entire program has now completed successfully for all 6 clusters, namely Abell 2744, Abell S1063, Abell 370, MACS J0416.1-2403, MACS J0717.5+3745 and MACS J1149.5+2223,. Each of these was observed over two epochs, to a total depth of 140 orbits on the main cluster and an associated parallel field, obtaining images in ACS (F435W, F606W, F814W) and WFC3/IR (F105W, F125W, F140W, F160W) on both the main cluster and the parallel field in all cases. Full sets of high-level science products have been generated for all these clusters by the team at STScI, including cumulative-depth data releases during each epoch, as well as full-depth releases after the completion of each epoch. These products include all the full-depth distortion-corrected drizzled mosaics and associated products for each cluster, which are science-ready to facilitate the construction of lensing models as well as enabling a wide range of other science projects. Many improvements beyond default calibration for ACS and WFC3/IR are implemented in these data products, including corrections for persistence, time-variable sky, and low-level dark current residuals, as well as improvements in astrometric alignment to achieve milliarcsecond-level accuracy. The full set of resulting high-level science products and mosaics are publicly delivered to the community via the Mikulski Archive for Space Telescopes (MAST) to enable the widest scientific use of these data, as well as ensuring a public legacy dataset of the highest possible quality that is of lasting value to the entire community.

AEGIS-X: Deep Chandra Imaging of the Central Groth Strip

NASA Astrophysics Data System (ADS)

Nandra, K.; Laird, E. S.; Aird, J. A.; Salvato, M.; Georgakakis, A.; Barro, G.; Perez-Gonzalez, P. G.; Barmby, P.; Chary, R.-R.; Coil, A.; Cooper, M. C.; Davis, M.; Dickinson, M.; Faber, S. M.; Fazio, G. G.; Guhathakurta, P.; Gwyn, S.; Hsu, L.-T.; Huang, J.-S.; Ivison, R. J.; Koo, D. C.; Newman, J. A.; Rangel, C.; Yamada, T.; Willmer, C.

2015-09-01

We present the results of deep Chandra imaging of the central region of the Extended Groth Strip, the AEGIS-X Deep (AEGIS-XD) survey. When combined with previous Chandra observations of a wider area of the strip, AEGIS-X Wide (AEGIS-XW), these provide data to a nominal exposure depth of 800 ks in the three central ACIS-I fields, a region of approximately 0.29 deg2. This is currently the third deepest X-ray survey in existence; a factor ∼ 2-3 shallower than the Chandra Deep Fields (CDFs), but over an area ∼3 times greater than each CDF. We present a catalog of 937 point sources detected in the deep Chandra observations, along with identifications of our X-ray sources from deep ground-based, Spitzer, GALEX, and Hubble Space Telescope imaging. Using a likelihood ratio analysis, we associate multiband counterparts for 929/937 of our X-ray sources, with an estimated 95% reliability, making the identification completeness approximately 94% in a statistical sense. Reliable spectroscopic redshifts for 353 of our X-ray sources are available predominantly from Keck (DEEP2/3) and MMT Hectospec, so the current spectroscopic completeness is ∼38%. For the remainder of the X-ray sources, we compute photometric redshifts based on multiband photometry in up to 35 bands from the UV to mid-IR. Particular attention is given to the fact that the vast majority the X-ray sources are active galactic nuclei and require hybrid templates. Our photometric redshifts have mean accuracy of σ =0.04 and an outlier fraction of approximately 5%, reaching σ =0.03 with less than 4% outliers in the area covered by CANDELS . The X-ray, multiwavelength photometry, and redshift catalogs are made publicly available.

X-UDS: The Chandra Legacy Survey of the UKIDSS Ultra Deep Survey Field

NASA Astrophysics Data System (ADS)

Kocevski, Dale D.; Hasinger, Guenther; Brightman, Murray; Nandra, Kirpal; Georgakakis, Antonis; Cappelluti, Nico; Civano, Francesca; Li, Yuxuan; Li, Yanxia; Aird, James; Alexander, David M.; Almaini, Omar; Brusa, Marcella; Buchner, Johannes; Comastri, Andrea; Conselice, Christopher J.; Dickinson, Mark A.; Finoguenov, Alexis; Gilli, Roberto; Koekemoer, Anton M.; Miyaji, Takamitsu; Mullaney, James R.; Papovich, Casey; Rosario, David; Salvato, Mara; Silverman, John D.; Somerville, Rachel S.; Ueda, Yoshihiro

2018-06-01

We present the X-UDS survey, a set of wide and deep Chandra observations of the Subaru-XMM Deep/UKIDSS Ultra Deep Survey (SXDS/UDS) field. The survey consists of 25 observations that cover a total area of 0.33 deg2. The observations are combined to provide a nominal depth of ∼600 ks in the central 100 arcmin2 region of the field that has been imaged with Hubble/WFC3 by the CANDELS survey and ∼200 ks in the remainder of the field. In this paper, we outline the survey’s scientific goals, describe our observing strategy, and detail our data reduction and point source detection algorithms. Our analysis has resulted in a total of 868 band-merged point sources detected with a false-positive Poisson probability of <1 × 10‑4. In addition, we present the results of an X-ray spectral analysis and provide best-fitting neutral hydrogen column densities, N H, as well as a sample of 51 Compton-thick active galactic nucleus candidates. Using this sample, we find the intrinsic Compton-thick fraction to be 30%–35% over a wide range in redshift (z = 0.1–3), suggesting the obscured fraction does not evolve very strongly with epoch. However, if we assume that the Compton-thick fraction is dependent on luminosity, as is seen for Compton-thin sources, then our results are consistent with a rise in the obscured fraction out to z ∼ 3. Finally, an examination of the host morphologies of our Compton-thick candidates shows a high fraction of morphological disturbances, in agreement with our previous results. All data products described in this paper are made available via a public website.

The ALMA Spectroscopic Survey in the Hubble Ultra Deep Field: Molecular Gas Reservoirs in High-redshift Galaxies

NASA Astrophysics Data System (ADS)

Decarli, Roberto; Walter, Fabian; Aravena, Manuel; Carilli, Chris; Bouwens, Rychard; da Cunha, Elisabete; Daddi, Emanuele; Elbaz, David; Riechers, Dominik; Smail, Ian; Swinbank, Mark; Weiss, Axel; Bacon, Roland; Bauer, Franz; Bell, Eric F.; Bertoldi, Frank; Chapman, Scott; Colina, Luis; Cortes, Paulo C.; Cox, Pierre; Gónzalez-López, Jorge; Inami, Hanae; Ivison, Rob; Hodge, Jacqueline; Karim, Alex; Magnelli, Benjamin; Ota, Kazuaki; Popping, Gergö; Rix, Hans-Walter; Sargent, Mark; van der Wel, Arjen; van der Werf, Paul

2016-12-01

We study the molecular gas properties of high-z galaxies observed in the ALMA Spectroscopic Survey (ASPECS) that targets an ˜1 arcmin2 region in the Hubble Ultra Deep Field (UDF), a blind survey of CO emission (tracing molecular gas) in the 3 and 1 mm bands. Of a total of 1302 galaxies in the field, 56 have spectroscopic redshifts and correspondingly well-defined physical properties. Among these, 11 have infrared luminosities {L}{IR}\\gt {10}11 {L}⊙ , I.e., a detection in CO emission was expected. Out of these, 7 are detected at various significance in CO, and 4 are undetected in CO emission. In the CO-detected sources, we find CO excitation conditions that are lower than those typically found in starburst/sub-mm galaxy/QSO environments. We use the CO luminosities (including limits for non-detections) to derive molecular gas masses. We discuss our findings in the context of previous molecular gas observations at high redshift (star formation law, gas depletion times, gas fractions): the CO-detected galaxies in the UDF tend to reside on the low-{L}{IR} envelope of the scatter in the {L}{IR}{--}{L}{CO}\\prime relation, but exceptions exist. For the CO-detected sources, we find an average depletion time of ˜1 Gyr, with significant scatter. The average molecular-to-stellar mass ratio ({M}{{H}2}/M *) is consistent with earlier measurements of main-sequence galaxies at these redshifts, and again shows large variations among sources. In some cases, we also measure dust continuum emission. On average, the dust-based estimates of the molecular gas are a factor ˜2-5× smaller than those based on CO. When we account for detections as well as non-detections, we find large diversity in the molecular gas properties of the high-redshift galaxies covered by ASPECS.

FRONTIER FIELDS CLUSTERS: DEEP CHANDRA OBSERVATIONS OF THE COMPLEX MERGER MACS J1149.6+2223

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ogrean, G. A.; Weeren, R. J. van; Jones, C.

2016-03-10

The Hubble Space Telescope Frontier Fields cluster MACS J1149.6+2223 is one of the most complex merging clusters, believed to consist of four dark matter halos. We present results from deep (365 ks) Chandra observations of the cluster, which reveal the most distant cold front (z  =  0.544) discovered to date. In the cluster outskirts, we also detect hints of a surface brightness edge that could be the bow shock preceding the cold front. The substructure analysis of the cluster identified several components with large relative radial velocities, thus indicating that at least some collisions occur almost along the line of sight.more » The inclination of the mergers with respect to the plane of the sky poses significant observational challenges at X-ray wavelengths. MACS J1149.6+2223 possibly hosts a steep-spectrum radio halo. If the steepness of the radio halo is confirmed, then the radio spectrum, combined with the relatively regular ICM morphology, could indicate that MACS J1149.6+2223 is an old merging cluster.« less

Frontier Fields Clusters: Deep Chandra Observations of the Complex Merger MACS J1149.6+2223

DOE PAGES

Ogrean, G. A.; Weeren, R. J. van; Jones, C.; ...

2016-03-04

The Hubble Space Telescope Frontier Fields cluster MACS J1149.6+2223 is one of the most complex merging clusters, believed to consist of four dark matter halos. Here, we present results from deep (365 ks) Chandra observations of the cluster, which reveal the most distant cold front (z = 0.544) discovered to date. In the cluster outskirts, we also detect hints of a surface brightness edge that could be the bow shock preceding the cold front. The substructure analysis of the cluster identified several components with large relative radial velocities, thus indicating that at least some collisions occur almost along the linemore » of sight. The inclination of the mergers with respect to the plane of the sky poses significant observational challenges at X-ray wavelengths. MACS J1149.6+2223 possibly hosts a steep-spectrum radio halo. Lastly, if the steepness of the radio halo is confirmed, then the radio spectrum, combined with the relatively regular ICM morphology, could indicate that MACS J1149.6+2223 is an old merging cluster.« less

White Dwarf Stars

NASA Technical Reports Server (NTRS)

1999-01-01

Peering deep inside a cluster of several hundred thousand stars, NASA's Hubble Space Telescope has uncovered the oldest burned-out stars in our Milky Way Galaxy, giving astronomers a fresh reading on the age of the universe.

Located in the globular cluster M4, these small, burned-out stars -- called white dwarfs -- are about 12 to 13 billion years old. By adding the one billion years it took the cluster to form after the Big Bang, astronomers found that the age of the white dwarfs agrees with previous estimates that the universe is 13 to 14 billion years old.

The images, including some taken by Hubble's Wide Field and Planetary Camera 2, are available online at

http://oposite.stsci.edu/pubinfo/pr/2002/10/ or

http://www.jpl.nasa.gov/images/wfpc .

The camera was designed and built by NASA's Jet Propulsion Laboratory, Pasadena, Calif.

In the top panel, a ground-based observatory snapped a panoramic view of the entire cluster, which contains several hundred thousand stars within a volume of 10 to 30 light-years across. The Kitt Peak National Observatory's .9-meter telescope took this picture in March 1995. The box at left indicates the region observed by the Hubble telescope.

The Hubble telescope studied a small region of the cluster. A section of that region is seen in the picture at bottom left. A sampling of an even smaller region is shown at bottom right. This region is only about one light-year across. In this smaller region, Hubble pinpointed a number of faint white dwarfs. The blue circles indicate the dwarfs. It took nearly eight days of exposure time over a 67-day period to find these extremely faint stars.

Globular clusters are among the oldest clusters of stars in the universe. The faintest and coolest white dwarfs within globular clusters can yield a globular cluster's age. Earlier Hubble observations showed that the first stars formed less than 1 billion years after the universe's birth in the big bang. So, finding the oldest stars puts astronomers within arm's reach of the universe's age.

Hubble's Wide Field and Planetary Camera 2 made the observations from January through April 2001. These optical observations were combined to create the above images. Spectral data were also taken. M4 is 7,000 light-years away in the constellation Scorpius.

The full press release on the latest findings is online at

http://oposite.stsci.edu/pubinfo/pr/2002/10/pr.html .

The Space Telescope Science Institute is operated by the Association of Universities for Research in Astronomy, Inc., for NASA under contract with the Goddard Space Flight Center, Greenbelt, Md. The Hubble Space Telescope is a project of international cooperation between the European Space Agency and NASA. The California Institute of Technology in Pasadena manages JPL for NASA.

Hubble's diagram and cosmic expansion

PubMed Central

Kirshner, Robert P.

2004-01-01

Edwin Hubble's classic article on the expanding universe appeared in PNAS in 1929 [Hubble, E. P. (1929) Proc. Natl. Acad. Sci. USA 15, 168–173]. The chief result, that a galaxy's distance is proportional to its redshift, is so well known and so deeply embedded into the language of astronomy through the Hubble diagram, the Hubble constant, Hubble's Law, and the Hubble time, that the article itself is rarely referenced. Even though Hubble's distances have a large systematic error, Hubble's velocities come chiefly from Vesto Melvin Slipher, and the interpretation in terms of the de Sitter effect is out of the mainstream of modern cosmology, this article opened the way to investigation of the expanding, evolving, and accelerating universe that engages today's burgeoning field of cosmology. PMID:14695886

Comparing Stellar Populations Across the Hubble Sequence

NASA Astrophysics Data System (ADS)

Loeffler, Shane; Kaleida, Catherine C.; Parkash, Vaishali

2015-01-01

Previous work (Jansen et al., 2000, Taylor et al., 2005) has revealed trends in the optical wavelength radial profiles of galaxies across the Hubble Sequence. Radial profiles offer insight into stellar populations, metallicity, and dust concentrations, aspects which are deeply tied to the individual evolution of a galaxy. The Nearby Field Galaxy Survey (NFGS) provides a sampling of nearby galaxies that spans the range of morphological types, luminosities, and masses. Currently available NFGS data includes optical radial surface profiles and spectra of 196 nearby galaxies. We aim to look for trends in the infrared portion of the spectrum for these galaxies, but find that existing 2MASS data is not sufficiently deep. Herein, we expand the available data for the NGFS galaxy IC1639 deeper into the infrared using new data taken with the Infrared Sideport Imager (ISPI) on the 4-m Blanco Telescope at the Cerro Tololo Inter-American Observatory (CTIO) in Chile. Images taken in J, H, and Ks were reduced using standard IRAF and IDL procedures. Photometric calibrations were completed by using the highest quality (AAA) 2MASS stars in the field. Aperture photometry was then performed on the galaxy and radial profiles of surface brightness, J-H color, and H-Ks color were produced. For IC1639, the new ISPI data reveals flat color gradients and surface brightness gradients that decrease with radius. These trends reveal an archetypal elliptical galaxy, with a relatively homogeneous stellar population, stellar density decreasing with radius, and little-to-no obscuration by dust. We have obtained ISPI images for an additional 8 galaxies, and further reduction and analysis of these data will allow for investigation of radial trends in the infrared for galaxies across the Hubble Sequence.

Planetary nebulae: 20 years of Hubble inquiry

NASA Astrophysics Data System (ADS)

Balick, Bruce

2012-08-01

The Hubble Space Telescope has served the critical roles of microscope and movie camera in the past 20 years of research on planetary nebulae (``PNe''). We have glimpsed the details of the evolving structures of neutral and ionized post-AGB objects, built ingenious heuristic models that mimic these structures, and constrained most of the relevant physical processes with careful observations and interpretation. We have searched for close physical binary stars with spatial resolution ~50 AU at 1 AU, located jets emerging from the nucleus at speeds up to 2000 km s-1 and matched newly discovered molecular and X-ray emission regions to physical substructures in order to better understand how stellar winds and ionizing radiation interact to form the lovely symmetries that are observed. Ultraviolet spectra of CNO in PNe help to uncover how stars process deep inside AGB stars with unstable nuclear burning zones. HST broadband imaging has been at the forefront of uncovering surprisingly complex wind morphologies produced at the tip of the AGB, and has led to an increasing realization of the potentially vital roles of close binary stars and emerging magnetic fields in shaping stellar winds.

The varying cosmological constant: a new approximation to the Friedmann equations and universe model

NASA Astrophysics Data System (ADS)

Öztaş, Ahmet M.; Dil, Emre; Smith, Michael L.

2018-05-01

We investigate the time-dependent nature of the cosmological constant, Λ, of the Einstein Field Equation (EFE). Beginning with the Einstein-Hilbert action as our fundamental principle we develop a modified version of the EFE allowing the value of Λ to vary as a function of time, Λ(t), indirectly, for an expanding universe. We follow the evolving Λ presuming four-dimensional space-time and a flat universe geometry and present derivations of Λ(t) as functions of the Hubble constant, matter density, and volume changes which can be traced back to the radiation epoch. The models are more detailed descriptions of the Λ dependence on cosmological factors than previous, allowing calculations of the important parameters, Ωm and Ωr, to deep lookback times. Since we derive these without the need for extra dimensions or other special conditions our derivations are useful for model evaluation with astronomical data. This should aid resolution of several difficult problems of astronomy such as the best value for the Hubble constant at present and at recombination.

Full-data Results of Hubble Frontier Fields: UV Luminosity Functions at z ∼ 6–10 and a Consistent Picture of Cosmic Reionization

NASA Astrophysics Data System (ADS)

Ishigaki, Masafumi; Kawamata, Ryota; Ouchi, Masami; Oguri, Masamune; Shimasaku, Kazuhiro; Ono, Yoshiaki

2018-02-01

We present UV luminosity functions of dropout galaxies at z∼ 6{--}10 with the complete Hubble Frontier Fields data. We obtain a catalog of ∼450 dropout-galaxy candidates (350, 66, and 40 at z∼ 6{--}7, 8, and 9, respectively), with UV absolute magnitudes that reach ∼ -14 mag, ∼2 mag deeper than the Hubble Ultra Deep Field detection limits. We carefully evaluate number densities of the dropout galaxies by Monte Carlo simulations, including all lensing effects such as magnification, distortion, and multiplication of images as well as detection completeness and contamination effects in a self-consistent manner. We find that UV luminosity functions at z∼ 6{--}8 have steep faint-end slopes, α ∼ -2, and likely steeper slopes, α ≲ -2 at z∼ 9{--}10. We also find that the evolution of UV luminosity densities shows a non-accelerated decline beyond z∼ 8 in the case of {M}trunc}=-15, but an accelerated one in the case of {M}trunc}=-17. We examine whether our results are consistent with the Thomson scattering optical depth from the Planck satellite and the ionized hydrogen fraction Q H II at z≲ 7 based on the standard analytic reionization model. We find that reionization scenarios exist that consistently explain all of the observational measurements with the allowed parameters of {f}esc}={0.17}-0.03+0.07 and {M}trunc}> -14.0 for {log}{ξ }ion}/[{erg}}-1 {Hz}]=25.34, where {f}esc} is the escape fraction, M trunc is the faint limit of the UV luminosity function, and {ξ }ion} is the conversion factor of the UV luminosity to the ionizing photon emission rate. The length of the reionization period is estimated to be {{Δ }}z={3.9}-1.6+2.0 (for 0.1< {Q}{{H}{{II}}}< 0.99), consistent with the recent estimate from Planck.

Hubble induced mass after inflation in spectator field models

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fujita, Tomohiro; Harigaya, Keisuke, E-mail: tomofuji@stanford.edu, E-mail: keisukeh@icrr.u-tokyo.ac.jp

2016-12-01

Spectator field models such as the curvaton scenario and the modulated reheating are attractive scenarios for the generation of the cosmic curvature perturbation, as the constraints on inflation models are relaxed. In this paper, we discuss the effect of Hubble induced masses on the dynamics of spectator fields after inflation. We pay particular attention to the Hubble induced mass by the kinetic energy of an oscillating inflaton, which is generically unsuppressed but often overlooked. In the curvaton scenario, the Hubble induced mass relaxes the constraint on the property of the inflaton and the curvaton, such as the reheating temperature andmore » the inflation scale. We comment on the implication of our discussion for baryogenesis in the curvaton scenario. In the modulated reheating, the predictions of models e.g. the non-gaussianity can be considerably altered. Furthermore, we propose a new model of the modulated reheating utilizing the Hubble induced mass which realizes a wide range of the local non-gaussianity parameter.« less

Measuring the Value of the Hubble Constant “à la Refsdal”

NASA Astrophysics Data System (ADS)

Grillo, C.; Rosati, P.; Suyu, S. H.; Balestra, I.; Caminha, G. B.; Halkola, A.; Kelly, P. L.; Lombardi, M.; Mercurio, A.; Rodney, S. A.; Treu, T.

2018-06-01

Realizing Refsdal’s original idea from 1964, we present estimates of the Hubble constant that are complementary to, and potentially competitive with, those of other cosmological probes. We use the observed positions of 89 multiple images, with extensive spectroscopic information, from 28 background sources and the measured time delays between the images S1–S4 and SX of supernova “Refsdal” (z = 1.489), which were obtained thanks to Hubble Space Telescope deep imaging and Multi Unit Spectroscopic Explorer data. We extend the strong-lensing modeling of the Hubble Frontier Fields galaxy cluster MACS J1149.5+2223 (z = 0.542), published by Grillo et al. (2016), and explore different ΛCDM models. Taking advantage of the lensing information associated to the presence of very close pairs of multiple images at various redshifts, and to the extended surface brightness distribution of the SN Refsdal host, we can reconstruct the total mass-density profile of the cluster very precisely. The combined dependence of the multiple-image positions and time delays on the cosmological parameters allows us to infer the values of H 0 and Ωm with relative (1σ) statistical errors of, respectively, 6% (7%) and 31% (26%) in flat (general) cosmological models, assuming a conservative 3% uncertainty on the final time delay of image SX and, remarkably, no priors from other cosmological experiments. Our best estimate of H 0, based on the model described in this work, will be presented when the final time-delay measurement becomes available. Our results show that it is possible to utilize time delays in lens galaxy clusters as an important alternative tool for measuring the expansion rate and the geometry of the universe.

The Evolution of the Galaxy Rest-Frame Ultraviolet Luminosity Function Over the First Two Billion Years

NASA Technical Reports Server (NTRS)

Finkelstein, Steven L.; Ryan, Russell E., Jr.; Papovich, Casey; Dickinson, Mark; Song, Mimi; Somerville, Rachel; Ferguson, Henry C.; Salmon, Brett; Giavalisco, Mauro; Koekomoer, Anton M.;

KSC-08pd2456

NASA Image and Video Library

2008-08-18

CAPE CANAVERAL, Fla. – In the Payload Hazardous Servicing Facility at NASA's Kennedy Space Center, a technicians clean the radiator on the Wide Field Camera 3, or WFC3,that will be installed on NASA's Hubble Space Telescope. The radiator is the "outside" of WFC3 that will be exposed to space. It will expel heat out of Hubble and into space through black body radiation. WFC3 is part of the payload on space shuttle Atlantis' STS-125 mission for the fifth and final Hubble servicing flight to NASA's Hubble Space Telescope. As Hubble enters the last stage of its life, WFC3 will be Hubble's next evolutionary step, allowing Hubble to peer ever further into the mysteries of the cosmos. WFC3 will study a diverse range of objects and phenomena, from young and extremely distant galaxies, to much more nearby stellar systems, to objects within our very own solar system. WFC3 will take the place of Wide Field Planetary Camera 2, which astronauts will bring back to Earth aboard the shuttle. Launch of Atlantis is targeted at 1:34 a.m. EDT Oct. 8. Photo credit: NASA/Amanda Diller

White Dwarf Stars

NASA Image and Video Library

1999-12-01

Peering deep inside a cluster of several hundred thousand stars, NASA Hubble Space Telescope has uncovered the oldest burned-out stars in our Milky Way Galaxy, giving astronomers a fresh reading on the age of the universe.

The ALMA Spectroscopic Survey in the Hubble Ultra Deep Field: Continuum Number Counts, Resolved 1.2 mm Extragalactic Background, and Properties of the Faintest Dusty Star-forming Galaxies

NASA Astrophysics Data System (ADS)

Aravena, M.; Decarli, R.; Walter, F.; Da Cunha, E.; Bauer, F. E.; Carilli, C. L.; Daddi, E.; Elbaz, D.; Ivison, R. J.; Riechers, D. A.; Smail, I.; Swinbank, A. M.; Weiss, A.; Anguita, T.; Assef, R. J.; Bell, E.; Bertoldi, F.; Bacon, R.; Bouwens, R.; Cortes, P.; Cox, P.; Gónzalez-López, J.; Hodge, J.; Ibar, E.; Inami, H.; Infante, L.; Karim, A.; Le Le Fèvre, O.; Magnelli, B.; Ota, K.; Popping, G.; Sheth, K.; van der Werf, P.; Wagg, J.

2016-12-01

We present an analysis of a deep (1σ = 13 μJy) cosmological 1.2 mm continuum map based on ASPECS, the ALMA Spectroscopic Survey in the Hubble Ultra Deep Field. In the 1 arcmin2 covered by ASPECS we detect nine sources at \\gt 3.5σ significance at 1.2 mm. Our ALMA-selected sample has a median redshift of z=1.6+/- 0.4, with only one galaxy detected at z > 2 within the survey area. This value is significantly lower than that found in millimeter samples selected at a higher flux density cutoff and similar frequencies. Most galaxies have specific star formation rates (SFRs) similar to that of main-sequence galaxies at the same epoch, and we find median values of stellar mass and SFRs of 4.0× {10}10 {M}⊙ and ˜ 40 {M}⊙ yr-1, respectively. Using the dust emission as a tracer for the interstellar medium (ISM) mass, we derive depletion times that are typically longer than 300 Myr, and we find molecular gas fractions ranging from ˜0.1 to 1.0. As noted by previous studies, these values are lower than those using CO-based ISM estimates by a factor of ˜2. The 1 mm number counts (corrected for fidelity and completeness) are in agreement with previous studies that were typically restricted to brighter sources. With our individual detections only, we recover 55% ± 4% of the extragalactic background light (EBL) at 1.2 mm measured by the Planck satellite, and we recover 80% ± 7% of this EBL if we include the bright end of the number counts and additional detections from stacking. The stacked contribution is dominated by galaxies at z˜ 1{--}2, with stellar masses of (1-3) × 1010 M {}⊙ . For the first time, we are able to characterize the population of galaxies that dominate the EBL at 1.2 mm.

ALMA Spectroscopic Survey in the Hubble Ultra Deep Field: The Infrared Excess of UV-Selected z = 2-10 Galaxies as a Function of UV-Continuum Slope and Stellar Mass

NASA Astrophysics Data System (ADS)

Bouwens, Rychard J.; Aravena, Manuel; Decarli, Roberto; Walter, Fabian; da Cunha, Elisabete; Labbé, Ivo; Bauer, Franz E.; Bertoldi, Frank; Carilli, Chris; Chapman, Scott; Daddi, Emanuele; Hodge, Jacqueline; Ivison, Rob J.; Karim, Alex; Le Fevre, Olivier; Magnelli, Benjamin; Ota, Kazuaki; Riechers, Dominik; Smail, Ian R.; van der Werf, Paul; Weiss, Axel; Cox, Pierre; Elbaz, David; Gonzalez-Lopez, Jorge; Infante, Leopoldo; Oesch, Pascal; Wagg, Jeff; Wilkins, Steve

2016-12-01

We make use of deep 1.2 mm continuum observations (12.7 μJy beam-1 rms) of a 1 arcmin2 region in the Hubble Ultra Deep Field to probe dust-enshrouded star formation from 330 Lyman-break galaxies spanning the redshift range z = 2-10 (to ˜2-3 M ⊙ yr-1 at 1σ over the entire range). Given the depth and area of ASPECS, we would expect to tentatively detect 35 galaxies, extrapolating the Meurer z ˜ 0 IRX-β relation to z ≥ 2 (assuming dust temperature T d ˜ 35 K). However, only six tentative detections are found at z ≳ 2 in ASPECS, with just three at >3σ. Subdividing our z = 2-10 galaxy samples according to stellar mass, UV luminosity, and UV-continuum slope and stacking the results, we find a significant detection only in the most massive (>109.75 M ⊙) subsample, with an infrared excess (IRX = L IR/L UV) consistent with previous z ˜ 2 results. However, the infrared excess we measure from our large selection of sub-L ∗ (<109.75 M ⊙) galaxies is {0.11}-0.42+0.32 ± 0.34 (bootstrap and formal uncertainties) and {0.14}-0.14+0.15 ± 0.18 at z = 2-3 and z = 4-10, respectively, lying below even an IRX-β relation for the Small Magellanic Cloud (95% confidence). These results demonstrate the relevance of stellar mass for predicting the IR luminosity of z ≳ 2 galaxies. We find that the evolution of the IRX-stellar mass relationship depends on the evolution of the dust temperature. If the dust temperature increases monotonically with redshift (\\propto {(1+z)}0.32) such that T d ˜ 44-50 K at z ≥ 4, current results are suggestive of little evolution in this relationship to z ˜ 6. We use these results to revisit recent estimates of the z ≥ 3 star formation rate density.

Optical Spectroscopy of Distant Red Galaxies

NASA Astrophysics Data System (ADS)

Wuyts, Stijn; van Dokkum, Pieter G.; Franx, Marijn; Förster Schreiber, Natascha M.; Illingworth, Garth D.; Labbé, Ivo; Rudnick, Gregory

2009-11-01

We present optical spectroscopic follow-up of a sample of distant red galaxies (DRGs) with K tot s,Vega < 22.5, selected by (J - K)Vega>2.3, in the Hubble Deep Field South (HDFS), the MS 1054-03 field, and the Chandra Deep Field South (CDFS). Spectroscopic redshifts were obtained for 15 DRGs. Only two out of 15 DRGs are located at z < 2, suggesting a high efficiency to select high-redshift sources. From other spectroscopic surveys in the CDFS targeting intermediate to high-redshift populations selected with different criteria, we find spectroscopic redshifts for a further 30 DRGs. We use the sample of spectroscopically confirmed DRGs to establish the high quality (scatter in Δz/(1 + z) of ~0.05) of their photometric redshifts in the considered deep fields, as derived with EAZY. Combining the spectroscopic and photometric redshifts, we find that 74% of DRGs with K tot s,Vega < 22.5 lie at z>2. The combined spectroscopic and photometric sample is used to analyze the distinct intrinsic and observed properties of DRGs at z < 2 and z>2. In our photometric sample to K tot s,Vega < 22.5, low-redshift DRGs are brighter in Ks than high-redshift DRGs by 0.7 mag, and more extincted by 1.2 mag in AV . Our analysis shows that the DRG criterion selects galaxies with different properties at different redshifts. Such biases can be largely avoided by selecting galaxies based on their rest-frame properties, which requires very good multi-band photometry and high quality photometric redshifts.

Morphology and Structure of High-redshift Massive Galaxies in the CANDELS Fields

NASA Astrophysics Data System (ADS)

Guan-wen, Fang; Ze-sen, Lin; Xu, Kong

2018-01-01

Using the multi-band photometric data of all five CANDELS (Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey) fields and the near-infrared (F125W and F160W) high-resolution images of HST WFC3 (Hubble Space Telescope Wide Field Camera 3), a quantitative study of morphology and structure of mass-selected galaxies is presented. The sample includes 8002 galaxies with a redshift 1 < z < 3 and stellar mass M*> 1010M⊙. Based on the Convolutional Neural Network (ConvNet) criteria, we classify the sample galaxies into SPHeroids (SPH), Early-Type Disks (ETD), Late-Type Disks (LTD), and IRRegulars (IRR) in different redshift bins. The findings indicate that the galaxy morphology and structure evolve with redshift up to z ∼ 3, from irregular galaxies in the high-redshift universe to the formation of the Hubble sequence dominated by disks and spheroids. For the same redshift interval, the median values of effective radii (re) of different morphological types are in a descending order: IRR, LTD, ETD, and SPH. But for the Sérsic index (n), the order is reversed (SPH, ETD, LTD, and IRR). In the meantime, the evolution of galaxy size (re) with the redshift is explored for the galaxies of different morphological types, and it is confirmed that their size will enlarge with time. However, such a phenomenon is not found in the relations between the redshift (1 < z < 3) and the mean axis ratio (b/a), as well as the Sérsic index (n).

CANDELS: A Cosmic Quest for Distant Galaxies Offering Live Views of Galaxy Evolution

NASA Astrophysics Data System (ADS)

Koo, David C.; CANDELS

2017-06-01

For decades, the study of distant galaxies has been pushing the frontiers of extra-galactic research, with observations from the best suite of telescopes and instruments and with theory from the most advanced computer simulations. This talk will focus on observations taken within the CANDELS fields to reveal the richness and complexity of this still-growing field. CANDELS (Cosmic Assembly Near-IR Deep Extragalactic Legacy Survey) itself is the largest project ever taken by Hubble and is composed of optical and near-infrared images of five tiny regions of sky containing over 200,000 distant galaxies. All these regions, two of which are GOODS North and South, were already outstanding in possessing years of prior surveys taken by many teams worldwide and have continued to attract more and better spectra and panchromatic images from Keck, Hubble, Chandra, Spitzer, and other telescopes ranging from X-ray to radio. Combined together, the rich data within the CANDELS fields offer live views of galaxy evolution from “Cosmic Dawn” when the first infant galaxies and cosmic black holes were born, through “Cosmic Noon” during the peak of galaxy and black hole growth, and then to “Cosmic Afternoon” when star formation and black hole activities, morphologies, motions, and contents settled to those of our Milky Way and its zoo of cousins today. The talk will highlight some interesting discoveries from the last two periods and close with new mysteries challenging our field in the 21st century and future prospects for solving them.

KSC-08pd2457

NASA Image and Video Library

2008-08-18

CAPE CANAVERAL, Fla. – In the Payload Hazardous Servicing Facility at NASA's Kennedy Space Center, a technician checks the pick-off mirror on the Wide Field Camera 3, or WFC3, that will be installed on NASA's Hubble Space Telescope. WFC3 is part of the payload on space shuttle Atlantis' STS-125 mission for the fifth and final Hubble servicing flight to Hubble. As Hubble enters the last stage of its life, WFC3 will be Hubble's next evolutionary step, allowing Hubble to peer ever further into the mysteries of the cosmos. WFC3 will study a diverse range of objects and phenomena, from young and extremely distant galaxies, to much more nearby stellar systems, to objects within our very own solar system. WFC3 will take the place of Wide Field Planetary Camera 2, which astronauts will bring back to Earth aboard the shuttle. Launch of Atlantis is targeted at 1:34 a.m. EDT Oct. 8. Photo credit: NASA/Amanda Diller

HUBBLE IDENTIFIES SOURCE OF ULTRAVIOLET LIGHT IN AN OLD GALAXY

NASA Technical Reports Server (NTRS)

2002-01-01

Hubble Space Telescope's exquisite resolution has allowed astronomers to resolve, for the first time, hot blue stars deep inside an elliptical galaxy. The swarm of nearly 8,000 blue stars resembles a blizzard of snowflakes near the core (lower right) of the neighboring galaxy M32, located 2.5 million light-years away in the constellation Andromeda. Hubble confirms that the ultraviolet light comes from a population of extremely hot helium-burning stars at a late stage in their lives. Unlike the Sun, which burns hydrogen into helium, these old stars exhausted their central hydrogen long ago, and now burn helium into heavier elements. The observations, taken in October 1998, were made with the camera mode of the Space Telescope Imaging Spectrograph (STIS) in ultraviolet light. The STIS field of view is only a small portion of the entire galaxy, which is 20 times wider on the sky. For reference, the full moon is 70 times wider than the STIS field-of-view. The bright center of the galaxy was placed on the right side of the image, allowing fainter stars to be seen on the left side of the image. These results are to be published in the March 1, 2000 issue of The Astrophysical Journal. Thirty years ago, the first ultraviolet observations of elliptical galaxies showed that they were surprisingly bright when viewed in ultraviolet light. Before those pioneering UV observations, old groups of stars were assumed to be relatively cool and thus extremely faint in the ultraviolet. Over the years since the initial discovery of this unexpected ultraviolet light, indirect evidence has accumulated that it originates in a population of old, but hot, helium-burning stars. Now Hubble provides the first direct visual evidence. Nearby elliptical galaxies are thought to be relatively simple galaxies comprised of old stars. Because they are among the brightest objects in the Universe, this simplicity makes them useful for tracing the evolution of stars and galaxies. Credits: NASA and Thomas M. Brown, Charles W. Bowers, Randy A. Kimble, Allen V. Sweigart (NASA Goddard Space Flight Center) and Henry C. Ferguson (Space Telescope Science Institute).

The HST Frontier Fields

NASA Astrophysics Data System (ADS)

Lotz, Jennifer; Mountain, M.; Grogin, N. A.; Koekemoer, A. M.; Capak, P. L.; Mack, J.; Coe, D. A.; Barker, E. A.; Adler, D. S.; Avila, R. J.; Anderson, J.; Casertano, S.; Christian, C. A.; Gonzaga, S.; Ferguson, H. C.; Fruchter, A. S.; Jenkner, H.; Jordan, I. J.; Hammer, D.; Hilbert, B.; Lawton, B. L.; Lee, J. C.; Lucas, R. A.; MacKenty, J. W.; Mutchler, M. J.; Ogaz, S.; Reid, I. N.; Royle, P.; Robberto, M.; Sembach, K.; Smith, L. J.; Sokol, J.; Surace, J. A.; Taylor, D.; Tumlinson, J.; Viana, A.; Williams, R. E.; Workman, W.

2014-01-01

Using Director's Discretionary observing time, HST is undertaking a revolutionary deep field observing program to peer deeper into the Universe than ever before. The Frontier Fields will combine the power of HST with the natural gravitational telescopes of high-magnification clusters of galaxies to produce the deepest observations of clusters and their lensed galaxies and the second-deepest observations of blank fields ever obtained. Up to six strong-lensing clusters (Abell 2744, MACSJ0416.1-2403, MACSJ0717.5+3745, MACSJ1149.5+2223, AbellS1063, and Abell 370) will be targeted with coordinated parallels of adjacent blank fields with ACS/WFC and WFC3/IR cameras to ~29th ABmag depths in seven bandpasses over the next three years. These observations will reveal distant galaxy populations ~10-100 times fainter than any previously observed, and improve our statistical understanding of galaxies during the epoch of reionization. Here we present Hubble Space Telescope observations of the first set of the Frontier Fields, Abell 2744, and describe the HST Frontier Fields observing strategy and schedule. All data for this observing program is nonproprietary and available immediately upon entry into the Mikulski Archive for Space Telescopes.

STScI-PRC02-11a FARAWAY GALAXIES PROVIDE A STUNNING 'WALLPAPER' BACKDROP FOR A RUNAWAY GALAXY

NASA Technical Reports Server (NTRS)

2002-01-01

Against a stunning backdrop of thousands of galaxies, this odd-looking galaxy with the long streamer of stars appears to be racing through space, like a runaway pinwheel firework. This picture of the galaxy UGC 10214 was taken by the Advanced Camera for Surveys (ACS), which was installed aboard NASA's Hubble Space Telescope in March during Servicing Mission 3B. Dubbed the 'Tadpole,' this spiral galaxy is unlike the textbook images of stately galaxies. Its distorted shape was caused by a small interloper, a very blue, compact galaxy visible in the upper left corner of the more massive Tadpole. The Tadpole resides about 420 million light-years away in the constellation Draco. Seen shining through the Tadpole's disk, the tiny intruder is likely a hit-and-run galaxy that is now leaving the scene of the accident. Strong gravitational forces from the interaction created the long tail of debris, consisting of stars and gas that stretch out more than 280,000 light-years. Numerous young blue stars and star clusters, spawned by the galaxy collision, are seen in the spiral arms, as well as in the long 'tidal' tail of stars. Each of these clusters represents the formation of up to about a million stars. Their color is blue because they contain very massive stars, which are 10 times hotter and 1 million times brighter than our Sun. Once formed, the star clusters become redder with age as the most massive and bluest stars exhaust their fuel and burn out. These clusters will eventually become old globular clusters similar to those found in essentially all halos of galaxies, including our own Milky Way. Two prominent clumps of young bright blue stars in the long tail are separated by a 'gap' -- a section that is fainter than the rest of the tail. These clumps of stars will likely become dwarf galaxies that orbit in the Tadpole's halo. The galactic carnage and torrent of star birth are playing out against a spectacular backdrop: a 'wallpaper pattern' of 6,000 galaxies. These galaxies represent twice the number of those discovered in the legendary Hubble Deep Field, the orbiting observatory's 'deepest' view of the heavens, taken in 1995 by the Wide Field and Planetary Camera 2. The ACS picture, however, was taken in one-twelfth the time it took to observe the original Hubble Deep Field. In blue light, ACS sees even fainter objects than were seen in the 'deep field.' The galaxies in the ACS picture, like those in the deep field, stretch back to nearly the beginning of time. They are a myriad of shapes and represent fossil samples of the universe's 13-billion-year evolution. The ACS image is so sharp that astronomers can identify distant colliding galaxies, the 'building blocks' of galaxies, an exquisite 'Whitman's Sampler' of galaxies, and many extremely faraway galaxies. ACS made this observation on April 1 and 9, 2002. The color image is constructed from three separate images taken in near-infrared, orange, and blue filters. Credit: NASA, H. Ford (JHU), G. Illingworth (USCS/LO), M.Clampin (STScI), G. Hartig (STScI), the ACS Science Team, and ESA The ACS Science Team: (H. Ford, G. Illingworth, M. Clampin, G. Hartig, T. Allen, K. Anderson, F. Bartko, N. Benitez, J. Blakeslee, R. Bouwens, T. Broadhurst, R. Brown, C. Burrows, D. Campbell, E. Cheng, N. Cross, P. Feldman, M. Franx, D. Golimowski, C. Gronwall, R. Kimble, J. Krist, M. Lesser, D. Magee, A. Martel, W. J. McCann, G. Meurer, G. Miley, M. Postman, P. Rosati, M. Sirianni, W. Sparks, P. Sullivan, H. Tran, Z. Tsvetanov, R. White, and R. Woodruff)

Probing Large-scale Coherence between Spitzer IR and Chandra X-Ray Source-subtracted Cosmic Backgrounds

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cappelluti, N.; Urry, M.; Arendt, R.

2017-09-20

We present new measurements of the large-scale clustering component of the cross-power spectra of the source-subtracted Spitzer -IRAC cosmic infrared background and Chandra -ACIS cosmic X-ray background surface brightness fluctuations Our investigation uses data from the Chandra Deep Field South, Hubble Deep Field North, Extended Groth Strip/AEGIS field, and UDS/SXDF surveys, comprising 1160 Spitzer hours and ∼12 Ms of Chandra data collected over a total area of 0.3 deg{sup 2}. We report the first (>5 σ ) detection of a cross-power signal on large angular scales >20″ between [0.5–2] keV and the 3.6 and 4.5 μ m bands, at ∼5more » σ and 6.3 σ significance, respectively. The correlation with harder X-ray bands is marginally significant. Comparing the new observations with existing models for the contribution of the known unmasked source population at z < 7, we find an excess of about an order of magnitude at 5 σ confidence. We discuss possible interpretations for the origin of this excess in terms of the contribution from accreting early black holes (BHs), including both direct collapse BHs and primordial BHs, as well as from scattering in the interstellar medium and intra-halo light.« less

Age Crises, Scalar Fields, and the Apocalypse

NASA Astrophysics Data System (ADS)

Jackson, J. C.

Recent observations suggest that Hubble's constant is large, to the extent that the oldest stars appear to have ages which are greater than the Hubble time, and that the Hubble expansion is slowing down, so that according to conventional cosmology the age of the Universe is less than the Hubble time. The concepts of weak and strong age crises (respectively t0<1/H0 but longer than the age inferred from some lower limit on q0, and t0>1/H0 and q0>0) are introduced. These observations are reconciled in models which are dynamically dominated by a homogeneous scalar field, corresponding to an ultra-light boson whose Compton wavelength is of the same order as the Hubble radius. Two such models are considered, an open one with vacuum energy comprising a conventional cosmological term and a scalar field component, and a flat one with a scalar component only, aimed respectively at weak and strong age crises. Both models suggest that anti-gravity plays a significant role in the evolution of the Universe.

Hubble Sees 'Island Universe' in the Coma Cluster

NASA Image and Video Library

2017-12-08

NASA image release August 10, 2010 A long-exposure Hubble Space Telescope image shows a majestic face-on spiral galaxy located deep within the Coma Cluster of galaxies, which lies 320 million light-years away in the northern constellation Coma Berenices. The galaxy, known as NGC 4911, contains rich lanes of dust and gas near its center. These are silhouetted against glowing newborn star clusters and iridescent pink clouds of hydrogen, the existence of which indicates ongoing star formation. Hubble has also captured the outer spiral arms of NGC 4911, along with thousands of other galaxies of varying sizes. The high resolution of Hubble's cameras, paired with considerably long exposures, made it possible to observe these faint details. NGC 4911 and other spirals near the center of the cluster are being transformed by the gravitational tug of their neighbors. In the case of NGC 4911, wispy arcs of the galaxy's outer spiral arms are being pulled and distorted by forces from a companion galaxy (NGC 4911A), to the upper right. The resultant stripped material will eventually be dispersed throughout the core of the Coma Cluster, where it will fuel the intergalactic populations of stars and star clusters. The Coma Cluster is home to almost 1,000 galaxies, making it one of the densest collections of galaxies in the nearby universe. It continues to transform galaxies at the present epoch, due to the interactions of close-proximity galaxy systems within the dense cluster. Vigorous star formation is triggered in such collisions. Galaxies in this cluster are so densely packed that they undergo frequent interactions and collisions. When galaxies of nearly equal masses merge, they form elliptical galaxies. Merging is more likely to occur in the center of the cluster where the density of galaxies is higher, giving rise to more elliptical galaxies. This natural-color Hubble image, which combines data obtained in 2006, 2007, and 2009 from the Wide Field Planetary Camera 2 and the Advanced Camera for Surveys, required 28 hours of exposure time. The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency. NASA's Goddard Space Flight Center manages the telescope. The Space Telescope Science Institute (STScI) conducts Hubble science operations. STScI is operated for NASA by the Association of Universities for Research in Astronomy, Inc. in Washington, D.C. Credit: NASA, ESA, and the Hubble Heritage Team (STScI/AURA) Acknowledgment: K. Cook (Lawrence Livermore National Laboratory) To learn more about Hubble go to: www.nasa.gov/mission_pages/hubble/main/index.html NASA Goddard Space Flight Center is home to the nation's largest organization of combined scientists, engineers and technologists that build spacecraft, instruments and new technology to study the Earth, the sun, our solar system, and the universe. Follow us on Twitter Join us on Facebook

The assembly of stellar haloes in massive Early-Type Galaxies

NASA Astrophysics Data System (ADS)

Buitrago, F.

2017-03-01

Massive (Mstellar >= 5×1010 M⊙) Early-Type Galaxies (ETGs) must build an outer stellar envelope over cosmic time in order to account for their remarkable size evolution. This is similar to what occurs to nearby Late-Type Galaxies (LTGs), which create their stellar haloes out of the debris of lower mass systems. We analysed the outer parts of massive ETGs at z < 1 by exploiting the Hubble Ultra Deep Field imaging. These galaxies store 10-30% of their stellar mass at distances 10 < R/kpc < 50, in contrast to the low percentages (< 5%) found for LTGs. We find evidence for a progressive outskirt development with redshift driven solely via merging.

Least-Squares Self-Calibration of Imaging Array Data

NASA Technical Reports Server (NTRS)

Arendt, R. G.; Moseley, S. H.; Fixsen, D. J.

2004-01-01

When arrays are used to collect multiple appropriately-dithered images of the same region of sky, the resulting data set can be calibrated using a least-squares minimization procedure that determines the optimal fit between the data and a model of that data. The model parameters include the desired sky intensities as well as instrument parameters such as pixel-to-pixel gains and offsets. The least-squares solution simultaneously provides the formal error estimates for the model parameters. With a suitable observing strategy, the need for separate calibration observations is reduced or eliminated. We show examples of this calibration technique applied to HST NICMOS observations of the Hubble Deep Fields and simulated SIRTF IRAC observations.

Tracing the growth of Milky Way-like galaxies

NASA Image and Video Library

2013-11-15

This composite image shows examples of galaxies similar to our Milky Way at various stages of construction over a time span of 11 billion years. The galaxies are arranged according to time. Those on the left reside nearby; those at far right existed when the cosmos was about 2 billion years old. The bluish glow from young stars dominates the color of the galaxies on the right. The galaxies at left are redder from the glow of older stellar populations. Astronomers found the distant galaxies in two Hubble Space Telescope surveys: 3D-HST and the Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey, or CANDELS. The observations were made in visible and near-infrared light by Hubble's Wide Field Camera 3 and Advanced Camera for Surveys. The nearby galaxies were taken from the Sloan Digital Sky Survey. This image traces Milky Way-like galaxies over most of cosmic history, revealing how they evolve over time. Hubble's sharp vision resolved the galaxies' shapes, showing that their bulges and disks grew simultaneously. Credit: NASA, ESA, P. van Dokkum (Yale University), S. Patel (Leiden University), and the 3D-HST Team NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Like us on Facebook Find us on Instagram

Circumstantial Starbirth in Starbursts: Systematic Variations in the Stellar and Nebular Content of Giant HII Regions in the Local Group Galaxy M33

NASA Astrophysics Data System (ADS)

Waller, W. H.; Murphy, E. J.; Gherz, R. D.; Polomski, E.; Woodward, C. E.; Fazio, G. G.; Rieke, G. H.; Spitzer/M33 Research Team

2005-12-01

From the Orion Nebula to the Hubble Deep Field, starburst activity can be seen transforming galaxian clouds of gas into populous clusters of stars. The pyrotechnics and chemical enrichment associated with this activity have led to outcomes as ubiquitous as interstellar dust and as exquisite as life on Earth. In this talk, I will focus on the circumstances of star formation in the environmental context of ongoing starburst activity. I begin with the premises that (1) the formation of a single star takes time, (2) the formation of a populous cluster takes even more time, and (3) ''stuff'' happens in the interim. Hubble images of the Orion Nebula and Eagle Nebula show how hot stars can excavate neighboring clouds of gas and photoevaporate the star-forming cores that are exposed. Hubble observations of giant HII regions in M33 reveal a significant variation in the stellar populations, such that the most metal-rich HII regions contain the greatest proportions of the most massive stars. ISO and Spitzer observations of these same HII regions reveal corresponding variations in the nebular content. These multi-wavelength diagnostics of the stellar-nebular feedback in galaxian starbursts suggest a star-forming mechanism which is subject to photo-evaporative ablation -- an erosive process that is systematically mediated by the metal abundance and corresponding amounts of protective dust in the starbursting environment.

KSC-08pd2453

NASA Image and Video Library

2008-08-18

CAPE CANAVERAL, Fla. – In the Payload Hazardous Servicing Facility at NASA's Kennedy Space Center, technicians check the Wide Field Camera 3, or WFC3, after removal of its protective cover. WFC3 is part of the payload on space shuttle Atlantis' STS-125 mission for the fifth and final Hubble servicing flight to NASA's Hubble Space Telescope. As Hubble enters the last stage of its life, WFC3 will be Hubble's next evolutionary step, allowing Hubble to peer ever further into the mysteries of the cosmos. WFC3 will study a diverse range of objects and phenomena, from young and extremely distant galaxies, to much more nearby stellar systems, to objects within our very own solar system. WFC3 will take the place of Wide Field Planetary Camera 2, which astronauts will bring back to Earth aboard the shuttle. Launch of Atlantis is targeted at 1:34 a.m. EDT Oct. 8. Photo credit: NASA/Amanda Diller

KSC-08pd2454

NASA Image and Video Library

2008-08-18

CAPE CANAVERAL, Fla. – In the Payload Hazardous Servicing Facility at NASA's Kennedy Space Center, technicians check the Wide Field Camera 3, or WFC3, after removal of its protective cover. WFC3 is part of the payload on space shuttle Atlantis' STS-125 mission for the fifth and final Hubble servicing flight to NASA's Hubble Space Telescope. As Hubble enters the last stage of its life, WFC3 will be Hubble's next evolutionary step, allowing Hubble to peer ever further into the mysteries of the cosmos. WFC3 will study a diverse range of objects and phenomena, from young and extremely distant galaxies, to much more nearby stellar systems, to objects within our very own solar system. WFC3 will take the place of Wide Field Planetary Camera 2, which astronauts will bring back to Earth aboard the shuttle. Launch of Atlantis is targeted at 1:34 a.m. EDT Oct. 8. Photo credit: NASA/Amanda Diller

KSC-08pd2474

NASA Image and Video Library

2008-08-18

CAPE CANAVERAL, Fla. – In the Payload Hazardous Servicing Facility at NASA's Kennedy Space Center, the Wide Field Camera 3, or WFC3, is lowered onto the Super Lightweight Interchangeable Carrier. WFC3 is part of the payload on space shuttle Atlantis' STS-125 mission for the fifth and final Hubble servicing flight to NASA's Hubble Space Telescope. As Hubble enters the last stage of its life, WFC3 will be Hubble's next evolutionary step, allowing Hubble to peer ever further into the mysteries of the cosmos. WFC3 will study a diverse range of objects and phenomena, from young and extremely distant galaxies, to much more nearby stellar systems, to objects within our very own solar system. WFC3 will take the place of Wide Field Planetary Camera 2, which astronauts will bring back to Earth aboard the shuttle. Launch of Atlantis is targeted at 1:34 a.m. EDT Oct. 8. Photo credit: NASA/Amanda Diller

KSC-08pd2472

NASA Image and Video Library

2008-08-18

CAPE CANAVERAL, Fla. – In the Payload Hazardous Servicing Facility at NASA's Kennedy Space Center, the Wide Field Camera 3, or WFC3, is moved toward the Super Lightweight Interchangeable Carrier. WFC3 is part of the payload on space shuttle Atlantis' STS-125 mission for the fifth and final Hubble servicing flight to NASA's Hubble Space Telescope. As Hubble enters the last stage of its life, WFC3 will be Hubble's next evolutionary step, allowing Hubble to peer ever further into the mysteries of the cosmos. WFC3 will study a diverse range of objects and phenomena, from young and extremely distant galaxies, to much more nearby stellar systems, to objects within our very own solar system. WFC3 will take the place of Wide Field Planetary Camera 2, which astronauts will bring back to Earth aboard the shuttle. Launch of Atlantis is targeted at 1:34 a.m. EDT Oct. 8. Photo credit: NASA/Amanda Diller

KSC-08pd2473

NASA Image and Video Library

2008-08-18

CAPE CANAVERAL, Fla. – In the Payload Hazardous Servicing Facility at NASA's Kennedy Space Center, the Wide Field Camera 3, or WFC3, is lowered toward the Super Lightweight Interchangeable Carrier. WFC3 is part of the payload on space shuttle Atlantis' STS-125 mission for the fifth and final Hubble servicing flight to NASA's Hubble Space Telescope. As Hubble enters the last stage of its life, WFC3 will be Hubble's next evolutionary step, allowing Hubble to peer ever further into the mysteries of the cosmos. WFC3 will study a diverse range of objects and phenomena, from young and extremely distant galaxies, to much more nearby stellar systems, to objects within our very own solar system. WFC3 will take the place of Wide Field Planetary Camera 2, which astronauts will bring back to Earth aboard the shuttle. Launch of Atlantis is targeted at 1:34 a.m. EDT Oct. 8. Photo credit: NASA/Amanda Diller

KSC-08pd2471

NASA Image and Video Library

2008-08-18

CAPE CANAVERAL, Fla. – In the Payload Hazardous Servicing Facility at NASA's Kennedy Space Center, an overhead crane lifts the Wide Field Camera 3, or WFC3, above the stand holding the Super Lightweight Interchangeable Carrier. WFC3 is part of the payload on space shuttle Atlantis' STS-125 mission for the fifth and final Hubble servicing flight to NASA's Hubble Space Telescope. As Hubble enters the last stage of its life, WFC3 will be Hubble's next evolutionary step, allowing Hubble to peer ever further into the mysteries of the cosmos. WFC3 will study a diverse range of objects and phenomena, from young and extremely distant galaxies, to much more nearby stellar systems, to objects within our very own solar system. WFC3 will take the place of Wide Field Planetary Camera 2, which astronauts will bring back to Earth aboard the shuttle. Launch of Atlantis is targeted at 1:34 a.m. EDT Oct. 8. Photo credit: NASA/Amanda Diller

KSC-08pd2458

NASA Image and Video Library

2008-08-18

CAPE CANAVERAL, Fla. – In the Payload Hazardous Servicing Facility at NASA's Kennedy Space Center, the Wide Field Camera 3, or WFC3, is ready to be transferred to the Super Lightweight Interchangeable Carrier. WFC3 is part of the payload on space shuttle Atlantis' STS-125 mission for the fifth and final Hubble servicing flight to NASA's Hubble Space Telescope. As Hubble enters the last stage of its life, WFC3 will be Hubble's next evolutionary step, allowing Hubble to peer ever further into the mysteries of the cosmos. WFC3 will study a diverse range of objects and phenomena, from young and extremely distant galaxies, to much more nearby stellar systems, to objects within our very own solar system. WFC3 will take the place of Wide Field Planetary Camera 2, which astronauts will bring back to Earth aboard the shuttle. Launch of Atlantis is targeted at 1:34 a.m. EDT Oct. 8. Photo credit: NASA/Amanda Diller

KSC-08pd2455

NASA Image and Video Library

2008-08-18

CAPE CANAVERAL, Fla. – In the Payload Hazardous Servicing Facility at NASA's Kennedy Space Center, a technician cleans the edge of the radiator on the Wide Field Camera 3, or WFC3,that will be installed on NASA's Hubble Space Telescope. The radiator is the "outside" of WFC3 that will be exposed to space. It will expel heat out of Hubble and into space through black body radiation. WFC3 is part of the payload on space shuttle Atlantis' STS-125 mission for the fifth and final Hubble servicing flight to NASA's Hubble Space Telescope. As Hubble enters the last stage of its life, WFC3 will be Hubble's next evolutionary step, allowing Hubble to peer ever further into the mysteries of the cosmos. WFC3 will study a diverse range of objects and phenomena, from young and extremely distant galaxies, to much more nearby stellar systems, to objects within our very own solar system. WFC3 will take the place of Wide Field Planetary Camera 2, which astronauts will bring back to Earth aboard the shuttle. Launch of Atlantis is targeted at 1:34 a.m. EDT Oct. 8. Photo credit: NASA/Amanda Diller

Astronomers Set a New Galaxy Distance Record

NASA Image and Video Library

2015-05-06

This is a Hubble Space Telescope image of the farthest spectroscopically confirmed galaxy observed to date (inset). It was identified in this Hubble image of a field of galaxies in the CANDELS survey (Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey). NASA’s Spitzer Space Telescope also observed the unique galaxy. The W. M. Keck Observatory was used to obtain a spectroscopic redshift (z=7.7), extending the previous redshift record. Measurements of the stretching of light, or redshift, give the most reliable distances to other galaxies. This source is thus currently the most distant confirmed galaxy known, and it appears to also be one of the brightest and most massive sources at that time. The galaxy existed over 13 billion years ago. The near-infrared light image of the galaxy (inset) has been colored blue as suggestive of its young, and hence very blue, stars. The CANDELS field is a combination of visible-light and near-infrared exposures. Read more: www.nasa.gov/feature/goddard/astronomers-set-a-new-galaxy... Credits: NASA, ESA, P. Oesch (Yale U.) NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Like us on Facebook Find us on Instagram

Physical Properties of Sub-galactic Clumps at 0.5 ≤ Z ≤ 1.5 in the UVUDF

NASA Astrophysics Data System (ADS)

Soto, Emmaris; de Mello, Duilia F.; Rafelski, Marc; Gardner, Jonathan P.; Teplitz, Harry I.; Koekemoer, Anton M.; Ravindranath, Swara; Grogin, Norman A.; Scarlata, Claudia; Kurczynski, Peter; Gawiser, Eric

2017-03-01

We present an investigation of clumpy galaxies in the Hubble Ultra Deep Field at 0.5≤slant z≤slant 1.5 in the rest-frame far-ultraviolet (FUV) using Hubble Space Telescope Wide Field Camera 3 broadband imaging in F225W, F275W, and F336W. An analysis of 1404 galaxies yields 209 galaxies that host 403 kpc scale clumps. These host galaxies appear to be typical star-forming galaxies, with an average of 2 clumps per galaxy and reaching a maximum of 8 clumps. We measure the photometry of the clumps and determine the mass, age, and star formation rates (SFR) using the spectral energy distribution fitting code FAST. We find that clumps make an average contribution of 19% to the total rest-frame FUV flux of their host galaxy. Individually, clumps contribute a median of 5% to the host galaxy SFR and an average of ˜4% to the host galaxy mass, with total clump contributions to the host galaxy stellar mass ranging widely from lower than 1% up to 93%. Clumps in the outskirts of galaxies are typically younger, with higher SFRs, than clumps in the inner regions. The results are consistent with clump migration theories in which clumps form through violent gravitational instabilities in gas-rich turbulent disks, eventually migrate toward the center of the galaxies, and coalesce into the bulge.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kehagias, Alex; Riotto, Antonio, E-mail: kehagias@central.ntua.gr, E-mail: Antonio.Riotto@unige.ch

Cosmological perturbations of massive higher-spin fields are generated during inflation, but they decay on scales larger than the Hubble radius as a consequence of the Higuchi bound. By introducing suitable couplings to the inflaton field, we show that one can obtain statistical correlators of massive higher-spin fields which remain constant or decay very slowly outside the Hubble radius. This opens up the possibility of new observational signatures from inflation.

LUMINOUS AND HIGH STELLAR MASS CANDIDATE GALAXIES AT z Almost-Equal-To 8 DISCOVERED IN THE COSMIC ASSEMBLY NEAR-INFRARED DEEP EXTRAGALACTIC LEGACY SURVEY

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yan Haojing; Finkelstein, Steven L.; Huang, Kuang-Han

One key goal of the Hubble Space Telescope Cosmic Assembly Near-Infrared Deep Extragalactic Legacy Survey is to track galaxy evolution back to z Almost-Equal-To 8. Its two-tiered ''wide and deep'' strategy bridges significant gaps in existing near-infrared surveys. Here we report on z Almost-Equal-To 8 galaxy candidates selected as F105W-band dropouts in one of its deep fields, which covers 50.1 arcmin{sup 2} to 4 ks depth in each of three near-infrared bands in the Great Observatories Origins Deep Survey southern field. Two of our candidates have J < 26.2 mag, and are >1 mag brighter than any previously known F105W-dropouts.more » We derive constraints on the bright end of the rest-frame ultraviolet luminosity function of galaxies at z Almost-Equal-To 8, and show that the number density of such very bright objects is higher than expected from the previous Schechter luminosity function estimates at this redshift. Another two candidates are securely detected in Spitzer Infrared Array Camera images, which are the first such individual detections at z Almost-Equal-To 8. Their derived stellar masses are on the order of a few Multiplication-Sign 10{sup 9} M{sub Sun }, from which we obtain the first measurement of the high-mass end of the galaxy stellar mass function at z Almost-Equal-To 8. The high number density of very luminous and very massive galaxies at z Almost-Equal-To 8, if real, could imply a large stellar-to-halo mass ratio and an efficient conversion of baryons to stars at such an early time.« less

The Hubble Legacy Archive: Data Processing in the Era of AstroDrizzle

NASA Astrophysics Data System (ADS)

Strolger, Louis-Gregory; Hubble Legacy Archive Team, The Hubble Source Catalog Team

2015-01-01

The Hubble Legacy Archive (HLA) expands the utility of Hubble Space Telescope wide-field imaging data by providing high-level composite images and source lists, perusable and immediately available online. The latest HLA data release (DR8.0) marks a fundamental change in how these image combinations are produced, using DrizzlePac tools and Astrodrizzle to reduce geometric distortion and provide improved source catalogs for all publicly available data. We detail the HLA data processing and source list schemas, what products are newly updated and available for WFC3 and ACS, and how these data products are further utilized in the production of the Hubble Source Catalog. We also discuss plans for future development, including updates to WFPC2 products and field mosaics.

KSC-08pd2460

NASA Image and Video Library

2008-08-18

CAPE CANAVERAL, Fla. – In the Payload Hazardous Servicing Facility at NASA's Kennedy Space Center, the Wide Field Camera 3, or WFC3, waits to be transferred to the Super Lightweight Interchangeable Carrier. WFC3 is part of the payload on space shuttle Atlantis' STS-125 mission for the fifth and final Hubble servicing flight to NASA's Hubble Space Telescope. The part shown here is the radiator, the "outside" of WFC3 that will be exposed to space and will expel heat out of Hubble and into space through black body radiation. As Hubble enters the last stage of its life, WFC3 will be Hubble's next evolutionary step, allowing Hubble to peer ever further into the mysteries of the cosmos. WFC3 will study a diverse range of objects and phenomena, from young and extremely distant galaxies, to much more nearby stellar systems, to objects within our very own solar system. WFC3 will take the place of Wide Field Planetary Camera 2, which astronauts will bring back to Earth aboard the shuttle. Launch of Atlantis is targeted at 1:34 a.m. EDT Oct. 8. Photo credit: NASA/Amanda Diller

Probing the Building Blocks of Galactic Disks: An Analysis of Ultraviolet Clumps

NASA Astrophysics Data System (ADS)

Soto, Emmaris

The universe is filled with a diversity of galaxies; however, despite these diversities we are able to group galaxies into morphological categories, such as Hubble types, that may indicate different paths of evolution. In order to understand the evolution of galaxies, such as our own Milk Way, it is necessary to study the underlying star formation over cosmic time. At high redshift (z>2) star-forming galaxies reveal asymmetric and clumpy morphologies. However, the evolutionary process which takes clumpy galaxies from z>2 to the smooth axially symmetric Hubble-type galaxies in place at z˜0.5 is still unknown. Therefore, it is vital to make a connection between the morphologies of galaxies at the peak epoch of cosmic star formation at z˜2 with the galaxies observed in the local universe to better understand the mechanisms that led to their evolution. To address this and chronicle the progression of galaxy evolution, deep high resolution multi-wavelength data is used to study galaxies across cosmic time. This dissertation provides a detailed study of clumpy star-forming galaxies at intermediate redshifts, 0.5 ≤ z ≤ 1.5, focusing on sub-galactic regions of star formation which provide a mechanism to explain the evolution of clumpy galaxies to the spiral galaxies we observe today. We developed a clump-finding algorithm to select a sample of clumpy galaxies from the Ultraviolet Ultra Deep Field (UVUDF). The UVUDF was the first deep image (˜28 AB mag) ever taken with the Hubble Space Telescope (HST) showing the rest-frame far-ultraviolet (FUV, 1500A) at intermediate-z. The rest-frame FUV probes the young star-forming regions which are often seen in clumpy galaxies at high redshift. We identified 209 clumpy galaxies (hereafter host galaxies) from 1,404 candidates at intermediate redshifts. We used the HST Wide Field Camera 3 (WFC3) and the Advanced Camera for Surveys (ACS) broadband images from the UVUDF with observed near-ultraviolet, optical, and near-infrared photometry to determine their stellar properties via spectral energy distribution (SED) fitting. We estimated properties such as the mass, age, star formation rate (SFR), and metallicity of host galaxies. The deep high resolution WFC3 rest-frame FUV data allowed us to detect and measure the sizes of 403 clumps. The results provided evidence to support clump migration as a mechanism for galaxy evolution. We show that clumps make an average contribution of 19% to the total rest-frame FUV flux of their host galaxy. Additionally, individual clumps contribute a median of 5% to the host galaxy SFR and an average of ˜4% to the host galaxy mass, with total clump contributions to the host galaxy stellar mass ranging widely from less than 1% up to 93%. We showed that clumps in the outskirts of galaxies are typically younger, with higher star formation rates than clumps in the inner regions. The results are consistent with clump migration theories in which clumps form through violent gravitational instabilities in gas-rich turbulent disks, eventually migrate toward the center of the galaxies, and coalesce into the bulge.

High-redshift galaxies and low-mass stars

NASA Astrophysics Data System (ADS)

Wilkins, Stephen M.; Stanway, Elizabeth R.; Bremer, Malcolm N.

2014-03-01

The sensitivity available to near-infrared surveys has recently allowed us to probe the galaxy population at z ≈ 7 and beyond. The existing Hubble Wide Field Camera 3 (WFC3) and Visible and Infrared Survey Telescope for Astronomy (VISTA) Infrared Camera (VIRCam) instruments allow deep surveys to be undertaken well beyond 1 μm - a capability that will be further extended with the launch and commissioning of the James Webb Space Telescope (JWST). As new regions of parameter space in both colour and depth are probed, new challenges for distant galaxy surveys are identified. In this paper, we present an analysis of the colours of L- and T-dwarf stars in widely used photometric systems. We also consider the implications of the newly identified Y-dwarf population - stars that are still cooler and less massive than T-dwarfs for both the photometric selection and spectroscopic follow-up of faint and distant galaxies. We highlight the dangers of working in the low-signal-to-noise regime, and the potential contamination of existing and future samples. We find that Hubble/WFC3 and VISTA/VIRCam Y-drop selections targeting galaxies at z ˜ 7.5 are vulnerable to contamination from T- and Y-class stars. Future observations using JWST, targeting the z ˜ 7 galaxy population, are also likely to prove difficult without deep medium-band observations. We demonstrate that single emission line detections in typical low-signal-to-noise spectroscopic observations may also be suspect, due to the unusual spectral characteristics of the cool dwarf star population.

The Hubble Space Telescope Medium Deep Survey Cluster Sample: Methodology and Data

NASA Astrophysics Data System (ADS)

Ostrander, E. J.; Nichol, R. C.; Ratnatunga, K. U.; Griffiths, R. E.

1998-12-01

We present a new, objectively selected, sample of galaxy overdensities detected in the Hubble Space Telescope Medium Deep Survey (MDS). These clusters/groups were found using an automated procedure that involved searching for statistically significant galaxy overdensities. The contrast of the clusters against the field galaxy population is increased when morphological data are used to search around bulge-dominated galaxies. In total, we present 92 overdensities above a probability threshold of 99.5%. We show, via extensive Monte Carlo simulations, that at least 60% of these overdensities are likely to be real clusters and groups and not random line-of-sight superpositions of galaxies. For each overdensity in the MDS cluster sample, we provide a richness and the average of the bulge-to-total ratio of galaxies within each system. This MDS cluster sample potentially contains some of the most distant clusters/groups ever detected, with about 25% of the overdensities having estimated redshifts z > ~0.9. We have made this sample publicly available to facilitate spectroscopic confirmation of these clusters and help more detailed studies of cluster and galaxy evolution. We also report the serendipitous discovery of a new cluster close on the sky to the rich optical cluster Cl l0016+16 at z = 0.546. This new overdensity, HST 001831+16208, may be coincident with both an X-ray source and a radio source. HST 001831+16208 is the third cluster/group discovered near to Cl 0016+16 and appears to strengthen the claims of Connolly et al. of superclustering at high redshift.

The ALMA Spectroscopic Survey in the Hubble Ultra Deep Field: Search for [CII] Line and Dust Emission in 6

NASA Astrophysics Data System (ADS)

Aravena, M.; Decarli, R.; Walter, F.; Bouwens, R.; Oesch, P. A.; Carilli, C. L.; Bauer, F. E.; Da Cunha, E.; Daddi, E.; Gónzalez-López, J.; Ivison, R. J.; Riechers, D. A.; Smail, I.; Swinbank, A. M.; Weiss, A.; Anguita, T.; Bacon, R.; Bell, E.; Bertoldi, F.; Cortes, P.; Cox, P.; Hodge, J.; Ibar, E.; Inami, H.; Infante, L.; Karim, A.; Magnelli, B.; Ota, K.; Popping, G.; van der Werf, P.; Wagg, J.; Fudamoto, Y.

2016-12-01

We present a search for [C II] line and dust continuum emission from optical dropout galaxies at z > 6 using ASPECS, our Atacama Large Millimeter submillimeter Array Spectroscopic Survey in the Hubble Ultra-deep Field (UDF). Our observations, which cover the frequency range of 212-272 GHz, encompass approximately the range of 6 < z < 8 for [C II] line emission and reach a limiting luminosity of L [C II] ˜ (1.6-2.5) × 108 L ⊙. We identify 14 [C II] line emitting candidates in this redshift range with significances >4.5σ, two of which correspond to blind detections with no optical counterparts. At this significance level, our statistical analysis shows that about 60% of our candidates are expected to be spurious. For one of our blindly selected [C II] line candidates, we tentatively detect the CO(6-5) line in our parallel 3 mm line scan. None of the line candidates are individually detected in the 1.2 mm continuum. A stack of all [C II] candidates results in a tentative detection with S 1.2 mm = 14 ± 5 μJy. This implies a dust-obscured star-formation rate (SFR) of (3 ± 1) M ⊙ yr-1. We find that the two highest-SFR objects have candidate [C II] lines with luminosities that are consistent with the low-redshift L [C II] versus SFR relation. The other candidates have significantly higher [C II] luminosities than expected from their UV-based SFR. At the current sensitivity, it is unclear whether the majority of these sources are intrinsically bright [C II] emitters, or spurious sources. If only one of our line candidates was real (a scenario greatly favored by our statistical analysis), we find a source density for [C II] emitters at 6 < z < 8 that is significantly higher than predicted by current models and some extrapolations from galaxies in the local universe.

Automated Morphological Classification in Deep Hubble Space Telescope UBVI Fields: Rapidly and Passively Evolving Faint Galaxy Populations

NASA Astrophysics Data System (ADS)

Odewahn, Stephen C.; Windhorst, Rogier A.; Driver, Simon P.; Keel, William C.

1996-11-01

We analyze deep Hubble Space Telescope Wide Field Planetary Camera 2 (WFPC2) images in U, B, V, I using artificial neural network (ANN) classifiers, which are based on galaxy surface brightness and light profile (but not on color nor on scale length, rhl). The ANN distinguishes quite well between E/S0, Sabc, and Sd/Irr+M galaxies (M for merging systems) for BJ <~ 27 mag. We discuss effects from the cosmological surface brightness (SB) dimming and from the redshifted UV morphology on the classifications, and we correct for the latter. We present classifications in UBVI from (a) four independent human classifiers; (b) ANNs trained on V606 and I814 images; and (c) an ANN trained on images in the rest-frame UBV according to the expected redshift distribution as a function of BJ. For each of the three methods, we find that the fraction of galaxy types does not depend significantly on wavelength, and that they produce consistent counts as a function of type. The median scale length at BJ ~= 27 mag is rhl ~= 0."25--0."3 (1--2 kpc at z ~ 1--2). Early- and late-type galaxies are fairly well separated in BVI color-magnitude diagrams for B <~ 27 mag, with E/S0 galaxies being the reddest and Sd/Irr+M galaxies generally blue. We present the B-band galaxy counts for five WFPC2 fields as a function of morphological type for BJ <~ 27 mag. E/S0 galaxies are only marginally above the no-evolution predictions, and Sabc galaxies are at most 0.5 dex above the nonevolving models for BJ >~ 24 mag. The faint blue galaxy counts in the B band are dominated by Sd/Irr+M galaxies and can be explained by a moderately steep local luminosity function (LF) undergoing strong luminosity evolution. We suggest that these faint late-type objects (24 mag <~ BJ <~ 28 mag) are a combination of low-luminosity lower redshift dwarf galaxies, plus compact star-forming galaxies and merging systems at z ~= 1--3, possibly the building blocks of the luminous early-type galaxies seen today.

Studying Cosmic Dawn with WFIRST

NASA Astrophysics Data System (ADS)

Rhoads, James; Malhotra, Sangeeta; Jansen, Rolf A.; Windhorst, Rogier; Tilvi, Vithal; Finkelstein, Steven; Wold, Isak; Papovich, Casey; Fan, Xiaohui; Mellema, Garrelt; Zackrisson, Erik; Jensen, Hannes; T

2018-01-01

Our understanding of Cosmic Dawn can be revolutionized using WFIRST's combination of wide-field, sensitive, high resolution near-infrared imaging and spectroscopy. Guest investigator studies of WFIRST's high latitude imaging survey and supernova search fields will yield orders of magnitude increases in our samples of Lyman break galaxies from z=7 to z>12. The high latitude spectrsocopic survey will enable an unprecedented search for z>7 quasars. Guest observer deep fields can extend these studies to flux levels of Hubble's deepest fields, over regions measured in square degrees. The resulting census of luminous objects in the Cosmic Dawn will provide key insights into the sources of the ultraviolet photons that powered reionization. Moreover, because WFIRST has a wide field (slitless) spectroscopic capability, it can be used to search for Lyman alpha emitting galaxies over the full history of reionization. By comparing the Lyman alpha galaxy statistics to those of continuum sources, we can directly probe the transparency of the intergalactic gas and chart reionization history.Our team is planning for both Guest Investigator and Guest Observer applications of WFIRST to studying Cosmic Dawn, and welcomes dialog with other interested members of the community.

The Great Observatories Origins Deep Survey (GOODS) Spitzer Legacy Science Program

NASA Astrophysics Data System (ADS)

Dickinson, M.; GOODS Team

2004-12-01

The Great Observatories Origins Deep Survey (GOODS) is an anthology of observing programs that are creating a rich, public, multiwavelength data set for studying galaxy formation and evolution. GOODS is observing two fields, one in each hemisphere, with extremely deep imaging and spectroscopy using the most powerful telescopes in space and on the ground. The GOODS Spitzer Legacy Science Program completes the trio of observations from NASA's Great Observatories, joining already-completed GOODS data from Chandra and Hubble. Barring unforeseen difficulties, the GOODS Spitzer observing program will have been completed by the end of 2004, and the first data products will have been released to the astronomical community. In this Special Oral Session, and in an accompanying poster session, the GOODS team presents early scientific results from this Spitzer Legacy program, as well as new research based on other GOODS data sets. I will introduce the session with a brief description of the Legacy observations and data set. Support for this work, part of the Spitzer Space Telescope Legacy Science Program, was provided by NASA through Contract Number 1224666 issued by the Jet Propulsion Laboratory, California Institute of Technology under NASA contract 1407.

KSC-08pd3185

NASA Image and Video Library

2008-10-14

CAPE CANAVERAL, Fla. – The deep-red sunset sky puts Launch pad 39A in silhouette. Space shuttle Atlantis is on the pad. Atlantis’ October target launch date for the STS-125 Hubble Space Telescope servicing mission was delayed after a device on board Hubble used in the storage and transmission of science data to Earth shut down on Sept. 27. Replacing the broken device will be added to Atlantis’ servicing mission to the telescope. In the interim, Atlantis will be rolled back to the Vehicle Assembly Building until a new target launch date can be set for the mission in 2009. Photo credit: NASA/Troy Cryder

KSC-08pd2470

NASA Image and Video Library

2008-08-18

CAPE CANAVERAL, Fla. – In the Payload Hazardous Servicing Facility at NASA's Kennedy Space Center, an overhead crane lifts the Wide Field Camera 3, or WFC3, high above the floor for transfer to the Super Lightweight Interchangeable Carrier. WFC3 is part of the payload on space shuttle Atlantis' STS-125 mission for the fifth and final Hubble servicing flight to NASA's Hubble Space Telescope. As Hubble enters the last stage of its life, WFC3 will be Hubble's next evolutionary step, allowing Hubble to peer ever further into the mysteries of the cosmos. WFC3 will study a diverse range of objects and phenomena, from young and extremely distant galaxies, to much more nearby stellar systems, to objects within our very own solar system. WFC3 will take the place of Wide Field Planetary Camera 2, which astronauts will bring back to Earth aboard the shuttle. Launch of Atlantis is targeted at 1:34 a.m. EDT Oct. 8. Photo credit: NASA/Amanda Diller

KSC-08pd2459

NASA Image and Video Library

2008-08-18

CAPE CANAVERAL, Fla. – In the Payload Hazardous Servicing Facility at NASA's Kennedy Space Center, technicians check the placement of an overhead crane to the Wide Field Camera 3, or WFC3, that will transfer the WFC3 to the Super Lightweight Interchangeable Carrier. WFC3 is part of the payload on space shuttle Atlantis' STS-125 mission for the fifth and final Hubble servicing flight to NASA's Hubble Space Telescope. As Hubble enters the last stage of its life, WFC3 will be Hubble's next evolutionary step, allowing Hubble to peer ever further into the mysteries of the cosmos. WFC3 will study a diverse range of objects and phenomena, from young and extremely distant galaxies, to much more nearby stellar systems, to objects within our very own solar system. WFC3 will take the place of Wide Field Planetary Camera 2, which astronauts will bring back to Earth aboard the shuttle. Launch of Atlantis is targeted at 1:34 a.m. EDT Oct. 8. Photo credit: NASA/Amanda Diller

KSC-08pd2469

NASA Image and Video Library

2008-08-18

CAPE CANAVERAL, Fla. – In the Payload Hazardous Servicing Facility at NASA's Kennedy Space Center, an overhead crane moves the Wide Field Camera 3, or WFC3, from its stand. The WFC3 will be transferred to the Super Lightweight Interchangeable Carrier. WFC3 is part of the payload on space shuttle Atlantis' STS-125 mission for the fifth and final Hubble servicing flight to NASA's Hubble Space Telescope. As Hubble enters the last stage of its life, WFC3 will be Hubble's next evolutionary step, allowing Hubble to peer ever further into the mysteries of the cosmos. WFC3 will study a diverse range of objects and phenomena, from young and extremely distant galaxies, to much more nearby stellar systems, to objects within our very own solar system. WFC3 will take the place of Wide Field Planetary Camera 2, which astronauts will bring back to Earth aboard the shuttle. Launch of Atlantis is targeted at 1:34 a.m. EDT Oct. 8. Photo credit: NASA/Amanda Diller

The Hubble Space Telescope UV Legacy Survey of Galactic globular clusters - XIII. ACS/WFC parallel-field catalogues

NASA Astrophysics Data System (ADS)

Simioni, M.; Bedin, L. R.; Aparicio, A.; Piotto, G.; Milone, A. P.; Nardiello, D.; Anderson, J.; Bellini, A.; Brown, T. M.; Cassisi, S.; Cunial, A.; Granata, V.; Ortolani, S.; van der Marel, R. P.; Vesperini, E.

2018-05-01

As part of the Hubble Space Telescope UV Legacy Survey of Galactic globular clusters, 110 parallel fields were observed with the Wide Field Channel of the Advanced Camera for Surveys, in the outskirts of 48 globular clusters, plus the open cluster NGC 6791. Totalling about 0.3 deg2 of observed sky, this is the largest homogeneous Hubble Space Telescope photometric survey of Galalctic globular clusters outskirts to date. In particular, two distinct pointings have been obtained for each target on average, all centred at about 6.5 arcmin from the cluster centre, thus covering a mean area of about 23 arcmin2 for each globular cluster. For each field, at least one exposure in both F475W and F814W filters was collected. In this work, we publicly release the astrometric and photometric catalogues and the astrometrized atlases for each of these fields.

Hubble Frontier Fields view of MACSJ0717.5+3745

NASA Image and Video Library

2015-10-22

This image from the NASA/ESA Hubble Space Telescope shows the galaxy cluster MACSJ0717.5+3745. This is one of six being studied by the Hubble Frontier Fields programme, which together have produced the deepest images of gravitational lensing ever made. Due to the huge mass of the cluster it is bending the light of background objects, acting as a magnifying lens. It is one of the most massive galaxy clusters known, and it is also the largest known gravitational lens. Of all of the galaxy clusters known and measured, MACS J0717 lenses the largest area of the sky.

A Guided Inquiry on Hubble Plots and the Big Bang

NASA Astrophysics Data System (ADS)

Forringer, Ted

2014-04-01

In our science for non-science majors course "21st Century Physics," we investigate modern "Hubble plots" (plots of velocity versus distance for deep space objects) in order to discuss the Big Bang, dark matter, and dark energy. There are two potential challenges that our students face when encountering these topics for the first time. The first challenge is in understanding and interpreting Hubble plots. The second is that some of our students have religious or cultural objections to the concept of a "Big Bang" or a universe that is billions of years old. This paper presents a guided inquiry exercise that was created with the goal of introducing students to Hubble plots and giving them the opportunity to discover for themselves why we believe our universe started with an explosion billions of years ago. The exercise is designed to be completed before the topics are discussed in the classroom. We did the exercise during a one hour and 45 minute "lab" time and it was done in groups of three or four students, but it would also work as an individual take-home assignment.

The HDUV Survey: Six Lyman Continuum Emitter Candidates at z ˜ 2 Revealed by HST UV Imaging

NASA Astrophysics Data System (ADS)

Naidu, R. P.; Oesch, P. A.; Reddy, N.; Holden, B.; Steidel, C. C.; Montes, M.; Atek, H.; Bouwens, R. J.; Carollo, C. M.; Cibinel, A.; Illingworth, G. D.; Labbé, I.; Magee, D.; Morselli, L.; Nelson, E. J.; van Dokkum, P. G.; Wilkins, S.

2017-09-01

We present six galaxies at z˜ 2 that show evidence of Lyman continuum (LyC) emission based on the newly acquired UV imaging of the Hubble Deep UV legacy survey (HDUV) conducted with the WFC3/UVIS camera on the Hubble Space Telescope (HST). At the redshift of these sources, the HDUV F275W images partially probe the ionizing continuum. By exploiting the HST multiwavelength data available in the HDUV/GOODS fields, models of the UV spectral energy distributions, and detailed Monte Carlo simulations of the intergalactic medium absorption, we estimate the absolute ionizing photon escape fractions of these galaxies to be very high—typically > 60 % (> 13 % for all sources at 90% likelihood). Our findings are in broad agreement with previous studies that found only a small fraction of galaxies with high escape fraction. These six galaxies compose the largest sample yet of LyC leaking candidates at z˜ 2 whose inferred LyC flux has been observed at HST resolution. While three of our six candidates show evidence of hosting an active galactic nucleus, two of these are heavily obscured and their LyC emission appears to originate from star-forming regions rather than the central nucleus. Extensive multiwavelength data in the GOODS fields, especially the near-IR grism spectra from the 3D-HST survey, enable us to study the candidates in detail and tentatively test some recently proposed indirect methods to probe LyC leakage. High-resolution spectroscopic follow-up of our candidates will help constrain such indirect methods, which are our only hope of studying f esc at z˜ 5-9 in the JWST era. Based on observations made with the NASA/ESA Hubble Space Telescope, obtained from the data archive at the Space Telescope Science Institute. STScI is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555.

KSC-08pd2465

NASA Image and Video Library

2008-08-18

CAPE CANAVERAL, Fla. – In the Payload Hazardous Servicing Facility at NASA's Kennedy Space Center, technicians observe as the Wide Field Camera 3, or WFC3, is rotated. The WFC3 will be transferred to the Super Lightweight Interchangeable Carrier. WFC3 is part of the payload on space shuttle Atlantis' STS-125 mission for the fifth and final Hubble servicing flight to NASA's Hubble Space Telescope. The curved edge shown at the back is the radiator, the "outside" of WFC3 that will be exposed to space and will expel heat out of Hubble and into space through black body radiation. As Hubble enters the last stage of its life, WFC3 will be Hubble's next evolutionary step, allowing Hubble to peer ever further into the mysteries of the cosmos. WFC3 will study a diverse range of objects and phenomena, from young and extremely distant galaxies, to much more nearby stellar systems, to objects within our very own solar system. WFC3 will take the place of Wide Field Planetary Camera 2, which astronauts will bring back to Earth aboard the shuttle. Launch of Atlantis is targeted at 1:34 a.m. EDT Oct. 8. Photo credit: NASA/Amanda Diller

KSC-08pd2466

NASA Image and Video Library

2008-08-18

CAPE CANAVERAL, Fla. – In the Payload Hazardous Servicing Facility at NASA's Kennedy Space Center, technicians observe as the Wide Field Camera 3, or WFC3, is rotated to vertical. The WFC3 will be transferred to the Super Lightweight Interchangeable Carrier. WFC3 is part of the payload on space shuttle Atlantis' STS-125 mission for the fifth and final Hubble servicing flight to NASA's Hubble Space Telescope. The curved edge shown at top is the radiator, the "outside" of WFC3 that will be exposed to space and will expel heat out of Hubble and into space through black body radiation. As Hubble enters the last stage of its life, WFC3 will be Hubble's next evolutionary step, allowing Hubble to peer ever further into the mysteries of the cosmos. WFC3 will study a diverse range of objects and phenomena, from young and extremely distant galaxies, to much more nearby stellar systems, to objects within our very own solar system. WFC3 will take the place of Wide Field Planetary Camera 2, which astronauts will bring back to Earth aboard the shuttle. Launch of Atlantis is targeted at 1:34 a.m. EDT Oct. 8. Photo credit: NASA/Amanda Diller

KSC-08pd2467

NASA Image and Video Library

2008-08-18

CAPE CANAVERAL, Fla. – After rotation of the Wide Field Camera 3 (background left), or WFC3, in the Payload Hazardous Servicing Facility at NASA's Kennedy Space Center, technicians check the data. The WFC3 will be transferred to the Super Lightweight Interchangeable Carrier. WFC3 is part of the payload on space shuttle Atlantis' STS-125 mission for the fifth and final Hubble servicing flight to NASA's Hubble Space Telescope. The curved edge shown at top is the radiator, the "outside" of WFC3 that will be exposed to space and will expel heat out of Hubble and into space through black body radiation. As Hubble enters the last stage of its life, WFC3 will be Hubble's next evolutionary step, allowing Hubble to peer ever further into the mysteries of the cosmos. WFC3 will study a diverse range of objects and phenomena, from young and extremely distant galaxies, to much more nearby stellar systems, to objects within our very own solar system. WFC3 will take the place of Wide Field Planetary Camera 2, which astronauts will bring back to Earth aboard the shuttle. Launch of Atlantis is targeted at 1:34 a.m. EDT Oct. 8. Photo credit: NASA/Amanda Diller

KSC-08pd2464

NASA Image and Video Library

2008-08-18

CAPE CANAVERAL, Fla. – In the Payload Hazardous Servicing Facility at NASA's Kennedy Space Center, the Wide Field Camera 3, or WFC3, has been rotated. The WFC3 will be transferred to the Super Lightweight Interchangeable Carrier. WFC3 is part of the payload on space shuttle Atlantis' STS-125 mission for the fifth and final Hubble servicing flight to NASA's Hubble Space Telescope. The curved edge shown at top is the radiator, the "outside" of WFC3 that will be exposed to space and will expel heat out of Hubble and into space through black body radiation. As Hubble enters the last stage of its life, WFC3 will be Hubble's next evolutionary step, allowing Hubble to peer ever further into the mysteries of the cosmos. WFC3 will study a diverse range of objects and phenomena, from young and extremely distant galaxies, to much more nearby stellar systems, to objects within our very own solar system. WFC3 will take the place of Wide Field Planetary Camera 2, which astronauts will bring back to Earth aboard the shuttle. Launch of Atlantis is targeted at 1:34 a.m. EDT Oct. 8. Photo credit: NASA/Amanda Diller

KSC-08pd2461

NASA Image and Video Library

2008-08-18

CAPE CANAVERAL, Fla. – In the Payload Hazardous Servicing Facility at NASA's Kennedy Space Center, technicians wait for the rotation of the Wide Field Camera 3, or WFC3, in order to attach a crane. The WFC3 will be transferred to the Super Lightweight Interchangeable Carrier. WFC3 is part of the payload on space shuttle Atlantis' STS-125 mission for the fifth and final Hubble servicing flight to NASA's Hubble Space Telescope. The part shown here is the radiator, the "outside" of WFC3 that will be exposed to space and will expel heat out of Hubble and into space through black body radiation. As Hubble enters the last stage of its life, WFC3 will be Hubble's next evolutionary step, allowing Hubble to peer ever further into the mysteries of the cosmos. WFC3 will study a diverse range of objects and phenomena, from young and extremely distant galaxies, to much more nearby stellar systems, to objects within our very own solar system. WFC3 will take the place of Wide Field Planetary Camera 2, which astronauts will bring back to Earth aboard the shuttle. Launch of Atlantis is targeted at 1:34 a.m. EDT Oct. 8. Photo credit: NASA/Amanda Diller

KSC-08pd2462

NASA Image and Video Library

2008-08-18

CAPE CANAVERAL, Fla. – In the Payload Hazardous Servicing Facility at NASA's Kennedy Space Center, technicians wait for the rotation of the Wide Field Camera 3, or WFC3, in order to attach a crane. The WFC3 will be transferred to the Super Lightweight Interchangeable Carrier. WFC3 is part of the payload on space shuttle Atlantis' STS-125 mission for the fifth and final Hubble servicing flight to NASA's Hubble Space Telescope. The curved edge shown at left is the radiator, the "outside" of WFC3 that will be exposed to space and will expel heat out of Hubble and into space through black body radiation. As Hubble enters the last stage of its life, WFC3 will be Hubble's next evolutionary step, allowing Hubble to peer ever further into the mysteries of the cosmos. WFC3 will study a diverse range of objects and phenomena, from young and extremely distant galaxies, to much more nearby stellar systems, to objects within our very own solar system. WFC3 will take the place of Wide Field Planetary Camera 2, which astronauts will bring back to Earth aboard the shuttle. Launch of Atlantis is targeted at 1:34 a.m. EDT Oct. 8. Photo credit: NASA/Amanda Diller

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NASA Image and Video Library

2008-08-18

CAPE CANAVERAL, Fla. – In the Payload Hazardous Servicing Facility at NASA's Kennedy Space Center, technicians stand by as the Wide Field Camera 3, or WFC3, is rotated. The WFC3 will be transferred to the Super Lightweight Interchangeable Carrier. WFC3 is part of the payload on space shuttle Atlantis' STS-125 mission for the fifth and final Hubble servicing flight to NASA's Hubble Space Telescope. The curved edge shown at left is the radiator, the "outside" of WFC3 that will be exposed to space and will expel heat out of Hubble and into space through black body radiation. As Hubble enters the last stage of its life, WFC3 will be Hubble's next evolutionary step, allowing Hubble to peer ever further into the mysteries of the cosmos. WFC3 will study a diverse range of objects and phenomena, from young and extremely distant galaxies, to much more nearby stellar systems, to objects within our very own solar system. WFC3 will take the place of Wide Field Planetary Camera 2, which astronauts will bring back to Earth aboard the shuttle. Launch of Atlantis is targeted at 1:34 a.m. EDT Oct. 8. Photo credit: NASA/Amanda Diller

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NASA Image and Video Library

2008-08-18

CAPE CANAVERAL, Fla. – In the Payload Hazardous Servicing Facility at NASA's Kennedy Space Center, a technician guides a crane for attachment to the radiator on the Wide Field Camera 3, or WFC3. The WFC3 will be transferred to the Super Lightweight Interchangeable Carrier. WFC3 is part of the payload on space shuttle Atlantis' STS-125 mission for the fifth and final Hubble servicing flight to NASA's Hubble Space Telescope. The radiator is the "outside" of WFC3 that will be exposed to space and will expel heat out of Hubble and into space through black body radiation. As Hubble enters the last stage of its life, WFC3 will be Hubble's next evolutionary step, allowing Hubble to peer ever further into the mysteries of the cosmos. WFC3 will study a diverse range of objects and phenomena, from young and extremely distant galaxies, to much more nearby stellar systems, to objects within our very own solar system. WFC3 will take the place of Wide Field Planetary Camera 2, which astronauts will bring back to Earth aboard the shuttle. Launch of Atlantis is targeted at 1:34 a.m. EDT Oct. 8. Photo credit: NASA/Amanda Diller

Berkeley Lab Scientists to Play Role in New Space Telescope

Science.gov Websites

circling distant suns, among other science aims. The Wide Field Infrared Survey Telescope (WFIRST) will Hubble Space Telescope's Wide Field Camera 3 infrared imager. A Hubble large-scale mapping survey of the survey of the M31 galaxy (shown here) required 432 "pointings" of its imager, while only two

The Secret Lives Of Galaxies Unveiled In Deep Survey

NASA Astrophysics Data System (ADS)

2003-06-01

Two of NASA's Great Observatories, bolstered by the largest ground-based telescopes around the world, are beginning to harvest new clues to the origin and evolution of galaxies. It's a bit like finding a family scrapbook containing snapshots that capture the lives of family members from infancy through adolescence to adulthood. "This is the first time the cosmic tale of how galaxies build themselves has been traced reliably to such early times in the universe's life," said Mauro Giavalisco, head of the Hubble Space Telescope (HST) portion of the survey, and research astronomer at the Space Telescope Science Institute (STScI) in Baltimore. The HST has joined forces with the Chandra X-ray Observatory to survey a relatively broad swath of sky encompassing tens of thousands of galaxies stretching far back into time. The Space Infrared Telescope Facility (SIRTF), scheduled for launch in August, will soon join this unprecedented survey. Called the Great Observatories Origins Deep Survey (GOODS), astronomers are studying galaxy formation and evolution over a wide range of distances and ages. The project is tracing the assembly history of galaxies, the evolution of their stellar populations, and the gusher of energy from star formation and active nuclei powered by immense black holes. HST astronomers report the sizes of galaxies clearly increase continuously from the time the universe was about 1 billion years old to an age of 6 billion years. This is approximately half the current age of the universe, 13.7 billion years. GOODS astronomers also find the star birth rate rose mildly, by about a factor of three, between the time the universe was about one billion years old and 1.5 billion years old, and remained high until about 7 billion years ago, when it quickly dropped to one-tenth the earlier "baby boomer" rate. This is further evidence major galaxy building trailed off when the universe was about half its current age. GOODS Chandra Deep Fields South Chandra Deep Field South This increase in galaxy size is consistent with "bottom-up" models, where galaxies grow hierarchically, through mergers and accretion of smaller satellite galaxies. This is also consistent with the idea the sizes of galaxies match hand-in-glove to a certain fraction of the sizes of their dark-matter halos. Dark matter is an invisible form of mass that comprises most of the matter in the universe. The theory is dark matter essentially pooled into gravitational "puddles" in the early universe, then collected normal gas that quickly contracted to build star clusters and small galaxies. These dwarf galaxies merged piece-by-piece over billions of years to build the immense spiral and elliptical galaxies we see today. The Chandra observations amounted to a "high-energy core sample" of the early universe, allowing us to "study the history of black holes over almost the entire age of the universe," said Niel Brandt of Penn State University, a co-investigator on the Chandra GOODS team. One of the fascinating findings in this deepest X-ray image ever taken is the discovery of mysterious black holes, which have no optical counterparts. "We found seven mysterious sources that are completely invisible in the optical with Hubble," said Anton Koekemoer of the STScI, a co-investigator on both the Hubble and Chandra GOODS teams. "Either they are the most distant black holes ever detected, or they are less distant black holes that are the most dust enshrouded known, a surprising result as well." When comparing the HST and Chandra fields, astronomers also found active black holes in distant, relatively small galaxies were rarer than expected. This may be due to the effects of early generations of massive stars that exploded as supernovae, evacuating galactic gas and thus reducing the supply of gas needed to feed a super massive black hole. These and other results from the GOODS project will be published in a special issue of the Astrophysical Journal Letters, entirely devoted to the team's results. The Chandra results are found in papers led by Koekemoer and Stefano Cristiani of the Trieste Astronomical Observatory. Hubble's findings came from papers led by Giavalisco, Mark Dickinson, and Harry Ferguson of the STScI. The image and additional information are available at: http://chandra.harvard.edu and http://hubblesite.org/newscenter/archive/2003/18/

Science Highlights from the First Year of Advanced Camera for Surveys

NASA Technical Reports Server (NTRS)

Clampin, M.; Ford, H. C.; Illingworth, G. D.; Hartig, G.; Ardila, D. R.; Blakeslee, J. P.; Bouwens, R. J.; Cross, N. J. G.; Feldman, P. D.; Golimowski, D. A.

2003-01-01

The Advanced Camera for Surveys (ACS) is a deep imaging camera installed on the Hubble Space Telescope during the fourth HST servicing mission. ACS recently entered its second year of science operations and continues to perform beyond pre-launch expectations. We present science highlights from the ACS Science Team's GTO program. These highlights include the evolution of Z approx. 6 galaxies from deep imaging observations; deep imaging of strongly lensed clusters which have been used to determine cluster mass, and independently constraint the geometry of the Universe; and coronagraphic observations of debris disks.

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NASA Image and Video Library

2008-08-12

CAPE CANAVERAL, Fla. – In the Payload Hazardous Servicing Facility at NASA's Kennedy Space Center, technicians monitor the movement of the Wide Field Camera 3, or WFC3, as it is lowered onto a work stand. As Hubble enters the last stage of its life, WFC3 will be Hubble's next evolutionary step, allowing Hubble to peer ever further into the mysteries of the cosmos. WFC3 will study a diverse range of objects and phenomena, from young and extremely distant galaxies, to much more nearby stellar systems, to objects within our very own solar system. WFC3 will take the place of Wide Field Planetary Camera 2, which astronauts will bring back to Earth aboard the shuttle. WFC3 is part of the payload on the fifth and final Hubble servicing mission, STS-125, targeted for launch Oct. 8. Photo credit: NASA/Jack Pfaller

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NASA Image and Video Library

2008-08-12

CAPE CANAVERAL, Fla. – In the Payload Hazardous Servicing Facility at NASA's Kennedy Space Center, technicians monitor the movement of the Wide Field Camera 3, or WFC3, as the overhead crane transfers it to a work stand. As Hubble enters the last stage of its life, WFC3 will be Hubble's next evolutionary step, allowing Hubble to peer ever further into the mysteries of the cosmos. WFC3 will study a diverse range of objects and phenomena, from young and extremely distant galaxies, to much more nearby stellar systems, to objects within our very own solar system. WFC3 will take the place of Wide Field Planetary Camera 2, which astronauts will bring back to Earth aboard the shuttle. WFC3 is part of the payload on the fifth and final Hubble servicing mission, STS-125, targeted for launch Oct. 8. Photo credit: NASA/Jack Pfaller

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NASA Image and Video Library

2008-08-12

CAPE CANAVERAL, Fla. – In the Payload Hazardous Servicing Facility at NASA's Kennedy Space Center, the cover of the Wide Field Camera 3, or WFC3, shipping container is lifted away from the mobile base. As Hubble enters the last stage of its life, WFC3 will be Hubble's next evolutionary step, allowing Hubble to peer ever further into the mysteries of the cosmos. WFC3 will study a diverse range of objects and phenomena, from young and extremely distant galaxies, to much more nearby stellar systems, to objects within our very own solar system. WFC3 will take the place of Wide Field Planetary Camera 2, which astronauts will bring back to Earth aboard the shuttle. WFC3 is part of the payload on the fifth and final Hubble servicing mission, STS-125, targeted for launch Oct. 8. Photo credit: NASA/Jack Pfaller

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NASA Image and Video Library

2008-08-12

CAPE CANAVERAL, Fla. – In the Payload Hazardous Servicing Facility at NASA's Kennedy Space Center, technicians move the base of the shipping container holding the Wide Field Camera 3, or WFC3, into the high bay. As Hubble enters the last stage of its life, WFC3 will be Hubble's next evolutionary step, allowing Hubble to peer ever further into the mysteries of the cosmos. WFC3 will study a diverse range of objects and phenomena, from young and extremely distant galaxies, to much more nearby stellar systems, to objects within our very own solar system. WFC3 will take the place of Wide Field Planetary Camera 2, which astronauts will bring back to Earth aboard the shuttle. WFC3 is part of the payload on the fifth and final Hubble servicing mission, STS-125, targeted for launch Oct. 8. Photo credit: NASA/Jack Pfaller

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NASA Image and Video Library

2008-08-12

CAPE CANAVERAL, Fla. – In the Payload Hazardous Servicing Facility at NASA's Kennedy Space Center, technicians move the base of the shipping container holding the Wide Field Camera 3, or WFC3. As Hubble enters the last stage of its life, WFC3 will be Hubble's next evolutionary step, allowing Hubble to peer ever further into the mysteries of the cosmos. WFC3 will study a diverse range of objects and phenomena, from young and extremely distant galaxies, to much more nearby stellar systems, to objects within our very own solar system. WFC3 will take the place of Wide Field Planetary Camera 2, which astronauts will bring back to Earth aboard the shuttle. WFC3 is part of the payload on the fifth and final Hubble servicing mission, STS-125, targeted for launch Oct. 8. Photo credit: NASA/Jack Pfaller

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NASA Image and Video Library

2008-08-12

CAPE CANAVERAL, Fla. – In the Payload Hazardous Servicing Facility at NASA's Kennedy Space Center, technicians monitor the placement of the Wide Field Camera 3, or WFC3, on a work stand. As Hubble enters the last stage of its life, WFC3 will be Hubble's next evolutionary step, allowing Hubble to peer ever further into the mysteries of the cosmos. WFC3 will study a diverse range of objects and phenomena, from young and extremely distant galaxies, to much more nearby stellar systems, to objects within our very own solar system. WFC3 will take the place of Wide Field Planetary Camera 2, which astronauts will bring back to Earth aboard the shuttle. WFC3 is part of the payload on the fifth and final Hubble servicing mission, STS-125, targeted for launch Oct. 8. Photo credit: NASA/Jack Pfaller

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NASA Image and Video Library

2008-08-16

CAPE CANAVERAL, Fla. – Technicians in the Payload Hazardous Servicing Facility remove the protective cover from the Wide Field Camera 3, or WFC3. The WFC3 is part of the payload on space shuttle Atlantis for the fifth and final Hubble servicing mission, STS-125. As Hubble enters the last stage of its life, WFC3 will be Hubble's next evolutionary step, allowing Hubble to peer ever further into the mysteries of the cosmos. WFC3 will study a diverse range of objects and phenomena, from young and extremely distant galaxies, to much more nearby stellar systems, to objects within our very own solar system. WFC3 will take the place of Wide Field Planetary Camera 2, which astronauts will bring back to Earth aboard the shuttle. Launch of Atlantis is targeted at 1:34 a.m. EDT Oct. 8. Photo credit: NASA/Jack Pfaller

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NASA Image and Video Library

2008-08-12

CAPE CANAVERAL, Fla. – In the Payload Hazardous Servicing Facility at NASA's Kennedy Space Center, technicians attach an overhead crane to the cover of the Wide Field Camera 3, or WFC3, shipping container. As Hubble enters the last stage of its life, WFC3 will be Hubble's next evolutionary step, allowing Hubble to peer ever further into the mysteries of the cosmos. WFC3 will study a diverse range of objects and phenomena, from young and extremely distant galaxies, to much more nearby stellar systems, to objects within our very own solar system. WFC3 will take the place of Wide Field Planetary Camera 2, which astronauts will bring back to Earth aboard the shuttle. WFC3 is part of the payload on the fifth and final Hubble servicing mission, STS-125, targeted for launch Oct. 8. Photo credit: NASA/Jack Pfaller

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NASA Image and Video Library

2008-08-16

CAPE CANAVERAL, Fla. – Technicians in the Payload Hazardous Servicing Facility begin removing the protective cover from the Wide Field Camera 3, or WFC3. The WFC3 is part of the payload on space shuttle Atlantis for the fifth and final Hubble servicing mission, STS-125. As Hubble enters the last stage of its life, WFC3 will be Hubble's next evolutionary step, allowing Hubble to peer ever further into the mysteries of the cosmos. WFC3 will study a diverse range of objects and phenomena, from young and extremely distant galaxies, to much more nearby stellar systems, to objects within our very own solar system. WFC3 will take the place of Wide Field Planetary Camera 2, which astronauts will bring back to Earth aboard the shuttle. Launch of Atlantis is targeted at 1:34 a.m. EDT Oct. 8. Photo credit: NASA/Jack Pfaller

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NASA Image and Video Library

2008-08-12

CAPE CANAVERAL, Fla. – The shipping container with the Wide Field Camera 3, or WFC3, inside is removed from the truck outside the Payload Hazardous Servicing Facility at NASA's Kennedy Space Center. As Hubble enters the last stage of its life, WFC3 will be Hubble's next evolutionary step, allowing Hubble to peer ever further into the mysteries of the cosmos. WFC3 will study a diverse range of objects and phenomena, from young and extremely distant galaxies, to much more nearby stellar systems, to objects within our very own solar system. WFC3 will take the place of Wide Field Planetary Camera 2, which astronauts will bring back to Earth aboard the shuttle. WFC3 is part of the payload on the fifth and final Hubble servicing mission, STS-125, targeted for launch Oct. 8. Photo credit: NASA/Jack Pfaller

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NASA Image and Video Library

2008-08-12

CAPE CANAVERAL, Fla. – In the Payload Hazardous Servicing Facility at NASA's Kennedy Space Center, technicians begin lifting the cover of the Wide Field Camera 3, or WFC3, shipping container. As Hubble enters the last stage of its life, WFC3 will be Hubble's next evolutionary step, allowing Hubble to peer ever further into the mysteries of the cosmos. WFC3 will study a diverse range of objects and phenomena, from young and extremely distant galaxies, to much more nearby stellar systems, to objects within our very own solar system. WFC3 will take the place of Wide Field Planetary Camera 2, which astronauts will bring back to Earth aboard the shuttle. WFC3 is part of the payload on the fifth and final Hubble servicing mission, STS-125, targeted for launch Oct. 8. Photo credit: NASA/Jack Pfaller

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NASA Image and Video Library

2008-08-12

CAPE CANAVERAL, Fla. – In the Payload Hazardous Servicing Facility at NASA's Kennedy Space Center, technicians unlatch the cover of the Wide Field Camera 3, or WFC3,shipping container before removing it. As Hubble enters the last stage of its life, WFC3 will be Hubble's next evolutionary step, allowing Hubble to peer ever further into the mysteries of the cosmos. WFC3 will study a diverse range of objects and phenomena, from young and extremely distant galaxies, to much more nearby stellar systems, to objects within our very own solar system. WFC3 will take the place of Wide Field Planetary Camera 2, which astronauts will bring back to Earth aboard the shuttle. WFC3 is part of the payload on the fifth and final Hubble servicing mission, STS-125, targeted for launch Oct. 8. Photo credit: NASA/Jack Pfaller

Galaxies at z~7-8: z850-Dropouts in the Hubble Ultra Deep Field

NASA Astrophysics Data System (ADS)

Bouwens, R. J.; Thompson, R. I.; Illingworth, G. D.; Franx, M.; van Dokkum, P. G.; Fan, X.; Dickinson, M. E.; Eisenstein, D. J.; Rieke, M. J.

2004-12-01

We have detected likely z~7-8 galaxies in the 144''×144'' Near-Infrared Camera and Multi-Object Spectrometer (NICMOS) observations of the Hubble Ultra Deep Field. Objects are required to be >=3 σ detections in both NICMOS bands, J110 and H160. The selection criteria for this sample are (z850-J110)AB>0.8, (z850-J110)AB>0.66(J110-H160)AB+0.8, (J110-H160)AB<1.2 and no detection at less than 8500 Å. The five selected sources have total magnitudes H160,AB~27. Four of the five sources are quite blue compared to typical lower redshift dropout galaxies and are clustered within a 1 arcmin2 region. Because all five sources are near the limit of the NICMOS data, we have carefully evaluated their reality. Each of the candidates is visible in different splits of the data and a median stack. We analyzed several noise images and estimate the number of spurious sources to be 1+/-1. A search using an independent reduction of this same data set clearly revealed three of the five candidates and weakly detected a fourth candidate, suggesting that the contamination could be higher. For comparison with predictions from lower redshift samples, we take a conservative approach and adopt four z~7-8 galaxies as our sample. With the same detection criteria on simulated data sets, assuming no evolution from z~3.8, we predict 10 sources at z~7-8, or 14 if we use a more realistic (1+z)-1 size scaling. We estimate that the rest-frame continuum UV (~1800 Å) luminosity density at z~7.5 (integrated down to 0.3L*z=3) is just 0.20+0.12-0.08 times that found at z~3.8 (or 0.20+0.23-0.12 times this quantity including cosmic variance). Effectively this sets an upper limit on the luminosity density down to 0.3L*z=3 and is consistent with significant evolution at the bright end of the luminosity function from z~7.5 to 3.8. Even with the lower UV luminosity density at z~7.5, it appears that galaxies could still play an important role in reionization at these redshifts, although definitive measurements remain to be made. Based on observations made with the NASA/ESA Hubble Space Telescope, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555.

Strong-lensing analysis of A2744 with MUSE and Hubble Frontier Fields images

NASA Astrophysics Data System (ADS)

Mahler, G.; Richard, J.; Clément, B.; Lagattuta, D.; Schmidt, K.; Patrício, V.; Soucail, G.; Bacon, R.; Pello, R.; Bouwens, R.; Maseda, M.; Martinez, J.; Carollo, M.; Inami, H.; Leclercq, F.; Wisotzki, L.

2018-01-01

We present an analysis of Multi Unit Spectroscopic Explorer (MUSE) observations obtained on the massive Frontier Fields (FFs) cluster A2744. This new data set covers the entire multiply imaged region around the cluster core. The combined catalogue consists of 514 spectroscopic redshifts (with 414 new identifications). We use this redshift information to perform a strong-lensing analysis revising multiple images previously found in the deep FF images, and add three new MUSE-detected multiply imaged systems with no obvious Hubble Space Telescope counterpart. The combined strong-lensing constraints include a total of 60 systems producing 188 images altogether, out of which 29 systems and 83 images are spectroscopically confirmed, making A2744 one of the most well-constrained clusters to date. Thanks to the large amount of spectroscopic redshifts, we model the influence of substructures at larger radii, using a parametrization including two cluster-scale components in the cluster core and several group scale in the outskirts. The resulting model accurately reproduces all the spectroscopic multiple systems, reaching an rms of 0.67 arcsec in the image plane. The large number of MUSE spectroscopic redshifts gives us a robust model, which we estimate reduces the systematic uncertainty on the 2D mass distribution by up to ∼2.5 times the statistical uncertainty in the cluster core. In addition, from a combination of the parametrization and the set of constraints, we estimate the relative systematic uncertainty to be up to 9 per cent at 200 kpc.

Hubble Spies a Loopy Galaxy

NASA Image and Video Library

2015-02-02

This NASA Hubble Space Telescope photo of NGC 7714 presents an especially striking view of the galaxy's smoke-ring-like structure. The golden loop is made of sun-like stars that have been pulled deep into space, far from the galaxy's center. The galaxy is located approximately 100 million light-years from Earth in the direction of the constellation Pisces. The universe is full of such galaxies that are gravitationally stretched and pulled and otherwise distorted in gravitational tug-o'-wars with bypassing galaxies. The companion galaxy doing the "taffy pulling" in this case, NGC 7715, lies just out of the field of view in this image. A very faint bridge of stars extends to the unseen companion. The close encounter has compressed interstellar gas to trigger bursts of star formation seen in bright blue arcs extending around NGC 7714's center. The gravitational disruption of NGC 7714 began between 100 million and 200 million years ago, at the epoch when dinosaurs ruled the Earth. The image was taken with the Wide Field Camera 3 and the Advanced Camera for Surveys in October 2011. Credit: NASA and ESA. Acknowledgment: A. Gal-Yam (Weizmann Institute of Science) NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Like us on Facebook Find us on Instagram

The Spectral Energy Distributions of z ~ 8 Galaxies from the IRAC Ultra Deep Fields: Emission Lines, Stellar Masses, and Specific Star Formation Rates at 650 Myr

NASA Astrophysics Data System (ADS)

Labbé, I.; Oesch, P. A.; Bouwens, R. J.; Illingworth, G. D.; Magee, D.; González, V.; Carollo, C. M.; Franx, M.; Trenti, M.; van Dokkum, P. G.; Stiavelli, M.

2013-11-01

Using new ultradeep Spitzer/InfraRed Array Camera (IRAC) photometry from the IRAC Ultra Deep Field program, we investigate the stellar populations of a sample of 63 Y-dropout galaxy candidates at z ~ 8, only 650 Myr after the big bang. The sources are selected from HST/ACS+WFC3/IR data over the Hubble Ultra Deep Field (HUDF), two HUDF parallel fields, and wide area data over the CANDELS/GOODS-South. The new Spitzer/IRAC data increase the coverage in [3.6] and [4.5] to ~120h over the HUDF reaching depths of ~28 (AB,1σ). The improved depth and inclusion of brighter candidates result in direct >=3σ InfraRed Array Camera (IRAC) detections of 20/63 sources, of which 11/63 are detected at >=5σ. The average [3.6]-[4.5] colors of IRAC detected galaxies at z ~ 8 are markedly redder than those at z ~ 7, observed only 130 Myr later. The simplest explanation is that we witness strong rest-frame optical emission lines (in particular [O III] λλ4959, 5007 + Hβ) moving through the IRAC bandpasses with redshift. Assuming that the average rest-frame spectrum is the same at both z ~ 7 and z ~ 8 we estimate a rest-frame equivalent width of {W}_{[O\\,\\scriptsize{III}]\\ \\lambda \\lambda 4959,5007+H\\beta }=670^{+260}_{-170} Å contributing 0.56^{+0.16}_{-0.11} mag to the [4.5] filter at z ~ 8. The corresponding {W}_{H\\alpha }=430^{+160}_{-110} Å implies an average specific star formation rate of sSFR=11_{-5}^{+11} Gyr-1 and a stellar population age of 100_{-50}^{+100} Myr. Correcting the spectral energy distribution for the contribution of emission lines lowers the average best-fit stellar masses and mass-to-light ratios by ~3 ×, decreasing the integrated stellar mass density to \\rho ^*(z=8,M_{\\rm{UV}}<-18)=0.6^{+0.4}_{-0.3}\\times 10^6 \\,M_\\odot Mpc-3. Based on observations made with the NASA/ESA Hubble Space Telescope, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555. These observations are associated with programs #11563, 9797. Based on observations with the Spitzer Space Telescope, which is operated by the Jet Propulsion Laboratory, California Institute of Technology under NASA contract 1407. Support for this work was provided by NASA through contract 125790 issued by JPL/Caltech. Based on service mode observations collected at the European Southern Observatory, Paranal, Chile (ESO Program 073.A-0764A). Based on data gathered with the 6.5 m Magellan Telescopes located at Las Campanas Observatory, Chile.

Critical points of the cosmic velocity field and the uncertainties in the value of the Hubble constant

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, Hao; Naselsky, Pavel; Mohayaee, Roya, E-mail: liuhao@nbi.dk, E-mail: roya@iap.fr, E-mail: naselsky@nbi.dk

2016-06-01

The existence of critical points for the peculiar velocity field is a natural feature of the correlated vector field. These points appear at the junctions of velocity domains with different orientations of their averaged velocity vectors. Since peculiar velocities are the important cause of the scatter in the Hubble expansion rate, we propose that a more precise determination of the Hubble constant can be made by restricting analysis to a subsample of observational data containing only the zones around the critical points of the peculiar velocity field, associated with voids and saddle points. On large-scales the critical points, where themore » first derivative of the gravitational potential vanishes, can easily be identified using the density field and classified by the behavior of the Hessian of the gravitational potential. We use high-resolution N-body simulations to show that these regions are stable in time and hence are excellent tracers of the initial conditions. Furthermore, we show that the variance of the Hubble flow can be substantially minimized by restricting observations to the subsample of such regions of vanishing velocity instead of aiming at increasing the statistics by averaging indiscriminately using the full data sets, as is the common approach.« less

HUBBLE'S ULTRAVIOLET VIEWS OF NEARBY GALAXIES YIELD CLUES TO EARLY UNIVERSE

NASA Technical Reports Server (NTRS)

2002-01-01

Astronomers are using these three NASA Hubble Space Telescope images to help tackle the question of why distant galaxies have such odd shapes, appearing markedly different from the typical elliptical and spiral galaxies seen in the nearby universe. Do faraway galaxies look weird because they are truly weird? Or, are they actually normal galaxies that look like oddballs, because astronomers are getting an incomplete picture of them, seeing only the brightest pieces? Light from these galaxies travels great distances (billions of light-years) to reach Earth. During its journey, the light is 'stretched' due to the expansion of space. As a result, the light is no longer visible, but has been shifted to the infrared where present instruments are less sensitive. About the only light astronomers can see comes from regions where hot, young stars reside. These stars emit mostly ultraviolet light. But this light is stretched, appearing as visible light by the time it reaches Earth. Studying these distant galaxies is like trying to put together a puzzle with some of the pieces missing. What, then, do distant galaxies really look like? Astronomers studied 37 nearby galaxies to find out. By viewing these galaxies in ultraviolet light, astronomers can compare their shapes with those of their distant relatives. These three Hubble telescope pictures, taken with the Wide Field and Planetary Camera 2, represent a sampling from that survey. Astronomers observed the galaxies in ultraviolet and visible light to study all the stars that make up these 'cities of stars.' The results of their survey support the idea that astronomers are detecting the 'tip of the iceberg' of very distant galaxies. Based on these Hubble ultraviolet images, not all the faraway galaxies necessarily possess intrinsically odd shapes. The results are being presented today at the 197th meeting of the American Astronomical Society in San Diego, CA. The central region of the 'star-burst' spiral galaxy at far left, NGC 3310, shows young and old stars evenly distributed. If this were the case with most galaxies, astronomers would be able to recognize faraway galaxies fairly easily. In most galaxies, however, the stars are segregated by age, making classifying the distant ones more difficult. NGC 3310 is 46 million light-years from Earth in the constellation Ursa Major. The image was taken Sept. 12-13, 2000. The middle image is an example of a tiny, youthful spiral galaxy. ESO 418-008 is representative of the myriad of dwarf galaxies astronomers have seen in deep surveys. These galaxies are much smaller than typical ones like our Milky Way. In this galaxy, the population of stars is more strongly segregated by age. The older stars [red] reside in the center; the younger [blue], in the developing spiral arms. These small, young galaxies may be the building blocks of galaxy formation. ESO 418-008 is 56 million light-years from Earth in the southern constellation Fornax. The image was taken Oct. 10, 2000. The picture at right shows a cosmic collision between two galaxies, UGC 06471 and UGC 06472. These collisions occurred frequently in the early universe, producing galaxies of unusual shapes. The Hubble telescope has spied many such galaxies in the deep field surveys. The ultraviolet images of this galaxy merger suggest the presence of large amounts of dust, which were produced by massive stars that formed before or during this dramatic collision. This dust reddens the starlight in many places, just like a dusty atmosphere reddens the sunset. Studying the effects of this nearby collision could help astronomers explain the peculiar shapes seen in some of the distant galaxies. UGC 06471 and UGC 06472 are 145 million light-years from Earth in the constellation Ursa Major. The image was taken July 11, 2000. Photo credits: NASA, Rogier Windhorst (Arizona State University, Tempe, AZ), and the Hubble mid-UV team

Hubble Frontier Field Abell 2744

NASA Image and Video Library

2014-01-07

This long-exposure image from NASA Hubble Space Telescope of massive galaxy cluster Abell 2744 is the deepest ever made of any cluster of galaxies. Shown in the foreground is Abell 2744, located in the constellation Sculptor.

The M31 Velocity Vector. I. Hubble Space Telescope Proper-motion Measurements

NASA Astrophysics Data System (ADS)

Sohn, Sangmo Tony; Anderson, Jay; van der Marel, Roeland P.

2012-07-01

We present the first proper-motion (PM) measurements for the galaxy M31. We obtained new V-band imaging data with the Hubble Space Telescope ACS/WFC and the WFC3/UVIS instruments of three fields: a spheroid field near the minor axis, an outer disk field along the major axis, and a field on the Giant Southern Stream. The data provide five to seven year time baselines with respect to pre-existing deep first-epoch observations of the same fields. We measure the positions of thousands of M31 stars and hundreds of compact background galaxies in each field. High accuracy and robustness is achieved by building and fitting a unique template for each individual object. The average PM for each field is obtained from the average motion of the M31 stars between the epochs with respect to the background galaxies. For the three fields, the observed PMs (μ W , μ N ) are, in units of mas yr-1, (- 0.0458, -0.0376) ± (0.0165, 0.0154), (- 0.0533, -0.0104) ± (0.0246, 0.0244), and (- 0.0179, -0.0357) ± (0.0278, 0.0272), respectively. The ability to average over large numbers of objects and over the three fields yields a final displacement accuracy of a few thousandths of a pixel, corresponding to only 12 μas yr-1. This is comparable to what has been achieved for other Local Group galaxies using Very Long Baseline Array observations of water masers. Potential systematic errors are controlled by an analysis strategy that corrects for detector charge transfer inefficiency, spatially and time-dependent geometric distortion, and point-spread function variations. The robustness of the PM measurements and uncertainties are supported by the fact that data from different instruments, taken at different times and with different telescope orientations, as well as measurements of different fields, all yield statistically consistent results. Papers II and III of this series explore the implications of the new measurements for our understanding of the history, future, and mass of the Local Group.

Galactic Pairs in the Early Universe

NASA Astrophysics Data System (ADS)

Kohler, Susanna

2018-02-01

In the spirit of Valentines Day, today well be exploring apparent pairs of galaxies in the distant, early universe. How can we tell whether these duos are actually paired galaxies, as opposed to disguised singles?Real Pair, or Trick of the Light?In the schematic timeline of the universe, the epoch of reionization is when the first galaxies and quasars began to form and evolve. [NASA]The statistics of merging galaxies throughout the universe reveal not only direct information about how galaxies interact, but also cosmological information about the structure of the universe. While weve observed many merging galaxy pairs at low redshift, however, its much more challenging to identify these duos in the early universe.A merging pair of galaxies at high redshift appears to us as a pair of unresolved blobs that lie close to each other in the sky. But spotting such a set of objects doesnt necessarily mean were looking at a merger! There are three possible scenarios to explain an observed apparent duo:Its a pair of galaxies in a stage of merger.Its a projection coincidence; the two galaxies arent truly near each other.Its a single galaxy being gravitationally lensed by a foreground object. This strong lensing produces the appearance of multiple galaxies.Hubble photometry of one of the three galaxy groups identified at z 8, with the galaxies in the image labeled with their corresponding approximate photometric redshifts. [Adapted from Chaikin et al. 2018]Hunting for Distant DuosIn a recent study led by Evgenii Chaikin (Peter the Great St. Petersburg Polytechnic University, Russia), a team of scientists has explored the Hubble Ultra Deep Field in search ofhigh-redshift galaxies merging during the epoch of reionization, when the first galaxies formed and evolved.Using an approach called the dropout technique, which leverages the visibility of the galaxies in different wavelength filters, Chaikin and collaborators obtain approximate redshifts for an initial sample of 7,000 objects. They find that roughly 50 have a redshift of z 7, and 22 have a redshift of z 8. None of the galaxies at z 7 are in pairs, but the sample at z 8 includes three groups for which the distance between galaxies is less than 1 arcsecond.But are these three pairs actual merging galaxies?Conclusions from StatisticsTop: Gas density at z 7.7 in the authors simulation output. Bottom: Mock observations of this output withHubbles WFC3 (left) and JWSTs NIRCam (right). [Adapted from Chaikin et al. 2018]To answer this question, the authors next perform numerical simulations of galaxy formation and produce mock observations showing what the simulatedfield would look like in an equivalent deep Hubble exposure.Based on their simulation statistics, Chaikin and collaborators argue that the three pairs at z 8 do represent an unusually high merger fraction but projection coincidences or lensing are far less likely scenarios to account for all three pairs. If the three pairs are indeed all merging galaxies, it could indicate that this Hubble field corresponds to a local overdensity at a redshift of z 8.Looking AheadThe best way to improve on these measurements is to repeat this study with more advanced telescopes. Chaikin and collaborators demonstrate the superiority of the observations that the upcoming James Webb Space Telescope (JWST) will provide. They also point out the potential power of the Wide Field Infrared Survey Telescope (WFIRST) currently under threat under the proposed 2019 federal budget to extend the observational horizon well into the epoch of reionization.Continued studies backed by the power of these future telescopes are sure to discover a wealth of additional distant galactic duos, helping us to characterize the universe in its early stages.CitationEvgenii A. Chaikin et al 2018 ApJ 853 81. doi:10.3847/1538-4357/aaa196

PdBI cold dust imaging of two extremely red H – [4.5] > 4 galaxies discovered with SEDS and CANDELS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Caputi, K. I.; Popping, G.; Spaans, M.

2014-06-20

We report Plateau de Bure Interferometer (PdBI) 1.1 mm continuum imaging toward two extremely red H – [4.5] > 4 (AB) galaxies at z > 3, which we have previously discovered making use of Spitzer SEDS and Hubble Space Telescope CANDELS ultra-deep images of the Ultra Deep Survey field. One of our objects is detected on the PdBI map with a 4.3σ significance, corresponding to S{sub ν}(1.1 mm)=0.78±0.18 mJy. By combining this detection with the Spitzer 8 and 24 μm photometry for this source, and SCUBA2 flux density upper limits, we infer that this galaxy is a composite active galacticmore » nucleus/star-forming system. The infrared (IR)-derived star formation rate is SFR ≈ 200 ± 100 M {sub ☉} yr{sup –1}, which implies that this galaxy is a higher-redshift analogue of the ordinary ultra-luminous infrared galaxies more commonly found at z ∼ 2-3. In the field of the other target, we find a tentative 3.1σ detection on the PdBI 1.1 mm map, but 3.7 arcsec away of our target position, so it likely corresponds to a different object. In spite of the lower significance, the PdBI detection is supported by a close SCUBA2 3.3σ detection. No counterpart is found on either the deep SEDS or CANDELS maps, so, if real, the PdBI source could be similar in nature to the submillimeter source GN10. We conclude that the analysis of ultra-deep near- and mid-IR images offers an efficient, alternative route to discover new sites of powerful star formation activity at high redshifts.« less

KSC-08pd2451

NASA Image and Video Library

2008-08-16

CAPE CANAVERAL, Fla. – Technicians in the Payload Hazardous Servicing Facility complete removal of the protective cover from the Wide Field Camera 3, or WFC3. The WFC3 is part of the payload on space shuttle Atlantis for the fifth and final Hubble servicing mission, STS-125. As Hubble enters the last stage of its life, WFC3 will be Hubble's next evolutionary step, allowing Hubble to peer ever further into the mysteries of the cosmos. WFC3 will study a diverse range of objects and phenomena, from young and extremely distant galaxies, to much more nearby stellar systems, to objects within our very own solar system. WFC3 will take the place of Wide Field Planetary Camera 2, which astronauts will bring back to Earth aboard the shuttle. Launch of Atlantis is targeted at 1:34 a.m. EDT Oct. 8. Photo credit: NASA/Jack Pfaller

KSC-08pd2393

NASA Image and Video Library

2008-08-12

CAPE CANAVERAL, Fla. – In the Payload Hazardous Servicing Facility at NASA's Kennedy Space Center, an overhead crane is moved above the Wide Field Camera 3, or WFC3, for attachment. The WFC3 will be lifted and transferred to a work stand. As Hubble enters the last stage of its life, WFC3 will be Hubble's next evolutionary step, allowing Hubble to peer ever further into the mysteries of the cosmos. WFC3 will study a diverse range of objects and phenomena, from young and extremely distant galaxies, to much more nearby stellar systems, to objects within our very own solar system. WFC3 will take the place of Wide Field Planetary Camera 2, which astronauts will bring back to Earth aboard the shuttle. WFC3 is part of the payload on the fifth and final Hubble servicing mission, STS-125, targeted for launch Oct. 8. Photo credit: NASA/Jack Pfaller

KSC-08pd2448

NASA Image and Video Library

2008-08-16

CAPE CANAVERAL, Fla. – The Wide Field Camera 3, or WFC3, rests on a work stand in the Payload Hazardous Servicing Facility since its arrival Aug. 12. WFC3 is part of the payload on space shuttle Atlantis for the fifth and final Hubble servicing mission, STS-125. As Hubble enters the last stage of its life, WFC3 will be Hubble's next evolutionary step, allowing Hubble to peer ever further into the mysteries of the cosmos. WFC3 will study a diverse range of objects and phenomena, from young and extremely distant galaxies, to much more nearby stellar systems, to objects within our very own solar system. WFC3 will take the place of Wide Field Planetary Camera 2, which astronauts will bring back to Earth aboard the shuttle. Launch of Atlantis is targeted at 1:34 a.m. EDT Oct. 8. Photo credit: NASA/Jack Pfaller

KSC-08pd2394

NASA Image and Video Library

2008-08-12

CAPE CANAVERAL, Fla. – In the Payload Hazardous Servicing Facility at NASA's Kennedy Space Center, an overhead crane begins to lift the Wide Field Camera 3, or WFC3, from the base of the shipping container. The WFC3 will be transferred to a work stand. As Hubble enters the last stage of its life, WFC3 will be Hubble's next evolutionary step, allowing Hubble to peer ever further into the mysteries of the cosmos. WFC3 will study a diverse range of objects and phenomena, from young and extremely distant galaxies, to much more nearby stellar systems, to objects within our very own solar system. WFC3 will take the place of Wide Field Planetary Camera 2, which astronauts will bring back to Earth aboard the shuttle. WFC3 is part of the payload on the fifth and final Hubble servicing mission, STS-125, targeted for launch Oct. 8. Photo credit: NASA/Jack Pfaller

KSC-08pd2395

NASA Image and Video Library

2008-08-12

CAPE CANAVERAL, Fla. – In the Payload Hazardous Servicing Facility at NASA's Kennedy Space Center, an overhead crane lifts the Wide Field Camera 3, or WFC3, from the base of the shipping container. The WFC3 will be transferred to a work stand. As Hubble enters the last stage of its life, WFC3 will be Hubble's next evolutionary step, allowing Hubble to peer ever further into the mysteries of the cosmos. WFC3 will study a diverse range of objects and phenomena, from young and extremely distant galaxies, to much more nearby stellar systems, to objects within our very own solar system. WFC3 will take the place of Wide Field Planetary Camera 2, which astronauts will bring back to Earth aboard the shuttle. WFC3 is part of the payload on the fifth and final Hubble servicing mission, STS-125, targeted for launch Oct. 8. Photo credit: NASA/Jack Pfaller

KSC-08pd2452

NASA Image and Video Library

2008-08-16

CAPE CANAVERAL, Fla. – Technicians in the Payload Hazardous Servicing Facility complete removal of the protective cover from the Wide Field Camera 3, or WFC3. The WFC3 is part of the payload on space shuttle Atlantis for the fifth and final Hubble servicing mission, STS-125. As Hubble enters the last stage of its life, WFC3 will be Hubble's next evolutionary step, allowing Hubble to peer ever further into the mysteries of the cosmos. WFC3 will study a diverse range of objects and phenomena, from young and extremely distant galaxies, to much more nearby stellar systems, to objects within our very own solar system. WFC3 will take the place of Wide Field Planetary Camera 2, which astronauts will bring back to Earth aboard the shuttle. Launch of Atlantis is targeted at 1:34 a.m. EDT Oct. 8. Photo credit: NASA/Jack Pfaller

History of Hubble Space Telescope (HST)

NASA Image and Video Library

1997-01-02

What look like giant twisters are spotted by the Hubble Space Telescope (HST). These images are, in actuality, pillars of gases that are in the process of the formation of a new star. These pillars can be billions of miles in length and may have been forming for millions of years. This one formation is located in the Lagoon Nebula and was captured by the Hubble's wide field planetary camera-2 (WFPC-2).

ISOCAM observations of the Hubble Deep Field reduced with the PRETI method

NASA Astrophysics Data System (ADS)

Aussel, H.; Cesarsky, C. J.; Elbaz, D.; Starck, J. L.

1999-02-01

We have developed a new ISOCAM data reduction technique based on wavelet analysis, especially designed for the detection of faint sources in mid-infrared surveys. This method, the Pattern REcognition Technique for Isocam data (PRETI) has been used to reduce the observations of the Hubble Deep Field (HDF) and flanking fields with ISOCAM at 6.75 (LW2) and 15 mu m (LW3) (Rowan-Robinson et al. \\cite{RowanRobinson}). Simulations of ISOCAM data allow us to test the photometric accuracy and completeness of the reduction. According to these simulations, the PRETI source list is 95% complete in the 15 mu m band at 200 mu Jy and in the 6.75 mu m band at 65 mu Jy, using detection thresholds which minimize the number of false detections. We detect 49 objects in the ISO-HDF at high confidence secure level, 42 in the LW3 filter, 3 in the LW2 filter, and 4 in both filters. An additional, less secure, list of 100 sources is presented, of which 89 are detected at 15 mu m only, 7 at 6.75 mu m only and 4 in both filters. All ISO-HDF objects detected in the HDF itself have optical or infrared counterparts, except for one from the additional list. All except one of the radio sources detected in the field by Fomalont et al. (\\cite{Fomalont}) are detected with ISOCAM. Using a precise correction for the field of view distortion of ISOCAM allows us to separate blended sources. This, together with the fact that PRETI allows to correct data on the tail of cosmic rays glitches, lead us to produce deeper source lists than previous authors. Our list of bright sources agree with those of Désert et al. (\\cite{IAS}) in both filters, and with those of Goldschmidt et al. (\\cite{Goldschmidt}) in the LW3 filter, with systematic difference in photometry. Number counts derived from our results show an excess by a factor of 10 with respect to the prediction of a no evolution model (Franceschini \\cite{Franceschini98}) in the LW3 band. On the contrary, the number of sources in the LW2 band is compatible with the prediction of such a model, but with greater uncertainties, given the small number of detections. Based on observations with the Infrared Space Observatory (ISO). ISO is an ESA project with instruments funded by ESA Member States (especially the PI countries: France, Germany, The Netherlands and the United Kingdom) and with participation of ISAS and NASA.

HUBBLE SPACE TELESCOPE AND HI IMAGING OF STRONG RAM PRESSURE STRIPPING IN THE COMA SPIRAL NGC 4921: DENSE CLOUD DECOUPLING AND EVIDENCE FOR MAGNETIC BINDING IN THE ISM

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kenney, Jeffrey D. P.; Abramson, Anne; Bravo-Alfaro, Hector, E-mail: jeff.kenney@yale.edu

Remarkable dust extinction features in the deep Hubble Space Telescope (HST) V and I images of the face-on Coma cluster spiral galaxy NGC 4921 show in unprecedented ways how ram pressure strips the ISM from the disk of a spiral galaxy. New VLA HI maps show a truncated and highly asymmetric HI disk with a compressed HI distribution in the NW, providing evidence for ram pressure acting from the NW. Where the HI distribution is truncated in the NW region, HST images show a well-defined, continuous front of dust that extends over 90° and 20 kpc. This dust front separatesmore » the dusty from dust-free regions of the galaxy, and we interpret it as galaxy ISM swept up near the leading side of the ICM–ISM interaction. We identify and characterize 100 pc–1 kpc scale substructure within this dust front caused by ram pressure, including head–tail filaments, C-shaped filaments, and long smooth dust fronts. The morphology of these features strongly suggests that dense gas clouds partially decouple from surrounding lower density gas during stripping, but decoupling is inhibited, possibly by magnetic fields that link and bind distant parts of the ISM.« less

Results of a hubble space telescope search for natural satellites of dwarf planet 1 ceres

NASA Astrophysics Data System (ADS)

DeMario, Benjamin E.; Schmidt, Britney E.; Mutchler, Max J.; Li, Jian-Yang; McFadden, Lucy A.; McLean, Brian J.; Russell, Christopher T.

2016-12-01

In order to prepare for the arrival of the Dawn spacecraft at Ceres, a search for satellites was undertaken by the Hubble Space Telescope (HST) to enhance the mission science return and to ensure spacecraft safety. Previous satellite searches from ground-based telescopes have detected no satellites within Ceres' Hill sphere down to a size of 3 km (Gehrels et al. 1987) and early HST investigations searched to a limit of 1-2 km (Bieryla et al. 2011). The Wide Field Camera 3 (WFC3) on board the HST was used to image Ceres between 14 April-28 April 2014. These images cover approximately the inner third of Ceres' Hill sphere, where the Hill sphere is the region surrounding Ceres where stable satellite orbits are possible. We performed a deep search for possible companions orbiting Ceres. No natural companions were located down to a diameter of 48 m, over most of the Hill sphere to a distance of 205,000 km (434 Ceres radii) from the surface of Ceres. It was impossible to search all the way to the surface of Ceres because of scattered light, but at a distance of 2865 km (five Ceres radii), the search limit was determined to be 925 m.

Interferometry from Space

NASA Technical Reports Server (NTRS)

Carpenter, Kenneth

2007-01-01

Space-based interferometric observatories will be challenging projects, equal at least to that of building the Great Observatories (the Hubble Space Telescope (HST), Spitzer Space Telescope (SST), Chandra X-ray Observatory, and the Gamma Ray Observatory), if not the Pyramids of Eygpt - but they represent the next logical step in examining our Universe at substantially higher angular resolution. Increasing our resolving power by factors of 100 or more (as is needed to make meaningful improvements in this observational arena) over existing facilities such as HST and SST requires mirror diameters (100's to 1000's of meters) much larger than can be supported by single or segmented mirrors - and thus the design and construction of sparse aperture, inteferometric arrays such as those described herein will be required. But just imagine the rewards of being able to see, for the first time, the surfaces of other stars, the location and type of extrasolar planets and even pictures of those same planets, the inner workings of Active Galactic Nuclei, the close-in details of supernovae explosions, black hole event horizons, and the infrared universe at the same resolution of the UV-optical Hubble Deep Fields. As a slight variation on the "Star Trek: Enterprise" theme song might say, it'll be a "long road, getting from here to there", but it will one well-worth taking.

Galactic Teamwork Makes Distant Bubbles

NASA Astrophysics Data System (ADS)

Kohler, Susanna

2016-03-01

During the period of reionization that followed the dark ages of our universe, hydrogen was transformed from a neutral state, which is opaque to radiation, to an ionized one, which is transparent to radiation. But what generated the initial ionizing radiation? The recent discovery of multiple distant galaxies offers evidence for how this process occurred.Two Distant GalaxiesWe believe reionization occurred somewhere between a redshift of z = 6 and 7, because Ly-emitting galaxies drop out at roughly this redshift. Beyond this distance, were generally unable to see the light from these galaxies, because the universe is no longer transparent to their emission. This is not always the case, however: if a bubble of ionized gas exists around a distant galaxy, the radiation can escape, allowing us to see the galaxy.This is true of two recently-discovered Ly-emitting galaxies, confirmed to be at a redshift of z~7 and located near one another in a region known as the Bremer Deep Field. The fact that were able to see the radiation from these galaxies means that they are in an ionized HII region presumably one of the earlier regions to have become reionized in the universe.But on their own, neither of these galaxies is capable of generating an ionized bubble large enough for their light to escape. So what ionized the region around them, and what does this mean for our understanding of how reionization occurred in the universe?A Little Help From FriendsLocation in different filters of the objects in the Hubble Bremer Deep Field catalog. The z~7 selection region is outlined by the grey box. BDF-521 and BDF-3299 were the two originally discovered galaxies; the remaining red markers indicate the additional six galaxies discovered in the same region. [Castellano et al. 2016]A team of scientists led by Marco Castellano (Rome Observatory, INAF) investigated the possibility that there are other, faint galaxies near these two that have helped to ionize the region. Performing a survey using deep field Hubble observations, Castellano and collaborators found an additional 6 galaxies in the same region as the first two, also at a redshift of z~7!The authors believe these galaxies provide a simple explanation of the ionized bubble: each of these faint, normal galaxies produced a small ionized bubble. The overlap of these many small bubbles provided the larger ionized region from which the light of the two originally discovered galaxies was able to escape.How normal is this clustering of galaxies found by Castellano and collaborators? The team demonstrates via cosmological modeling that the number density of galaxies in this region is a factor of 34 greater than would be expected at this distance in a random pointing of the same size.These results greatly support the theoretical prediction that the first ionization fronts in the universe were formed in regions with significant galaxy overdensities. The discovery of this deep-field collection of galaxies strongly suggests that reionization was driven by faint, normal star-forming galaxies in a clumpy process.CitationM. Castellano et al 2016 ApJ 818 L3. doi:10.3847/2041-8205/818/1/L3

Characterizing the Young Galaxies at Cosmic Dawn

NASA Astrophysics Data System (ADS)

Zheng, Wei

2013-10-01

We propose to analyze the data of the Hubble Frontier Fields, in order to discover and study galaxies at the highest redshifts and to an unprecedented depth. The redshift range of z 10-12 marks the beginning of the IGM reionization and remains as HST's last frontier. In the framework of the CLASH and related projects, our team has succeeded in finding the most distant galaxies. We will carry out a systematic search for galaxy candidates at z 10-12 in the proposed deep observations. At this redshift range, most of the spectral features are shifted longward of the WFC3/IR bands, and additional data are therefore needed in order to secure the candidates and study their intrinsic properties. We will {1} obtain deep photometry in complementary ground-based K-band observations; {2} estimate the global star-formation rate density; {3} measure the sources' UV continuum slope and {4} carry out ALMA observations to study the dust content. Finally, we will estimate the effect of these young galaxies in ionizing the IGM. Our study will serve as an ideal bridge between HST and JWST in exploring the cosmic dawn.

New insights on the accuracy of photometric redshift measurements

NASA Astrophysics Data System (ADS)

Massarotti, M.; Iovino, A.; Buzzoni, A.; Valls-Gabaud, D.

2001-12-01

We use the deepest and most complete redshift catalog currently available (the Hubble Deep Field (HDF) North supplemented by new HDF South redshift data) to minimize residuals between photometric and spectroscopic redshift estimates. The good agreement at zspec < 1.5 shows that model libraries provide a good description of the galaxy population. At zspec >= 2.0, the systematic shift between photometric and spectroscopic redshifts decreases when the modeling of the absorption by the interstellar and intergalactic media is refined. As a result, in the entire redshift range z in [0, 6], residuals between photometric and spectroscopic redshifts are roughly halved. For objects fainter than the spectroscopic limit, the main source of uncertainty in photometric redshifts is related to photometric errors, and can be assessed with Monte Carlo simulations.

Galaxy Merger Candidates in High-redshift Cluster Environments

NASA Astrophysics Data System (ADS)

Delahaye, A. G.; Webb, T. M. A.; Nantais, J.; DeGroot, A.; Wilson, G.; Muzzin, A.; Yee, H. K. C.; Foltz, R.; Noble, A. G.; Demarco, R.; Tudorica, A.; Cooper, M. C.; Lidman, C.; Perlmutter, S.; Hayden, B.; Boone, K.; Surace, J.

2017-07-01

We compile a sample of spectroscopically and photometrically selected cluster galaxies from four high-redshift galaxy clusters (1.59< z< 1.71) from the Spitzer Adaptation of the Red-Sequence Cluster Survey (SpARCS), and a comparison field sample selected from the UKIDSS Deep Survey. Using near-infrared imaging from the Hubble Space Telescope, we classify potential mergers involving massive ({M}* ≥slant 3× {10}10 {M}⊙ ) cluster members by eye, based on morphological properties such as tidal distortions, double nuclei, and projected near neighbors within 20 kpc. With a catalog of 23 spectroscopic and 32 photometric massive cluster members across the four clusters and 65 spectroscopic and 26 photometric comparable field galaxies, we find that after taking into account contamination from interlopers, {11.0}-5.6+7.0 % of the cluster members are involved in potential mergers, compared to {24.7}-4.6+5.3 % of the field galaxies. We see no evidence of merger enhancement in the central cluster environment with respect to the field, suggesting that galaxy-galaxy merging is not a stronger source of galaxy evolution in cluster environments compared to the field at these redshifts.

Setting initial conditions for inflation with reaction-diffusion equation

NASA Astrophysics Data System (ADS)

Bagchi, Partha; Das, Arpan; Dave, Shreyansh S.; Sengupta, Srikumar; Srivastava, Ajit M.

2018-03-01

We discuss the issue of setting appropriate initial conditions for inflation. Specifically, we consider natural inflation model and discuss the fine tuning required for setting almost homogeneous initial conditions over a region of order several times the Hubble size which is orders of magnitude larger than any relevant correlation length for field fluctuations. We then propose to use the special propagating front solutions of reaction-diffusion equations for localized field domains of smaller sizes. Due to very small velocities of these propagating fronts we find that the inflaton field in such a field domain changes very slowly, contrary to naive expectation of rapid roll down to the true vacuum. Continued expansion leads to the energy density in the Hubble region being dominated by the vacuum energy, thereby beginning the inflationary phase. Our results show that inflation can occur even with a single localized field domain of size smaller than the Hubble size. We discuss possible extensions of our results for different inflationary models, as well as various limitations of our analysis (e.g. neglecting self gravity of the localized field domain).

Cosmic shear analysis of archival HST/ACS data. I. Comparison of early ACS pure parallel data to the HST/GEMS survey

NASA Astrophysics Data System (ADS)

Schrabback, T.; Erben, T.; Simon, P.; Miralles, J.-M.; Schneider, P.; Heymans, C.; Eifler, T.; Fosbury, R. A. E.; Freudling, W.; Hetterscheidt, M.; Hildebrandt, H.; Pirzkal, N.

2007-06-01

Context: This is the first paper of a series describing our measurement of weak lensing by large-scale structure, also termed “cosmic shear”, using archival observations from the Advanced Camera for Surveys (ACS) on board the Hubble Space Telescope (HST). Aims: In this work we present results from a pilot study testing the capabilities of the ACS for cosmic shear measurements with early parallel observations and presenting a re-analysis of HST/ACS data from the GEMS survey and the GOODS observations of the Chandra Deep Field South (CDFS). Methods: We describe the data reduction and, in particular, a new correction scheme for the time-dependent ACS point-spread-function (PSF) based on observations of stellar fields. This is currently the only technique which takes the full time variation of the PSF between individual ACS exposures into account. We estimate that our PSF correction scheme reduces the systematic contribution to the shear correlation functions due to PSF distortions to <2 × 10-6 for galaxy fields containing at least 10 stars, which corresponds to ⪉5% of the cosmological signal expected on scales of a single ACS field. Results: We perform a number of diagnostic tests indicating that the remaining level of systematics is consistent with zero for the GEMS and GOODS data confirming the success of our PSF correction scheme. For the parallel data we detect a low level of remaining systematics which we interpret to be caused by a lack of sufficient dithering of the data. Combining the shear estimate of the GEMS and GOODS observations using 96 galaxies arcmin-2 with the photometric redshift catalogue of the GOODS-MUSIC sample, we determine a local single field estimate for the mass power spectrum normalisation σ8, CDFS=0.52+0.11-0.15 (stat) ± 0.07(sys) (68% confidence assuming Gaussian cosmic variance) at a fixed matter density Ω_m=0.3 for a ΛCDM cosmology marginalising over the uncertainty of the Hubble parameter and the redshift distribution. We interpret this exceptionally low estimate to be due to a local under-density of the foreground structures in the CDFS. Based on observations made with the NASA/ESA Hubble Space Telescope, obtained from the data archives at the Space Telescope European Coordinating Facility and the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555.

HUBBLE FINDS A BARE BLACK HOLE POURING OUT LIGHT

NASA Technical Reports Server (NTRS)

2002-01-01

NASA's Hubble Space Telescope has provided a never-before-seen view of a warped disk flooded with a torrent of ultraviolet light from hot gas trapped around a suspected massive black hole. [Right] This composite image of the core of the galaxy was constructed by combining a visible light image taken with Hubble's Wide Field Planetary Camera 2 (WFPC2), with a separate image taken in ultraviolet light with the Faint Object Camera (FOC). While the visible light image shows a dark dust disk, the ultraviolet image (color-coded blue) shows a bright feature along one side of the disk. Because Hubble sees ultraviolet light reflected from only one side of the disk, astronomers conclude the disk must be warped like the brim of a hat. The bright white spot at the image's center is light from the vicinity of the black hole which is illuminating the disk. [Left] A ground-based telescopic view of the core of the elliptical galaxy NGC 6251. The inset box shows Hubble Space Telescope's field of view. The galaxy is 300 million light-years away in the constellation Ursa Minor. Photo Credit: Philippe Crane (European Southern Observatory), and NASA

Spatially resolved spectroscopy of lensed galaxies in the Frontier Fields

NASA Astrophysics Data System (ADS)

Jones, Tucker; Aff004

The Grism Lens-Amplified Survey from Space (GLASS) has obtained slitless near-infrared spectroscopy of 10 galaxy clusters selected for their strong lensing properties, including all six Hubble Frontier Fields. Slitless grism spectra are ideal for mapping emission lines such as [O ii], [O iii], and Hα at z=1-3. The combination of strong gravitational lensing and Hubble's diffraction limit provides excellent sensitivity with spatial resolution as fine as 100 pc for highly magnified sources, and ~500 pc for less magnified sources near the edge of the field of view. The GLASS survey represents the largest spectroscopic sample with such high resolution at z > 1. GLASS and Hubble Frontier Field data provide the distribution of stellar mass, star formation, gas-phase metallicity, and other aspects of the physical structure of high redshift galaxies, reaching stellar masses as low as ~107 M⊙ at z=2. I discuss precise measurements of these physical properties and implications for galaxy evolution.

HUBBLE'S NEW IMPROVED OPTICS PROBE THE CORE OF A DISTANT GALAXY

NASA Technical Reports Server (NTRS)

2002-01-01

This comparison image of the core of the galaxy M100 shows the dramatic improvement in Hubble Space Telescope's view of the universe. The new image was taken with the second generation Wide Field and Planetary Camera (WFPC-2) which was installed during the STS-61 Hubble Servicing Mission. The picture beautifully demonstrates that the corrective optics incorporated within the WFPC-2 compensate fully for optical aberration in Hubble's primary mirror. The new camera will allow Hubble to probe the universe with unprecedented clarity and sensitivity, and to fulfill many of the most important scientific objectives for which the telescope was originally built. [ Right ] The core of the grand design spiral galaxy M100, as imaged by Hubble Space Telescope's Wide Field Planetary Camera 2 in its high resolution channel. The WFPC-2 contains modified optics that correct for Hubble's previously blurry vision, allowing the telescope for the first time to cleanly resolve faint structure as small as 30 light-years across in a galaxy which is tens of millions of light years away. The image was taken on December 31, 1993. [Left ] For comparison, a picture taken with the WFPC-1 camera in wide field mode, on November 27, 1993, just a few days prior to the STS-61 servicing mission. The effects of optical aberration in HST's 2.4-meter primary mirror blur starlight, smear out fine detail, and limit the telescope's ability to see faint structure. Both Hubble images are 'raw;' they have not been subject to computer image reconstruction techniques commonly used in aberrated images made before the servicing mission. TARGET INFORMATION: M100 The galaxy M100 (100th object in the Messier Catalog of non-stellar objects) is one of the brightest members of the Virgo Cluster of galaxies. The galaxy is in the spring constellation Coma Berenices and can be seen through a moderate-sized amateur telescope. M100 is spiral shaped, like our Milky Way, and tilted nearly face-on as seen from earth. The galaxy has two prominent arms of bright stars and several fainter arms. Though the galaxy is estimated to be tens of millions of light-years away, Hubble reveals the sort of detail only seen previously (with ground based telescopes) in neighboring galaxies that are ten times closer. Before HST, astronomers could only see such a level of detail in roughly a dozen galaxies in our Local Group. Now, with Hubble's improved vision, the portion of the universe which can be studied with such clarity has grown a thousand fold. Only the future will tell what revelations await as Hubble's spectacular vision is applied to a host of fascinating and important questions about the universe and our place in it. PHOTO RELEASE NO.: STScI-PR94-01

Hubble Finds a Lenticular Galaxy Standing Out in the Crowd

NASA Image and Video Library

2017-12-08

A lone source shines out brightly from the dark expanse of deep space, glowing softly against a picturesque backdrop of distant stars and colorful galaxies. Captured by the NASA/ESA Hubble Space Telescope’s Advanced Camera for Surveys (ACS), this scene shows PGC 83677, a lenticular galaxy — a galaxy type that sits between the more familiar elliptical and spiral varieties. It reveals both the relatively calm outskirts and intriguing core of PGC 83677. Here, studies have uncovered signs of a monstrous black hole that is spewing out high-energy X-rays and ultraviolet light. Credit: NASA/ESA/Hubble; acknowledgements: Judy Schmidt (Geckzilla) NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Like us on Facebook Find us on Instagram

What do you gain from deconvolution? - Observing faint galaxies with the Hubble Space Telescope Wide Field Camera

NASA Technical Reports Server (NTRS)

Schade, David J.; Elson, Rebecca A. W.

1993-01-01

We describe experiments with deconvolutions of simulations of deep HST Wide Field Camera images containing faint, compact galaxies to determine under what circumstances there is a quantitative advantage to image deconvolution, and explore whether it is (1) helpful for distinguishing between stars and compact galaxies, or between spiral and elliptical galaxies, and whether it (2) improves the accuracy with which characteristic radii and integrated magnitudes may be determined. The Maximum Entropy and Richardson-Lucy deconvolution algorithms give the same results. For medium and low S/N images, deconvolution does not significantly improve our ability to distinguish between faint stars and compact galaxies, nor between spiral and elliptical galaxies. Measurements from both raw and deconvolved images are biased and must be corrected; it is easier to quantify and remove the biases for cases that have not been deconvolved. We find no benefit from deconvolution for measuring luminosity profiles, but these results are limited to low S/N images of very compact (often undersampled) galaxies.

Weak Lensing from Space I: Instrumentation and Survey Strategy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rhodes, Jason; Refregier, Alexandre; Massey, Richard

A wide field space-based imaging telescope is necessary to fully exploit the technique of observing dark matter via weak gravitational lensing. This first paper in a three part series outlines the survey strategies and relevant instrumental parameters for such a mission. As a concrete example of hardware design, we consider the proposed Supernova/Acceleration Probe (SNAP). Using SNAP engineering models, we quantify the major contributions to this telescope's Point Spread Function (PSF). These PSF contributions are relevant to any similar wide field space telescope. We further show that the PSF of SNAP or a similar telescope will be smaller than currentmore » ground-based PSFs, and more isotropic and stable over time than the PSF of the Hubble Space Telescope. We outline survey strategies for two different regimes - a ''wide'' 300 square degree survey and a ''deep'' 15 square degree survey that will accomplish various weak lensing goals including statistical studies and dark matter mapping.« less

THE HUBBLE SPACE TELESCOPE WIDE FIELD CAMERA 3 EARLY RELEASE SCIENCE DATA: PANCHROMATIC FAINT OBJECT COUNTS FOR 0.2-2 {mu}m WAVELENGTH

DOE Office of Scientific and Technical Information (OSTI.GOV)

Windhorst, Rogier A.; Cohen, Seth H.; Mechtley, Matt

2011-04-01

We describe the Hubble Space Telescope (HST) Wide Field Camera 3 (WFC3) Early Release Science (ERS) observations in the Great Observatories Origins Deep Survey (GOODS) South field. The new WFC3 ERS data provide calibrated, drizzled mosaics in the UV filters F225W, F275W, and F336W, as well as in the near-IR filters F098M (Y{sub s} ), F125W (J), and F160W (H) with 1-2 HST orbits per filter. Together with the existing HST Advanced Camera for Surveys (ACS) GOODS-South mosaics in the BViz filters, these panchromatic 10-band ERS data cover 40-50 arcmin{sup 2} at 0.2-1.7 {mu}m in wavelength at 0.''07-0.''15 FWHM resolutionmore » and 0.''090 Multidrizzled pixels to depths of AB {approx_equal} 26.0-27.0 mag (5{sigma}) for point sources, and AB {approx_equal} 25.5-26.5 mag for compact galaxies. In this paper, we describe (1) the scientific rationale, and the data taking plus reduction procedures of the panchromatic 10-band ERS mosaics, (2) the procedure of generating object catalogs across the 10 different ERS filters, and the specific star-galaxy separation techniques used, and (3) the reliability and completeness of the object catalogs from the WFC3 ERS mosaics. The excellent 0.''07-0.''15 FWHM resolution of HST/WFC3 and ACS makes star-galaxy separation straightforward over a factor of 10 in wavelength to AB {approx_equal} 25-26 mag from the UV to the near-IR, respectively. Our main results are: (1) proper motion of faint ERS stars is detected over 6 years at 3.06 {+-} 0.66 mas year{sup -1} (4.6{sigma}), consistent with Galactic structure models; (2) both the Galactic star counts and the galaxy counts show mild but significant trends of decreasing count slopes from the mid-UV to the near-IR over a factor of 10 in wavelength; (3) combining the 10-band ERS counts with the panchromatic Galaxy and Mass Assembly survey counts at the bright end (10 mag {approx}< AB {approx}< 20 mag) and the Hubble Ultra Deep Field counts in the BVizY{sub s}JH filters at the faint end (24 mag {approx}< AB {approx}< 30 mag) yields galaxy counts that are well measured over the entire flux range 10 mag {approx}< AB {approx}< 30 mag for 0.2-2 {mu}m in wavelength; (4) simple luminosity+density evolution models can fit the galaxy counts over this entire flux range. However, no single model can explain the counts over this entire flux range in all 10 filters simultaneously. More sophisticated models of galaxy assembly are needed to reproduce the overall constraints provided by the current panchromatic galaxy counts for 10 mag {approx}< AB {approx}< 30 mag over a factor of 10 in wavelength.« less

Towards an understanding of dark matter: Precise gravitational lensing analysis complemented by robust photometric redshifts

NASA Astrophysics Data System (ADS)

Coe, Daniel Aaron

The goal of thesis is to help scientists resolve one of the great mysteries of our time: the nature of Dark Matter. Dark Matter is currently believed to make up over 80% of the material in our universe, yet we have so far inferred but a few of its basic properties. Here we study the Dark Matter surrounding a galaxy cluster, Abell 1689, via the most direct method currently available--gravitational lensing. Abell 1689 is a "strong" gravitational lens, meaning it produces multiple images of more distant galaxies. The observed positions of these images can be measured very precisely and act as a blueprint allowing us to reconstruct the Dark Matter distribution of the lens. Until now, such mass models of Abell 1689 have reproduced the observed multiple images well but with significant positional offsets. Using a new method we develop here, we obtain a new mass model which perfectly reproduces the observed positions of 168 knots identified within 135 multiple images of 42 galaxies. An important ingredient to our mass model is the accurate measurement of distances to the lensed galaxies via their photometric redshifts. Here we develop tools which improve the accuracy of these measurements based on our study of the Hubble Ultra Deep Field, the only image yet taken to comparable depth as the magnified regions of Abell 1689. We present results both for objects in the Hubble Ultra Deep Field and for galaxies gravitationally lensed by Abell 1689. As part of this thesis, we also provide reviews of Dark Matter and Gravitational Lensing, including a chapter devoted to the mass profiles of Dark Matter halos realized in simulations. The original work presented here was performed primarily by myself under the guidance of Narciso Benítez and Holland Ford as a member of the Advanced Camera for Surveys GTO Science Team at Johns Hopkins University and the Instituto de Astrofisica de Andalucfa. My advisors served on my thesis committee along with Rick White, Gabor Domokos, and Steve Zelditch.

Improving time-delay cosmography with spatially resolved kinematics

NASA Astrophysics Data System (ADS)

Shajib, Anowar J.; Treu, Tommaso; Agnello, Adriano

2018-01-01

Strongly gravitational lensed quasars can be used to measure the so-called time-delay distance DΔt, and thus the Hubble constant H0 and other cosmological parameters. Stellar kinematics of the deflector galaxy play an essential role in this measurement by: (i) helping break the mass-sheet degeneracy; (ii) determining in principle the angular diameter distance Dd to the deflector and thus further improving the cosmological constraints. In this paper we simulate observations of lensed quasars with integral field spectrographs and show that spatially resolved kinematics of the deflector enables further progress by helping break the mass-anisotropy degeneracy. Furthermore, we use our simulations to obtain realistic error estimates with current/upcoming instruments like OSIRIS on Keck and NIRSPEC on the James Webb Space Telescope for both distances (typically ∼6 per cent on DΔt and ∼10 per cent on Dd). We use the error estimates to compute cosmological forecasts for the sample of nine lenses that currently have well-measured time delays and deep Hubble Space Telescope images and for a sample of 40 lenses that is projected to be available in a few years through follow-up of candidates found in ongoing wide field surveys. We find that H0 can be measured with 2 per cent (1 per cent) precision from nine (40) lenses in a flat Λcold dark matter cosmology. We study several other cosmological models beyond the flat Λcold dark matter model and find that time-delay lenses with spatially resolved kinematics can greatly improve the precision of the cosmological parameters measured by cosmic microwave background data.

Frontier Fields: Engaging Educators, the Youth, and the Public in Exploring the Cosmic Frontier

NASA Astrophysics Data System (ADS)

Lawton, Brandon L.; Eisenhamer, Bonnie; Smith, Denise A.; Summers, Frank; Darnell, John A.; Ryer, Holly

2015-01-01

The Frontier Fields is a multi-cycle program of six deep-field observations of strong-lensing galaxy clusters that will be taken in parallel with six deep 'blank fields.' The three-year long collaborative program is led by observations from NASA's Great Observatories. The observations allow astronomers to look deeper into the universe than ever before, and potentially uncover galaxies that are as much as 100 times fainter than what the telescopes can typically observe. The Frontier Fields science program is ideal for informing audiences about scientific advances and topics in STEM. The study of galaxy properties, statistics, optics, and Einstein's theory of general relativity naturally leverages off of the science returns of the Frontier Fields program. As a result, the Space Telescope Science Institute's Office of Public Outreach (OPO) has initiated an education and public outreach (EPO) project to follow the progress of the Frontier Fields.For over two decades, the Hubble EPO program has sought to bring the wonders of the universe to the education community, the youth, and the public, and engage audiences in the adventure of scientific discovery. Program components include standards-based curriculum-support materials, exhibits and exhibit components, professional development workshops, and direct interactions with scientists. We are also leveraging our new social media strategy to bring the science program to the public in the form of an ongoing blog. The main underpinnings of the program's infrastructure are scientist-educator development teams, partnerships, and an embedded program evaluation component. OPO is leveraging this existing infrastructure to bring the Frontier Fields science program to the education community and the public in a cost-effective way.The Frontier Fields program has just completed its first year. This talk will feature the goals and current status of the Frontier Fields EPO program. We will highlight OPO's strategies and infrastructure that allows for the quick delivery of groundbreaking science to the education community and public.

Detection of the Red Giant Branch Stars in the M82 Using the Hubble Space Telescope

NASA Technical Reports Server (NTRS)

Madore, B.; Sakai, S.

1999-01-01

We present color-magnitude diagrams and luminosity functions or stars in two halo regions of the irregular galaxy in M82, based on F555W and F814W photometry taken with the Hubble Space Telescope and Wide Field Planetary Camera 2.

VizieR Online Data Catalog: GLASS. VI. MCS J0416.1-2403 HFF imaging & spectra (Hoag+, 2016)

NASA Astrophysics Data System (ADS)

Hoag, A.; Huang, K.-H.; Treu, T.; Bradac, M.; Schmidt, K. B.; Wang, X.; Brammer, G. B.; Broussard, A.; Amorin, R.; Castellano, M.; Fontana, A.; Merlin, E.; Schrabback, T.; Trenti, M.; Vulcani, B.

2017-02-01

The Grism Lens-Amplified Survey from Space (GLASS; GO-13459, PI: Treu; Schmidt+ 2014ApJ...782L..36S; Treu+ 2015, J/ApJ/812/114) observed 10 massive galaxy clusters with the HST WFC3-IR G102 and G141 grism between 2013 December and 2015 January. Each of the clusters targeted by GLASS has deep multi-band HST imaging from the Hubble Frontier Fields (HFF) in 2014 September and/or from CLASH (ESO VIMOS large program CLASH-VLT; 186.A-0798; PI: P. Rosati; Balestra+, 2016, J/ApJS/224/33). We also use mid-IR imaging data acquired with the IRAC on board the Spitzer Space Telescope obtained by the DDT program #90258 (PI: Soifer; P. Capak+ 2016, in prep.) and #80168 (PI: Bouwens). (2 data files).

The Mass Function of Young Star Clusters in the "Antennae" Galaxies.

PubMed

Zhang; Fall

1999-12-20

We determine the mass function of young star clusters in the merging galaxies known as the "Antennae" (NGC 4038/9) from deep images taken with the Wide Field Planetary Camera 2 on the refurbished Hubble Space Telescope. This is accomplished by means of reddening-free parameters and a comparison with stellar population synthesis tracks to estimate the intrinsic luminosity and age, and hence the mass, of each cluster. We find that the mass function of the young star clusters (with ages less, similar160 Myr) is well represented by a power law of the form psi&parl0;M&parr0;~M-2 over the range 104 less, similarM less, similar106 M middle dot in circle. This result may have important implications for our understanding of the origin of globular clusters during the early phases of galactic evolution.

NASA's Hubble Celebrates 21st Anniversary with "Rose" of Galaxies

NASA Image and Video Library

2017-12-08

NASA image release April 20, 2011 To see a video of this image go here: www.flickr.com/photos/gsfc/5637796622 To celebrate the 21st anniversary of the Hubble Space Telescope's deployment into space, astronomers at the Space Telescope Science Institute in Baltimore, Md., pointed Hubble's eye at an especially photogenic pair of interacting galaxies called Arp 273. The larger of the spiral galaxies, known as UGC 1810, has a disk that is distorted into a rose-like shape by the gravitational tidal pull of the companion galaxy below it, known as UGC 1813. This image is a composite of Hubble Wide Field Camera 3 data taken on December 17, 2010, with three separate filters that allow a broad range of wavelengths covering the ultraviolet, blue, and red portions of the spectrum. Hubble was launched April 24, 1990, aboard Discovery's STS-31 mission. Hubble discoveries revolutionized nearly all areas of current astronomical research from planetary science to cosmology. Credit: NASA, ESA, and the Hubble Heritage Team (STScI/AURA) To read more about this image go here: www.nasa.gov/mission_pages/hubble/science/hubble-rose.html NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Join us on Facebook

Hubble Finds New Dark Spot on Neptune

NASA Technical Reports Server (NTRS)

1995-01-01

NASA's Hubble Space Telescope has discovered a new great dark spot, located in the northern hemisphere of the planet Neptune. Because the planet's northern hemisphere is now tilted away from Earth, the new feature appears near the limb of the planet.

The spot is a near mirror-image to a similar southern hemisphere dark spot that was discovered in 1989 by the Voyager 2 probe. In 1994, Hubble showed that the southern dark spot had disappeared.

Like its predecessor, the new spot has high altitude clouds along its edge, caused by gasses that have been pushed to higher altitudes where they cool to form methane ice crystal clouds. The dark spot may be a zone of clear gas that is a window to a cloud deck lower in the atmosphere.

Planetary scientists don t know how long lived this new feature might be. Hubble's high resolution will allow astronomers to follow the spot's evolution and other unexpected changes in Neptune's dynamic atmosphere.

The image was taken on November 2, 1994 with Hubble's Wide Field Planetary Camera 2, when Neptune was 2.8 billion miles (4.5 billion kilometers) from Earth. Hubble can resolve features as small as 625 miles (1,000 kilometers) across in Neptune's cloud tops.

The Wide Field/Planetary Camera 2 was developed by the Jet Propulsion Laboratory and managed by the Goddard Spaced Flight Center for NASA's Office of Space Science.

This image and other images and data received from the Hubble Space Telescope are posted on the World Wide Web on the Space Telescope Science Institute home page at URL http://oposite.stsci.edu/pubinfo/

Deep Sky Diving with the ESO New Technology Telescope

NASA Astrophysics Data System (ADS)

1998-01-01

Preparations for future cosmological observations with the VLT Within a few months, the first 8.2-meter Unit Telescope of the ESO Very Large Telescope (VLT) array will open its eye towards the sky above the Atacama desert. As documented by recent Press Photos from ESO, the construction work at the Paranal VLT Observatory is proceeding rapidly. Virtually all of the telescope components, including the giant Zerodur mirror (cf. ESO PR Photos 35a-l/97 ), are now on the mountain. While the integration of the telescope and its many optical, mechanical and electronic components continues, astronomers in the ESO member countries and at ESO are now busy defining the observing programmes that will be carried out with the new telescope, soon after it enters into operation. In this context, new and exciting observations have recently been obtained with the 3.5-m New Technology Telescope at the ESO La Silla Observatory, 600 km to the south of Paranal. How to record the faintest and most remote astronomical objects With its very large mirror surface (and correspondingly great light collecting power), as well as an unsurpassed optical quality, the VLT will be able to look exceedingly far out into the Universe, well beyond current horizons. The best technique to record the faintest possible light and thus the most remote celestial objects, is to combine large numbers of exposures of the same field with slightly different telescope pointing. This increases the total number of photons recorded and by imaging the stars and galaxies on different areas (pixels) of the detector, the signal-to-noise ratio and hence the visibility of the faintest objects is improved. The famous Hubble Deep Field Images were obtained in this way by combining over 300 single exposures and they show myriads of faint galaxies in the distant realms of the Universe. The NTT as test bench for the VLT ESO is in the fortunate situation of possessing a `prototype' model of the Very Large Telescope, the 3.5-m New Technology Telescope. Many of the advanced technological concepts now incorporated into the VLT were first tested in the NTT. When this new facility entered into operation at La Silla in 1990, it represented a break-through in telescope technology and it has since then made many valuable contributions to front-line astronomical projects. Last year, the control and data flow system at the NTT was thoroughly refurbished to the high VLT standards and current observations with the NTT closely simulate the future operation of the VLT. The successful, early tests with the new operations system have been described in ESO Press Release 03/97. The NTT SUSI Deep Field With the possibility to test already now observing procedures which will become standard for the operation of the VLT, a group of astronomers [1] was granted NTT time for observations of Faint Galaxies in an Ultra-Deep Multicolour SUSI field . This is a programme aimed at the study of the distribution of faint galaxies in the field and of gravitational lensing effects (cosmic mirages and deformation of images of distant galaxies caused by the gravitational field of intervening matter). SUSI (SUperb Seeing Imager) is a high-resolution CCD-camera at the NTT that is particularly efficient under excellent sky conditions. The observations were fully defined in advance and were carried out in service mode from February to April 1997 with flexible scheduling by a team of dedicated ESO astronomers (the NTT team). Only in this way was it possible to obtain the exposures under optimal atmospheric conditions, i.e. `photometric' sky and little atmospheric turbulence (seeing better than 1 arcsec). A total of 122 CCD frames were obtained in four colours (blue, green-yellow, red and near-infrared) with a total exposure time of no less than 31.5 hours. The frames cover a 2.3 x 2.3 arcmin `empty' sky field centered south of the high-redshift quasar QSO BR 1202-0725 (z=4.7), located just south of the celestial equator. ESO PR Photo 01a/98 Caption to ESO PR Photo 01/98 and access to two versions of the photo The frames were computer processed and combined to yield a colour view of the corresponding sky field ( ESO Press Photo 01/98 ). This is indeed a very deep look into the southern sky. The astronomers have found that the limiting magnitude (at a signal-to-noise ratio of 3) is beyond 27 in the blue and red frames and only slightly brighter in the two others. Magnitude 27 corresponds to a brightness that is 250 million times fainter than what can be perceived with the unaided eye. Although not as deep as the Hubble Deep Field due to the shorter exposure time and brighter sky background (caused by light emission in the upper layers of the terrestrial atmosphere), this new set of data is among the best ground-based observations of this type ever obtained. Galaxies down to a magnitude of roughly 25 will soon be targets of detailed spectroscopic observations with the VLT. They will provide a measure of their basic physical parameters like redshift, luminosity and mass. How to access the new data This scientific program aims at the study of the photometric redshift distribution of the faint galaxies [2] and of gravitational lensing effects (cosmic mirages). It has been decided to make the complete data set available to the wide scientific community and it is expected that many astronomers all over the world will want to perform their own investigations by means of this unique observational material. A full description of the project is available on the ESO Web at http://www.eso.org/ndf/. Here you will find a comprehensive explanation of the scientific background, details about the observations and the data reduction, as well as easy access to the corresponding data files. Notes: [1] The group consists of Sandro D'Odorico (Principal Investigator, ESO) and Jacqueline Bergeron (ESO), Hans-Martin Adorf (ESO), Stephane Charlot (IAP, Paris, France), David Clements (IAS, Orsay, France), Stefano Cristiani (Univ. of Padova, Italy), Luiz da Costa (ESO), Eiichi Egami (MPI Extraterrestrial Physics, Garching, Germany), Adriano Fontana (Rome Observatory, Italy), Bernard Fort (Paris Observatory, France), Laurent Gautret (Paris Observatory, France), Emanuele Giallongo (Rome Observatory, Italy), Roberto Gilmozzi, Richard N.Hook and Bruno Leibundgut (ESO), Yannick Mellier and Patrick Petitjean (IAP, Paris, France), Alvio Renzini, Sandra Savaglio and Peter Shaver (ESO), Stella Seitz (Munich Observatory, Germany) and Lin Yan (ESO). [2]. The photometric redshift method allows to determine an approximate distance of a distant galaxy by measuring its colour, i.e., its relative brightness (magnitude) in different wavebands. It is based on the proportionality between the distance of a galaxy and its recession velocity (the Hubble law). The higher the velocity, the more its emission will be shifted towards longer wavelengths and the redder is the colour. Recent investigations of galaxies seen in the Hubble Deep Field have shown that the redshifts (and thus distances) found by this method are quite accurate in most cases. How to obtain ESO Press Information ESO Press Information is made available on the World-Wide Web (URL: http://www.eso.org ). ESO Press Photos may be reproduced, if credit is given to the European Southern Observatory.

The rotating universe.

NASA Astrophysics Data System (ADS)

Surdin, M.

A closed universe obeying the Hubble equation v = Hu·r, where Hu is the Hubble constant, is considered. It is shown that such a universe is equivalent to a universe rotating around one of its diameters at an angular velocity Ωu = Hu. If one revives Blackett's conjecture, viz., a rotating body creates at its center a magnetic dipole, one computes the value of the magnetic field as B ≅ 2.5×10-5G. Intergalactic magnetic fields of the order of 10-6G were deduced from observations.

NASA Astrophysics Education and Public Outreach: Engaging Educators and Students in Exploring the Cosmic Frontier

NASA Astrophysics Data System (ADS)

Lawton, Brandon L.; Eisenhamer, Bonnie; Smith, Denise Anne; Jirdeh, Hussein; Summers, Frank; Darnell, John T.; Ryer, Holly

2015-08-01

NASA’s Frontier Fields is an ambitious three-year Great Observatories program that will expand our understanding of galaxy formation and evolution in the early universe. The program includes six deep-field observations of strong-lensing galaxy clusters that will be taken in parallel with six deep “blank fields.” The observations allow astronomers to look deeper into the universe than ever before, and potentially uncover galaxies that are as much as 100 times fainter than what the telescopes can typically observe. The Frontier Fields science program is ideal for informing audiences about scientific advances and topics in STEM. The study of galaxy properties, statistics, optics, and Einstein’s theory of general relativity naturally leverages off of the science returns of the Frontier Fields program. As a result, the Space Telescope Science Institute’s Office of Public Outreach (OPO) has initiated an E/PO project to follow the progress of the Frontier Fields.For over two decades, the Hubble E/PO program has sought to bring the wonders of the universe to the education community, the youth, and the public, and engage audiences in the adventure of scientific discovery. Program components include standards-based curriculum-support materials, exhibits and exhibit components, professional development workshops, and direct interactions with scientists. We are also leveraging our new social media strategy to bring the science program to the public in the form of an ongoing blog. The main underpinnings of the program’s infrastructure are scientist-educator development teams, partnerships, and an embedded program evaluation component. OPO is leveraging this existing infrastructure to bring the Frontier Fields science program to the education community and the public in a cost-effective way.This talk features the goals and current status of the Frontier Fields E/PO program, with a particular emphasis on our education goals and achievements. We also highlight OPO’s strategies and infrastructure which allows for the quick delivery of groundbreaking science to the education community and public.

Faint blue galaxies revisited

NASA Astrophysics Data System (ADS)

Ferguson, Henry C.

If dwarf-elliptical galaxies formed their stars very rapdily (on timescales of less than 1 Gyr), they may in principle be detectable out to high redshift. Prior to the discovery of cosmic acceleration, it appeared that rapid and late formation dwarf elliptical galaxies might be required to explain the number counts of faint galaxies. A plausible hypothesis emerged: that photoionization by the UV background prevents gas cooling in low-mass halos until z ≲ 1.5. The discovery of cosmic acceleration eased the tension between predicted galaxy number counts and galaxy-evolution models. Nevertheless, there is some evidence for relatively late star formation in nearby dE's, and the photoionization delay mechanism still appears to have some merit. It is thus of interest to look back in time to see if we can find starbursting dwarf galaxies at moderate redshift. We review the connection between faint-blue galaxies and bursting-dwarf galaxies and discuss some attempts to identify progenitors to dE galaxies in the Hubble Ultra Deep Field (HUDF) observations. We find roughly 85 galaxies in the HUDF with redshifts 0.6 that appear to have formed most of their stars at z. Of these, 70% have half-light radii less than 1.5 kpc. These are thus "smoking gun" candidates for dwarf galaxies that are either collapsing for the first time at moderate redshifts or have otherwise been unable to form stars for more than 1/3 of a Hubble time.

Results of a Hubble Space Telescope Search for Natural Satellites of Dwarf Planet 1 Ceres

NASA Astrophysics Data System (ADS)

DeMario, Benjamin; Schmidt, Britney E.; Mutchler, Maximilian J.; Li, Jian-Yang; McFadden, Lucy Ann; McLean, Brian; Russell, Christopher T.

2016-10-01

In order to prepare for the arrival of the Dawn spacecraft at Ceres, a search for satellites was undertaken by the Hubble Space Telescope (HST) to enhance the mission science return and to ensure spacecraft safety. Previous satellite searches from ground-based telescopes have detected no satellites within Ceres' Hill sphere down to a size of 3 km (Gehrels et al. 1987) and early HST investigations searched to a limit of 1-2 km (Bieryla et al. 2011). The Wide Field Camera 3 (WFC3) on board the HST was used to image Ceres between 14 April - 28 April 2014. These images cover approximately the inner third of Ceres' Hill sphere, where the Hill sphere is the region surrounding Ceres where stable satellite orbits are possible. We performed a deep search for possible companions orbiting Ceres. No natural companions were located down to a diameter of 48 meters, over most of the Hill sphere to a distance of 205,000 km (434 Ceres radii) from the surface of Ceres. It was impossible to search all the way to the surface of Ceres because of scattered light, but at a distance of 2865 km (five Ceres radii), the search limit was determined to be 925 meters. The absence of a satellite around Ceres could, in the future, support more refined theories about satellite formation or capture mechanisms in the solar system.

Hubble Frontier Fields: systematic errors in strong lensing models of galaxy clusters - implications for cosmography

NASA Astrophysics Data System (ADS)

Acebron, Ana; Jullo, Eric; Limousin, Marceau; Tilquin, André; Giocoli, Carlo; Jauzac, Mathilde; Mahler, Guillaume; Richard, Johan

2017-09-01

Strong gravitational lensing by galaxy clusters is a fundamental tool to study dark matter and constrain the geometry of the Universe. Recently, the Hubble Space Telescope Frontier Fields programme has allowed a significant improvement of mass and magnification measurements but lensing models still have a residual root mean square between 0.2 arcsec and few arcseconds, not yet completely understood. Systematic errors have to be better understood and treated in order to use strong lensing clusters as reliable cosmological probes. We have analysed two simulated Hubble-Frontier-Fields-like clusters from the Hubble Frontier Fields Comparison Challenge, Ares and Hera. We use several estimators (relative bias on magnification, density profiles, ellipticity and orientation) to quantify the goodness of our reconstructions by comparing our multiple models, optimized with the parametric software lenstool, with the input models. We have quantified the impact of systematic errors arising, first, from the choice of different density profiles and configurations and, secondly, from the availability of constraints (spectroscopic or photometric redshifts, redshift ranges of the background sources) in the parametric modelling of strong lensing galaxy clusters and therefore on the retrieval of cosmological parameters. We find that substructures in the outskirts have a significant impact on the position of the multiple images, yielding tighter cosmological contours. The need for wide-field imaging around massive clusters is thus reinforced. We show that competitive cosmological constraints can be obtained also with complex multimodal clusters and that photometric redshifts improve the constraints on cosmological parameters when considering a narrow range of (spectroscopic) redshifts for the sources.

H0, q0 and the local velocity field. [Hubble and deceleration constants in Big Bang expansion

NASA Technical Reports Server (NTRS)

Sandage, A.; Tammann, G. A.

1982-01-01

An attempt is made to find a systematic deviation from linearity for distances that are under the control of the Virgo cluster, and to determine the value of the mean random motion about the systematic flow, in order to improve the measurement of the Hubble and the deceleration constants. The velocity-distance relation for large and intermediate distances is studied, and type I supernovae are calibrated relatively as distance indicators and absolutely to obtain a new value for the Hubble constant. Methods of determining the deceleration constant are assessed, including determination from direct measurement, mean luminosity density, virgocentric motion, and the time scale test. The very local velocity field is investigated, and a solution is preferred with a random peculiar radial velocity of very nearby field galaxies of 90-100 km/s, and a Virgocentric motion of the local group of 220 km/s, leading to an underlying expansion rate of 55, in satisfactory agreement with the global value.

A Public Outreach Blog for the CANDELS Project

NASA Astrophysics Data System (ADS)

Kartaltepe, Jeyhan S.; Pforr, J.; CANDELS Collaboration

2013-01-01

In May 2012 the CANDELS collaboration launched a public outreach blog, aimed at the general public, where we discuss CANDELS related science. CANDELS (the Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey) is a large Hubble Space Telescope Multi-Cycle Treasury Program to image portions of the five most commonly studied deep fields in the near-infrared with WFC3. This large collaboration encompasses a wide range of science topics including galaxy evolution and observational cosmology. We seek to understand how galaxies in the early universe formed and evolved to become the galaxies we see today. We post on a wide variety of topics including general background discussion on many issues in extragalactic astronomy, current science results and papers, highlights from meetings that we have attended, and what life as an astronomer is like (going on observing runs, writing proposals, and how we became interested in astronomy). The posts are written by a large number of collaboration members at different career stages (including students, postdocs, and permanent staff/faculty members) and is widely read and advertised on Facebook, Twitter, and Google+. Our blog can be found here: http://candels-collaboration.blogspot.com

The Grism Lens-amplified Survey from Space (GLASS). IV. Mass Reconstruction of the Lensing Cluster Abell 2744 from Frontier Field Imaging and GLASS Spectroscopy

NASA Astrophysics Data System (ADS)

Wang, X.; Hoag, A.; Huang, K.-H.; Treu, T.; Bradač, M.; Schmidt, K. B.; Brammer, G. B.; Vulcani, B.; Jones, T. A.; Ryan, R. E., Jr.; Amorín, R.; Castellano, M.; Fontana, A.; Merlin, E.; Trenti, M.

2015-09-01

We present a strong and weak lensing reconstruction of the massive cluster Abell 2744, the first cluster for which deep Hubble Frontier Fields (HFF) images and spectroscopy from the Grism Lens-Amplified Survey from Space (GLASS) are available. By performing a targeted search for emission lines in multiply imaged sources using the GLASS spectra, we obtain five high-confidence spectroscopic redshifts and two tentative ones. We confirm one strongly lensed system by detecting the same emission lines in all three multiple images. We also search for additional line emitters blindly and use the full GLASS spectroscopic catalog to test reliability of photometric redshifts for faint line emitters. We see a reasonable agreement between our photometric and spectroscopic redshift measurements, when including nebular emission in photometric redshift estimations. We introduce a stringent procedure to identify only secure multiple image sets based on colors, morphology, and spectroscopy. By combining 7 multiple image systems with secure spectroscopic redshifts (at 5 distinct redshift planes) with 18 multiple image systems with secure photometric redshifts, we reconstruct the gravitational potential of the cluster pixellated on an adaptive grid, using a total of 72 images. The resulting mass map is compared with a stellar mass map obtained from the deep Spitzer Frontier Fields data to study the relative distribution of stars and dark matter in the cluster. We find that the stellar to total mass ratio varies substantially across the cluster field, suggesting that stars do not trace exactly the total mass in this interacting system. The maps of convergence, shear, and magnification are made available in the standard HFF format.

THE GRISM LENS-AMPLIFIED SURVEY FROM SPACE (GLASS). IV. MASS RECONSTRUCTION OF THE LENSING CLUSTER ABELL 2744 FROM FRONTIER FIELD IMAGING AND GLASS SPECTROSCOPY

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, X.; Schmidt, K. B.; Jones, T. A.

2015-09-20

We present a strong and weak lensing reconstruction of the massive cluster Abell 2744, the first cluster for which deep Hubble Frontier Fields (HFF) images and spectroscopy from the Grism Lens-Amplified Survey from Space (GLASS) are available. By performing a targeted search for emission lines in multiply imaged sources using the GLASS spectra, we obtain five high-confidence spectroscopic redshifts and two tentative ones. We confirm one strongly lensed system by detecting the same emission lines in all three multiple images. We also search for additional line emitters blindly and use the full GLASS spectroscopic catalog to test reliability of photometricmore » redshifts for faint line emitters. We see a reasonable agreement between our photometric and spectroscopic redshift measurements, when including nebular emission in photometric redshift estimations. We introduce a stringent procedure to identify only secure multiple image sets based on colors, morphology, and spectroscopy. By combining 7 multiple image systems with secure spectroscopic redshifts (at 5 distinct redshift planes) with 18 multiple image systems with secure photometric redshifts, we reconstruct the gravitational potential of the cluster pixellated on an adaptive grid, using a total of 72 images. The resulting mass map is compared with a stellar mass map obtained from the deep Spitzer Frontier Fields data to study the relative distribution of stars and dark matter in the cluster. We find that the stellar to total mass ratio varies substantially across the cluster field, suggesting that stars do not trace exactly the total mass in this interacting system. The maps of convergence, shear, and magnification are made available in the standard HFF format.« less

VizieR Online Data Catalog: z>~5 AGN in Chandra Deep Field-South (Weigel+, 2015)

NASA Astrophysics Data System (ADS)

Weigel, A. K.; Schawinski, K.; Treister, E.; Urry, C. M.; Koss, M.; Trakhtenbrot, B.

2015-09-01

The Chandra 4-Ms source catalogue by Xue et al. (2011, Cat. J/ApJS/195/10) is the starting point of this work. It contains 740 sources and provides counts and observed frame fluxes in the soft (0.5-2keV), hard (2-8keV) and full (0.5-8keV) band. All object IDs used in this work refer to the source numbers listed in the Xue et al. (2011, Cat. J/ApJS/195/10) Chandra 4-Ms catalogue. We make use of Hubble Space Telescope (HST)/Advanced Camera for Surveys (ACS) data from the Great Observatories Origins Deep Survey South (GOODS-south) in the optical wavelength range. We use catalogues and images for filters F435W (B), F606W (V), F775W (i) and 850LP (z) from the second GOODS/ACS data release (v2.0; Giavalisco et al., 2004, Cat. II/261). We use Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey (CANDELS) Wide Field Camera 3 (WFC3)/infrared data from the first data release (DR1, v1.0) for passbands F105W (Y), F125W (J) and F160W (H) (Grogin et al., 2011ApJS..197...35G; Koekemoer et al., 2011ApJS..197...36K). To determine which objects are red, dusty, low-redshift interlopers, we also include the 3.6 and 4.5 micron Spitzer Infrared Array Camera (IRAC) channels. We use SIMPLE image data from the DR1 (van Dokkum et al., 2005, Spitzer Proposal, 2005.20708) and the first version of the extended SIMPLE catalogue by Damen et al. (2011, Cat. J/ApJ/727/1). (6 data files).

The ALMA Spectroscopic Survey in the Hubble Ultra Deep Field: Implications for Spectral Line Intensity Mapping at Millimeter Wavelengths and CMB Spectral Distortions

NASA Astrophysics Data System (ADS)

Carilli, C. L.; Chluba, J.; Decarli, R.; Walter, F.; Aravena, M.; Wagg, J.; Popping, G.; Cortes, P.; Hodge, J.; Weiss, A.; Bertoldi, F.; Riechers, D.

2016-12-01

We present direct estimates of the mean sky brightness temperature in observing bands around 99 and 242 GHz due to line emission from distant galaxies. These values are calculated from the summed line emission observed in a blind, deep survey for spectral line emission from high redshift galaxies using ALMA (the ALMA spectral deep field observations “ASPECS” survey). In the 99 GHz band, the mean brightness will be dominated by rotational transitions of CO from intermediate and high redshift galaxies. In the 242 GHz band, the emission could be a combination of higher order CO lines, and possibly [C II] 158 μm line emission from very high redshift galaxies (z ˜ 6-7). The mean line surface brightness is a quantity that is relevant to measurements of spectral distortions of the cosmic microwave background, and as a potential tool for studying large-scale structures in the early universe using intensity mapping. While the cosmic volume and the number of detections are admittedly small, this pilot survey provides a direct measure of the mean line surface brightness, independent of conversion factors, excitation, or other galaxy formation model assumptions. The mean surface brightness in the 99 GHZ band is: T B = 0.94 ± 0.09 μK. In the 242 GHz band, the mean brightness is: T B = 0.55 ± 0.033 μK. These should be interpreted as lower limits on the average sky signal, since we only include lines detected individually in the blind survey, while in a low resolution intensity mapping experiment, there will also be the summed contribution from lower luminosity galaxies that cannot be detected individually in the current blind survey.

Crater Copernicus

NASA Technical Reports Server (NTRS)

1999-01-01

HUBBLE SHOOTS THE MOON in a change of venue from peering at the distant universe, NASA's Hubble Space Telescope has taken a look at Earth's closest neighbor in space, the Moon. Hubble was aimed at one of the Moon's most dramatic and photogenic targets, the 58 mile-wide (93 km) impact crater Copernicus. The image was taken while the Space Telescope Imaging Spectrograph(STIS) was aimed at a different part of the moon to measure the colors of sunlight reflected off the Moon. Hubble cannot look at the Sun directly and so must use reflected light to make measurements of the Sun's spectrum. Once calibrated by measuring the Sun's spectrum, the STIS can be used to study how the planets both absorb and reflect sunlight.(upper left)The Moon is so close to Earth that Hubble would need to take a mosaic of 130 pictures to cover the entire disk. This ground-based picture from Lick Observatory shows the area covered in Hubble's photomosaic with the WideField Planetary Camera 2..(center)Hubble's crisp bird's-eye view clearly shows the ray pattern of bright dust ejected out of the crater over one billion years ago, when an asteroid larger than a mile across slammed into the Moon. Hubble can resolve features as small as 600 feet across in the terraced walls of the crater, and the hummock-like blanket of material blasted out by the meteor impact.(lower right)A close-up view of Copernicus' terraced walls. Hubble can resolve features as small as 280 feet across.

The new European Hubble archive

NASA Astrophysics Data System (ADS)

De Marchi, Guido; Arevalo, Maria; Merin, Bruno

2016-01-01

The European Hubble Archive (hereafter eHST), hosted at ESA's European Space Astronomy Centre, has been released for public use in October 2015. The eHST is now fully integrated with the other ESA science archives to ensure long-term preservation of the Hubble data, consisting of more than 1 million observations from 10 different scientific instruments. The public HST data, the Hubble Legacy Archive, and the high-level science data products are now all available to scientists through a single, carefully designed and user friendly web interface. In this talk, I will show how the the eHST can help boost archival research, including how to search on sources in the field of view thanks to precise footprints projected onto the sky, how to obtain enhanced previews of imaging data and interactive spectral plots, and how to directly link observations with already published papers. To maximise the scientific exploitation of Hubble's data, the eHST offers connectivity to virtual observatory tools, easily integrates with the recently released Hubble Source Catalog, and is fully accessible through ESA's archives multi-mission interface.

A search for radio emission from Galactic supersoft X-ray sources

NASA Astrophysics Data System (ADS)

Ogley, R. N.; Chaty, S.; Crocker, M.; Eyres, S. P. S.; Kenworthy, M. A.; Richards, A. M. S.; Rodríguez, L. F.; Stirling, A. M.

2002-03-01

We have made a deep search for radio emission from all the northern hemisphere supersoft X-ray sources using the Very Large Array (VLA) and multi-element radio-linked interferometer network (MERLIN) telescopes, at 5 and 8.4GHz. Three previously undetected sources, T Pyx, V1974 Cygni and RX J0019.8+2156, were imaged in quiescence using the VLA in order to search for any persistent emission. No radio emission was detected in any of the VLA fields down to a typical 1σ rms noise of 20μJybeam-1, however, 17 new point sources were detected in the fields with 5-GHz fluxes between 100 and 1500μJy, giving an average 100-μJy source density of ~200deg-2, comparable to what was found in the MERLIN Hubble Deep Field survey. The persistent source AG Draconis was observed by MERLIN to provide a confirmation of previous VLA observations and to investigate the source at a higher resolution. The core is resolved at the milliarcsec scale into two components that have a combined flux of ~1mJy. It is possible that we are detecting nebulosity, which is becoming resolved out by the higher MERLIN resolution. We have investigated possible causes of radio emission from a wind environment, both directly from the secondary star, and also consequently, of the high X-ray luminosity from the white dwarf. There is an order of magnitude discrepancy between observed and modelled values that can be explained by the uncertainty in fundamental quantities within these systems.

HUBBLE SEES MINI-COMET FRAGMENTS FROM COMET LINEAR

NASA Technical Reports Server (NTRS)

2002-01-01

[lower right] In one stunning Hubble picture the fate of the mysteriously vanished solid nucleus of Comet LINEAR has been settled. The Hubble picture shows that the comet nucleus has been reduced to a shower of glowing 'mini-comets' resembling the fiery fragments from an exploding aerial firework. This is the first time astronomers have ever gotten a close-up look at what may be the smallest building blocks of cometary nuclei, the icy solid pieces called 'cometesimals', which are thought to be less than 100 feet across. The farthest fragment to the left, which is now very faint, may be the remains of the parent nucleus that fragmented into the cluster of smaller pieces to the right. The comet broke apart around July 26, when it made its closest approach to the Sun. The picture was taken with Hubble's Wide Field Planetary Camera 2 on August 5, 2000, when the comet was at a distance of 64 million miles (102 million kilometers) from Earth. Credit: NASA, Harold Weaver (the Johns Hopkins University), and the HST Comet LINEAR Investigation Team [upper left] A ground-based telescopic view (2.2-meter telescope) of Comet LINEAR taken on August 5, at nearly the same time as the Hubble observations. The comet appears as a diffuse elongated cloud of debris without any visible nucleus. Based on these images, some astronomers had concluded that the ices in the nucleus had completely vaporized, leaving behind a loose swarm of dust. Hubble's resolution was needed to pinpoint the remaining nuclei (inset box shows HST field of view as shown in lower right). Credit: University of Hawaii

Unveiling the nature of bright z ≃ 7 galaxies with the Hubble Space Telescope

NASA Astrophysics Data System (ADS)

Bowler, R. A. A.; Dunlop, J. S.; McLure, R. J.; McLeod, D. J.

2017-04-01

We present new Hubble Space Telescope/Wide Field Camera 3 (HST/WFC3) imaging of 25 extremely luminous (-23.2 ≤ MUV ≲ -21.2) Lyman-break galaxies (LBGs) at z ≃ 7. The sample was initially selected from 1.65 deg2 of ground-based imaging in the UltraVISTA/COSMOS and UDS/SXDS fields, and includes the extreme Lyman α emitters, 'Himiko' and 'CR7'. A deconfusion analysis of the deep Spitzer photometry available suggests that these galaxies exhibit strong rest-frame optical nebular emission lines (EW0(Hβ + [O III]) > 600 Å). We find that irregular, multiple-component morphologies suggestive of clumpy or merging systems are common (fmulti > 0.4) in bright z ≃ 7 galaxies, and ubiquitous at the very bright end (MUV < -22.5). The galaxies have half-light radii in the range r1/2 ˜ 0.5-3 kpc. The size measurements provide the first determination of the size-luminosity relation at z ≃ 7 that extends to MUV ˜ -23. We find the relation to be steep with r1/2 ∝ L1/2. Excluding clumpy, multicomponent galaxies however, we find a shallower relation that implies an increased star formation rate surface density in bright LBGs. Using the new, independent, HST/WFC3 data we confirm that the rest-frame UV luminosity function at z ≃ 7 favours a power-law decline at the bright end, compared to an exponential Schechter function drop-off. Finally, these results have important implications for the Euclid mission, which we predict will detect >1000 similarly bright galaxies at z ≃ 7. Our new HST imaging suggests that the vast majority of these galaxies will be spatially resolved by Euclid, mitigating concerns over dwarf star contamination.

No evidence for Lyman α emission in spectroscopy of z > 7 candidate galaxies

NASA Astrophysics Data System (ADS)

Caruana, Joseph; Bunker, Andrew J.; Wilkins, Stephen M.; Stanway, Elizabeth R.; Lacy, Mark; Jarvis, Matt J.; Lorenzoni, Silvio; Hickey, Samantha

2012-12-01

We present Gemini/Gemini Near Infrared Spectrograph (GNIRS) spectroscopic observations of four z-band (z ≈ 7) dropout galaxies and Very Large Telescope (VLT)/XSHOOTER observations of one z-band dropout and three Y-band (z ≈ 8-9) dropout galaxies in the Hubble Ultra Deep Field, which were selected with Wide Field Camera 3 imaging on the Hubble Space Telescope. We find no evidence of Lyman α emission with a typical 5σ sensitivity of 5 × 10-18 erg cm-2 s-1, and use the upper limits on Lyman α flux and the broad-band magnitudes to constrain the rest-frame equivalent widths for this line emission. Accounting for incomplete spectral coverage, we survey 3.0 z-band dropouts and 2.9 Y-band dropouts to a Lyman α rest-frame equivalent width limit >120 Å (for an unresolved emission line); for an equivalent width limit of 50 Å the effective numbers of drop-outs surveyed fall to 1.2 z-band drop-outs and 1.5 Y-band drop-outs. A simple model where the fraction of high rest-frame equivalent width emitters follows the trend seen at z = 3-6.5 is inconsistent with our non-detections at z = 7-9 at the ≈1σ level for spectrally unresolved lines, which may indicate that a significant neutral H I fraction in the intergalactic medium suppresses the Lyman α line in z-drop and Y-drop galaxies at z > 7. Based on observations collected at the European Organization for Astronomical Research in the Southern Hemisphere, Chile, as part of programme 086.A-0968(B).

CLASH: COMPLETE LENSING ANALYSIS OF THE LARGEST COSMIC LENS MACS J0717.5+3745 AND SURROUNDING STRUCTURES

DOE Office of Scientific and Technical Information (OSTI.GOV)

Medezinski, Elinor; Lemze, Doron; Ford, Holland

2013-11-01

The galaxy cluster MACS J0717.5+3745 (z = 0.55) is the largest known cosmic lens, with complex internal structures seen in deep X-ray, Sunyaev-Zel'dovich effect, and dynamical observations. We perform a combined weak- and strong-lensing analysis with wide-field BVR{sub c} i'z' Subaru/Suprime-Cam observations and 16-band Hubble Space Telescope observations taken as part of the Cluster Lensing And Supernova survey with Hubble. We find consistent weak distortion and magnification measurements of background galaxies and combine these signals to construct an optimally estimated radial mass profile of the cluster and its surrounding large-scale structure out to 5 Mpc h {sup –1}. We findmore » consistency between strong-lensing and weak-lensing in the region where these independent data overlap, <500 kpc h {sup –1}. The two-dimensional weak-lensing map reveals a clear filamentary structure traced by distinct mass halos. We model the lensing shear field with nine halos, including the main cluster, corresponding to mass peaks detected above 2.5σ{sub κ}. The total mass of the cluster as determined by the different methods is M{sub vir} ≈ (2.8 ± 0.4) × 10{sup 15} M{sub ☉}. Although this is the most massive cluster known at z > 0.5, in terms of extreme value statistics, we conclude that the mass of MACS J0717.5+3745 by itself is not in serious tension with ΛCDM, representing only a ∼2σ departure above the maximum simulated halo mass at this redshift.« less

The Star Formation Main Sequence in the Hubble Space Telescope Frontier Fields

NASA Astrophysics Data System (ADS)

Santini, Paola; Fontana, Adriano; Castellano, Marco; Di Criscienzo, Marcella; Merlin, Emiliano; Amorin, Ricardo; Cullen, Fergus; Daddi, Emanuele; Dickinson, Mark; Dunlop, James S.; Grazian, Andrea; Lamastra, Alessandra; McLure, Ross J.; Michałowski, Michał. J.; Pentericci, Laura; Shu, Xinwen

2017-09-01

We investigate the relation between star formation rate (SFR) and stellar mass (M), I.e., the main sequence (MS) relation of star-forming galaxies, at 1.3≤slant z< 6 in the first four Hubble Space Telescope (HST) Frontier Fields, on the basis of rest-frame UV observations. Gravitational lensing combined with deep HST observations allows us to extend the analysis of the MS down to {log} M/{M}⊙ ˜ 7.5 at z≲ 4 and {log} M/{M}⊙ ˜ 8 at higher redshifts, a factor of ˜10 below most previous results. We perform an accurate simulation to take into account the effect of observational uncertainties and correct for the Eddington bias. This step allows us to reliably measure the MS and in particular its slope. While the normalization increases with redshift, we fit an unevolving and approximately linear slope. We nicely extend to lower masses the results of brighter surveys. Thanks to the large dynamic range in mass and by making use of the simulation, we analyzed any possible mass dependence of the dispersion around the MS. We find tentative evidence that the scatter decreases with increasing mass, suggesting a larger variety of star formation histories in low-mass galaxies. This trend agrees with theoretical predictions and is explained as either a consequence of the smaller number of progenitors of low-mass galaxies in a hierarchical scenario and/or of the efficient but intermittent stellar feedback processes in low-mass halos. Finally, we observe an increase in the SFR per unit stellar mass with redshift milder than predicted by theoretical models, implying a still incomplete understanding of the processes responsible for galaxy growth.

The Top 10 List of Gravitational Lens Candidates from the HUBBLE SPACE TELESCOPE Medium Deep Survey

NASA Astrophysics Data System (ADS)

Ratnatunga, Kavan U.; Griffiths, Richard E.; Ostrander, Eric J.

1999-05-01

A total of 10 good candidates for gravitational lensing have been discovered in the WFPC2 images from the Hubble Space Telescope (HST) Medium Deep Survey (MDS) and archival primary observations. These candidate lenses are unique HST discoveries, i.e., they are faint systems with subarcsecond separations between the lensing objects and the lensed source images. Most of them are difficult objects for ground-based spectroscopic confirmation or for measurement of the lens and source redshifts. Seven are ``strong lens'' candidates that appear to have multiple images of the source. Three are cases in which the single image of the source galaxy has been significantly distorted into an arc. The first two quadruply lensed candidates were reported by Ratnatunga et al. We report on the subsequent eight candidates and describe them with simple models based on the assumption of singular isothermal potentials. Residuals from the simple models for some of the candidates indicate that a more complex model for the potential will probably be required to explain the full structural detail of the observations once they are confirmed to be lenses. We also discuss the effective survey area that was searched for these candidate lens objects.

The stochastic spectator

NASA Astrophysics Data System (ADS)

Hardwick, Robert J.; Vennin, Vincent; Byrnes, Christian T.; Torrado, Jesús; Wands, David

2017-10-01

We study the stochastic distribution of spectator fields predicted in different slow-roll inflation backgrounds. Spectator fields have a negligible energy density during inflation but may play an important dynamical role later, even giving rise to primordial density perturbations within our observational horizon today. During de-Sitter expansion there is an equilibrium solution for the spectator field which is often used to estimate the stochastic distribution during slow-roll inflation. However slow roll only requires that the Hubble rate varies slowly compared to the Hubble time, while the time taken for the stochastic distribution to evolve to the de-Sitter equilibrium solution can be much longer than a Hubble time. We study both chaotic (monomial) and plateau inflaton potentials, with quadratic, quartic and axionic spectator fields. We give an adiabaticity condition for the spectator field distribution to relax to the de-Sitter equilibrium, and find that the de-Sitter approximation is never a reliable estimate for the typical distribution at the end of inflation for a quadratic spectator during monomial inflation. The existence of an adiabatic regime at early times can erase the dependence on initial conditions of the final distribution of field values. In these cases, spectator fields acquire sub-Planckian expectation values. Otherwise spectator fields may acquire much larger field displacements than suggested by the de-Sitter equilibrium solution. We quantify the information about initial conditions that can be obtained from the final field distribution. Our results may have important consequences for the viability of spectator models for the origin of structure, such as the simplest curvaton models.

Hubble's View of Little Blue Dots

NASA Astrophysics Data System (ADS)

Kohler, Susanna

2018-02-01

The recent discovery of a new type of tiny, star-forming galaxy is the latest in a zoo of detections shedding light on our early universe. What can we learn from the unique little blue dots found in archival Hubble data?Peas, Berries, and DotsGreen pea galaxies identified by citizen scientists with Galaxy Zoo. [Richard Nowell Carolin Cardamone]As telescope capabilities improve and we develop increasingly deeper large-scale surveys of our universe, we continue to learn more about small, faraway galaxies. In recent years, increasing sensitivity first enabled the detection of green peas luminous, compact, low-mass (10 billion solar masses; compare this to the Milky Ways 1 trillion solar masses!) galaxies with high rates of star formation.Not long thereafter, we discovered galaxies that form stars similarly rapidly, but are even smaller only 330 million solar masses, spanning less than 3,000 light-years in size. These tiny powerhouses were termed blueberries for their distinctive color.Now, scientists Debra and Bruce Elmegreen (of Vassar College and IBM Research Division, respectively) report the discovery of galaxies that have even higher star formation rates and even lower masses: little blue dots.Exploring Tiny Star FactoriesThe Elmegreens discovered these unique galaxies by exploring archival Hubble data. The Hubble Frontier Fields data consist of deep images of six distant galaxy clusters and the parallel fields next to them. It was in the archival data for two Frontier Field Parallels, those for clusters Abell 2744 and MAS J0416.1-2403, that the authors noticed several galaxies that stand out as tiny, bright, blue objects that are nearly point sources.Top: a few examples of the little blue dots recently identified in two Hubble Frontier Field Parallels. Bottom: stacked images for three different groups of little blue dots. [Elmegreen Elmegreen 2017]The authors performed a search through the two Frontier Field Parallels, discovering a total of 55 little blue dots with masses spanning 105.8107.4solar masses, specific star formation rates of 10-7.4, and redshifts of 0.5 z 5.4.Exploring these little blue dots, the Elmegreens find that the galaxies sizes tend to be just a few hundred light-years across. They are gas-dominated; gas currently outweighs stars in these galaxies by perhaps a factor of five. Impressively, based on the incredibly high specific star formation rates observed in these little blue dots, they appear to have formed all of their stars in the last 1% of the age of the universe for them.An Origin for Globulars?Log-log plot of star formation rate vs. mass for the three main groups of little blue dots (red, green, and blue markers), a fourth group of candidates with different properties (brown markers), and previously discovered local blueberry galaxies. The three main groups of little blue dots appear to be low-mass analogs of blueberries. [Elmegreen Elmegreen 2017]Intriguingly, this rapid star formation might be the key to answering a long-standing question: where do globular clusters come from? The Elmegreens propose that little blue dots might actually be an explanation for the origin of these orbiting, spherical, low-metallicity clusters of stars.The authors demonstrate that, if the current star formation rates observed in little blue dots were to persist for another 50 Myr before feedback or gas exhaustion halted star production, the little blue dots could form enough stars to create clusters of roughly a million solar masses which is large enough to explain the globular clusters we observe today.If little blue dots indeed rapidly produced such star clusters in the past, the clusters could later be absorbed into the halos of todays spiral and elliptical galaxies, appearing to us as the low-metallicity globular clusters that orbit large galaxies today.CitationDebra Meloy Elmegreen and Bruce G. Elmegreen 2017 ApJL 851 L44. doi:10.3847/2041-8213/aaa0ce

The DEEP2 Galaxy Redshift Survey: Design, Observations, Data Reduction, and Redshifts

NASA Technical Reports Server (NTRS)

Newman, Jeffrey A.; Cooper, Michael C.; Davis, Marc; Faber, S. M.; Coil, Alison L; Guhathakurta, Puraga; Koo, David C.; Phillips, Andrew C.; Conroy, Charlie; Dutton, Aaron A.;

Morphology and Structure of Ultraluminous Infrared Galaxies at z ≈ 2 in the EGS Field

NASA Astrophysics Data System (ADS)

Fang, G. W.; Ma, Z. Y.; Chen, Y.; Kong, X.

2014-11-01

Using high-resolution HST WFC3 (Hubble Space Telescope Wide Field Camera 3) F160W imaging from the CANDELS-EGS (Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey-Extended Groth Strip) field, we present the morphology analysis of 9 ultraluminous infrared galaxies (ULIRGs) at z≈2. We find a wide range of morphological diversities for these ULIRGs, from spheroid to multiple bright nuclei or diffuse structures, e.g., double nuclei, bridges, dual asymmetries, irregular, or elliptical structures. In quantitative, these sources show a lower Gini coefficient (G) and a higher moment (M_{20}) in the rest-frame optical morphology, compared to the lower redshift counterparts, indicating less concentrated and symmetric spatial distribution of the stellar mass of ULIRGs at z≈2. Moreover, we derive accurate effective radii of these ULIRGs through 2-D profile fitting, which range from 2.4 to 5.8 kpc, with a mean value of (3.9±1.1) kpc. We find that the sizes of these ULIRGs at z≈2 are on average one to two times smaller than those of the local star-forming galaxies with analogous stellar mass. Our results are consistent with those studies at similar redshift and infrared luminosity.

VizieR Online Data Catalog: Hubble Tarantula Treasury Project (HTTP). III. (Sabbi+, 2016)

NASA Astrophysics Data System (ADS)

Sabbi, E.; Lennon, D. J.; Anderson, J.; Cignoni, M.; van der Marel, R. P.; Zaritsky, D.; de Marchi, G.; Panagia, N.; Gouliermis, D. A.; Grebel, E. K.; Gallagher, J. S., III; Smith, L. J.; Sana, H.; Aloisi, A.; Tosi, M.; Evans, C. J.; Arab, H.; Boyer, M.; de Mink, S. E.; Gordon, K.; Koekemoer, A. M.; Larsen, S. S.; Ryon, J. E.; Zeidler, P.

2016-02-01

Hubble Tarantula Treasury Project (HTTP; HST 12939, PI Elena Sabbi + HST 12499, PI Danny Lennon) was awarded 60 orbits of HST time in cycle 20 to survey the entire Tarantula Nebula (30 Doradus), using both the UVIS and the IR channels of the Wide Field Camera 3 (WFC3), and, in parallel, the Wide Field Channel (WFC) of the Advanced Camera for Surveys (ACS). See log of the observations (from 2011 Oct 03 to 2013 Sep 17) in table 1. (2 data files).

Survival Of Pure Disc Galaxies Over The Last 8 Billion Years

NASA Astrophysics Data System (ADS)

Sachdeva, Sonali

2016-09-01

The presence of pure disk galaxies without any bulge component, i.e., neither classical nor pseudo, poses a severe challenge not just to the hierarchical galaxy formation models but also to the theories of internal secular evolution. We discover that a significant fraction of disk galaxies ( 15-18 %) in the Hubble Deep Field (0.4 < z < 1.0) as well as in the local Universe (0.02 < z < 0.05) are such pure disk systems (PDS). We trace the evolution of this population to find how they survived the merger violence and other disk instabilities to remain dynamically undisturbed. We find that smooth accretion of cold gas via cosmic filaments is the most probable mode of their growth in mass and size since z 1. We speculate that PDSs are dynamically hotter and cushioned in massive dark matter haloes which may prevent them from undergoing strong secular evolution.

Astronomy Laboratory Exercise on Olbers’ Paradox and the Age of the Universe

NASA Astrophysics Data System (ADS)

Glazer, Kelsey Samantha; Edwards, Charlotte; Overduin, James; Storrs, Alex

2018-01-01

We describe the development of a new laboratory exercise for undergraduate introductory astronomy courses. Students begin by estimating the intensity of the extragalactic background light using a simple Newtonian cosmological model that agrees with recent measurements to within a factor of two. They then use the 0.5m Towson University telescope to image a dark patch of sky such as the Hubble Deep Field near or during new Moon, and compare the intensity actually observed with that predicted. This comparison leads to a new appreciation of foreground contributions such as light pollution, airglow, zodiacal light, starlight and others. Students pick up important skills in uncertainty analysis and astronomical unit conversion. But the most valuable aspect of the exercise in our view is that it enables students to draw a direct connection between the evidence of their own eyes and the age of the Universe.

A Lyman Break Galaxy in the Epoch of Reionization from Hubble Space Telescope (HST) Grism Spectroscopy

NASA Technical Reports Server (NTRS)

Rhoads, James E.; Malhotra, Sangeeta; Stern, Daniel K.; Gardner, Jonathan P.; Dickinson, Mark; Pirzkal, Norbert; Spinrad, Hyron; Reddy, Naveen; Dey, Arjun; Hathi, Nimish;

Size–Luminosity Relations and UV Luminosity Functions at z = 6–9 Simultaneously Derived from the Complete Hubble Frontier Fields Data

NASA Astrophysics Data System (ADS)

Kawamata, Ryota; Ishigaki, Masafumi; Shimasaku, Kazuhiro; Oguri, Masamune; Ouchi, Masami; Tanigawa, Shingo

2018-03-01

We construct z ∼ 6–7, 8, and 9 faint Lyman break galaxy samples (334, 61, and 37 galaxies, respectively) with accurate size measurements with the software glafic from the complete Hubble Frontier Fields (HFF) cluster and parallel fields data. These are the largest samples hitherto and reach down to the faint ends of recently obtained deep luminosity functions. At faint magnitudes, however, these samples are highly incomplete for galaxies with large sizes, implying that derivation of the luminosity function sensitively depends on the intrinsic size–luminosity relation. We thus conduct simultaneous maximum-likelihood estimation of luminosity function and size–luminosity relation parameters from the observed distribution of galaxies on the size–luminosity plane with the help of a completeness map as a function of size and luminosity. At z ∼ 6–7, we find that the intrinsic size–luminosity relation expressed as r e ∝ L β has a notably steeper slope of β ={0.46}-0.09+0.08 than those at lower redshifts, which in turn implies that the luminosity function has a relatively shallow faint-end slope of α =-{1.86}-0.18+0.17. This steep β can be reproduced by a simple analytical model in which smaller galaxies have lower specific angular momenta. The β and α values for the z ∼ 8 and 9 samples are consistent with those for z ∼ 6–7 but with larger errors. For all three samples, there is a large, positive covariance between β and α, implying that the simultaneous determination of these two parameters is important. We also provide new strong lens mass models of Abell S1063 and Abell 370, as well as updated mass models of Abell 2744 and MACS J0416.1‑2403.

Variation of fundamental constants on sub- and super-Hubble scales: From the equivalence principle to the multiverse

NASA Astrophysics Data System (ADS)

Uzan, Jean-Philippe

2013-02-01

Fundamental constants play a central role in many modern developments in gravitation and cosmology. Most extensions of general relativity lead to the conclusion that dimensionless constants are actually dynamical fields. Any detection of their variation on sub-Hubble scales would signal a violation of the Einstein equivalence principle and hence a lead to gravity beyond general relativity. On super-Hubble scales, or maybe should we say on super-universe scales, such variations are invoked as a solution to the fine-tuning problem, in connection with an anthropic approach.

HUBBLE SHOOTS THE MOON

NASA Technical Reports Server (NTRS)

2002-01-01

In a change of venue from peering at the distant universe, NASA's Hubble Space Telescope has taken a look at Earth's closest neighbor in space, the Moon. Hubble was aimed at one of the Moon's most dramatic and photogenic targets, the 58 mile-wide (93 km) impact crater Copernicus. The image was taken while the Space Telescope Imaging Spectrograph (STIS) was aimed at a different part of the moon to measure the colors of sunlight reflected off the Moon. Hubble cannot look at the Sun directly and so must use reflected light to make measurements of the Sun's spectrum. Once calibrated by measuring the Sun's spectrum, the STIS can be used to study how the planets both absorb and reflect sunlight. (upper left) The Moon is so close to Earth that Hubble would need to take a mosaic of 130 pictures to cover the entire disk. This ground-based picture from Lick Observatory shows the area covered in Hubble's photomosaic with the Wide Field Planetary Camera 2.. (center) Hubble's crisp bird's-eye view clearly shows the ray pattern of bright dust ejected out of the crater over one billion years ago, when an asteroid larger than a mile across slammed into the Moon. Hubble can resolve features as small as 600 feet across in the terraced walls of the crater, and the hummock-like blanket of material blasted out by the meteor impact. (lower right) A close-up view of Copernicus' terraced walls. Hubble can resolve features as small as 280 feet across. Credit: John Caldwell (York University, Ontario), Alex Storrs (STScI), and NASA

The X-Ray Luminosity Functions of Field Low-Mass X-Ray Binaries in Early-Type Galaxies: Evidence for a Stellar Age Dependence

NASA Technical Reports Server (NTRS)

Lehmer, B. D.; Berkeley, M.; Zezas, A.; Alexander, D. M.; Basu-Zych, A.; Bauer, F. E.; Brandt, W. N.; Fragos, T.; Hornschemeier, A. E.; Kalogera, V.;

ESO imaging survey: infrared observations of CDF-S and HDF-S

NASA Astrophysics Data System (ADS)

Olsen, L. F.; Miralles, J.-M.; da Costa, L.; Benoist, C.; Vandame, B.; Rengelink, R.; Rité, C.; Scodeggio, M.; Slijkhuis, R.; Wicenec, A.; Zaggia, S.

2006-06-01

This paper presents infrared data obtained from observations carried out at the ESO 3.5 m New Technology Telescope (NTT) of the Hubble Deep Field South (HDF-S) and the Chandra Deep Field South (CDF-S). These data were taken as part of the ESO Imaging Survey (EIS) program, a public survey conducted by ESO to promote follow-up observations with the VLT. In the HDF-S field the infrared observations cover an area of ~53 square arcmin, encompassing the HST WFPC2 and STIS fields, in the JHKs passbands. The seeing measured in the final stacked images ranges from 0.79 arcsec to 1.22 arcsec and the median limiting magnitudes (AB system, 2'' aperture, 5σ detection limit) are J_AB˜23.0, H_AB˜22.8 and K_AB˜23.0 mag. Less complete data are also available in JKs for the adjacent HST NICMOS field. For CDF-S, the infrared observations cover a total area of ~100 square arcmin, reaching median limiting magnitudes (as defined above) of J_AB˜23.6 and K_AB˜22.7 mag. For one CDF-S field H band data are also available. This paper describes the observations and presents the results of new reductions carried out entirely through the un-supervised, high-throughput EIS Data Reduction System and its associated EIS/MVM C++-based image processing library developed, over the past 5 years, by the EIS project and now publicly available. The paper also presents source catalogs extracted from the final co-added images which are used to evaluate the scientific quality of the survey products, and hence the performance of the software. This is done comparing the results obtained in the present work with those obtained by other authors from independent data and/or reductions carried out with different software packages and techniques. The final science-grade catalogs together with the astrometrically and photometrically calibrated co-added images are available at CDS.

Dwarfs in the Deepest Fields at Noon: Studying Size and Shape of Low-mass Galaxies out to z 3 in Five HST Legacy Fields

NASA Astrophysics Data System (ADS)

Guo, Yicheng

2017-08-01

Galaxies with stellar mass 100x-1000x times smaller than our Milky Way (hereafter dwarf galaxies or DGs) are important for understanding galaxy formation and evolution by being the most sensitive probes of both the macro-physics of dark matter halos and the micro-physics of the different physical mechanisms that regulate star formation and shape galaxies. Currently, however, observations of distant DGs have been hampered by small samples and poor quality due to their faintness. We propose an archival study of the size, morphology, and structures of DGs out to z 3.0 by combining the archived data from five of the deepest regions that HST has ever observed: eXtreme Deep Field (XDF, updated from HUDF) and the Hubble Legacy Fields (HLFs). Our program would be the first to advance the morphology studies of DGs to the Cosmic Noon (z 2), and hence place unprecedented constraints on models of galaxy structure formation. Equally important is the data product of our program: multi-wavelength photometry and morphology catalogs for all detected galaxies in these fields. These catalogs would be a timely treasure for the public to prepare for the coming JWST era by providing detailed information of small, faint, but important objects in some deepest HST fields for JWST observations.

Reconstruction from scalar-tensor theory and the inhomogeneous equation of state in f( T) gravity

NASA Astrophysics Data System (ADS)

Said, Jackson Levi

2017-12-01

General relativity (GR) characterizes gravity as a geometric properly exhibited as curvature on spacetime. Teleparallelism describes gravity through torsional properties, and can reproduce GR at the level of equations. Similar to f( R) gravity, on taking a generalization, f( T) gravity can produce various modifications its gravitational mechanism. The resulting field equations are inherently distinct to f( R) gravity in that they are second order. In the present work, f( T) gravity is examined in the cosmological context with a number of solutions reconstructed by means of an auxiliary scalar field. To do this, various forms of the Hubble parameter are considered with an f( T) Lagrangian emerging for each instance. In addition, the inhomogeneous equation of state (EoS) is investigated with a particular Hubble parameter model used to show how this can be used to reconstruct the f( T) Lagrangian. Observationally, the auxiliary scalar field and the exotic terms in the FRW field equations give the same results, meaning that the variation in the Hubble parameter may be interpreted as the need to reformulate gravity in some way, as in f( T) gravity.

The MUSE Hubble Ultra Deep Field Survey. VIII. Extended Lyman-α haloes around high-z star-forming galaxies

NASA Astrophysics Data System (ADS)

Leclercq, Floriane; Bacon, Roland; Wisotzki, Lutz; Mitchell, Peter; Garel, Thibault; Verhamme, Anne; Blaizot, Jérémy; Hashimoto, Takuya; Herenz, Edmund Christian; Conseil, Simon; Cantalupo, Sebastiano; Inami, Hanae; Contini, Thierry; Richard, Johan; Maseda, Michael; Schaye, Joop; Marino, Raffaella Anna; Akhlaghi, Mohammad; Brinchmann, Jarle; Carollo, Marcella

2017-11-01

We report the detection of extended Lyα haloes around 145 individual star-forming galaxies at redshifts 3 ≤ z ≤ 6 in the Hubble Ultra Deep Field observed with the Multi-Unit Spectroscopic Explorer (MUSE) at ESO-VLT. Our sample consists of continuum-faint (- 15 ≥ MUV ≥ -22) Lyα emitters (LAEs). Using a 2D, two-component (continuum-like and halo) decomposition of Lyα emission assuming circular exponential distributions, we measure scale lengths and luminosities of Lyα haloes. We find that 80% of our objects having reliable Lyα halo measurements show Lyα emission that is significantly more extended than the UV continuum detected by HST (by a factor ≈4 to >20). The median exponential scale length of the Lyα haloes in our sample is ≈4.5 kpc with a few haloes exceeding 10 kpc. By comparing the maximal detected extent of the Lyα emission with the predicted dark matter halo virial radii of simulated galaxies, we show that the detected Lyα emission of our selected sample of Lyα emitters probes a significant portion of the cold circum-galactic medium of these galaxies (>50% in average). This result therefore shows that there must be significant HI reservoirs in the circum-galactic medium and reinforces the idea that Lyα haloes are ubiquitous around high-redshift Lyα emitting galaxies. Our characterization of the Lyα haloes indicates that the majority of the Lyα flux comes from the halo (≈65%) and that their scale lengths seem to be linked to the UV properties of the galaxies (sizes and magnitudes). We do not observe a significant Lyα halo size evolution with redshift, although our sample for z> 5 is very small. We also explore the diversity of the Lyα line profiles in our sample and we find that the Lyα lines cover a large range of full width at half maximum (FWHM) from 118 to 512 km s-1. While the FWHM does not seem to be correlated to the Lyα scale length, most compact Lyα haloes and those that are not detected with high significance tend to have narrower Lyα profiles (<350 km s-1). Finally, we investigate the origin of the extended Lyα emission but we conclude that our data do not allow us to disentangle the possible processes, i.e. scattering from star-forming regions, fluorescence, cooling radiation from cold gas accretion, and emission from satellite galaxies. MUSE Ultra Deep Field Lyα haloes catalog (Table B.1) is also available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/608/A8

Amateur and Professional Astronomers Team Up to Create a Cosmological Masterpiece

NASA Image and Video Library

2017-12-08

To view a video of this story go to: www.flickr.com/photos/gsfc/8448332724 Working with astronomical image processors at the Space Telescope Science Institute in Baltimore, Md., renowned astro-photographer Robert Gendler has taken science data from the Hubble Space Telescope (HST) archive and combined it with his own ground-based observations to assemble a photo illustration of the magnificent spiral galaxy M106. Gendler retrieved archival Hubble images of M106 to assemble a mosaic of the center of the galaxy. He then used his own and fellow astro-photographer Jay GaBany's observations of M106 to combine with the Hubble data in areas where there was less coverage, and finally, to fill in the holes and gaps where no Hubble data existed. The center of the galaxy is composed almost entirely of HST data taken by the Advanced Camera for Surveys, Wide Field Camera 3, and Wide Field Planetary Camera 2 detectors. The outer spiral arms are predominantly HST data colorized with ground-based data taken by Gendler's and GaBany's 12.5-inch and 20-inch telescopes, located at very dark remote sites in New Mexico. The image also reveals the optical component of the "anomalous arms" of M106, seen here as red, glowing hydrogen emission. To read more go to: www.nasa.gov/mission_pages/hubble/science/m106.html Credit: NASA, ESA, the Hubble Heritage Team (STScI/AURA), R. Gendler (for the Hubble Heritage Team), and G. Bacon (STScI) NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Like us on Facebook Find us on Instagram

HUBBLE SPIES BROWN DWARFS IN NEARBY STELLAR NURSERY

NASA Technical Reports Server (NTRS)

2002-01-01

Probing deep within a neighborhood stellar nursery, NASA's Hubble Space Telescope uncovered a swarm of newborn brown dwarfs. The orbiting observatory's near-infrared camera revealed about 50 of these objects throughout the Orion Nebula's Trapezium cluster [image at right], about 1,500 light-years from Earth. Appearing like glistening precious stones surrounding a setting of sparkling diamonds, more than 300 fledgling stars and brown dwarfs surround the brightest, most massive stars [center of picture] in Hubble's view of the Trapezium cluster's central region. All of the celestial objects in the Trapezium were born together in this hotbed of star formation. The cluster is named for the trapezoidal alignment of those central massive stars. Brown dwarfs are gaseous objects with masses so low that their cores never become hot enough to fuse hydrogen, the thermonuclear fuel stars like the Sun need to shine steadily. Instead, these gaseous objects fade and cool as they grow older. Brown dwarfs around the age of the Sun (5 billion years old) are very cool and dim, and therefore are difficult for telescopes to find. The brown dwarfs discovered in the Trapezium, however, are youngsters (1 million years old). So they're still hot and bright, and easier to see. This finding, along with observations from ground-based telescopes, is further evidence that brown dwarfs, once considered exotic objects, are nearly as abundant as stars. The image and results appear in the Sept. 20 issue of the Astrophysical Journal. The brown dwarfs are too dim to be seen in a visible-light image taken by the Hubble telescope's Wide Field and Planetary Camera 2 [picture at left]. This view also doesn't show the assemblage of infant stars seen in the near-infrared image. That's because the young stars are embedded in dense clouds of dust and gas. The Hubble telescope's near-infrared camera, the Near Infrared Camera and Multi-Object Spectrometer, penetrated those clouds to capture a view of those objects. The brown dwarfs are the faintest objects in the image. Surveying the cluster's central region, the Hubble telescope spied brown dwarfs with masses equaling 10 to 80 Jupiters. Researchers think there may be less massive brown dwarfs that are beyond the limits of Hubble's vision. The near-infrared image was taken Jan. 17, 1998. Two near-infrared filters were used to obtain information on the colors of the stars at two wavelengths (1.1 and 1.6 microns). The Trapezium picture is 1 light-year across. This composite image was made from a 'mosaic' of nine separate, but adjoining images. In this false-color image, blue corresponds to warmer, more massive stars, and red to cooler, less massive stars and brown dwarfs, and stars that are heavily obscured by dust. The visible-light data were taken in 1994 and 1995. Credits for near-infrared image: NASA; K.L. Luhman (Harvard-Smithsonian Center for Astrophysics, Cambridge, Mass.); and G. Schneider, E. Young, G. Rieke, A. Cotera, H. Chen, M. Rieke, R. Thompson (Steward Observatory, University of Arizona, Tucson, Ariz.) Credits for visible-light picture: NASA, C.R. O'Dell and S.K. Wong (Rice University)

Exploring the Universe with the Hubble Space Telescope

NASA Technical Reports Server (NTRS)

1990-01-01

A general overview is given of the operations, engineering challenges, and components of the Hubble Space Telescope. Deployment, checkout and servicing in space are discussed. The optical telescope assembly, focal plane scientific instruments, wide field/planetary camera, faint object spectrograph, faint object camera, Goddard high resolution spectrograph, high speed photometer, fine guidance sensors, second generation technology, and support systems and services are reviewed.

Galaxy distances and deviations from universal expansion; Proceedings of the NATO Advanced Research Workshop, Kona, HI, Jan. 13-17, 1986

NASA Astrophysics Data System (ADS)

Madore, Barry F.; Tully, R. Brent

A collection of papers on galaxy distances and deviations from universal expansion is presented. Individual topics addressed include: new results on the distance scale and the Hubble constant, Magellanic Clouds and the distance scale, CCD observations of Cepheids in nearby galaxies, distances using A supergiant stars, infrared calibration of the Cepheid distance scale, two stepping stones to the Hubble constant, physical models of supernovae and the distance scale, 21 cm line widths and distances of spiral galaxies, infrared color-luminosity relations for field galaxies, minimizing the scatter in the Tully-Fisher relation, photometry of galaxies and the local peculiar motion, elliptical galaxies and nonuniformities in the Hubble flow, and large-scale anisotropy in the Hubble flow. Also discussed are: improved distance indicator for elliptical galaxies, anisotropy of galaxies detected by IRAS, the local gravitational field, measurements of the CBR, measure of cosmological times, ages from nuclear cosmochronology, extragalactic gas at high redshift, supercluster infall models, Virgo infall and the mass density of the universe, dynamics of superclusters and Omega(0), distribution of galaxies versus dark matter, peculiar velocities and galaxy formation, cosmological shells and blast waves.

FIRST OBSERVATIONAL SUPPORT FOR OVERLAPPING REIONIZED BUBBLES GENERATED BY A GALAXY OVERDENSITY

DOE Office of Scientific and Technical Information (OSTI.GOV)

Castellano, M.; Pentericci, L.; Fontana, A.

2016-02-10

We present an analysis of deep Hubble Space Telescope (HST) multi-band imaging of the BDF field specifically designed to identify faint companions around two of the few Lyα emitting galaxies spectroscopically confirmed at z ∼ 7. Although separated by only 4.4 proper Mpc these galaxies cannot generate H ii regions large enough to explain the visibility of their Lyα lines, thus requiring a population of fainter ionizing sources in their vicinity. We use deep HST and VLT-Hawk-I data to select z ∼ 7 Lyman break galaxies around the emitters. We select six new robust z ∼ 7 LBGs at Y ∼ 26.5–27.5 whose average spectral energy distribution ismore » consistent with the objects being at the redshift of the close-by Lyα emitters. The resulting number density of z ∼ 7 LBGs in the BDF field is a factor of approximately three to four higher than expected in random pointings of the same size. We compare these findings with cosmological hydrodynamic plus radiative transfer simulations of a universe with a half neutral IGM: we find that indeed Lyα emitter pairs are only found in completely ionized regions characterized by significant LBG overdensities. Our findings match the theoretical prediction that the first ionization fronts are generated within significant galaxy overdensities and support a scenario where faint, “normal” star-forming galaxies are responsible for reionization.« less

Direct Detection of The Lyman Continuum of Star-forming Galaxies at z~3

NASA Astrophysics Data System (ADS)

Vasei, Kaveh; Siana, Brian; Shapley, Alice; Alavi, Anahita; Rafelski, Marc

2018-01-01

Star-forming galaxies are widely believed to be responsible for the reionization of the Universe and much of the ionizing background at z>3. Therefore, there has been much interest in quantifying the escape fraction of the Lyman continuum (LyC) radiation of the star-forming galaxies. Yet direct detection of LyC has proven to be exceptionally challenging. Despite numerous efforts only 7 galaxies at z<2 (all with escape fractions less than 0.04) and 3 galaxies at z>2 have been robustly confirmed as LyC leakers. To avoid these challenges many studies use indirect methods to infer the LyC escape fraction. We tested these indirect methods by attempting to detect escaping LyC with a 10-orbit Hubble near-UV (F275W) image that is just below the Lyman limit at the redshift of the Cosmic Horseshoe (a lensed galaxy at z=2.4). We concluded that the measured escape fraction is lower, by more than a factor of five, than the expected escape fraction based on the indirect methods. This emphasizes that indirect determinations should only be interpreted as upper-limits. We also investigated the deepest near-UV Hubble images of the SSA22 field to detect LyC leakage from a large sample of candidate star-forming galaxies at z~3.1, whose redshift was obtained by deep Keck/LRIS spectroscopy and for which Keck narrow-band imaging was showing possible LyC leakage. The high spatial resolution of Hubble images is crucial to confirm our detections are clean from foreground contaminating galaxies, and also to ascertain the escape fraction of our final candidates. We identify five clean LyC emitting star-forming galaxies. The follow up investigation of these galaxies will significantly increase our knowledge of the LyC escape fraction and the mechanisms allowing for LyC escape.

Hubble Takes Mars Portrait Near Close Approach

NASA Image and Video Library

2017-12-08

Mars is looking mighty fine in this portrait nabbed by the Hubble Space Telescope on a near close approach! Read more: go.nasa.gov/1rWYiBT The Hubble Space Telescope is more well known for its picturesque views of nebulae and galaxies, but it's also useful for studying our own planets, including Mars. Hubble imaged Mars on May 12, 2016 - ten days before Mars would be on the exact opposite side of the Earth from the Sun. Bright, frosty polar caps, and clouds above a vivid, rust-colored landscape reveal Mars as a dynamic seasonal planet in this NASA Hubble Space Telescope view taken on May 12, 2016, when Mars was 50 million miles from Earth. The Hubble image reveals details as small as 20 to 30 miles across. The large, dark region at far right is Syrtis Major Planitia, one of the first features identified on the surface of the planet by seventeenth-century observers. Christiaan Huygens used this feature to measure the rotation rate of Mars. (A Martian day is about 24 hours and 37 minutes.) Today we know that Syrtis Major is an ancient, inactive shield volcano. Late-afternoon clouds surround its summit in this view. A large oval feature to the south of Syrtis Major is the bright Hellas Planitia basin. About 1,100 miles across and nearly five miles deep, it was formed about 3.5 billion years ago by an asteroid impact. The orange area in the center of the image is Arabia Terra, a vast upland region in northern Mars that covers about 2,800 miles. The landscape is densely cratered and heavily eroded, indicating that it could be among the oldest terrains on the planet. Dried river canyons (too small to be seen here) wind through the region and empty into the large northern lowlands. Credit: NASA, ESA, the Hubble Heritage Team (STScI/AURA), J. Bell (ASU), and M. Wolff (Space Science Institute) #nasagoddard #mars #hubble #space NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Like us on Facebook Find us on Instagram

Possible evolution of a bouncing universe in cosmological models with non-minimally coupled scalar fields

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pozdeeva, Ekaterina O.; Vernov, Sergey Yu.; Skugoreva, Maria A.

2016-12-01

We explore dynamics of cosmological models with bounce solutions evolving on a spatially flat Friedmann-Lemaître-Robertson-Walker background. We consider cosmological models that contain the Hilbert-Einstein curvature term, the induced gravity term with a negative coupled constant, and even polynomial potentials of the scalar field. Bounce solutions with non-monotonic Hubble parameters have been obtained and analyzed. The case when the scalar field has the conformal coupling and the Higgs-like potential with an opposite sign is studied in detail. In this model the evolution of the Hubble parameter of the bounce solution essentially depends on the sign of the cosmological constant.

X-Ray Properties of Lyman Break Galaxies in the Hubble Deep Field North Region

NASA Technical Reports Server (NTRS)

Nandra, K.; Mushotzky, R. F.; Arnaud, K.; Steidel, C. C.; Adelberger, K. L.; Gardner, J. P.; Teplitz, H. I.; Windhorst, R. A.; White, Nicholas E. (Technical Monitor)

2002-01-01

We describe the X-ray properties of a large sample of z approximately 3 Lyman Break Galaxies (LBGs) in the region of the Hubble Deep Field North, derived from the 1 Ms public Chandra observation. Of our sample of 148 LBGs, four are detected individually. This immediately gives a measure of the bright AGN (active galactic nuclei) fraction in these galaxies of approximately 3 per cent, which is in agreement with that derived from the UV (ultraviolet) spectra. The X-ray color of the detected sources indicates that they are probably moderately obscured. Stacking of the remainder shows a significant detection (6 sigma) with an average luminosity of 3.5 x 10(exp 41) erg/s per galaxy in the rest frame 2-10 keV band. We have also studied a comparison sample of 95 z approximately 1 "Balmer Break" galaxies. Eight of these are detected directly, with at least two clear AGN based on their high X-ray luminosity and very hard X-ray spectra respectively. The remainder are of relatively low luminosity (< 10(exp 42) erg/s, and the X-rays could arise from either AGN or rapid star-formation. The X-ray colors and evidence from other wavebands favor the latter interpretation. Excluding the clear AGN, we deduce a mean X-ray luminosity of 6.6 x 10(exp 40) erg/s, a factor approximately 5 lower than the LBGs. The average ratio of the UV and X-ray luminosities of these star forming galaxies L(sub UV)/L (sub X), however, is approximately the same at z = 1 as it is at z = 3. This scaling implies that the X-ray emission follows the current star formation rate, as measured by the UV luminosity. We use our results to constrain the star formation rate at z approximately 3 from an X-ray perspective. Assuming the locally established correlation between X-ray and far-IR (infrared) luminosity, the average inferred star formation rate in each Lyman break galaxy is found to be approximately 60 solar mass/yr, in excellent agreement with the extinction-corrected UV estimates. This provides an external check on the UV estimates of the star formation rates, and on the use of X-ray luminosities to infer these rates in rapidly starforming galaxies at high redshift.

NASA Astrophysics E/PO: The Impact of the Space Telescope Science Institute Office of Public Outreach

NASA Astrophysics Data System (ADS)

Smith, Denise A.; Jirdeh, Hussein; Eisenhamer, Bonnie; Villard, Ray

2015-01-01

As the science operations center for Hubble and Webb, the Space Telescope Science Institute (STScI) is uniquely positioned to captivate the imagination and inspire learners of all ages in humanity's quest to understand fundamental questions about our universe and our place in it. With the 25th anniversary of Hubble's launch and deployment approaching in April 2015, this presentation will provide an overview of the impact of the STScI's Office of Public Outreach's programs to engage students, educators, and the public in exploring the universe through audience-based news, education, and outreach programs. At the heart of our programs lies a tight coupling of scientific, education, and communications expertise. By partnering scientists and educators, we assure current, accurate science content and education products and programs that are classroom-ready and held to the highest pedagogical standards. Likewise, news and outreach programs accurately convey cutting-edge science and technology in a way that is attuned to audience needs. The combination of Hubble's scientific capabilities and majestic imagery, together with a deep commitment to creating effective programs to share Hubble science with the education community and the public, has enabled the STScI Office of Public Outreach programs to engage 6 million students and ½ million educators per year, and 24 million online viewers per year. Hubble press releases generate approximately 5,000 online news articles per year with an average circulation of 125 million potential readers per press release news story. We will also share how best practices and lessons learned from this long-lived program are already being applied to engage a new generation of explorers in the science and technology of the James Webb Space Telescope.

The Carnegie–Chicago Hubble Program. III. The Distance to NGC 1365 via the Tip of the Red Giant Branch

NASA Astrophysics Data System (ADS)

Jang, In Sung; Hatt, Dylan; Beaton, Rachael L.; Lee, Myung Gyoon; Freedman, Wendy L.; Madore, Barry F.; Hoyt, Taylor J.; Monson, Andrew J.; Rich, Jeffrey A.; Scowcroft, Victoria; Seibert, Mark

2018-01-01

The Carnegie–Chicago Hubble Program (CCHP) seeks to anchor the distance scale of Type Ia supernovae via the Tip of the Red Giant Branch (TRGB) method. Based on deep Hubble Space Telescope ACS/WFC imaging, we present an analysis of the TRGB for the metal-poor halo of NGC 1365, a giant spiral galaxy in the Fornax cluster that was host to the Type Ia supernova SN 2012fr. We have measured the extinction-corrected TRGB magnitude of NGC 1365 to be F814W = 27.34 ± 0.03stat ± 0.04sys mag. In advance of future direct calibration by Gaia, we adopt a provisional I-band TRGB luminosity set at the Large Magellanic Cloud and find a true distance modulus μ 0 = 31.29 ± 0.04stat ± 0.06sys mag or D = 18.1 ± 0.3stat ± 0.5sys Mpc. This measurement is in excellent agreement with recent Cepheid-based distances to NGC 1365 and reveals no significant difference in the distances derived from stars of Populations I and II for this galaxy. We revisit the error budget for the CCHP path to the Hubble constant based on the analysis presented here, i.e., that for one of the most distant Type Ia supernova hosts within our Program, and find that a 2.5% measurement is feasible with the current sample of galaxies and TRGB absolute calibration. Based in part on observations made with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555. These observations are associated with program #13691.

The stochastic spectator

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hardwick, Robert J.; Vennin, Vincent; Wands, David

We study the stochastic distribution of spectator fields predicted in different slow-roll inflation backgrounds. Spectator fields have a negligible energy density during inflation but may play an important dynamical role later, even giving rise to primordial density perturbations within our observational horizon today. During de-Sitter expansion there is an equilibrium solution for the spectator field which is often used to estimate the stochastic distribution during slow-roll inflation. However slow roll only requires that the Hubble rate varies slowly compared to the Hubble time, while the time taken for the stochastic distribution to evolve to the de-Sitter equilibrium solution can bemore » much longer than a Hubble time. We study both chaotic (monomial) and plateau inflaton potentials, with quadratic, quartic and axionic spectator fields. We give an adiabaticity condition for the spectator field distribution to relax to the de-Sitter equilibrium, and find that the de-Sitter approximation is never a reliable estimate for the typical distribution at the end of inflation for a quadratic spectator during monomial inflation. The existence of an adiabatic regime at early times can erase the dependence on initial conditions of the final distribution of field values. In these cases, spectator fields acquire sub-Planckian expectation values. Otherwise spectator fields may acquire much larger field displacements than suggested by the de-Sitter equilibrium solution. We quantify the information about initial conditions that can be obtained from the final field distribution. Our results may have important consequences for the viability of spectator models for the origin of structure, such as the simplest curvaton models.« less

Reflective correctors for the Hubble Space Telescope axial instruments

NASA Technical Reports Server (NTRS)

Bottema, Murk

1993-01-01

Reflective correctors to compensate the spherical aberration in the Hubble Space Telescope are placed in front of three of the axial scientific instruments (a camera and two spectrographs) during the first scheduled refurbishment mission. The five correctors required are deployed from a new module that replaces the fourth axial instrument. Each corrector consists of a field mirror and an aspherical, aberration-correcting reimaging mirror. In the camera the angular resolution capability is restored, be it in reduced fields, and in the spectrographs the potential for observations in crowded areas is regained along with effective light collection at the slits.

Micrometeoroid Impacts on the Hubble Space Telescope Wide Field and Planetary Camera 2: Larger Particles

NASA Technical Reports Server (NTRS)

Kearsley, A. T.; Grime, G. W.; Webb, R. P.; Jeynes, C.; Palitsin, V.; Colaux, J. L.; Ross, D. K.; Anz-Meador, P.; Liou, J. C.; Opiela, J.;

Hubble's Wide View of 'Mystic Mountain' in Infrared

NASA Image and Video Library

2010-04-23

NASA image release April 22, 2010 This is a NASA Hubble Space Telescope near-infrared-light image of a three-light-year-tall pillar of gas and dust that is being eaten away by the brilliant light from nearby stars in the tempestuous stellar nursery called the Carina Nebula, located 7,500 light-years away in the southern constellation Carina. The image marks the 20th anniversary of Hubble's launch and deployment into an orbit around Earth. The image reveals a plethora of stars behind the gaseous veil of the nebula's wall of hydrogen, laced with dust. The foreground pillar becomes semi-transparent because infrared light from background stars penetrates through much of the dust. A few stars inside the pillar also become visible. The false colors are assigned to three different infrared wavelength ranges. Hubble's Wide Field Camera 3 observed the pillar in February and March 2010. Object Names: HH 901, HH 902 Image Type: Astronomical Credit: NASA, ESA, and M. Livio and the Hubble 20th Anniversary Team (STScI) To read learn more about this image go to: www.nasa.gov/mission_pages/hubble/science/hubble20th-img.... NASA Goddard Space Flight Center is home to the nation's largest organization of combined scientists, engineers and technologists that build spacecraft, instruments and new technology to study the Earth, the sun, our solar system, and the universe.

CANDELS Visual Classifications: Scheme, Data Release, and First Results

NASA Technical Reports Server (NTRS)

Kartaltepe, Jeyhan S.; Mozena, Mark; Kocevski, Dale; McIntosh, Daniel H.; Lotz, Jennifer; Bell, Eric F.; Faber, Sandy; Ferguson, Henry; Koo, David; Bassett, Robert;

HUBBLE PEEKS INTO A STELLAR NURSERY IN A NEARBY GALAXY

NASA Technical Reports Server (NTRS)

2002-01-01

HUBBLE PEEKS INTO A STELLAR NURSERY IN A NEARBY GALAXY NASA's Hubble Space Telescope has peered deep into a neighboring galaxy to reveal details of the formation of new stars. Hubble's target was a newborn star cluster within the Small Magellanic Cloud, a small galaxy that is a satellite of our own Milky Way. The new images show young, brilliant stars cradled within a nebula, or glowing cloud of gas, cataloged as N 81. These massive, recently formed stars inside N 81 are losing material at a high rate, sending out strong stellar winds and shock waves and hollowing out a cocoon within the surrounding nebula. The two most luminous stars, seen in the Hubble image as a very close pair near the center of N 81, emit copious ultraviolet radiation, causing the nebula to glow through fluorescence. Outside the hot, glowing gas is cooler material consisting of hydrogen molecules and dust. Normally this material is invisible, but some of it can be seen in silhouette against the nebular background, as long dust lanes and a small, dark, elliptical-shaped knot. It is believed that the young stars have formed from this cold matter through gravitational contraction. Few features can be seen in N 81 from ground-based telescopes, earning it the informal nick-name 'The Blob.' Astronomers were not sure if just one or a few hot stars were embedded in the cloud, or if it was a stellar nursery containing a large number of less massive stars. Hubble's high-resolution imaging shows the latter to be the case, revealing that numerous young, white-hot stars---easily visible in the color picture---are contained within N 81. This crucial information bears strongly on theories of star formation, and N 81 offers a singular opportunity for a close-up look at the turbulent conditions accompanying the birth of massive stars. The brightest stars in the cluster have a luminosity equal to 300,000 stars like our own Sun. Astronomers are especially keen to study star formation in the Small Magellanic Cloud, because its chemical composition is different from that of the Milky Way. All of the chemical elements, other than hydrogen and helium, have only about one-tenth the abundances seen in our own galaxy. The study of N81 thus provides an excellent template for studying the star formation that occurred long ago in very distant galaxies, before nuclear reactions inside stars had synthesized the elements heavier than helium. The Small Magellanic Cloud, named after the explorer Ferdinand Magellan, lies 200,000 light-years away, and is visible only from the Earth's southern hemisphere. N 81 is the 81st nebula cataloged in a survey of the SMC carried out in the 1950's by astronomer Karl Henize, who later became an astronomer-astronaut who flew into space aboard NASA's space shuttle. The Hubble Heritage image of N 81 is a color representation of data taken in September, 1997, with Hubble's Wide Field Planetary Camera 2. Color filters were used to sample light emitted by oxygen ([O III]) and hydrogen (H-alpha, H-beta). N 81 is the target of investigations by European astronomers Mohammad Heydari-Malayeri from the Paris Observatory in France; Michael Rosa from the Space Telescope-European Coordinating Facility in Munich, Germany; Hans Zinnecker of the Astrophysical Institute in Potsdam, Germany; Lise Deharveng of Marseille Observatory, France; and Vassilis Charmadaris of Cornell University, USA (formerly at Paris Observatory). Members of this team are interested in understanding the formation of hot, massive stars, especially under conditions different from those in the Milky Way. Image Credit: NASA and The Hubble Heritage Team (STScI/AURA) Acknowledgement: Mohammad Heydari-Malayeri (Paris Observatory, France) EDITOR'S

Interpretation of the Hubble diagram in a nonhomogeneous universe

NASA Astrophysics Data System (ADS)

Fleury, Pierre; Dupuy, Hélène; Uzan, Jean-Philippe

2013-06-01

In the standard cosmological framework, the Hubble diagram is interpreted by assuming that the light emitted by standard candles propagates in a spatially homogeneous and isotropic spacetime. However, the light from “point sources”—such as supernovae—probes the Universe on scales where the homogeneity principle is no longer valid. Inhomogeneities are expected to induce a bias and a dispersion of the Hubble diagram. This is investigated by considering a Swiss-cheese cosmological model, which (1) is an exact solution of the Einstein field equations, (2) is strongly inhomogeneous on small scales, but (3) has the same expansion history as a strictly homogeneous and isotropic universe. By simulating Hubble diagrams in such models, we quantify the influence of inhomogeneities on the measurement of the cosmological parameters. Though significant in general, the effects reduce drastically for a universe dominated by the cosmological constant.

Astronomy Software

NASA Technical Reports Server (NTRS)

1995-01-01

Software Bisque's TheSky, SkyPro and Remote Astronomy Software incorporate technology developed for the Hubble Space Telescope. TheSky and SkyPro work together to orchestrate locating, identifying and acquiring images of deep sky objects. With all three systems, the user can directly control computer-driven telescopes and charge coupled device (CCD) cameras through serial ports. Through the systems, astronomers and students can remotely operate a telescope at the Mount Wilson Observatory Institute.

A Deep Chandra Observation of the Distant Galaxy Cluster MS 1137.5+6625

NASA Astrophysics Data System (ADS)

Grego, Laura; Vrtilek, J. M.; Van Speybroeck, Leon; David, Laurence P.; Forman, William; Carlstrom, John E.; Reese, Erik D.; Joy, Marshall K.

2004-06-01

We present results from a deep Chandra observation of MS 1137.5+66, a distant (z=0.783) and massive cluster of galaxies. Only a few similarly massive clusters are currently known at such high redshifts; accordingly, this observation provides much needed information on the dynamical state of these rare systems. The cluster appears both regular and symmetric in the X-ray image. However, our analysis of the spectral and spatial X-ray data in conjunction with interferometric Sunyaev-Zel'dovich effect data and published deep optical imaging suggests that the cluster has a fairly complex structure. The angular diameter distance we calculate from the Chandra and Sunyaev-Zel'dovich effect data assuming an isothermal, spherically symmetric cluster implies a low value for the Hubble constant for which we explore possible explanations.

A Precision Metrology System for the Hubble Space Telescope Wide Field Camera 3 Instrument

NASA Technical Reports Server (NTRS)

Toland, Ronald W.

2003-01-01

The Wide Field Camera 3 (WFC3) instrument for the Hubble Space Telescope (HST) will replace the current Wide Field and Planetary Camera 2 (WFPC2). By providing higher throughput and sensitivity than WFPC2, and operating from the near-IR to the near-UV, WFC3 will once again bring the performance of HST above that from ground-based observatories. Crucial to the integration of the WFC3 optical bench is a pair of 2-axis cathetometers used to view targets which cannot be seen by other means when the bench is loaded into its enclosure. The setup and calibration of these cathetometers is described, along with results from a comparison of the cathetometer system with other metrology techniques.

HUBBLE FINDS NEW DARK SPOT ON NEPTUNE

NASA Technical Reports Server (NTRS)

2002-01-01

NASA's Hubble Space Telescope has discovered a new great dark spot, located in the northern hemisphere of the planet Neptune. Because the planet's northern hemisphere is now tilted away from Earth, the new feature appears near the limb of the planet. The spot is a near mirror-image to a similar southern hemisphere dark spot that was discovered in 1989 by the Voyager 2 probe. In 1994, Hubble showed that the southern dark spot had disappeared. Like its predecessor, the new spot has high altitude clouds along its edge, caused by gasses that have been pushed to higher altitudes where they cool to form methane ice crystal clouds. The dark spot may be a zone of clear gas that is a window to a cloud deck lower in the atmosphere. Planetary scientists don t know how long lived this new feature might be. Hubble's high resolution will allow astronomers to follow the spot's evolution and other unexpected changes in Neptune's dynamic atmosphere. The image was taken on November 2, 1994 with Hubble's Wide Field Planetary Camera 2, when Neptune was 2.8 billion miles (4.5 billion kilometers) from Earth. Hubble can resolve features as small as 625 miles (1,000 kilometers) across in Neptune's cloud tops. Credit: H. Hammel (Massachusetts Institute of Technology) and NASA

BY POPULAR DEMAND: HUBBLE OBSERVES THE HORSEHEAD NEBULA

NASA Technical Reports Server (NTRS)

2002-01-01

Rising from a sea of dust and gas like a giant seahorse, the Horsehead nebula is one of the most photographed objects in the sky. NASA's Hubble Space Telescope took a close-up look at this heavenly icon, revealing the cloud's intricate structure. This detailed view of the horse's head is being released to celebrate the orbiting observatory's eleventh anniversary. Produced by the Hubble Heritage Project, this picture is a testament to the Horsehead's popularity. Internet voters selected this object for the orbiting telescope to view. The Horsehead, also known as Barnard 33, is a cold, dark cloud of gas and dust, silhouetted against the bright nebula, IC 434. The bright area at the top left edge is a young star still embedded in its nursery of gas and dust. But radiation from this hot star is eroding the stellar nursery. The top of the nebula also is being sculpted by radiation from a massive star located out of Hubble's field of view. Only by chance does the nebula roughly resemble the head of a horse. Its unusual shape was first discovered on a photographic plate in the late 1800s. Located in the constellation Orion, the Horsehead is a cousin of the famous pillars of dust and gas known as the Eagle nebula. Both tower-like nebulas are cocoons of young stars. The Horsehead nebula lies just south of the bright star Zeta Orionis, which is easily visible to the unaided eye as the left-hand star in the line of three that form Orion's Belt. Amateur astronomers often use the Horsehead as a test of their observing skills; it is known as one of the more difficult objects to see visually in an amateur-sized telescope. The magnificent extent of the Horsehead is best appreciated in a new wide-field image of the nebula being released today by the National Optical Astronomy Observatory, taken by Travis Rector with the National Science Foundation's 0.9 meter telescope at Kitt Peak National Observatory near Tucson, AZ. This popular celestial target was the clear winner among more than 5,000 Internet voters, who were asked last year to select an astronomical target for the Hubble telescope to observe. The voters included students, teachers, and professional and amateur astronomers. This 11th anniversary release image was composed by the Hubble Heritage Team, which superimposed Hubble data onto ground-based data (limited to small triangular regions around the outer edge of the image). Ground-based image courtesy of Nigel A. Sharp (NOAO/AURA/NSF) taken at the 0.9-meter telescope on Kitt Peak. Image Credit: NASA, NOAO, ESA and The Hubble Heritage Team (STScI/AURA) Acknowledgment: K. Noll (Hubble Heritage PI/STScI), C. Luginbuhl (USNO), F. Hamilton (Hubble Heritage/STScI)

Hubble illuminates the universe

NASA Technical Reports Server (NTRS)

Maran, Stephen P.

1992-01-01

Latest observations by the Hubble Space Telescope (HST) are described, including the first 'parallel' observations (on January 6, 1992) by the two of the Hubble's instruments of two different targets at the same time. On this date, the faint-object camera made images of the quasar 3C 273 in Virgo, while the wide-field and planetary camera recorded an adjacent field. The new HST images include those of the nucleus and the jet of M85, the giant elliptical galaxy at the heart of the Virgo cluster, and what appears to be a black hole of mass 2.6 billion solar masses in M87, and an image of N66, a planetary nebula in the LMC. Other images yield evidence of 'blue stragglers' in the core of 47 Tucanae, a globular cluster about 16,000 light-years from earth. The Goddard spectrograph recorded the spectrum of the star Capella at very high wavelength resolution, which made it possible to measure deuterium from the Big Bang.

Conservation of ζ with radiative corrections from heavy field

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tanaka, Takahiro; Yukawa Institute for Theoretical Physics, Kyoto University,Kyoto, 606-8502; Urakawa, Yuko

2016-06-08

In this paper, we address a possible impact of radiative corrections from a heavy scalar field χ on the curvature perturbation ζ. Integrating out χ, we derive the effective action for ζ, which includes the loop corrections of the heavy field χ. When the mass of χ is much larger than the Hubble scale H, the loop corrections of χ only yield a local contribution to the effective action and hence the effective action simply gives an action for ζ in a single field model, where, as is widely known, ζ is conserved in time after the Hubble crossing time.more » Meanwhile, when the mass of χ is comparable to H, the loop corrections of χ can give a non-local contribution to the effective action. Because of the non-local contribution from χ, in general, ζ may not be conserved, even if the classical background trajectory is determined only by the evolution of the inflaton. In this paper, we derive the condition that ζ is conserved in time in the presence of the radiative corrections from χ. Namely, we show that when the dilatation invariance, which is a part of the diffeomorphism invariance, is preserved at the quantum level, the loop corrections of the massive field χ do not disturb the constant evolution of ζ at super Hubble scales. In this discussion, we show the Ward-Takahashi identity for the dilatation invariance, which yields a consistency relation for the correlation functions of the massive field χ.« less

Hubble Sees a Star ‘Inflating’ a Giant Bubble

NASA Image and Video Library

2017-12-08

For the 26th birthday of NASA’s Hubble Space Telescope, astronomers are highlighting a Hubble image of an enormous bubble being blown into space by a super-hot, massive star. The Hubble image of the Bubble Nebula, or NGC 7635, was chosen to mark the 26th anniversary of the launch of Hubble into Earth orbit by the STS-31 space shuttle crew on April 24, 1990 “As Hubble makes its 26th revolution around our home star, the sun, we celebrate the event with a spectacular image of a dynamic and exciting interaction of a young star with its environment. The view of the Bubble Nebula, crafted from WFC-3 images, reminds us that Hubble gives us a front row seat to the awe inspiring universe we live in,” said John Grunsfeld, Hubble astronaut and associate administrator of NASA’s Science Mission Directorate at NASA Headquarters, in Washington, D.C. The Bubble Nebula is seven light-years across—about one-and-a-half times the distance from our sun to its nearest stellar neighbor, Alpha Centauri, and resides 7,100 light-years from Earth in the constellation Cassiopeia. The seething star forming this nebula is 45 times more massive than our sun. Gas on the star gets so hot that it escapes away into space as a “stellar wind” moving at over four million miles per hour. This outflow sweeps up the cold, interstellar gas in front of it, forming the outer edge of the bubble much like a snowplow piles up snow in front of it as it moves forward. As the surface of the bubble's shell expands outward, it slams into dense regions of cold gas on one side of the bubble. This asymmetry makes the star appear dramatically off-center from the bubble, with its location in the 10 o’clock position in the Hubble view. Dense pillars of cool hydrogen gas laced with dust appear at the upper left of the picture, and more “fingers” can be seen nearly face-on, behind the translucent bubble. The gases heated to varying temperatures emit different colors: oxygen is hot enough to emit blue light in the bubble near the star, while the cooler pillars are yellow from the combined light of hydrogen and nitrogen. The pillars are similar to the iconic columns in the “Pillars of Creation” Eagle Nebula. As seen with the structures in the Eagle Nebula, the Bubble Nebula pillars are being illuminated by the strong ultraviolet radiation from the brilliant star inside the bubble. The Bubble Nebula was discovered in 1787 by William Herschel, a prominent British astronomer. It is being formed by a proto-typical Wolf-Rayet star, BD +60º2522, an extremely bright, massive, and short-lived star that has lost most of its outer hydrogen and is now fusing helium into heavier elements. The star is about four million years old, and in 10 million to 20 million years, it will likely detonate as a supernova. Hubble’s Wide Field Camera-3 imaged the nebula in visible light with unprecedented clarity in February 2016. The colors correspond to blue for oxygen, green for hydrogen, and red for nitrogen. This information will help astronomers understand the geometry and dynamics of this complex system. The Bubble Nebula is one of only a handful of astronomical objects that have been observed with several different instruments onboard Hubble. Hubble also imaged it with the Wide Field Planetary Camera (WFPC) in September 1992, and with Wide Field Planetary Camera-2 (WFPC2) in April 1999. The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency. NASA's Goddard Space Flight Center in Greenbelt, Maryland, manages the telescope. The Space Telescope Science Institute (STScI) in Baltimore, Maryland, conducts Hubble science operations. STScI is operated for NASA by the Association of Universities for Research in Astronomy in Washington, D.C. Credit: NASA, ESA, and the Hubble Heritage Team (STScI/AURA)

Impacts on the Hubble Space Telescope Wide Field and Planetary Camera 2: Experimental Simulation of Micrometeoroid Capture

NASA Technical Reports Server (NTRS)

Price, M. C.; Kearsley, A. T.; Wozniakiewicz, P. J.; Spratt, J.; Burchell, M. J.; Cole, M. J.; Anz-Meador, P.; Liou, J. C.; Ross, D. K.; Opiela, J.;

New Constraints on the Faint End of the UV Luminosity Function at z ~ 7-8 Using the Gravitational Lensing of the Hubble Frontier Fields Cluster A2744

NASA Astrophysics Data System (ADS)

Atek, Hakim; Richard, Johan; Kneib, Jean-Paul; Jauzac, Mathilde; Schaerer, Daniel; Clement, Benjamin; Limousin, Marceau; Jullo, Eric; Natarajan, Priyamvada; Egami, Eiichi; Ebeling, Harald

2015-02-01

Exploiting the power of gravitational lensing, the Hubble Frontier Fields (HFF) program aims at observing six massive galaxy clusters to explore the distant universe far beyond the limits of blank field surveys. Using the complete Hubble Space Telescope observations of the first HFF cluster A2744, we report the detection of 50 galaxy candidates at z ~ 7 and eight candidates at z ~ 8 in a total survey area of 0.96 arcmin2 in the source plane. Three of these galaxies are multiply imaged by the lensing cluster. Using an updated model of the mass distribution in the cluster we were able to calculate the magnification factor and the effective survey volume for each galaxy in order to compute the ultraviolet galaxy luminosity function (LF) at both redshifts 7 and 8. Our new measurements reliably extend the z ~ 7 UV LF down to an absolute magnitude of M UV ~ -15.5. We find a characteristic magnitude of M\\star UV = -20.90+0.90-0.73 mag and a faint-end slope α =-2.01+0.20-0.28, close to previous determinations in blank fields. We show here for the first time that this slope remains steep down to very faint luminosities of 0.01 L sstarf. Although prone to large uncertainties, our results at z ~ 8 also seem to confirm a steep faint-end slope below 0.1 L sstarf. The HFF program is therefore providing an extremely efficient way to study the faintest galaxy populations at z > 7 that would otherwise be inaccessible with current instrumentation. The full sample of six galaxy clusters will provide even better constraints on the buildup of galaxies at early epochs and their contribution to cosmic reionization. Based on observations made with the NASA/ESA Hubble Space Telescope, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555. These observations are associated with programs 13495, 11386, 13389, and 11689. STScI is operated by the Association of Universities for Research in Astronomy, Inc. under NASA contract NAS 5-26555. The Hubble Frontier Fields data were obtained from the Mikulski Archive for Space Telescopes (MAST).

Hubble reveals heart of Lagoon Nebula

NASA Image and Video Library

2010-09-22

Image release date September 22, 2010 To view a video of this image go here: www.flickr.com/photos/gsfc/5014452203 Caption: A spectacular new NASA/ESA Hubble Space Telescope image reveals the heart of the Lagoon Nebula. Seen as a massive cloud of glowing dust and gas, bombarded by the energetic radiation of new stars, this placid name hides a dramatic reality. The Advanced Camera for Surveys (ACS) on the NASA/ESA Hubble Space Telescope has captured a dramatic view of gas and dust sculpted by intense radiation from hot young stars deep in the heart of the Lagoon Nebula (Messier 8). This spectacular object is named after the wide, lagoon-shaped dust lane that crosses the glowing gas of the nebula. This structure is prominent in wide-field images, but cannot be seen in this close-up. However the strange billowing shapes and sandy texture visible in this image make the Lagoon Nebula’s watery name eerily appropriate from this viewpoint too. Located four to five thousand light-years away, in the constellation of Sagittarius (the Archer), Messier 8 is a huge region of star birth that stretches across one hundred light-years. Clouds of hydrogen gas are slowly collapsing to form new stars, whose bright ultraviolet rays then light up the surrounding gas in a distinctive shade of red. The wispy tendrils and beach-like features of the nebula are not caused by the ebb and flow of tides, but rather by ultraviolet radiation’s ability to erode and disperse the gas and dust into the distinctive shapes that we see. In recent years astronomers probing the secrets of the Lagoon Nebula have found the first unambiguous proof that star formation by accretion of matter from the gas cloud is ongoing in this region. Young stars that are still surrounded by an accretion disc occasionally shoot out long tendrils of matter from their poles. Several examples of these jets, known as Herbig-Haro objects, have been found in this nebula in the last five years, providing strong support for astronomers’ theories about star formation in such hydrogen-rich regions. The Lagoon Nebula is faintly visible to the naked eye on dark nights as a small patch of grey in the heart of the Milky Way. Without a telescope, the nebula looks underwhelming because human eyes are unable to distinguish clearly between colours at low light levels. Charles Messier, the 18th century French astronomer, observed the nebula and included it in his famous astronomical catalogue, from which the nebula’s alternative name comes. But his relatively small refracting telescope would only have hinted at the dramatic structures and colours now visible thanks to Hubble. The Hubble Space Telescope is a project of international cooperation between ESA and NASA. Image credit: NASA, ESA NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Like us on Facebook Find us on Instagram To learn more about the Hubble Space Telescope go here: www.nasa.gov/mission_pages/hubble/main/index.html

The shape of galaxy dark matter halos in massive galaxy clusters: Insights from strong gravitational lensing

NASA Astrophysics Data System (ADS)

Jauzac, Mathilde; Harvey, David; Massey, Richard

2018-04-01

We assess how much unused strong lensing information is available in the deep Hubble Space Telescope imaging and VLT/MUSE spectroscopy of the Frontier Field clusters. As a pilot study, we analyse galaxy cluster MACS J0416.1-2403 (z=0.397, M(R < 200 kpc)=1.6×1014M⊙), which has 141 multiple images with spectroscopic redshifts. We find that many additional parameters in a cluster mass model can be constrained, and that adding even small amounts of extra freedom to a model can dramatically improve its figures of merit. We use this information to constrain the distribution of dark matter around cluster member galaxies, simultaneously with the cluster's large-scale mass distribution. We find tentative evidence that some galaxies' dark matter has surprisingly similar ellipticity to their stars (unlike in the field, where it is more spherical), but that its orientation is often misaligned. When non-coincident dark matter and stellar halos are allowed, the model improves by 35%. This technique may provide a new way to investigate the processes and timescales on which dark matter is stripped from galaxies as they fall into a massive cluster. Our preliminary conclusions will be made more robust by analysing the remaining five Frontier Field clusters.

The shape of galaxy dark matter haloes in massive galaxy clusters: insights from strong gravitational lensing

NASA Astrophysics Data System (ADS)

Jauzac, Mathilde; Harvey, David; Massey, Richard

2018-07-01

We assess how much unused strong lensing information is available in the deep Hubble Space Telescope imaging and Very Large Telescope/Multi Unit Spectroscopic Explorer spectroscopy of the Frontier Field clusters. As a pilot study, we analyse galaxy cluster MACS J0416.1-2403 (z = 0.397, M(R < 200 kpc) = 1.6 × 1014 M⊙), which has 141 multiple images with spectroscopic redshifts. We find that many additional parameters in a cluster mass model can be constrained, and that adding even small amounts of extra freedom to a model can dramatically improve its figures of merit. We use this information to constrain the distribution of dark matter around cluster member galaxies, simultaneously with the cluster's large-scale mass distribution. We find tentative evidence that some galaxies' dark matter has surprisingly similar ellipticity to their stars (unlike in the field, where it is more spherical), but that its orientation is often misaligned. When non-coincident dark matter and stellar haloes are allowed, the model improves by 35 per cent. This technique may provide a new way to investigate the processes and time-scales on which dark matter is stripped from galaxies as they fall into a massive cluster. Our preliminary conclusions will be made more robust by analysing the remaining five Frontier Field clusters.

A Slow Merger History of Field Galaxies since z ~ 1

NASA Astrophysics Data System (ADS)

Bundy, Kevin; Fukugita, Masataka; Ellis, Richard S.; Kodama, Tadayuki; Conselice, Christopher J.

2004-02-01

Using deep infrared observations conducted with the CISCO imager on the Subaru Telescope, we investigate the field-corrected pair fraction and the implied merger rate of galaxies in redshift survey fields with Hubble Space Telescope (HST) imaging. In the redshift interval, 0.5

Deepest Infrared View of the Universe

NASA Astrophysics Data System (ADS)

2002-12-01

VLT Images Progenitors of Today's Large Galaxies Summary An international team of astronomers [2] has made the deepest-ever near-infrared Ks-band image of the sky, using the ISAAC multi-mode instrument on the 8.2-m VLT ANTU telescope. For this, the VLT was pointed for more than 100 hours under optimal observing conditions at the Hubble Deep Field South (HDF-S) and obtained images in three near-infrared filters. The resulting images reveal extremely distant galaxies, which appear at infrared wavelengths, but are barely detected in the deepest optical images acquired with the Hubble Space Telescope (HST). Astronomer Marijn Franx from the University of Leiden and leader of the team concludes: "These results demonstrate that very deep observations in the near-infrared are essential to obtain a proper census of the earliest phases of the universe. The new VLT images have opened a new research domain which has not been observationally accessible before". The HDF-S is a tiny field on the sky in the southern constellation Tucana (The Toucan) - only about 1% of the area of the full moon. The NASA/ESA Hubble Space Telescope (HST) observed it with a total exposure time of about 1 week, yielding the deepest optical images ever taken of the sky, similar to those made earlier on the Hubble Deep Field North (HDF-N). The VLT infrared images of the same field were obtained in the course of a major research project, the Faint InfraRed Extragalactic Survey (FIRES). They were made at wavelengths up to 2.3 µm where the HST is not competitive. Ivo Labbé, another team member from the University of Leiden, is certain: "Without the unique capabilities of the VLT and ISAAC we would never have been able to observe these very remote galaxies. In fact, the image in the Ks-band is the deepest which has ever been made at that wavelength". The optical light emitted by the distant galaxies has been redshifted to the near-infrared spectral region [3]. Indeed, some of the galaxies found in the new images are so remote that - due to the finite speed of light - they are observed as they were when the Universe was still extremely young, less than 2 billion years old. From these observations, two interesting conclusions have been drawn so far. One is that although the newly identified galaxies do not appear to form stars very actively they probably account for about half the mass of normal matter present at this epoch. This is in sharp contrast to the galaxies at this early time found during optical surveys - they are very blue because of young and hot stars. Another is that galaxies existed already at that epoch which are clearly rather large, and some show spiral structure similar to that seen in very nearby galaxies. This new important insight is having profound impact on the current attempts to understand the formation and evolution of galaxies. PR Photo 28a/02: Composite colour image of the sky field observed by HST and VLT. PR Photo 28b/02: The ISAAC K s -band image , the deepest of its kind ever obtained. PR Photo 28c/02: Images of very red, very distant compact galaxies in different wavebands. PR Photo 28d/02: Images of very distant extended galaxies in different wavebands. Formation and evolution of galaxies How did galaxies form in the early Universe? How did they evolve and when did the first stars form in those systems? These are some of the key questions in present-day astronomy. Thanks to powerful ground- and space-based telescopes, astronomers are now able to actively pursue studies in this direction. Recent front-line observational results are helping them to gain new insights into these fundamental issues. Light emitted by distant galaxies travels a long time before we observe it with our telescopes. In this way, astronomers can look back in time and directly study galaxies as they were when the universe was still very young. However, this is technically difficult, as the galaxies are extremely faint. Another complication is that, due to the expansion of the universe, their light is shifted towards longer wavelengths [3]. In order to study those early galaxies in some detail, astronomers thus need to use the largest ground-based telescopes, collecting their faint light during very long integrations. And they must work in the infrared region of the spectrum which is not visible to the human eye. The Hubble Deep Field South (HDF-S) was selected to be studied in great detail with the Hubble Space Telescope (HST) and other powerful telescopes. The HST images of this field represent a total exposure time of 140 hours. Many ground-based telescopes have obtained additional photos and spectra, in particular telescopes at the European Southern Observatory in Chile. The ISAAC observations The sky field in the direction of HDF-S observed in the present study (the Faint InfraRed Extragalactic Survey (FIRES)), measures 2.5 x 2.5 arcmin2. It is slightly larger than the field covered by the WFPC2 camera on the HST, but still 100 times smaller than the full moon. Whenever the field was visible from Paranal and the atmospheric conditions were optimal, ESO astronomers pointed the 8.2-m VLT ANTU telescope in the direction of this field, taking near-infrared images with the ISAAC multi-mode instrument. The data were transmitted by Internet to the astronomers of the team in Europe, who then combined them to construct some of the deepest infrared astronomical images ever taken from the ground. Colours and distance A crucial feature of the new observations is that they were made in three infrared bands (Js, H, Ks), allowing a 3-dimensional view of a small region of the Universe. This is because, by comparing the brightness of the galaxies in these colours with that in optical light, as measured by the HST, it is possible to estimate their redshifts [3] and thus how long ago the light we now see has been emitted. For the reddest of the galaxies the answer is that we are seeing them as they were when the Universe was only about 2 billion years old. The nature of the galaxies Two conclusions drawn so far about the nature of these galaxies are therefore all the more important in the context of formation and evolution of galaxies. One is that a few of them are clearly rather large and show spiral structure similar to that seen in very nearby galaxies, cf. PR Photo 28d/02. It is not obvious that current theoretical models can easily account for such galaxies having evolved to this stage so early in the life of the Universe. Another conclusion is that, in contrast to the galaxies at similar redshifts (and hence, at this early epoch) found most commonly in surveys at optical wavelengths, most of the 'infrared-selected' galaxies show relatively little visible star-forming activity. They appear in fact to have already formed most of their stars and in quantities sufficient to account for at least half the total luminous mass of the Universe at that time. Given the time to reach this state they must clearly have formed even earlier in the life of the Universe and are thus probably amongst the "oldest" galaxies now known. Rather than being randomly distributed in space, these red galaxies are also found to prefer company, i.e., they tend to cluster close to each other. In general terms this can be taken as support for the latest theoretical models in which galaxies, which consist of "normal" matter, form in the highest-density regions of the much more pervasive "dark" matter. Although the latter accounts for most of the mass of the universe, its origin so far is completely unknown. These new observations may, therefore, also add new insight into one of the biggest mysteries currently confronting cosmologists. Marijn Franx agrees, but also cautions against drawing firm conclusions on this aspect too quickly: "We now need similar images of a considerably larger region of the sky. We will soon follow-up these first, tantalizing results with more observations of other sky fields." More information The information presented in this Press Release is based on a research article ("Ultradeep Near-Infrared ISAAC Observations of the Hubble Deep Field South: Observations, Reduction, Multicolor Catalog, and Photometric Redshifts" by Ivo Labbé et al.) that will soon appear in the research journal "Astronomical Journal" (cf. astro-ph/0212236). A shorter account will appear in the December 2002 issue of ESO's house journal "The Messenger". Information, including photos and reduced data, is also available at the website of the FIRES project. Notes [1]: This press release is issued in coordination between ESO, Leiden Observatory, the Netherlands Research School for Research in Astronomy (NOVA) and the Netherlands Foundation for Research (NWO). A Dutch-language version is available here. [2]: The team consists of Ivo Labbé, Marijn Franx, Natascha M. Förster Schreiber, Paul van der Werf, Huub Röttgering, Lottie van Starkenburg, Arjen van de Wel and Konrad Kuijken (Leiden Observatory, The Netherlands), Gregory Rudnick (Max-Planck-Institut für Astrophysik, Garching, Germany), Hans-Walter Rix (Max-Planck-Institut für Astronomie, Heidelberg, Germany), Alan Moorwood and Emanuele Daddi (ESO, Garching, Germany) and Pieter G. van Dokkum (California Institute of Technology, Pasadena, USA). [3]: In astronomy, the redshift denotes the fraction by which the lines in the spectrum of an object are shifted towards longer wavelengths. The observed redshift of a remote galaxy provides an estimate of its distance.

Town Hall Meeting Presentation

NASA Technical Reports Server (NTRS)

Mather, John C.

2002-01-01

The James Webb Space Telescope (JWST), formerly known as the Next Generation Space Telescope (NGST), will be the successor to the Hubble Space Telescope. It will carry 3 instruments to a deep space orbit around the Sun-Earth Lagrange point L2, and will cover the wavelength range from 0.6 to 28 microns. The design concepts and current status of the project will be summarized, including the telescope and observatory contract proposed by the new prime contractor, TRW.

The ALMA Frontier Fields Survey. II. Multiwavelength Photometric analysis of 1.1 mm continuum sources in Abell 2744, MACSJ0416.1-2403 and MACSJ1149.5+2223

NASA Astrophysics Data System (ADS)

Laporte, N.; Bauer, F. E.; Troncoso-Iribarren, P.; Huang, X.; González-López, J.; Kim, S.; Anguita, T.; Aravena, M.; Barrientos, L. F.; Bouwens, R.; Bradley, L.; Brammer, G.; Carrasco, M.; Carvajal, R.; Coe, D.; Demarco, R.; Ellis, R. S.; Ford, H.; Francke, H.; Ibar, E.; Infante, L.; Kneissl, R.; Koekemoer, A. M.; Messias, H.; Muñoz Arancibia, A.; Nagar, N.; Padilla, N.; Pelló, R.; Postman, M.; Quénard, D.; Romero-Cañizales, C.; Treister, E.; Villard, E.; Zheng, W.; Zitrin, A.

2017-08-01

Context. The Hubble and Spitzer Space Telescope surveys of the Frontier Fields provide extremely deep images around six massive, strong-lensing clusters of galaxies. The ALMA Frontier Fields survey aims to cover the same fields at 1.1 mm, with maps reaching (unlensed) sensitivities of <70 μJy, in order to explore the properties of background dusty star-forming galaxies. Aims: We report on the multi-wavelength photometric analysis of all 12 significantly detected (>5σ) sources in the first three Frontier Fields clusters observed by ALMA, based on data from Hubble and Spitzer, the Very Large Telescope and the Herschel Space Observatory. Methods: We measure the total photometry in all available bands and determine the photometric redshifts and the physical properties of the counterparts via SED-fitting. In particular, we carefully estimate the far-infrared (FIR) photometry using 1.1 mm priors to limit the misidentification of blended FIR counterparts, which strongly affect some flux estimates in previous FIR catalogs. Due to the extremely red nature of these objects, we used a large range of parameters (e.g. 0.0

The Nature of Radio Emission from Distant Galaxies: The 1.4 GHZ Observations

NASA Astrophysics Data System (ADS)

Richards, E. A.

2000-04-01

We have conducted a deep radio survey with the Very Large Array at 1.4 GHz of a region containing the Hubble Deep Field (HDF). This survey overlaps previous observations at 8.5 GHz allowing us to investigate the radio spectral properties of microjansky sources to flux densities greater than 40 μJy at 1.4 GHz and greater than 8 μJy at 8.5 GHz. A total of 371 sources have been cataloged at 1.4 GHz as part of a complete sample within 20' of the HDF. The differential source count for this region is only marginally sub-Euclidean and is given by n(S)=(8.3+/-0.4)S-2.4+/-0.1 sr-1 Jy-1. Above about 100 μJy the radio source count is systematically lower in the HDF as compared to other fields. We conclude that there is clustering in our radio sample on size scales of 1'-40'. The 1.4 GHz-selected sample shows that the radio spectral indices are preferentially steep (α1.4=0.85) and that the sources are moderately extended with average angular size θ=1.8". Optical identification with disk-type systems at z~0.1-1 suggests that synchrotron emission, produced by supernovae remnants, is powering the radio emission in the majority of sources. The 8.5 GHz sample contains primarily moderately flat spectrum sources (α8.5=0.35), with less than 15% inverted. We argue that we may be observing an increased fraction of optically thin bremsstrahlung over synchrotron radiation in these distant star-forming galaxies.

The onset of spiral structure in the universe

DOE Office of Scientific and Technical Information (OSTI.GOV)

Elmegreen, Debra Meloy; Elmegreen, Bruce G.

2014-01-20

The onset of spiral structure in galaxies appears to occur between redshifts 1.4 and 1.8 when disks have developed a cool stellar component, rotation dominates over turbulent motions in the gas, and massive clumps become less frequent. During the transition from clumpy to spiral disks, two unusual types of spirals are found in the Hubble Ultra Deep Field that are massive, clumpy, and irregular like their predecessor clumpy disks, yet spiral-like or sheared like their descendants. One type is 'woolly' with massive clumpy arms all over the disk and is brighter than other disk galaxies at the same redshift, whilemore » another type has irregular multiple arms with high pitch angles, star formation knots, and no inner symmetry like today's multiple-arm galaxies. The common types of spirals seen locally are also present in a redshift range around z ∼ 1, namely grand design with two symmetric arms, multiple arm with symmetry in the inner parts and several long, thin arms in the outer parts, and flocculent, with short, irregular, and patchy arms that are mostly from star formation. Normal multiple-arm galaxies are found only closer than z ∼ 0.6 in the Ultra Deep Field. Grand design galaxies extend furthest to z ∼ 1.8, presumably because interactions can drive a two-arm spiral in a disk that would otherwise have a more irregular structure. The difference between these types is understandable in terms of the usual stability parameters for gas and stars, and the ratio of the velocity dispersion to rotation speed.« less

Astrometry of the omega Centauri Hubble Space Telescope Calibration Field

NASA Technical Reports Server (NTRS)

Mighell, Kenneth J.

2000-01-01

Astrometry, on the International Celestial Reference Frame (epoch J2000.0), is presented for the Walker (1994, PASP, 106, 828) stars in the omega Centauri (=NGC 5139=C 1323-1472) Hubble Space Telescope Wide Field/Planetary Camera (WF/PC) calibration field of Harris et al. (1993, AJ, 105, 1196). Harris et al. stars were first identified on a WFPC2 observation of the omega Cen HST calibration field. Relative astrometry of the Walker stars in this field was then obtained using Walker's CCD positions and astrometry derived using the STSDAS METRIC task on the positions of the Harris et al. stars on the WFPC2 observation. Finally, the relative astrometry, which was based on the HST Guide Star Catalog, is placed on the International Celestial Reference Frame with astrometry from the USNO-A2.0 catalog. An ASCII text version of the astrometric data of the Walker stars in the omega Cen HST calibration field is available electronically in the online version of the article.

New constraints on the average escape fraction of Lyman continuum radiation in z 4 galaxies from the VIMOS Ultra Deep Survey (VUDS)

NASA Astrophysics Data System (ADS)

Marchi, F.; Pentericci, L.; Guaita, L.; Ribeiro, B.; Castellano, M.; Schaerer, D.; Hathi, N. P.; Lemaux, B. C.; Grazian, A.; Le Fèvre, O.; Garilli, B.; Maccagni, D.; Amorin, R.; Bardelli, S.; Cassata, P.; Fontana, A.; Koekemoer, A. M.; Le Brun, V.; Tasca, L. A. M.; Thomas, R.; Vanzella, E.; Zamorani, G.; Zucca, E.

2017-05-01

Context. Determining the average fraction of Lyman continuum (LyC) photons escaping high redshift galaxies is essential for understanding how reionization proceeded in the z> 6 Universe. Aims: We want to measure the LyC signal from a sample of sources in the Chandra Deep Field South (CDFS) and COSMOS fields for which ultra-deep VIMOS spectroscopy as well as multi-wavelength Hubble Space Telescope (HST) imaging are available. Methods: We select a sample of 46 galaxies at z 4 from the VIMOS Ultra Deep Survey (VUDS) database, such that the VUDS spectra contain the LyC part, that is, the rest-frame range 880-910 Å. Taking advantage of the HST imaging, we apply a careful cleaning procedure and reject all the sources showing nearby clumps with different colours, that could potentially be lower-redshift interlopers. After this procedure, the sample is reduced to 33 galaxies. We measure the ratio between ionizing flux (LyC at 895 Å) and non-ionizing emission (at 1500 Å) for all individual sources. We also produce a normalized stacked spectrum of all sources. Results: Assuming an intrinsic average Lν(1470) /Lν(895) of 3, we estimate the individual and average relative escape fraction. We do not detect ionizing radiation from any individual source, although we identify a possible LyC emitter with very high Lyα equivalent width (EW). From the stacked spectrum and assuming a mean transmissivity for the sample, we measure a relative escape fraction . We also look for correlations between the limits in the LyC flux and source properties and find a tentative correlation between LyC flux and the EW of the Lyα emission line. Conclusions: Our results imply that the LyC flux emitted by V = 25-26 star-forming galaxies at z 4 is at most very modest, in agreement with previous upper limits from studies based on broad and narrow band imaging. Based on data obtained with the European Southern Observatory Very Large Telescope, Paranal, Chile, under Large Program 185.A-0791.

Cartan symmetries and global dynamical systems analysis in a higher-order modified teleparallel theory

NASA Astrophysics Data System (ADS)

Karpathopoulos, L.; Basilakos, S.; Leon, G.; Paliathanasis, A.; Tsamparlis, M.

2018-07-01

In a higher-order modified teleparallel theory cosmological we present analytical cosmological solutions. In particular we determine forms of the unknown potential which drives the scalar field such that the field equations form a Liouville integrable system. For the determination of the conservation laws we apply the Cartan symmetries. Furthermore, inspired from our solutions, a toy model is studied and it is shown that it can describe the Supernova data, while at the same time introduces dark matter components in the Hubble function. When the extra matter source is a stiff fluid then we show how analytical solutions for Bianchi I universes can be constructed from our analysis. Finally, we perform a global dynamical analysis of the field equations by using variables different from that of the Hubble-normalization.

Hubble's Slice of Sagittarius

NASA Image and Video Library

2017-12-08

This stunning image, captured by the NASA/ESA Hubble Space Telescope’s Advanced Camera for Surveys (ACS), shows part of the sky in the constellation of Sagittarius (The Archer). The region is rendered in exquisite detail — deep red and bright blue stars are scattered across the frame, set against a background of thousands of more distant stars and galaxies. Two features are particularly striking: the colors of the stars, and the dramatic crosses that burst from the centers of the brightest bodies. While some of the colors in this frame have been enhanced and tweaked during the process of creating the image from the observational data, different stars do indeed glow in different colors. Stars differ in color according to their surface temperature: very hot stars are blue or white, while cooler stars are redder. They may be cooler because they are smaller, or because they are very old and have entered the red giant phase, when an old star expands and cools dramatically as its core collapses. The crosses are nothing to do with the stars themselves, and, because Hubble orbits above Earth’s atmosphere, nor are they due to any kind of atmospheric disturbance. They are actually known as diffraction spikes, and are caused by the structure of the telescope itself. Like all big modern telescopes, Hubble uses mirrors to capture light and form images. Its secondary mirror is supported by struts, called telescope spiders, arranged in a cross formation, and they diffract the incoming light. Diffraction is the slight bending of light as it passes near the edge of an object. Every cross in this image is due to a single set of struts within Hubble itself! Whilst the spikes are technically an inaccuracy, many astrophotographers choose to emphasize and celebrate them as a beautiful feature of their images. Image credit: ESA/Hubble & NASA NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Like us on Facebook Find us on Instagram

VizieR Online Data Catalog: MgII/FeII absorption profile for 0.3

NASA Astrophysics Data System (ADS)

Rubin, K. H. R.; Prochaska, J. X.; Koo, D. C.; Phillips, A. C.; Martin, C. L.; Winstrom, L. O.

2017-05-01

In this work, we use rest-frame near-UV spectroscopy of a sample of 105 galaxies at 0.3~9.6 down to a SFR limit>~2 Msun/yr at z~0.5, permitting exploration of outflow properties over the entire breadth of the star-forming sequence at z>0.3 for the first time. Our galaxy sample is drawn from pre-existing photometric and spectroscopic redshift surveys in fields with deep imaging taken with the Hubble Space Telescope (HST) Advanced Camera for Surveys (ACS). (3 data files).

HUBBLE PROBES THE VIOLENT BIRTH OF STARS IN GALAXY NGC 253 [Left

NASA Technical Reports Server (NTRS)

2002-01-01

An image of the spiral galaxy NGC 253, taken with a ground-based telescope. The galaxy is located about 8 million light-years away in the constellation Sculptor. Credit: Jay Gallagher (University of Wisconsin-Madison), Alan Watson (Lowell Observatory, Flagstaff, AZ), and NASA [Right] This NASA Hubble Space Telescope image of the core of the nearest starburst spiral galaxy, NGC 253, reveals violent star formation within a region 1,000 light-years across. A starburst galaxy has an exceptionally high rate of star birth, first identified by its excess of infrared radiation from warm dust. Hubble's high resolution allows astronomers to quantify complex structures in the starburst core of the galaxy for the first time, including luminous star clusters, dust lanes which trace regions of dense gas and filaments of glowing gas. Hubble identifies several regions of intense star formation, which include a bright, super-compact star cluster. These observations confirm that stars are often born in dense clusters within starbursts, and that dense gas coexists with and obscures the starburst core. This image was taken with Hubble's Wide Field Planetary Camera 2 (in PC mode). Credit: Carnegie Institution of Washington

THE ALMA SPECTROSCOPIC SURVEY IN THE HUBBLE ULTRA DEEP FIELD: IMPLICATIONS FOR SPECTRAL LINE INTENSITY MAPPING AT MILLIMETER WAVELENGTHS AND CMB SPECTRAL DISTORTIONS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Carilli, C. L.; Walter, F.; Chluba, J.

We present direct estimates of the mean sky brightness temperature in observing bands around 99 and 242 GHz due to line emission from distant galaxies. These values are calculated from the summed line emission observed in a blind, deep survey for spectral line emission from high redshift galaxies using ALMA (the ALMA spectral deep field observations “ASPECS” survey). In the 99 GHz band, the mean brightness will be dominated by rotational transitions of CO from intermediate and high redshift galaxies. In the 242 GHz band, the emission could be a combination of higher order CO lines, and possibly [C ii]more » 158 μ m line emission from very high redshift galaxies ( z  ∼ 6–7). The mean line surface brightness is a quantity that is relevant to measurements of spectral distortions of the cosmic microwave background, and as a potential tool for studying large-scale structures in the early universe using intensity mapping. While the cosmic volume and the number of detections are admittedly small, this pilot survey provides a direct measure of the mean line surface brightness, independent of conversion factors, excitation, or other galaxy formation model assumptions. The mean surface brightness in the 99 GHZ band is: T{sub B}  = 0.94 ± 0.09 μ K. In the 242 GHz band, the mean brightness is: T{sub B}  = 0.55 ± 0.033 μ K. These should be interpreted as lower limits on the average sky signal, since we only include lines detected individually in the blind survey, while in a low resolution intensity mapping experiment, there will also be the summed contribution from lower luminosity galaxies that cannot be detected individually in the current blind survey.« less

HUBBLE VIEWS DISTANT GALAXIES THROUGH A COSMIC LENS

NASA Technical Reports Server (NTRS)

2002-01-01

This NASA Hubble Space Telescope image of the rich galaxy cluster, Abell 2218, is a spectacular example of gravitational lensing. The arc-like pattern spread across the picture like a spider web is an illusion caused by the gravitational field of the cluster. The cluster is so massive and compact that light rays passing through it are deflected by its enormous gravitational field, much as an optical lens bends light to form an image. The process magnifies, brightens and distorts images of objects that lie far beyond the cluster. This provides a powerful 'zoom lens' for viewing galaxies that are so far away they could not normally be observed with the largest available telescopes. Hubble's high resolution reveals numerous arcs which are difficult to detect with ground-based telescopes because they appear to be so thin. The arcs are the distorted images of a very distant galaxy population extending 5-10 times farther than the lensing cluster. This population existed when the universe was just one quarter of its present age. The arcs provide a direct glimpse of how star forming regions are distributed in remote galaxies, and other clues to the early evoution of galaxies. Hubble also reveals multiple imaging, a rarer lensing event that happens when the distortion is large enough to produce more than one image of the same galaxy. Abell 2218 has an unprecedented total of seven multiple systems. The abundance of lensing features in Abell 2218 has been used to make a detailed map of the distribution of matter in the cluster's center. From this, distances can be calculated for a sample of 120 faint arclets found on the Hubble image. These arclets represent galaxies that are 50 times fainter than objects that can be seen with ground-based telescopes. Studies of remote galaxies viewed through well-studied lenses like Abell 2218 promise to reveal the nature of normal galaxies at much earlier epochs than was previously possible. The technique is a powerful combination of Hubble's superlative capabilities and the 'natural' focusing properties of massive clusters like Abell 2218. The image was taken with the Wide Field Planetary Camera 2. Credits: W.Couch (University of New South Wales), R. Ellis (Cambridge University), and NASA

Unveiling the Low Surface Brightness Stellar Peripheries of Galaxies

NASA Astrophysics Data System (ADS)

Ferguson, Annette M. N.

2018-01-01

The low surface brightness peripheral regions of galaxies contain a gold mine of information about how minor mergers and accretions have influenced their evolution over cosmic time. Enormous stellar envelopes and copious amounts of faint tidal debris are natural outcomes of the hierarchical assembly process and the search for and study of these features, albeit highly challenging, offers the potential for unrivalled insight into the mechanisms of galaxy growth. Over the last two decades, there has been burgeoning interest in probing galaxy outskirts using resolved stellar populations. Wide-field surveys have uncovered vast tidal debris features and new populations of very remote globular clusters, while deep Hubble Space Telescope photometry has provided exquisite star formation histories back to the earliest epochs. I will highlight some recent results from studies within and beyond the Local Group and conclude by briefly discussing the great potential of future facilities, such as JWST, Euclid, LSST and WFIRST, for major breakthroughs in low surface brightness galaxy periphery science.

Hubble's new view of the cosmos

PubMed

Villard, R

1996-05-01

Since the December 1993 repair of NASA's Hubble Space Telescope's (HST) optics by the crew of the Space Shuttle Endeavour, the rapid-fire scientific achievements have brought a new era of discovery to the field of astronomy. Hubble has confirmed some astronomical theories, challenged others, and often come up with complete surprises. Some images are so unexpected that astronomers have to develop new theories to explain what they are seeing. The HST has detected galaxies out to the visible horizon of the cosmos, and has made an attempt at pinning down the universe's expansion rate. Both of these key research areas should ultimately yield answers to age-old questions: What has happened since the beginning of time, and will the universe go on forever?

Calibration of the Hubble Space Telescope polarimetric modes

NASA Technical Reports Server (NTRS)

Lupie, O. L.; Stockman, H. S.

1988-01-01

Stellar and galactic polarimetry from space is an unexplored observational regime and one which holds exciting promise for answering many fundamental astrophysical questions. The Hubble Space Telescope will be the first space observatory to provide a variety of polarimetric modes to astronomers including spectral, imaging, and single-aperture UV polarimetry. As part of the calibration program for these modes, the Space Telescope Science Institute has initiated a ground-based program to define faint standard fields and solicited community support to establish a temporal baseline for these potential standard targets. In this paper, the polarimetric capabilities of the Hubble Space Telescope, the philosophy and complications of in-flight calibration, and the status and direction of the standard targets program are discussed.

The FUV to Near-IR Morphologies of Luminous Infrared Galaxies in the Goals Sample

NASA Astrophysics Data System (ADS)

Petty, S. M.; Armus, L.; Charmandaris, V.; Evans, A. S.; Le Floc'h, E.; Bridge, C.; Díaz-Santos, T.; Howell, J. H.; Inami, H.; Psychogyios, A.; Stierwalt, S.; Surace, J. A.

2014-12-01

We compare the morphologies of a sample of 20 luminous infrared galaxies (LIRGs) from the Great Observatories All-sky LIRG Survey (GOALS) in the FUV, B, I, and H bands, using the Gini (G) and M20 parameters to quantitatively estimate the distribution and concentration of flux as a function of wavelength. Hubble Space Telescope (HST) images provide an average spatial resolution of ˜ 80 pc. While our LIRGs can be reliably classified as mergers across the entire range of wavelengths studied here, there is a clear shift toward more negative M20 (more bulge-dominated) and a less significant decrease in G values at longer wavelengths. We find no correlation between the derived FUV G-M20 parameters and the global measures of the IR to FUV flux ratio (IRX). Given the fine resolution in our HST data, this suggests either that the UV morphology and IRX are correlated on very small scales, or that the regions emitting the bulk of the IR emission emit almost no FUV light. We use our multi-wavelength data to simulate how merging LIRGs would appear from z˜ 0.5-3 in deep optical and near-infrared images such as the Hubble Ultra-Deep Field, and use these simulations to measure the G-M20 at these redshifts. Our simulations indicate a noticeable decrease in G, which flattens at z≥slant 2 by as much as 40%, resulting in mis-classifying our LIRGs as disk-like, even in the rest-frame FUV. The higher redshift values of M20 for the GOALS sources do not appear to change more than about 10% from the values at z˜ 0. The change in G-M20 is caused by the surface brightness dimming of extended tidal features and asymmetries, and also the decreased spatial resolution which reduced the number of individual clumps identified. This effect, seen as early as z˜ 0.5, could easily lead to an underestimate of the number of merging galaxies at high-redshift in the rest-frame FUV.

Version 1 of the Hubble Source Catalog

DOE PAGES

Whitmore, Bradley C.; Allam, Sahar S.; Budavari, Tamas; ...

2016-05-11

The Hubble Source Catalog is designed to help optimize science from the Hubble Space Telescope by combining the tens of thousands of visit-based source lists in the Hubble Legacy Archive into a single master catalog. Version 1 of the Hubble Source Catalog includes WFPC2, ACS/WFC, WFC3/UVIS, and WFC3/IR photometric data generated using SExtractor software to produce the individual source lists. The catalog includes roughly 80 million detections of 30 million objects involving 112 different detector/filter combinations, and about 160 thousand HST exposures. Source lists from Data Release 8 of the Hubble Legacy Archive are matched using an algorithm developed by Budavari & Lubow (2012). The mean photometric accuracy for the catalog as a whole is better than 0.10 mag, with relative accuracy as good as 0.02 mag in certain circumstances (e.g., bright isolated stars). The relative astrometric residuals are typically within 10 mas, with a value for the mode (i.e., most common value) of 2.3 mas. The absolute astrometric accuracy is better thanmore » $$\\sim$$0.1 arcsec for most sources, but can be much larger for a fraction of fields that could not be matched to the PanSTARRS, SDSS, or 2MASS reference systems. In this paper we describe the database design with emphasis on those aspects that enable the users to fully exploit the catalog while avoiding common misunderstandings and potential pitfalls. Here, we provide usage examples to illustrate some of the science capabilities and data quality characteristics, and briefly discuss plans for future improvements to the Hubble Source Catalog.« less

Hubble Images of Comet Hale-Bopp

NASA Technical Reports Server (NTRS)

1998-01-01

This is a series of Hubble Space Telescope observations of the region around the nucleus of Hale-Bopp, taken on eight different dates since September 1995. They chronicle changes in the evolution of the nucleus as it moves ever closer to, and is warmed by, the sun.

The first picture in the sequence, seen at upper left shows a strong dust outburst on the comet that occurred when it was beyond the orbit of Jupiter. Images in the Fall of 1996 show multiple jets that are presumably connected to the activation of multiple vents on the surface of the nucleus.

In these false color images, taken with the Wide Field and Planetary Camera 2, the faintest regions are black, the brightest regions are white, and intermediate intensities are represented by different levels of red. All images are processed at the same spatial scale of 280 miles per pixel (470 kilometers), so the solid nucleus, no larger than 25 miles across, is far below Hubble's resolution.

The Wide Field/Planetary Camera 2 was developed by the Jet Propulsion Laboratory and managed by the Goddard Spaced Flight Center for NASA's Office of Space Science.

This image and other images and data received from the Hubble Space Telescope are posted on the World Wide Web on the Space Telescope Science Institute home page at URL http://oposite.stsci.edu/pubinfo/

Tachyon constant-roll inflation

NASA Astrophysics Data System (ADS)

Mohammadi, A.; Saaidi, Kh.; Golanbari, T.

2018-04-01

The constant-roll inflation is studied where the inflaton is taken as a tachyon field. Based on this approach, the second slow-roll parameter is taken as a constant which leads to a differential equation for the Hubble parameter. Finding an exact solution for the Hubble parameter is difficult and leads us to a numerical solution for the Hubble parameter. On the other hand, since in this formalism the slow-roll parameter η is constant and could not be assumed to be necessarily small, the perturbation parameters should be reconsidered again which, in turn, results in new terms appearing in the amplitude of scalar perturbations and the scalar spectral index. Utilizing the numerical solution for the Hubble parameter, we estimate the perturbation parameter at the horizon exit time and compare it with observational data. The results show that, for specific values of the constant parameter η , we could have an almost scale-invariant amplitude of scalar perturbations. Finally, the attractor behavior for the solution of the model is presented, and we determine that the feature could be properly satisfied.

Hubble's Cosmic Atlas

NASA Image and Video Library

2017-12-08

Morphologies, masses, and structures - oh, my! This beautiful clump of glowing gas, dark dust and glittering stars is the spiral galaxy NGC 4248, located about 24 million light-years away in the constellation of Canes Venatici (The Hunting Dogs). This image was produced by the NASA/ESA Hubble Space Telescope as it embarked upon compiling the first Hubble ultraviolet “atlas,” for which the telescope targeted 50 nearby star-forming galaxies. The collection spans all kinds of different morphologies, masses, and structures. Studying this sample can help us to piece together the star-formation history of the Universe. By exploring how massive stars form and evolve within such galaxies, astronomers can learn more about how, when, and where star formation occurs, how star clusters change over time, and how the process of forming new stars is related to the properties of both the host galaxy and the surrounding interstellar medium (the gas and dust that fills the space between individual stars). This galaxy was imaged with observations from Hubble’s Wide Field Camera 3. Image credit: ESA/Hubble & NASA

Hubble Tarantula Treasury Project - VI. Identification of Pre-Main-Sequence Stars using Machine Learning techniques

NASA Astrophysics Data System (ADS)

Ksoll, Victor F.; Gouliermis, Dimitrios A.; Klessen, Ralf S.; Grebel, Eva K.; Sabbi, Elena; Anderson, Jay; Lennon, Daniel J.; Cignoni, Michele; de Marchi, Guido; Smith, Linda J.; Tosi, Monica; van der Marel, Roeland P.

2018-05-01

The Hubble Tarantula Treasury Project (HTTP) has provided an unprecedented photometric coverage of the entire star-burst region of 30 Doradus down to the half Solar mass limit. We use the deep stellar catalogue of HTTP to identify all the pre-main-sequence (PMS) stars of the region, i.e., stars that have not started their lives on the main-sequence yet. The photometric distinction of these stars from the more evolved populations is not a trivial task due to several factors that alter their colour-magnitude diagram positions. The identification of PMS stars requires, thus, sophisticated statistical methods. We employ Machine Learning Classification techniques on the HTTP survey of more than 800,000 sources to identify the PMS stellar content of the observed field. Our methodology consists of 1) carefully selecting the most probable low-mass PMS stellar population of the star-forming cluster NGC2070, 2) using this sample to train classification algorithms to build a predictive model for PMS stars, and 3) applying this model in order to identify the most probable PMS content across the entire Tarantula Nebula. We employ Decision Tree, Random Forest and Support Vector Machine classifiers to categorise the stars as PMS and Non-PMS. The Random Forest and Support Vector Machine provided the most accurate models, predicting about 20,000 sources with a candidateship probability higher than 50 percent, and almost 10,000 PMS candidates with a probability higher than 95 percent. This is the richest and most accurate photometric catalogue of extragalactic PMS candidates across the extent of a whole star-forming complex.

Infrared Photometry of 487 Sources in the Inner Regions of NGC 5128 (Centaurus A)

NASA Astrophysics Data System (ADS)

Alonso, M. Victoria; Minniti, Dante

1997-04-01

We study the sources present in the inner 3 kpc region of NGC 5128 (Cen A), most of which are star clusters of different ages. Photometry of archival Hubble Space Telescope WFPC images (F675W filter) is complemented with IR photometry (JHK' filters) obtained with the IRAC2B infrared array camera at the ESO/MPI 2.2 m telescope. From IR color maps we divide the field into two regions: a clear region outside the dust lane, and an obscured region well inside the dust lane of NGC 5128. In the unreddened region there is a great variety of sources such as globular clusters, star associations, and H II regions. These sources are not individual stars, which would be too faint to be resolved from ground-based telescopes. The vast majority of IR sources in the reddened region, where the dust lane dominates, are not seen at all in the deep HST images. The presence of large amounts of differential extinction makes it difficult to evaluate them. In total, there are 372 objects detected in the inner region of NGC 5128. From them, 125 objects are detected both in IR and HST frames. There are 247 IR sources without optical counterparts (47 in the clear region and 200 in the dust lane). Accounting for the small volume sampled, there must be a total of ~500 sources with K < 18 in the dust lane region. The distribution of these sources is rather uniform and not particularly centrally concentrated. This fact suggests that the majority of them are located in a disk, as would be expected if they are young associations or clusters. The degree of background and foreground contamination is evaluated using observations of a nearby field. We found 115 IR sources in this field. The nucleus itself is invisible in deep optical images, but it is clearly identified in the IR. In the region just south of the nucleus the extinction must be larger than AK = 3. In the clear region, where the effect of the dust lane is negligible, we have identified some objects as intermediate-age clusters containing carbon stars. From color-magnitude diagrams we do not find evidence of very young clusters in this region. Such clusters might be fainter than our detection limit in JHK'. We measure metallicities for 42 globular clusters, confirming the presence of a metallicity gradient with Δ[Fe/H]/ΔR = -0.06 dex kpc-1. Based on observations collected at La Silla Observatory and on archival data of the NASA/ESA Hubble Space Telescope, which is operated by AURA, Inc., under NASA contract NAS 5-26555.

HUBBLE FINDS MANY BRIGHT CLOUDS ON URANUS

NASA Technical Reports Server (NTRS)

2002-01-01

A recent Hubble Space Telescope view reveals Uranus surrounded by its four major rings and by 10 of its 17 known satellites. This false-color image was generated by Erich Karkoschka using data taken on August 8, 1998, with Hubble's Near Infrared Camera and Multi-Object Spectrometer. Hubble recently found about 20 clouds - nearly as many clouds on Uranus as the previous total in the history of modern observations. The orange-colored clouds near the prominent bright band circle the planet at more than 300 mph (500 km/h), according to team member Heidi Hammel (MIT). One of the clouds on the right-hand side is brighter than any other cloud ever seen on Uranus. The colors in the image indicate altitude. Team member Mark Marley (New Mexico State University) reports that green and blue regions show where the atmosphere is clear and sunlight can penetrate deep into Uranus. In yellow and grey regions the sunlight reflects from a higher haze or cloud layer. Orange and red colors indicate very high clouds, such as cirrus clouds on Earth. The Hubble image is one of the first images revealing the precession of the brightest ring with respect to a previous image [LINK to PRC97-36a]. Precession makes the fainter part of the ring (currently on the upper right-hand side) slide around Uranus once every nine months. The fading is caused by ring particles crowding and hiding each other on one side of their eight-hour orbit around Uranus. The blue, green and red components of this false-color image correspond to exposures taken at near-infrared wavelengths of 0.9, 1.1, and 1.7 micrometers. Thus, regions on Uranus appearing blue, for example, reflect more sunlight at 0.9 micrometer than at the longer wavelengths. Apparent colors on Uranus are caused by absorption of methane gas in its atmosphere, an effect comparable to absorption in our atmosphere which can make distant clouds appear red. Credit: Erich Karkoschka (University of Arizona) and NASA

RED DWARF DYNAMO RAISES PUZZLE OVER INTERIORS OF LOWEST-MASS STARS

NASA Technical Reports Server (NTRS)

2002-01-01

NASA's Hubble Space Telescope has uncovered surprising evidence that powerful magnetic fields might exist around the lowest mass stars in the universe, which are near the threshold of stellar burning processes. 'New theories will have to be developed to explain how these strong fields are produced, since conventional models predict that these low mass red dwarfs should have very weak or no magnetic fields,' says Dr. Jeffrey Linsky of the Joint Institute for Laboratory Astrophysics (JILA) in Boulder, Colorado. 'The Hubble observations provide clear evidence that very low mass red dwarf stars must have some form of dynamo to amplify their magnetic fields.' His conclusions are based upon Hubble's detection of a high-temperature outburst, called a flare, on the surface of the extremely small, cool red dwarf star Van Biesbroeck 10 (VB10) also known as Gliese 752B. Stellar flares are caused by intense, twisted magnetic fields that accelerate and contain gasses which are much hotter than a star's surface. Explosive flares are common on the Sun and expected for stars that have internal structures similar to our Sun's. Stars as small as VB10 are predicted to have a simpler internal structure than that of the Sun and so are not expected to generate the electric currents required for magnetic fields that drive flares. Besides leading to a clearer understanding of the interior structure of the smallest red dwarf stars known, these unexpected results might possibly shed light on brown dwarf stars. A brown dwarf is a long-sought class of astronomical object that is too small to shine like a star through nuclear fusion processes, but is too large to be considered a planet. 'Since VB10 is nearly a brown dwarf, it is likely brown dwarfs also have strong magnetic fields,' says Linsky. 'Additional Hubble searches for flares are needed to confirm this prediction.' A QUARTER-MILLION DEGREE TORCH The star VB10 and its companion star Gliese 752A make up a binary system located 19 light-years away in the constellation Aquila. Gliese 752A is a red dwarf that is one-third the mass of the Sun and slightly more than half its diameter. By contrast, VB10 is physically smaller than the planet Jupiter and only about nine percent the mass of our Sun. This very faint star is near the threshold of the lowest possible mass for a true star (.08 solar masses), below which nuclear fusion processes cannot take place according to current models. A team led by Linsky used Hubble's Goddard High Resolution Spectrograph (GHRS) to make a one-hour long exposure of VB10 on October 12, 1994. No detectable ultraviolet emission was seen until the last five minutes, when bright emission was detected in a flare. Though the star's normal surface temperature is 4,500 degrees Fahrenheit, Hubble's GHRS detected a sudden burst of 270,000 degrees Fahrenheit in the star's outer atmosphere. Linsky attributes this rapid heating to the presence of an intense, but unstable, magnetic field. THE INTERIOR WORKINGS OF A STELLAR DYNAMO Before the Hubble observation, astronomers thought magnetic fields in stars required the same dynamo process which creates magnetic fields on the Sun. In the classic solar model, heat generated by nuclear fusion reactions at the star's center escapes through a radiative zone just outside the core. The heat travels from the radiative core to the star's surface through a convection zone. In this region, heat bubbles to the surface by motions similar to boiling in a pot of water. Dynamos, which accelerate electrons to create magnetic forces, operate when the interior of a star rotates faster than the surface. Recent studies of the Sun indicate its convective zone rotates at nearly the same rate at all depths. This means the solar dynamo must operate in the more rapidly rotating radiative core just below the convective zone. The puzzle is that stars below 20 percent the mass of our Sun do not have radiative cores, but instead transport heat from their core through convection only. The new Hubble observations suggest a magnetic dynamo perhaps of a new type can operate inside these stars. These results are being reported at the 185th meeting of the American Astronomical Society in Tucson, Arizona. * * * * * * * * * * * * The Space Telescope Science Institute is operated by the Association of Universities for Research in Astronomy, Inc. (AURA) for NASA, under contract with the Goddard Space Flight Center, Greenbelt, MD. The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency (ESA). JILA is a joint institute of the University of Colorado and the National Institute of Standards and Technology (NIST). Dr. Linsky is a staff member of the Quantum Physics Division of NIST.

James Webb Space Telescope Studies of Dark Energy

NASA Technical Reports Server (NTRS)

Gardner, Jonathan P.; Stiavelli, Massimo; Mather, John C.

2010-01-01

The Hubble Space Telescope (HST) has contributed significantly to studies of dark energy. It was used to find the first evidence of deceleration at z=1.8 (Riess et al. 2001) through the serendipitous discovery of a type 1a supernova (SN1a) in the Hubble Deep Field. The discovery of deceleration at z greater than 1 was confirmation that the apparent acceleration at low redshift (Riess et al. 1998; Perlmutter et al. 1999) was due to dark energy rather than observational or astrophysical effects such as systematic errors, evolution in the SN1a population or intergalactic dust. The GOODS project and associated follow-up discovered 21 SN1a, expanding on this result (Riess et al. 2007). HST has also been used to constrain cosmological parameters and dark energy through weak lensing measurements in the COSMOS survey (Massey et al 2007; Schrabback et al 2009) and strong gravitational lensing with measured time delays (Suyu et al 2010). Constraints on dark energy are often parameterized as the equation of state, w = P/p. For the cosmological constant model, w = -1 at all times; other models predict a change with time, sometimes parameterized generally as w(a) or approximated as w(sub 0)+(1-a)w(sub a), where a = (1+z)(sup -1) is the scale factor of the universe relative to its current scale. Dark energy can be constrained through several measurements. Standard candles, such as SN1a, provide a direct measurement of the luminosity distance as a function of redshift, which can be converted to H(z), the change in the Hubble constant with redshift. An analysis of weak lensing in a galaxy field can be used to derive the angular-diameter distance from the weak-lensing equation and to measure the power spectrum of dark-matter halos, which constrains the growth of structure in the Universe. Baryonic acoustic oscillations (BAO), imprinted on the distribution of matter at recombination, provide a standard rod for measuring the cosmological geometry. Strong gravitational lensing of a time-variable source gives the angular diameter distance through measured time delays of multiple images. Finally, the growth of structure can also be constrained by measuring the mass of the largest galaxy clusters over cosmic time. HST has contributed to the study of dark energy through SN1a and gravitational lensing, as discussed above. HST has also helped to characterize galaxy clusters and the HST-measured constraints on the current Hubble constant H(sub 0) are relevant to the interpretation of dark energy measurements (Riess et al 2009a). HST has not been used to constrain BAO as the large number of galaxy redshifts required, of order 100 million, is poorly matched to HST's capabilities. As the successor to HST, the James Webb Space Telescope (JWST; Gardner et al 2006) will continue and extend HST's dark energy work in several ways.

Near Infrared Observations of a Redshift 5.34 Galaxy: Further Evidence for Significant Dust Absorption in the Early Universe

NASA Technical Reports Server (NTRS)

Armus, L.; Matthews, K.; Neugebauer, G.; Soifer, B. T.

1998-01-01

In the last several years, the combination of new wavelength dropout discovery techniques coupled with the incredible power of deep imaging of the Hubble Space Telescope and the spectroscopic capabilities of a new generation of large ground-based telescopes, has lead to an astonishing blossoming of the study of galaxies at redshifts of z=2-4, when the Universe was less than 10-20% of its current age.

Deep HST Photometry of NGC 6388: Age and Horizontal Branch Luminosity

NASA Technical Reports Server (NTRS)

Stetson, Peter B.; Catelan, M.; Pritzl, Barton J.; Smith, Horace A.; Kinemuchi, Karen; Layden, Andrew C.; Sweigart, Allen V.; Rich, R. M.

2006-01-01

We present the first deep color-magnitude diagram (CMD) of the Galactic globular cluster NGC 6388, obtained with the Hubble Space Telescope, that is able to reach the main-sequence turnoff point of the cluster. From a detailed comparison between the cluster CMD and that of 47 Tucanae (NGC 104), we find that the bulk of the stars in these two clusters have nearly the same age and chemical composition. On the other hand, our results indicate that the blue horizontal branch and RR Lyrae components in NGC 6388 are intrinsically over-luminous, which must be due to one or more, still undetermined, non-canonical second parameter(s) affecting a relatively minor fraction of the stars in NGC 6388.

CHEERS Results from NGC 3393. II. Investigating the Extended Narrow-line Region Using Deep Chandra Observations and Hubble Space Telescope Narrow-line Imaging

NASA Astrophysics Data System (ADS)

Maksym, W. Peter; Fabbiano, Giuseppina; Elvis, Martin; Karovska, Margarita; Paggi, Alessandro; Raymond, John; Wang, Junfeng; Storchi-Bergmann, Thaisa

2017-07-01

The CHandra Extended Emission Line Region Survey (CHEERS) is an X-ray study of nearby active galactic nuclei (AGNs) designed to take full advantage of Chandra's unique angular resolution by spatially resolving feedback signatures and effects. In the second paper of a series on CHEERS target NGC 3393, we examine deep high-resolution Chandra images and compare them with Hubble Space Telescope narrow-line images of [O III], [S II], and Hα, as well as previously unpublished mid-ultraviolet (MUV) images. The X-rays provide unprecedented evidence that the S-shaped arms that envelope the nuclear radio outflows extend only ≲0.″2 (≲50 pc) across. The high-resolution multiwavelength data suggest that the extended narrow-line region is a complex multiphase structure in the circumnuclear interstellar medium (ISM). Its ionization structure is highly stratified with respect to outflow-driven bubbles in the bicone and varies dramatically on scales of ˜10 pc. Multiple findings show likely contributions from shocks to the feedback in regions where radio outflows from the AGN most directly influence the ISM. These findings include Hα evidence for gas compression and extended MUV emission and are in agreement with existing STIS kinematics. Extended filamentary structure in the X-rays and optical suggests the presence of an undetected plasma component, whose existence could be tested with deeper radio observations.

Accounting for Cosmic Variance in Studies of Gravitationally Lensed High-redshift Galaxies in the Hubble Frontier Field Clusters

NASA Astrophysics Data System (ADS)

Robertson, Brant E.; Ellis, Richard S.; Dunlop, James S.; McLure, Ross J.; Stark, Dan P.; McLeod, Derek

2014-12-01

Strong gravitational lensing provides a powerful means for studying faint galaxies in the distant universe. By magnifying the apparent brightness of background sources, massive clusters enable the detection of galaxies fainter than the usual sensitivity limit for blank fields. However, this gain in effective sensitivity comes at the cost of a reduced survey volume and, in this Letter, we demonstrate that there is an associated increase in the cosmic variance uncertainty. As an example, we show that the cosmic variance uncertainty of the high-redshift population viewed through the Hubble Space Telescope Frontier Field cluster Abell 2744 increases from ~35% at redshift z ~ 7 to >~ 65% at z ~ 10. Previous studies of high-redshift galaxies identified in the Frontier Fields have underestimated the cosmic variance uncertainty that will affect the ultimate constraints on both the faint-end slope of the high-redshift luminosity function and the cosmic star formation rate density, key goals of the Frontier Field program.

Does Stellar Feedback Create H I Holes? A Hubble Space Telescope/Very Large Array Study of Holmberg II

NASA Astrophysics Data System (ADS)

Weisz, Daniel R.; Skillman, Evan D.; Cannon, John M.; Dolphin, Andrew E.; Kennicutt, Robert C., Jr.; Lee, Janice; Walter, Fabian

2009-10-01

We use deep Hubble Space Telescope (HST)/Advanced Camera for Surveys (ACS) F555W and F814W photometry of resolved stars in the M81 Group dwarf irregular galaxy Ho II to study the hypothesis that the holes identified in the neutral interstellar medium (H I) are created by stellar feedback. From the deep photometry, we construct color-magnitude diagrams (CMDs) and measure the star formation histories (SFHs) for stars contained in H I holes from two independent holes catalogs, as well as select control fields, i.e., similar sized regions that span a range of H I column densities. The CMDs reveal young (< 200 Myr) stellar populations inside all H I holes, which contain very few bright OB stars with ages less than 10 Myr, indicating they are not reliable tracers of H I hole locations while the recent SFHs confirm multiple episodes of star formation within most holes. Converting the recent SFHs into stellar feedback energies, we find that enough energy has been generated to have created all holes. However, the required energy is not always produced over a timescale that is less than the estimated kinematic age of the hole. A similar analysis of stars in the control fields finds that the stellar populations of the control fields and H I holes are statistically indistinguishable. However, because we are only sensitive to holes ~100 pc in diameter, we cannot tell if there are smaller holes inside the control fields. The combination of the CMDs, recent SFHs, and locations of young stars shows that the stellar populations inside H I holes are not coherent, single-aged, stellar clusters, as previously suggested, but rather multi-age populations distributed across each hole. From a comparison of the modeled and observed integrated magnitudes, and the locations and energetics of stars inside of H I holes, we propose a potential new model: a viable mechanism for creating the observed H I holes in Ho II is stellar feedback from multiple generations of SF spread out over tens or hundreds of Myr, and thus, the concept of an age for an H I hole is intrinsically ambiguous. For H I holes in the outer parts of Ho II, located beyond the HST/ACS coverage, we use Monte Carlo simulations of expected stellar populations to show that low level SF could provide the energy necessary to form these holes. Applying the same method to the SMC, we find that the holes that appear to be void of stars could have formed via stellar feedback from low level SF. We further find that Hα and 24 μm emission, tracers of the most recent star formation, do not correlate well with the positions of the H I holes. However, UV emission, which traces star formation over roughly the last 100 Myr, shows a much better correlation with the locations of the H I holes.

Hubble Observations of the Exomoon Candidate Kepler-1625b I

NASA Astrophysics Data System (ADS)

Teachey, Alexander; Kipping, David; Torres, Guillermo; Bakos, Gaspar A.; Nesvorný, David; Buchhave, Lars; Huang, Chelsea Xu; Hartman, Joel D.

2018-01-01

The exomoon candidate Kepler-1625b I was identified by the Hunt for Exomoons with Kepler (HEK) collaboration in August 2016 following an extensive program to characterize the occurrence rate of exomoons. Follow-up observations of the candidate for the purpose of validating the existence of the moon and constraining its properties were carried out on the Hubble Space Telescope on October 28th-29th 2017, using slitless spectroscopy on Wide Field Camera 3. We report preliminary results of that observation.

History of Hubble Space Telescope (HST)

NASA Image and Video Library

1969-01-01

This image of the Egg Nebula, also known as CRL-2688 and located roughly 3,000 light-years from us, was taken in red light with the Wide Field Planetary Camera 2 (WF/PC2) aboard the Hubble Space Telescope (HST). The image shows a pair of mysterious searchlight beams emerging from a hidden star, crisscrossed by numerous bright arcs. This image sheds new light on the poorly understood ejection of stellar matter that accompanies the slow death of Sun-like stars. The image is shown in false color.

Best Color Image of Jupiter's Little Red Spot

NASA Technical Reports Server (NTRS)

2007-01-01

This amazing color portrait of Jupiter's 'Little Red Spot' (LRS) combines high-resolution images from the New Horizons Long Range Reconnaissance Imager (LORRI), taken at 03:12 UT on February 27, 2007, with color images taken nearly simultaneously by the Wide Field Planetary Camera 2 (WFPC2) on the Hubble Space Telescope. The LORRI images provide details as fine as 9 miles across (15 kilometers), which is approximately 10 times better than Hubble can provide on its own. The improved resolution is possible because New Horizons was only 1.9 million miles (3 million kilometers) away from Jupiter when LORRI snapped its pictures, while Hubble was more than 500 million miles (800 million kilometers) away from the Gas Giant planet.

The Little Red Spot is the second largest storm on Jupiter, roughly 70% the size of the Earth, and it started turning red in late-2005. The clouds in the Little Red Spot rotate counterclockwise, or in the anticyclonic direction, because it is a high-pressure region. In that sense, the Little Red Spot is the opposite of a hurricane on Earth, which is a low-pressure region - and, of course, the Little Red Spot is far larger than any hurricane on Earth.

Scientists don't know exactly how or why the Little Red Spot turned red, though they speculate that the change could stem from a surge of exotic compounds from deep within Jupiter, caused by an intensification of the storm system. In particular, sulfur-bearing cloud droplets might have been propelled about 50 kilometers into the upper level of ammonia clouds, where brighter sunlight bathing the cloud tops released the red-hued sulfur embedded in the droplets, causing the storm to turn red. A similar mechanism has been proposed for the Little Red Spot's 'older brother,' the Great Red Spot, a massive energetic storm system that has persisted for over a century.

New Horizons is providing an opportunity to examine an 'infant' red storm system in detail, which may help scientists understand better how these giant weather patterns form and evolve.

HUBBLE SPIES HUGE CLUSTERS OF STARS FORMED

NASA Technical Reports Server (NTRS)

2002-01-01

BY ANCIENT ENCOUNTER This stunningly beautiful image [right] taken with the NASA Hubble Space Telescope shows the heart of the prototypical starburst galaxy M82. The ongoing violent star formation due to an ancient encounter with its large galactic neighbor, M81, gives this galaxy its disturbed appearance. The smaller picture at upper left shows the entire galaxy. The image was taken in December 1994 by the Kitt Peak National Observatory's 0.9-meter telescope. Hubble's view is represented by the white outline in the center. In the Hubble image, taken by the Wide Field and Planetary Camera 2, the huge lanes of dust that crisscross M82's disk are another telltale sign of the flurry of star formation. Below the center and to the right, a strong galactic wind is spewing knotty filaments of hydrogen and nitrogen gas. More than 100 super star clusters -- very bright, compact groupings of about 100,000 stars -- are seen in this detailed Hubble picture as white dots sprinkled throughout M82's central region. The dark region just above the center of the picture is a huge dust cloud. A collaboration of European and American scientists used these clusters to date the ancient interaction between M82 and M81. About 600 million years ago, a region called 'M82 B' (the bright area just below and to the left of the central dust cloud) exploded with new stars. Scientists have discovered that this ancient starburst was triggered by the violent encounter with M81. M82 is a bright (eighth magnitude), nearby (12 million light-years from Earth) galaxy in the constellation Ursa Major (the Great Bear). The Hubble picture was taken Sept. 15, 1997. The natural-color composite was constructed from three Wide Field and Planetary Camera 2 exposures, which were combined in chromatic order: 4,250 seconds through a blue filter (428 nm); 2,800 seconds through a green filter (520 nm); and 2,200 seconds through a red (820 nm) filter. Credits for Hubble image: NASA, ESA, R. de Grijs (Institute of Astronomy, Cambridge, UK) Credits for ground-based picture: N.A. Sharp (Association of Universities for Research in Astronomy, National Optical Astronomy Observatories, National Science Foundation)

Hubble Provides Clear Images of Saturn's Aurora

NASA Technical Reports Server (NTRS)

1998-01-01

This is the first image of Saturn's ultraviolet aurora taken by the Space Telescope Imaging Spectrograph (STIS) on board the Hubble Space Telescope in October 1997, when Saturn was a distance of 810 million miles (1.3 billion kilometers) from Earth. The new instrument, used as a camera, provides more than ten times the sensitivity of previous Hubble instruments in the ultraviolet. STIS images reveal exquisite detail never before seen in the spectacular auroral curtains of light that encircle Saturn's north and south poles and rise more than a thousand miles above the cloud tops.

Saturn's auroral displays are caused by an energetic wind from the Sun that sweeps over the planet, much like the Earths aurora that is occasionally seen in the nighttime sky and similar to the phenomenon that causes fluorescent lamps to glow. But unlike the Earth, Saturn's aurora is only seen in ultraviolet light that is invisible from the Earths surface, hence the aurora can only be observed from space. New Hubble images reveal ripples and overall patterns that evolve slowly, appearing generally fixed in our view and independent of planet rotation. At the same time, the curtains show local brightening that often follow the rotation of the planet and exhibit rapid variations on time scales of minutes. These variations and regularities indicate that the aurora is primarily shaped and powered by a continual tug-of-war between Saturn's magnetic field and the flow of charged particles from the Sun.

Study of the aurora on Saturn had its beginnings just seventeen years ago. The Pioneer 11 spacecraft observed a far-ultraviolet brightening on Saturn's poles in 1979. The Saturn flybys of the Voyager 1 and 2 spacecraft in the early 1980s provided a basic description of the aurora and mapped for the first time planets enormous magnetic field that guides energetic electrons into the atmosphere near the north and south poles.

The first images of Saturn's aurora were provided in 1994-5 by the Hubble Space Telescopes Wide Field and Planetary Camera (WFPC2). Much greater ultraviolet sensitivity of the new STIS instrument allows the workings of Saturn's magnetosphere and upper atmosphere to be studied in much greater detail. These Hubble aurora investigations provide a framework that will ultimately complement the in situ measurements of Saturn's magnetic field and charged particles by NASA/ ESA's Cassini spacecraft, now en route to its rendezvous with Saturn early in the next decade.

Two STIS imaging modes have been used to discriminate between ultraviolet emissions predominantly from hydrogen atoms (shown in red) and emissions due to molecular hydrogen (shown in blue). Hence the bright red aurora features are dominated by atomic hydrogen, while the white traces within them map the more tightly confined regions of molecular hydrogen emissions. The southern aurora is seen at lower right, the northern at upper left.

The Wide Field/Planetary Camera 2 was developed by the Jet Propulsion Laboratory and managed by the Goddard Spaced Flight Center for NASA's Office of Space Science.

This image and other images and data received from the Hubble Space Telescope are posted on the World Wide Web on the Space Telescope Science Institute home page at URL http://oposite.stsci.edu/pubinfo/

Ant nebula

NASA Technical Reports Server (NTRS)

1999-01-01

A new Hubble Space Telescope image of a celestial object called the Ant Nebula may shed new light on the future demise of our Sun. The image is available at http://www.jpl.nasa.gov/pictures/wfpc .

The nebula, imaged on July 20, 1997, and June 30, 1998, by Hubble's Wide Field and Planetary Camera 2, was observed by Drs. Raghvendra Sahai and John Trauger of NASA's Jet Propulsion Laboratory, Pasadena, Calif.; Bruce Balick of the University of Washington in Seattle; and Vincent Icke of Leiden University in the Netherlands. JPL designed and built the camera.

The Ant Nebula, whose technical name is Mz3, resembles the head and thorax of an ant when observed with ground-based telescopes. The new Hubble image, with 10 times the resolution revealing 100 times more detail, shows the 'ant's' body as a pair of fiery lobes protruding from a dying, Sun- like star. The Ant Nebula is located between 3,000 and 6,000 light years from Earth in the southern constellation Norma.

The image challenges old ideas about what happens to dying stars. This observation, along with other pictures of various remnants of dying stars called planetary nebulae, shows that our Sun's fate will probably be much more interesting, complex and dramatic than astronomers previously believed.

Although the ejection of gas from the dying star in the Ant Nebula is violent, it does not show the chaos one might expect from an ordinary explosion, but instead shows symmetrical patterns. One possibility is that the central star has a closely orbiting companion whose gravitational tidal forces shape the outflowing gas. A second possibility is that as the dying star spins, its strong magnetic fields are wound up into complex shapes like spaghetti in an eggbeater. Electrically charged winds, much like those in our Sun's solar wind but millions of times denser and moving at speeds up to 1,000 kilometers per second (more than 600 miles per second) from the star, follow the twisted field lines on their way out into space.

The Space Telescope Science Institute, Baltimore, Md., manages space operations for the Hubble Space Telescope for NASA's Office of Space Science, Washington, D.C. The Institute is operated by the Association of Universities for Research in Astronomy, Inc., for NASA under contract with NASA's Goddard Space Flight Center, Greenbelt, Md. The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency. JPL is a division of the California Institute of Technology in Pasadena.

Additional information about the Hubble Space Telescope is available at http://www.stsci.edu . More information about the Wide Field and Planetary Camera 2 is available at http://wfpc2.jpl.nasa.gov.

Hubble Probes Comet 103P/Hartley 2 in Preparation for DIXI flyby

NASA Image and Video Library

2017-12-08

NASA image release October 5, 2010 Hubble Space Telescope observations of comet 103P/Hartley 2, taken on September 25, are helping in the planning for a November 4 flyby of the comet by NASA's Deep Impact eXtended Investigation (DIXI) spacecraft. Analysis of the new Hubble data shows that the nucleus has a diameter of approximately 0.93 miles (1.5 km), which is consistent with previous estimates. The comet is in a highly active state, as it approaches the Sun. The Hubble data show that the coma is remarkably uniform, with no evidence for the types of outgassing jets seen from most "Jupiter Family" comets, of which Hartley 2 is a member. Jets can be produced when the dust emanates from a few specific icy regions, while most of the surface is covered with relatively inert, meteoritic-like material. In stark contrast, the activity from Hartley 2's nucleus appears to be more uniformly distributed over its entire surface, perhaps indicating a relatively "young" surface that hasn't yet been crusted over. Hubble's spectrographs - the Cosmic Origins Spectrograph (COS) and the Space Telescope Imaging Spectrograph (STIS) -- are expected to provide unique information about the comet's chemical composition that might not be obtainable any other way, including measurements by DIXI. The Hubble team is specifically searching for emissions from carbon monoxide (CO) and diatomic sulfur (S2). These molecules have been seen in other comets but have not yet been detected in 103P/Hartley 2. 103P/Hartley has an orbital period of 6.46 years. It was discovered by Malcolm Hartley in 1986 at the Schmidt Telescope Unit in Siding Spring, Australia. The comet will pass within 11 million miles of Earth (about 45 times the distance to the Moon) on October 20. During that time the comet may be visible to the naked eye as a 5th magnitude "fuzzy star" in the constellation Auriga. Credit: NASA, ESA, and H. Weaver (The Johns Hopkins University/Applied Physics Lab) The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency. NASA's Goddard Space Flight Center manages the telescope. The Space Telescope Science Institute (STScI) conducts Hubble science operations. STScI is operated for NASA by the Association of Universities for Research in Astronomy, Inc., in Washington, D.C. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Join us on Facebook

NASA Space Observatories Glimpse Faint Afterglow of Nearby Stellar Explosion

NASA Astrophysics Data System (ADS)

2005-10-01

Intricate wisps of glowing gas float amid a myriad of stars in this image created by combining data from NASA's Hubble Space Telescope and Chandra X-ray Observatory. The gas is a supernova remnant, cataloged as N132D, ejected from the explosion of a massive star that occurred some 3,000 years ago. This titanic explosion took place in the Large Magellanic Cloud, a nearby neighbor galaxy of our own Milky Way. The complex structure of N132D is due to the expanding supersonic shock wave from the explosion impacting the interstellar gas of the LMC. Deep within the remnant, the Hubble visible light image reveals a crescent-shaped cloud of pink emission from hydrogen gas, and soft purple wisps that correspond to regions of glowing oxygen emission. A dense background of colorful stars in the LMC is also shown in the Hubble image. The large horseshoe-shaped gas cloud on the left-hand side of the remnant is glowing in X-rays, as imaged by Chandra. In order to emit X-rays, the gas must have been heated to a temperature of about 18 million degrees Fahrenheit (10 million degrees Celsius). A supernova-generated shock wave traveling at a velocity of more than four million miles per hour (2,000 kilometers per second) is continuing to propagate through the low-density medium today. The shock front where the material from the supernova collides with ambient interstellar material in the LMC is responsible for these high temperatures. Chandra image of N132D Chandra image of N132D, 2002 It is estimated that the star that exploded as a supernova to produce the N132D remnant was 10 to 15 times more massive than our own Sun. As fast-moving ejecta from the explosion slam into the cool, dense interstellar clouds in the LMC, complex shock fronts are created. A supernova remnant like N132D provides a rare opportunity for direct observation of stellar material, because it is made of gas that was recently hidden deep inside a star. Thus it provides information on stellar evolution and the creation of chemical elements such as oxygen through nuclear reactions in their cores. Such observations also help reveal how the interstellar medium (the gas that occupies the vast spaces between the stars) is enriched with chemical elements because of supernova explosions. Later on, these elements are incorporated into new generations of stars and their accompanying planets. Visible only from Earth's southern hemisphere, the LMC is an irregular galaxy lying about 160,000 light-years from the Milky Way. The supernova remnant appears to be about 3,000 years old, but since its light took 160,000 years to reach us, the explosion actually occurred some 163,000 years ago. This composite image of N132D was created by the Hubble Heritage team from visible-light data taken in January 2004 with Hubble's Advanced Camera for Surveys, and X-ray images obtained in July 2000 by Chandra's Advanced CCD Imaging Spectrometer. This marks the first Hubble Heritage image that combines pictures taken by two separate space observatories. The Hubble data include color filters that sample starlight in the blue, green, and red portions of the spectrum, as well as the pink emission from glowing hydrogen gas. The Chandra data are assigned blue in the color composite, in accordance with the much higher energy of the X-rays, emitted from extremely hot gas. This gas does not emit a significant amount of optical light, and was only detected by Chandra. Image Credit: NASA, ESA, and The Hubble Heritage Team (STScI/AURA) Acknowledgment: J.C. Green (Univ. of Colorado) and the Cosmic Origins Spectrograph (COS) GTO team; NASA/CXO/SAO Electronic image files, video, illustrations and additional information are available at: http://hubblesite.org/news/2005/30 http://heritage.stsci.edu/2005/30 The Space Telescope Science Institute (STScI) is operated by the Association of Universities for Research in Astronomy, Inc. (AURA), for NASA, under contract with the Goddard Space Flight Center, Greenbelt, Md. The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency (ESA).

The Brightest of Reionizing Galaxies Survey: Constraints on the Bright End of the z ~ 8 Luminosity Function

NASA Astrophysics Data System (ADS)

Bradley, L. D.; Trenti, M.; Oesch, P. A.; Stiavelli, M.; Treu, T.; Bouwens, R. J.; Shull, J. M.; Holwerda, B. W.; Pirzkal, N.

2012-12-01

We report the discovery of 33 Lyman-break galaxy candidates at z ~ 8 detected in Hubble Space Telescope Wide Field Camera 3 (WFC3) imaging as part of the Brightest of Reionizing Galaxies (BoRG) pure-parallel survey. The ongoing BoRG survey currently has the largest area (274 arcmin2) with Y 098 (or Y 105), J 125, and H 160 band coverage needed to search for z ~ 8 galaxies, about three times the current CANDELS area, and slightly larger than what will be the final CANDELS wide component with Y 105 data (required to select z ~ 8 sources). Our sample of 33 relatively bright Y 098-dropout galaxies have J 125-band magnitudes between 25.5 and 27.4 mag. This is the largest sample of bright (J 125 <~ 27.4) z ~ 8 galaxy candidates presented to date. Combining our data set with the Hubble Ultra-Deep Field data set, we constrain the rest-frame ultraviolet galaxy luminosity function at z ~ 8 over the widest dynamic range currently available. The combined data sets are well fitted by a Schechter function, i.e., \\phi (L) = \\phi _{*} (L/L_{*})^{\\alpha }\\ e^{-(L/L_{*})}, without evidence for an excess of sources at the bright end. At 68% confidence, for h = 0.7 we derive phi* = (4.3+3.5 -2.1) × 10-4 Mpc-3, M * = -20.26+0.29 -0.34, and a very steep faint-end slope α = -1.98+0.23 -0.22. While the best-fit parameters still have a strong degeneracy, especially between phi* and M *, our improved coverage at the bright end has reduced the uncertainty of the faint-end power-law slope at z ~ 8 compared to the best previous determination at ±0.4. With a future expansion of the BoRG survey, combined with planned ultradeep WFC3/IR observations, it will be possible to further reduce this uncertainty and clearly demonstrate the steepening of the faint-end slope compared to measurements at lower redshift, thereby confirming the key role played by small galaxies in the reionization of the universe. Based on observations made with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy under NASA contract NAS5-26555. These observations are associated with programs 11519, 11520, 11524, 11528, 11530, 11533, 11534, 11541, 11700, 11702, 12024, 12025, and 12572.

An Extensive Census of Hubble Space Telescope Counterparts to Chandra X-Ray Sources in the Globular Cluster 47 Tucanae. I. Astrometry and Photometry

NASA Astrophysics Data System (ADS)

Edmonds, Peter D.; Gilliland, Ronald L.; Heinke, Craig O.; Grindlay, Jonathan E.

2003-10-01

We report in this study of 47 Tucanae the largest number of optical identifications of X-ray sources yet obtained in a single globular cluster. Using deep Chandra ACIS-I imaging and extensive Hubble Space Telescope studies with Wide Field Planetary Camera 2 (WFPC2; including a 120 orbit program giving superb V and I images), we have detected optical counterparts to at least 22 cataclysmic variables (CVs) and 29 chromospherically active binaries (BY Dra and RS CVn systems) in 47 Tuc. These identifications are all based on tight astrometric matches between X-ray sources and objects with unusual (non-main-sequence [non-MS]) optical colors and/or optical variability. Several other CVs and active binaries have likely been found, but these have marginal significance because of larger offsets between the X-ray and optical positions, or colors and variability that are not statistically convincing. These less secure optical identifications are not subsequently discussed in detail. In the U versus U-V color-magnitude diagram (CMD), where the U band corresponds to either F336W or F300W, the CVs all show evidence for blue colors compared with the MS, but most of them fall close to the main sequence in the V versus V-I CMD, showing that the secondary stars dominate the optical light. The X-ray-detected active binaries have magnitude offsets above the MS (in both the U versus U-V or V versus V-I CMDs) that are indistinguishable from those of the much larger sample of optical variables (eclipsing and contact binaries and BY Dra variables) detected in the recent WFPC2 studies of Albrow et al. We also present the results of a new, deeper search for optical companions to millisecond pulsars (MSPs). One possible optical companion to an MSP (47 Tuc T) was found, adding to the two optical companions already known. Finally, we study several blue stars with periodic variability from Albrow et al. that show little or no evidence for X-ray emission. The optical colors of these objects differ from those of 47 Tuc (and field) CVs. An accompanying paper will present time series results for these optical identifications and will discuss X-ray-to-optical flux ratios, spatial distributions, and an overall interpretation of the results. Based on observations with the NASA/ESA Hubble Space Telescope obtained at STScI, which is operated by AURA, Inc., under NASA contract NAS 5-26555.

NASA's Hubble Captures the Beating Heart of the Crab Nebula

NASA Image and Video Library

2017-12-08

Peering deep into the core of the Crab Nebula, this close-up image reveals the beating heart of one of the most historic and intensively studied remnants of a supernova, an exploding star. The inner region sends out clock-like pulses of radiation and tsunamis of charged particles embedded in magnetic fields. The neutron star at the very center of the Crab Nebula has about the same mass as the sun but compressed into an incredibly dense sphere that is only a few miles across. Spinning 30 times a second, the neutron star shoots out detectable beams of energy that make it look like it's pulsating. The NASA Hubble Space Telescope snapshot is centered on the region around the neutron star (the rightmost of the two bright stars near the center of this image) and the expanding, tattered, filamentary debris surrounding it. Hubble's sharp view captures the intricate details of glowing gas, shown in red, that forms a swirling medley of cavities and filaments. Inside this shell is a ghostly blue glow that is radiation given off by electrons spiraling at nearly the speed of light in the powerful magnetic field around the crushed stellar core. The neutron star is a showcase for extreme physical processes and unimaginable cosmic violence. Bright wisps are moving outward from the neutron star at half the speed of light to form an expanding ring. It is thought that these wisps originate from a shock wave that turns the high-speed wind from the neutron star into extremely energetic particles. When this "heartbeat" radiation signature was first discovered in 1968, astronomers realized they had discovered a new type of astronomical object. Now astronomers know it's the archetype of a class of supernova remnants called pulsars - or rapidly spinning neutron stars. These interstellar "lighthouse beacons" are invaluable for doing observational experiments on a variety of astronomical phenomena, including measuring gravity waves. Observations of the Crab supernova were recorded by Chinese astronomers in 1054 A.D. The nebula, bright enough to be visible in amateur telescopes, is located 6,500 light-years away in the constellation Taurus. Credits: NASA and ESA, Acknowledgment: J. Hester (ASU) and M. Weisskopf (NASA/MSFC) NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Like us on Facebook Find us on Instagram

A First Robust Measurement of the Aging of Field Low Mass X-ray Binary Populations from Hubble and Chandra

NASA Astrophysics Data System (ADS)

Lehmer, Bret

Our understanding of X-ray binary (XRB) formation and evolution have been revolutionized by HST and Chandra by allowing us to study in detail XRBs in extragalactic environments. Theoretically, XRB formation is sensitive to parent stellar population properties like metallicity and stellar age. These dependencies not only make XRBs promising populations for aiding in the measurement of galaxy properties themselves, but also have important astrophysical implications. For example, due to the relatively young stellar ages and primordial metallicities in the early Universe (z > 3), it is predicted that XRBs were more luminous than today and played a significant role in the heating of the intergalactic medium. Unlocking the potential of XRBs as useful probes of galaxy properties and understanding in detail their evolutionary pathways critically requires empirical constraints using well-studied galaxies that span a variety of evolutionary stages. In this ADAP, we will use the combined power of archival observations from Hubble and Chandra data of 16 nearby early-type galaxies to study how low-mass XRBs (LMXBs) populations evolve with age. LMXBs are critically important since they are the most numerous XRBs in the MW and are expected to dominate the normal galaxy Xray emissivity of the Universe out to z ~ 2. Understanding separately LMXBs that form via dynamical interactions (e.g., in globular clusters; GCs) versus those that form in-situ in galactic fields is an important poorly constrained area of XRB astrophysics. We are guided by the following key questions: 1. How does the shape and normalization of the field LMXB X-ray luminosity function (XLF) evolve as parent stellar populations age? Using theoretical population synthesis models, what can we learn about the evolution of contributions from various LMXB donor stars (e.g., red-giant, main-sequence, and white dwarf donors)? 2. Is there any evidence that globular cluster (GC) LMXBs seeded field LMXB populations through the dissolving of GCs or LMXBs being kicked out of their parent GCs? 3. What implications do our results have for the evolution of LMXBs throughout cosmic history and X-ray emission observed in distant galaxy populations (e.g., in the Chandra Deep Field surveys)? The combination of HST and Chandra are critical for addressing these questions, as HST can be used to decipher between GC and field LMXBs and Chandra can detect the sources. We will make public HST and Chandra data and catalogs of X-ray sources and GCs, and will include basic properties (eg.., GC sizes, colors, LMXB spectral shapes, fluxes, luminosities).

Hubble Legacy Archive And The Public

NASA Astrophysics Data System (ADS)

Harris, Jessica; Whitmore, B.; Eisenhamer, B.; Bishop, M.; Knisely, L.

2012-01-01

The Hubble Legacy Archive (HLA) at the Space Telescope Science Institute (STScI) hosts the Image of the Month (IOTM) Series. The HLA is a joint project of STScI, the Space Telescope European Coordinating Facility (ST-ECF), and the Canadian Astronomy Data Centre (CADC). The HLA is designed optimize science from the Hubble Space Telescope by providing online enhanced Hubble products and advanced browsing capabilities. The IOTM's are created for astronomers and the public to highlight various features within HLA, such as the "Interactive Display", "Footprint” and "Inventory” features to name a few. We have been working with the Office of Public Outreach (OPO) to create a standards based educational module for middle school to high school students of the IOTM: Rings and the Moons of Uranus. The set of Uranus activities are highlighted by a movie that displays the orbit of five of Uranus’ largest satellites. We made the movie based on eight visits of Uranus from 2000-06-16 to 2000-06-18, using the PC chip on the Wide Field Planetary Camera 2 (WFPC2) and filter F850LP (proposal ID: 8680). Students will be engaged in activities that will allow them to "discover” the rings and satellites around Uranus, calculate the orbit of the satellites, and introduces students to analyze real data from Hubble.

Constraints on Io's interior from auroral spot oscillations

NASA Astrophysics Data System (ADS)

Roth, Lorenz; Saur, Joachim; Retherford, Kurt D.; Blöcker, Aljona; Strobel, Darrell F.; Feldman, Paul D.

2017-02-01

The morphology of Io's aurora is dominated by bright spots near the equator that oscillate up and down in approximate correlation with the oscillating orientation of the Jovian magnetospheric field. Analyzing Hubble Space Telescope images, we find that the auroral spots oscillate in phase with the time-variable Jovian magnetic field at Io and that the amplitude of the spot oscillations is reduced by 15% (±5%) with respect to the amplitude of the magnetic field oscillation. We investigate the effects of Io's plasma interaction and magnetic induction in the moon's interior on the magnetic field topology and the aurora oscillations using a magnetohydrodynamic (MHD) simulation and an analytical induction model. The results from the MHD simulation suggest that the plasma interaction has minor effects on the oscillations, while the magnetic induction generally reduces magnetic field oscillations near the surface. However, the analytical model shows that induction in any near-surface layer for which the skin depth is larger than the thickness—like a conductive magma ocean—would induce a phase shift, in conflict with the observations. Under the assumption that the spot oscillations represent the magnetic field oscillation, we constrain the conductance of a near-surface layer to 1 × 103 S or lower. A magma ocean with conductances of 104 S or higher as derived from Galileo magnetometer measurements would cause overly strong attenuation of the amplitude in addition to the irreconcilable phase shift. The observed weakly attenuated, in-phase spot oscillation is consistent with induction in a deep, highly conductive layer like Io's metallic core.

Astronauts Greg Harbaugh and Joe Tanner suit up for training in WETF

NASA Image and Video Library

1996-06-11

S96-12829 (10 June 1996) --- Awaiting his helmet, astronaut Joseph R. Tanner, STS-82 mission specialist assigned to extravehicular activity (EVA) involved with the servicing of the Hubble Space Telescope (HST), is about to be submerged in a 25-ft. deep pool at the Johnson Space Center's weightless environment training facility (WET-F). Obscured in this frame, astronaut Gregory J. Harbaugh was on the other side of the platform, waiting to join Tanner in the spacewalk rehearsal.

Fermionic influence on inflationary fluctuations

NASA Astrophysics Data System (ADS)

Boyanovsky, Daniel

2016-04-01

Motivated by apparent persistent large scale anomalies in the cosmic microwave background we study the influence of fermionic degrees of freedom on the dynamics of inflaton fluctuations as a possible source of violations of (nearly) scale invariance on cosmological scales. We obtain the nonequilibrium effective action of an inflaton-like scalar field with Yukawa interactions (YD ,M) to light fermionic degrees of freedom both for Dirac and Majorana fields in de Sitter space-time. The effective action leads to Langevin equations of motion for the fluctuations of the inflaton-like field, with self-energy corrections and a stochastic Gaussian noise. We solve the Langevin equation in the super-Hubble limit implementing a dynamical renormalization group resummation. For a nearly massless inflaton its power spectrum of super-Hubble fluctuations is enhanced, P (k ;η )=(H/2 π )2eγt[-k η ] with γt[-k η ]=1/6 π2 [∑i =1 NDYi,D 2+2 ∑j =1 NMYj,M 2]{ln2[-k η ]-2 ln [-k η ]ln [-k η0]} for ND Dirac and NM Majorana fermions, and η0 is the renormalization scale at which the inflaton mass vanishes. The full power spectrum is shown to be renormalization group invariant. These corrections to the super-Hubble power spectrum entail a violation of scale invariance as a consequence of the coupling to the fermionic fields. The effective action is argued to be exact in the limit of a large number of fermionic fields. A cancellation between the enhancement from fermionic degrees of freedom and suppression from light scalar degrees of freedom conformally coupled to gravity suggests the possibility of a finely tuned supersymmetry among these fields.

Hubble Sees Spiral in Serpens

NASA Image and Video Library

2017-12-08

This new NASA/ESA Hubble Space Telescope image shows a beautiful spiral galaxy known as PGC 54493, located in the constellation of Serpens (The Serpent). This galaxy is part of a galaxy cluster that has been studied by astronomers exploring an intriguing phenomenon known as weak gravitational lensing. This effect, caused by the uneven distribution of matter (including dark matter) throughout the Universe, has been explored via surveys such as the Hubble Medium Deep Survey. Dark matter is one of the great mysteries in cosmology. It behaves very differently from ordinary matter as it does not emit or absorb light or other forms of electromagnetic energy — hence the term "dark." Even though we cannot observe dark matter directly, we know it exists. One prominent piece of evidence for the existence of this mysterious matter is known as the "galaxy rotation problem." Galaxies rotate at such speeds and in such a way that ordinary matter alone — the stuff we see — would not be able to hold them together. The amount of mass that is "missing" visibly is dark matter, which is thought to make up some 27 percent of the total contents of the Universe, with dark energy and normal matter making up the rest. PGC 55493 has been studied in connection with an effect known as cosmic shearing. This is a weak gravitational lensing effect that creates tiny distortions in images of distant galaxies. European Space Agency ESA/Hubble & NASA, Acknowledgement: Judy Schmidt NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Like us on Facebook Find us on Instagram

An automatic taxonomy of galaxy morphology using unsupervised machine learning

NASA Astrophysics Data System (ADS)

Hocking, Alex; Geach, James E.; Sun, Yi; Davey, Neil

2018-01-01

We present an unsupervised machine learning technique that automatically segments and labels galaxies in astronomical imaging surveys using only pixel data. Distinct from previous unsupervised machine learning approaches used in astronomy we use no pre-selection or pre-filtering of target galaxy type to identify galaxies that are similar. We demonstrate the technique on the Hubble Space Telescope (HST) Frontier Fields. By training the algorithm using galaxies from one field (Abell 2744) and applying the result to another (MACS 0416.1-2403), we show how the algorithm can cleanly separate early and late type galaxies without any form of pre-directed training for what an 'early' or 'late' type galaxy is. We then apply the technique to the HST Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey (CANDELS) fields, creating a catalogue of approximately 60 000 classifications. We show how the automatic classification groups galaxies of similar morphological (and photometric) type and make the classifications public via a catalogue, a visual catalogue and galaxy similarity search. We compare the CANDELS machine-based classifications to human-classifications from the Galaxy Zoo: CANDELS project. Although there is not a direct mapping between Galaxy Zoo and our hierarchical labelling, we demonstrate a good level of concordance between human and machine classifications. Finally, we show how the technique can be used to identify rarer objects and present lensed galaxy candidates from the CANDELS imaging.

The HST Frontier Fields: Complete High-Level Science Data Products for All 6 Clusters

NASA Astrophysics Data System (ADS)

Koekemoer, Anton M.; Mack, Jennifer; Lotz, Jennifer M.; Borncamp, David; Khandrika, Harish G.; Lucas, Ray A.; Martlin, Catherine; Porterfield, Blair; Sunnquist, Ben; Anderson, Jay; Avila, Roberto J.; Barker, Elizabeth A.; Grogin, Norman A.; Gunning, Heather C.; Hilbert, Bryan; Ogaz, Sara; Robberto, Massimo; Sembach, Kenneth; Flanagan, Kathryn; Mountain, Matt; HST Frontier Fields Team

2017-01-01

The Hubble Space Telescope Frontier Fields program (PI: J. Lotz) is a large Director's Discretionary program of 840 orbits, to obtain ultra-deep observations of six strong lensing clusters of galaxies, together with parallel deep blank fields, making use of the strong lensing amplification by these clusters of distant background galaxies to detect the faintest galaxies currently observable in the high-redshift universe. The entire program has now completed successfully for all 6 clusters, namely Abell 2744, Abell S1063, Abell 370, MACS J0416.1-2403, MACS J0717.5+3745 and MACS J1149.5+2223,. Each of these was observed over two epochs, to a total depth of 140 orbits on the main cluster and an associated parallel field, obtaining images in ACS (F435W, F606W, F814W) and WFC3/IR (F105W, F125W, F140W, F160W) on both the main cluster and the parallel field in all cases. Full sets of high-level science products have been generated for all these clusters by the team at STScI, including cumulative-depth data releases during each epoch, as well as full-depth releases after the completion of each epoch. These products include all the full-depth distortion-corrected drizzled mosaics and associated products for each cluster, which are science-ready to facilitate the construction of lensing models as well as enabling a wide range of other science projects. Many improvements beyond default calibration for ACS and WFC3/IR are implemented in these data products, including corrections for persistence, time-variable sky, and low-level dark current residuals, as well as improvements in astrometric alignment to achieve milliarcsecond-level accuracy. The full set of resulting high-level science products and mosaics are publicly delivered to the community via the Mikulski Archive for Space Telescopes (MAST) to enable the widest scientific use of these data, as well as ensuring a public legacy dataset of the highest possible quality that is of lasting value to the entire community.

The HST Frontier Fields: Complete Observations and High-Level Science Data Products for All 6 Clusters

NASA Astrophysics Data System (ADS)

Koekemoer, Anton M.; Mack, Jennifer; Lotz, Jennifer M.; Borncamp, David; Khandrika, Harish G.; Lucas, Ray A.; Martlin, Catherine; Martlin, Catherine; Porterfield, Blair; Sunnquist, Ben; Anderson, Jay; Avila, Roberto J.; Barker, Elizabeth A.; Grogin, Norman A.; Gunning, Heather C.; Hilbert, Bryan; Ogaz, Sara; Robberto, Massimo; Sembach, Kenneth; Flanagan, Kathryn; Mountain, Matt; HST Frontier Fields Team

2017-06-01

The Hubble Space Telescope Frontier Fields program is a large Director's Discretionary program of 840 orbits, to obtain ultra-deep observations of six strong lensing clusters of galaxies, together with parallel deep blank fields, making use of the strong lensing amplification by these clusters of distant background galaxies to detect the faintest galaxies currently observable in the high-redshift universe. The entire program has now completed successfully for all 6 clusters, namely Abell 2744, Abell S1063, Abell 370, MACS J0416.1-2403, MACS J0717.5+3745 and MACS J1149.5+2223,. Each of these was observed over two epochs, to a total depth of 140 orbits on the main cluster and an associated parallel field, obtaining images in ACS (F435W, F606W, F814W) and WFC3/IR (F105W, F125W, F140W, F160W) on both the main cluster and the parallel field in all cases. Full sets of high-level science products have been generated for all these clusters by the team at STScI, including cumulative-depth data releases during each epoch, as well as full-depth releases after the completion of each epoch. These products include all the full-depth distortion-corrected drizzled mosaics and associated products for each cluster, which are science-ready to facilitate the construction of lensing models as well as enabling a wide range of other science projects. Many improvements beyond default calibration for ACS and WFC3/IR are implemented in these data products, including corrections for persistence, time-variable sky, and low-level dark current residuals, as well as improvements in astrometric alignment to achieve milliarcsecond-level accuracy. The full set of resulting high-level science products and mosaics are publicly delivered to the community via the Mikulski Archive for Space Telescopes (MAST) to enable the widest scientific use of these data, as well as ensuring a public legacy dataset of the highest possible quality that is of lasting value to the entire community.

CANDELS Visual Classifications: Scheme, Data Release, and First Results

NASA Astrophysics Data System (ADS)

Kartaltepe, Jeyhan S.; Mozena, Mark; Kocevski, Dale; McIntosh, Daniel H.; Lotz, Jennifer; Bell, Eric F.; Faber, Sandy; Ferguson, Harry; Koo, David; Bassett, Robert; Bernyk, Maksym; Blancato, Kirsten; Bournaud, Frederic; Cassata, Paolo; Castellano, Marco; Cheung, Edmond; Conselice, Christopher J.; Croton, Darren; Dahlen, Tomas; de Mello, Duilia F.; DeGroot, Laura; Donley, Jennifer; Guedes, Javiera; Grogin, Norman; Hathi, Nimish; Hilton, Matt; Hollon, Brett; Koekemoer, Anton; Liu, Nick; Lucas, Ray A.; Martig, Marie; McGrath, Elizabeth; McPartland, Conor; Mobasher, Bahram; Morlock, Alice; O'Leary, Erin; Peth, Mike; Pforr, Janine; Pillepich, Annalisa; Rosario, David; Soto, Emmaris; Straughn, Amber; Telford, Olivia; Sunnquist, Ben; Trump, Jonathan; Weiner, Benjamin; Wuyts, Stijn; Inami, Hanae; Kassin, Susan; Lani, Caterina; Poole, Gregory B.; Rizer, Zachary

2015-11-01

We have undertaken an ambitious program to visually classify all galaxies in the five CANDELS fields down to H < 24.5 involving the dedicated efforts of over 65 individual classifiers. Once completed, we expect to have detailed morphological classifications for over 50,000 galaxies spanning 0 < z < 4 over all the fields, with classifications from 3 to 5 independent classifiers for each galaxy. Here, we present our detailed visual classification scheme, which was designed to cover a wide range of CANDELS science goals. This scheme includes the basic Hubble sequence types, but also includes a detailed look at mergers and interactions, the clumpiness of galaxies, k-corrections, and a variety of other structural properties. In this paper, we focus on the first field to be completed—GOODS-S, which has been classified at various depths. The wide area coverage spanning the full field (wide+deep+ERS) includes 7634 galaxies that have been classified by at least three different people. In the deep area of the field, 2534 galaxies have been classified by at least five different people at three different depths. With this paper, we release to the public all of the visual classifications in GOODS-S along with the Perl/Tk GUI that we developed to classify galaxies. We present our initial results here, including an analysis of our internal consistency and comparisons among multiple classifiers as well as a comparison to the Sérsic index. We find that the level of agreement among classifiers is quite good (>70% across the full magnitude range) and depends on both the galaxy magnitude and the galaxy type, with disks showing the highest level of agreement (>50%) and irregulars the lowest (<10%). A comparison of our classifications with the Sérsic index and rest-frame colors shows a clear separation between disk and spheroid populations. Finally, we explore morphological k-corrections between the V-band and H-band observations and find that a small fraction (84 galaxies in total) are classified as being very different between these two bands. These galaxies typically have very clumpy and extended morphology or are very faint in the V-band.

Cluster mass calibration at high redshift: HST weak lensing analysis of 13 distant galaxy clusters from the South Pole Telescope Sunyaev-Zel'dovich Survey

NASA Astrophysics Data System (ADS)

Schrabback, T.; Applegate, D.; Dietrich, J. P.; Hoekstra, H.; Bocquet, S.; Gonzalez, A. H.; von der Linden, A.; McDonald, M.; Morrison, C. B.; Raihan, S. F.; Allen, S. W.; Bayliss, M.; Benson, B. A.; Bleem, L. E.; Chiu, I.; Desai, S.; Foley, R. J.; de Haan, T.; High, F. W.; Hilbert, S.; Mantz, A. B.; Massey, R.; Mohr, J.; Reichardt, C. L.; Saro, A.; Simon, P.; Stern, C.; Stubbs, C. W.; Zenteno, A.

2018-02-01

We present an HST/Advanced Camera for Surveys (ACS) weak gravitational lensing analysis of 13 massive high-redshift (zmedian = 0.88) galaxy clusters discovered in the South Pole Telescope (SPT) Sunyaev-Zel'dovich Survey. This study is part of a larger campaign that aims to robustly calibrate mass-observable scaling relations over a wide range in redshift to enable improved cosmological constraints from the SPT cluster sample. We introduce new strategies to ensure that systematics in the lensing analysis do not degrade constraints on cluster scaling relations significantly. First, we efficiently remove cluster members from the source sample by selecting very blue galaxies in V - I colour. Our estimate of the source redshift distribution is based on Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey (CANDELS) data, where we carefully mimic the source selection criteria of the cluster fields. We apply a statistical correction for systematic photometric redshift errors as derived from Hubble Ultra Deep Field data and verified through spatial cross-correlations. We account for the impact of lensing magnification on the source redshift distribution, finding that this is particularly relevant for shallower surveys. Finally, we account for biases in the mass modelling caused by miscentring and uncertainties in the concentration-mass relation using simulations. In combination with temperature estimates from Chandra we constrain the normalization of the mass-temperature scaling relation ln (E(z)M500c/1014 M⊙) = A + 1.5ln (kT/7.2 keV) to A=1.81^{+0.24}_{-0.14}(stat.) {± } 0.09(sys.), consistent with self-similar redshift evolution when compared to lower redshift samples. Additionally, the lensing data constrain the average concentration of the clusters to c_200c=5.6^{+3.7}_{-1.8}.

GLASS: spatially resolved spectroscopy of lensed galaxies in the Frontier Fields

NASA Astrophysics Data System (ADS)

Jones, Tucker; Treu, Tommaso; Brammer, Gabriel; Borello Schmidt, Kasper; Malkan, Matthew A.

2015-08-01

The Grism Lens-Amplified Survey from Space (GLASS) has obtained slitless near-IR spectroscopy of 10 galaxy clusters selected for their strong lensing properties, including all six Hubble Frontier Fields. Slitless grism spectra are ideal for mapping emission lines such as [O II], [O III], and H alpha at z=1-3. The combination of strong gravitational lensing and HST's diffraction limit provides excellent sensitivity with spatial resolution as fine as 100 pc for highly magnified sources, and ~500 pc for less magnified sources near the edge of the field of view. The GLASS survey represents the largest spectroscopic sample with such high resolution at z>1. GLASS and Hubble Frontier Field data provide the distribution of stellar mass, star formation, gas-phase metallicity, and other aspects of the physical structure of high redshift galaxies, reaching unprecedented stellar masses as low as ~10^7 Msun at z=2. I will discuss precise measurements of these physical properties and implications for galaxy evolution.

Hubble Spies Spiral Galaxy

NASA Image and Video Library

2017-12-08

Spiral galaxy NGC 3274 is a relatively faint galaxy located over 20 million light-years away in the constellation of Leo (The Lion). This NASA/ESA Hubble Space Telescope image comes courtesy of Hubble's Wide Field Camera 3 (WFC3), whose multi-color vision allows astronomers to study a wide range of targets, from nearby star formation to galaxies in the most remote regions of the cosmos. This image combines observations gathered in five different filters, bringing together ultraviolet, visible and infrared light to show off NGC 3274 in all its glory. NGC 3274 was discovered by Wilhelm Herschel in 1783. The galaxy PGC 213714 is also visible on the upper right of the frame, located much farther away from Earth. Image Credit: ESA/Hubble & NASA, D. Calzetti NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Like us on Facebook Find us on Instagram

Hubble Space Telescope Metallized Teflon(registered trademark) FEP Thermal Control Materials: On-Orbit Degradation and Post-Retrieval Analysis

NASA Technical Reports Server (NTRS)

Townsend, Jacqueline A.; Hansen, Patricia A.; Dever, J. A.; deGroh, K. K.; Banks, B.; Wang, L.; He, C.

1988-01-01

During the Hubble Space Telescope (HST) Second Servicing Mission (SM2), degradation of unsupported Teflon(Registered Trademark) FEP (fluorinated ethylene propylene), used as the outer layer of the multilayer insulation (MLI) blankets, was evident as large cracks on the telescope light shield. A sample of the degraded outer layer was retrieved during the mission and returned to Earth for ground testing and evaluation. The results of the Teflon(Registered Trademark) FEP sample evaluation and additional testing of pristine Teflon(Registered Trademark) FEP led the investigative team to theorize that the HST damage was caused by thermal cycling with deep-layer damage from electron and proton radiation which allowed the propagation of cracks along stress concentrations , and that the damage increased with the combined total dose of electrons, protons, UV and x-rays along with thermal cycling. This paper discusses the testing and evaluation of the retrieved Teflon(Registered Trademark) FEP.

Space Shuttle Projects

NASA Image and Video Library

1993-10-01

Designed by the mission crew members, the STS-61 crew insignia depicts the astronaut symbol superimposed against the sky with the Earth underneath. Also seen are two circles representing the optical configuration of the Hubble Space Telescope (HST). Light is focused by reflections from a large primary mirror and a smaller secondary mirror. The light is analyzed by various instruments and, according to the crew members, brings to us on Earth knowledge about planets, stars, galaxies and other celestial objects, allowing us to better understand the complex physical processes at work in the universe. The Space Shuttle Endeavour is also represented as the fundamental tool that allows the crew to perform the first servicing of the Hubble Space Telescope so its scientific deep space mission may be extended for several years to come. The overall design of the emblem, with lines converging to a high point, is also a symbolic representation of the large-scale Earth-based effort which involves space agencies, industry, and the universities to reach goals of knowledge and perfection.

Deep space target location with Hubble Space Telescope (HST) and Hipparcos data

NASA Technical Reports Server (NTRS)

Null, George W.

1988-01-01

Interplanetary spacecraft navigation requires accurate a priori knowledge of target positions. A concept is presented for attaining improved target ephemeris accuracy using two future Earth-orbiting optical observatories, the European Space Agency (ESA) Hipparcos observatory and the Nasa Hubble Space Telescope (HST). Assuming nominal observatory performance, the Hipparcos data reduction will provide an accurate global star catalog, and HST will provide a capability for accurate angular measurements of stars and solar system bodies. The target location concept employs HST to observe solar system bodies relative to Hipparcos catalog stars and to determine the orientation (frame tie) of these stars to compact extragalactic radio sources. The target location process is described, the major error sources discussed, the potential target ephemeris error predicted, and mission applications identified. Preliminary results indicate that ephemeris accuracy comparable to the errors in individual Hipparcos catalog stars may be possible with a more extensive HST observing program. Possible future ground and spacebased replacements for Hipparcos and HST astrometric capabilities are also discussed.

Analysis of Retrieved Hubble Space Telescope Thermal Control Materials

NASA Technical Reports Server (NTRS)

Townsend, Jacqueline A.; Hansen, Patricia A.; Dever, Joyce A.; Triolo, Jack J.

1998-01-01

The mechanical and optical properties of the thermal control materials on the Hubble Space Telescope (HST) have degraded over the nearly seven years the telescope has been in orbit. Astronaut observations and photographs from the Second Servicing Mission (SM2) revealed large cracks in the metallized Teflon FEP, the outer-layer of the multi-layer insulation (MLI), in many locations around the telescope. Also, the emissivity of the bonded metallized Teflon FEP radiator surfaces of the telescope has increased over time. Samples of the top layer of the MLI and radiator material were retrieved during SM2, and a thorough investigation into the de-radiation followed in order to determine the primary cause of the damage. Mapping of the cracks on HST and the ground testing showed that thermal cycling with deep-layer damage from electron and proton radiation are necessary to cause the observed embrittlement. Further, strong, evidence was found indicating that chain scission (reduced molecular weight) is the dominant form of damage to the metallized Teflon FEP.

Evidence of Primordial Clustering around the QSO SDSS J1030+0524 at z=6.28

NASA Astrophysics Data System (ADS)

Stiavelli, M.; Djorgovski, S. G.; Pavlovsky, C.; Scarlata, C.; Stern, D.; Mahabal, A.; Thompson, D.; Dickinson, M.; Panagia, N.; Meylan, G.

2005-03-01

We present tentative evidence of primordial clustering, manifested as an excess of color-selected objects in the field of the QSO SDSS J1030+0524 at redshift z=6.28. We have selected objects red in i775-z850 on the basis of Hubble Space Telescope Advanced Camera for Surveys imaging of a field centered on the QSO. Compared to data at comparable depth obtained by the Great Observatories Origins Deep Survey, we find an excess of objects with i775-z850>=1.5 in the QSO field. The significance of the detection is estimated to be ~97% on the basis of the counts alone and increases to 99.4% if one takes into account the color distribution. If confirmed, this would represent the highest redshift example of galaxy clustering and would have implications on models for the growth of structure. Bias-driven clustering of first luminous objects forming in the highest peaks of the primordial density field is expected in most models of early structure formation. The redshift of one of the candidates has been found to be z=5.970 by our spectroscopy with the Keck I Low Resolution Imaging Spectrometer, confirming the validity of our color selection. Based, in part, on data obtained at the W. M. Keck Observatory, which is operated as a scientific partnership between the California Institute of Technology, the University of California, and NASA, and was made possible by the generous financial support of the W. M. Keck Foundation.

Hubble Supernova Bubble Resembles Holiday Ornament

NASA Image and Video Library

2017-12-08

NASA image release December 14, 2010 A delicate sphere of gas, photographed by NASA's Hubble Space Telescope, floats serenely in the depths of space. The pristine shell, or bubble, is the result of gas that is being shocked by the expanding blast wave from a supernova. Called SNR 0509-67.5 (or SNR 0509 for short), the bubble is the visible remnant of a powerful stellar explosion in the Large Magellanic Cloud (LMC), a small galaxy about 160,000 light-years from Earth. Ripples in the shell's surface may be caused by either subtle variations in the density of the ambient interstellar gas, or possibly driven from the interior by pieces of the ejecta. The bubble-shaped shroud of gas is 23 light-years across and is expanding at more than 11 million miles per hour (5,000 kilometers per second). Astronomers have concluded that the explosion was one of an especially energetic and bright variety of supernovae. Known as Type Ia, such supernova events are thought to result from a white dwarf star in a binary system that robs its partner of material, takes on much more mass than it is able to handle, and eventually explodes. Hubble's Advanced Camera for Surveys observed the supernova remnant on Oct. 28, 2006 with a filter that isolates light from glowing hydrogen seen in the expanding shell. These observations were then combined with visible-light images of the surrounding star field that were imaged with Hubble's Wide Field Camera 3 on Nov. 4, 2010. With an age of about 400 years as seen from Earth, the supernova might have been visible to southern hemisphere observers around the year 1600, however, there are no known records of a "new star" in the direction of the LMC near that time. A more recent supernova in the LMC, SN 1987A, did catch the eye of Earth viewers and continues to be studied with ground- and space-based telescopes, including Hubble. For images and more information about SNR 0509, visit: hubblesite.org/news/2010/27 heritage.stsci.edu/2010/27 www.nasa.gov/hubble The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency. NASA's Goddard Space Flight Center manages the telescope. The Space Telescope Science Institute (STScI) conducts Hubble science operations. STScI is operated for NASA by the Association of Universities for Research in Astronomy, Inc., in Washington, D.C. Credit: NASA, ESA, and the Hubble Heritage Team (STScI/AURA) Acknowledgment: J. Hughes (Rutgers University) NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Join us on Facebook

NASA’s Hubble Telescope Finds Potential Kuiper Belt Targets for New Horizons Pluto Mission

NASA Image and Video Library

2017-12-08

This is an artist’s impression of a Kuiper Belt object (KBO), located on the outer rim of our solar system at a staggering distance of 4 billion miles from the Sun. A HST survey uncovered three KBOs that are potentially reachable by NASA’s New Horizons spacecraft after it passes by Pluto in mid-2015. Credit: NASA, ESA, and G. Bacon (STScI) --- Peering out to the dim, outer reaches of our solar system, NASA’s Hubble Space Telescope has uncovered three Kuiper Belt objects (KBOs) the agency’s New Horizons spacecraft could potentially visit after it flies by Pluto in July 2015. The KBOs were detected through a dedicated Hubble observing program by a New Horizons search team that was awarded telescope time for this purpose. “This has been a very challenging search and it’s great that in the end Hubble could accomplish a detection – one NASA mission helping another,” said Alan Stern of the Southwest Research Institute (SwRI) in Boulder, Colorado, principal investigator of the New Horizons mission. The Kuiper Belt is a vast rim of primordial debris encircling our solar system. KBOs belong to a unique class of solar system objects that has never been visited by spacecraft and which contain clues to the origin of our solar system. The KBOs Hubble found are each about 10 times larger than typical comets, but only about 1-2 percent of the size of Pluto. Unlike asteroids, KBOs have not been heated by the sun and are thought to represent a pristine, well preserved deep-freeze sample of what the outer solar system was like following its birth 4.6 billion years ago. The KBOs found in the Hubble data are thought to be the building blocks of dwarf planets such as Pluto. Read more: 1.usa.gov/1vzUcyK NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Like us on Facebook Find us on Instagram

KSC-2009-2983

NASA Image and Video Library

2009-05-08

CAPE CANAVERAL, Fla. – On Launch Pad 39A at NASA's Kennedy Space Center in Florida, space shuttle Atlantis' payload bay is filled with hardware for the STS-125 mission to service NASA's Hubble Space Telescope. At the bottom is the Flight Support System with the Soft Capture mechanism. At center is the Orbital Replacement Unit Carrier with the Cosmic Origins Spectrograph, or COS, and an IMAX 3D camera. At top is the Super Lightweight Interchangeable Carrier with the Wide Field Camera 3. Atlantis' crew will service NASA's Hubble Space Telescope for the fifth and final time. The flight will include five spacewalks during which astronauts will refurbish and upgrade the telescope with state-of-the-art science instruments. As a result, Hubble's capabilities will be expanded and its operational lifespan extended through at least 2014. Photo credit: NASA/Kim Shiflett

KSC-2009-3074

NASA Image and Video Library

2009-05-11

CAPE CANAVERAL, Fla. – In the Firing Room at NASA's Kennedy Space Center in Florida, Steven Hoyle, left, and Russ Brucker, center, receive a VIP award for their efforts associated with the STS-125 mission and NASA's Hubble Space Telescope. Hoyle is the payload test operations manager with NASA's Goddard Space Flight Center; Brucker is the Atlantis payload project manager with United Space Alliance. A crew of seven launched today on space shuttle Atlantis to service Hubble. Liftoff was on time at 2:01 p.m. EDT. Atlantis' 11-day flight will include five spacewalks to refurbish and upgrade the telescope with state-of-the-art science instruments that will expand Hubble's capabilities and extend its operational lifespan through at least 2014. The payload includes a Wide Field Camera 3, fine guidance sensor and the Cosmic Origins Spectrograph. Photo credit: NASA/Kim Shiflett

Galaxy Zoo: morphological classifications for 120 000 galaxies in HST legacy imaging

NASA Astrophysics Data System (ADS)

Willett, Kyle W.; Galloway, Melanie A.; Bamford, Steven P.; Lintott, Chris J.; Masters, Karen L.; Scarlata, Claudia; Simmons, B. D.; Beck, Melanie; Cardamone, Carolin N.; Cheung, Edmond; Edmondson, Edward M.; Fortson, Lucy F.; Griffith, Roger L.; Häußler, Boris; Han, Anna; Hart, Ross; Melvin, Thomas; Parrish, Michael; Schawinski, Kevin; Smethurst, R. J.; Smith, Arfon M.

2017-02-01

We present the data release paper for the Galaxy Zoo: Hubble (GZH) project. This is the third phase in a large effort to measure reliable, detailed morphologies of galaxies by using crowdsourced visual classifications of colour-composite images. Images in GZH were selected from various publicly released Hubble Space Telescope legacy programmes conducted with the Advanced Camera for Surveys, with filters that probe the rest-frame optical emission from galaxies out to z ˜ 1. The bulk of the sample is selected to have mI814W < 23.5, but goes as faint as mI814W < 26.8 for deep images combined over five epochs. The median redshift of the combined samples is = 0.9 ± 0.6, with a tail extending out to z ≃ 4. The GZH morphological data include measurements of both bulge- and disc-dominated galaxies, details on spiral disc structure that relate to the Hubble type, bar identification, and numerous measurements of clump identification and geometry. This paper also describes a new method for calibrating morphologies for galaxies of different luminosities and at different redshifts by using artificially redshifted galaxy images as a baseline. The GZH catalogue contains both raw and calibrated morphological vote fractions for 119 849 galaxies, providing the largest data set to date suitable for large-scale studies of galaxy evolution out to z ˜ 1.

Structural Safety of a Hubble Space Telescope Science Instrument

NASA Technical Reports Server (NTRS)

Lou, M. C.; Brent, D. N.

1993-01-01

This paper gives an overview of safety requirements related to structural design and verificationof payloads to be launched and/or retrieved by the Space Shuttle. To demonstrate the generalapproach used to implement these requirements in the development of a typical Shuttle payload, theWide Field/Planetary Camera II, a second generation science instrument currently being developed bythe Jet Propulsion Laboratory (JPL) for the Hubble Space Telescope is used as an example. Inaddition to verification of strength and dynamic characteristics, special emphasis is placed upon thefracture control implementation process, including parts classification and fracture controlacceptability.

18 years of science with the Hubble Space Telescope.

PubMed

Dalcanton, Julianne J

2009-01-01

After several decades of planning, the Hubble Space Telescope (HST) was launched in 1990 as the first of NASA's Great Observatories. After a rocky start arising from an error in the fabrication of its main mirror, it went on to change forever many fields of astronomy, and to capture the public's imagination with its images. An ongoing programme of servicing missions has kept the telescope on the cutting edge of astronomical research. Here I review the advances made possible by the HST over the past 18 years.

ACCOUNTING FOR COSMIC VARIANCE IN STUDIES OF GRAVITATIONALLY LENSED HIGH-REDSHIFT GALAXIES IN THE HUBBLE FRONTIER FIELD CLUSTERS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Robertson, Brant E.; Stark, Dan P.; Ellis, Richard S.

Strong gravitational lensing provides a powerful means for studying faint galaxies in the distant universe. By magnifying the apparent brightness of background sources, massive clusters enable the detection of galaxies fainter than the usual sensitivity limit for blank fields. However, this gain in effective sensitivity comes at the cost of a reduced survey volume and, in this Letter, we demonstrate that there is an associated increase in the cosmic variance uncertainty. As an example, we show that the cosmic variance uncertainty of the high-redshift population viewed through the Hubble Space Telescope Frontier Field cluster Abell 2744 increases from ∼35% atmore » redshift z ∼ 7 to ≳ 65% at z ∼ 10. Previous studies of high-redshift galaxies identified in the Frontier Fields have underestimated the cosmic variance uncertainty that will affect the ultimate constraints on both the faint-end slope of the high-redshift luminosity function and the cosmic star formation rate density, key goals of the Frontier Field program.« less

Version 1 of the Hubble Source Catalog

NASA Astrophysics Data System (ADS)

Whitmore, Bradley C.; Allam, Sahar S.; Budavári, Tamás; Casertano, Stefano; Downes, Ronald A.; Donaldson, Thomas; Fall, S. Michael; Lubow, Stephen H.; Quick, Lee; Strolger, Louis-Gregory; Wallace, Geoff; White, Richard L.

2016-06-01

The Hubble Source Catalog is designed to help optimize science from the Hubble Space Telescope (HST) by combining the tens of thousands of visit-based source lists in the Hubble Legacy Archive (HLA) into a single master catalog. Version 1 of the Hubble Source Catalog includes WFPC2, ACS/WFC, WFC3/UVIS, and WFC3/IR photometric data generated using SExtractor software to produce the individual source lists. The catalog includes roughly 80 million detections of 30 million objects involving 112 different detector/filter combinations, and about 160,000 HST exposures. Source lists from Data Release 8 of the HLA are matched using an algorithm developed by Budavári & Lubow. The mean photometric accuracy for the catalog as a whole is better than 0.10 mag, with relative accuracy as good as 0.02 mag in certain circumstances (e.g., bright isolated stars). The relative astrometric residuals are typically within 10 mas, with a value for the mode (I.e., most common value) of 2.3 mas. The absolute astrometric accuracy is better than 0''\\hspace{-0.5em}. 1 for most sources, but can be much larger for a fraction of fields that could not be matched to the PanSTARRS, SDSS, or 2MASS reference systems. In this paper we describe the database design with emphasis on those aspects that enable the users to fully exploit the catalog while avoiding common misunderstandings and potential pitfalls. We provide usage examples to illustrate some of the science capabilities and data quality characteristics, and briefly discuss plans for future improvements to the Hubble Source Catalog.

He2-90'S APPEARANCE DECEIVES ASTRONOMERS

NASA Technical Reports Server (NTRS)

2002-01-01

Astronomers using NASA's Hubble Space Telescope have stumbled upon a mysterious object that is grudgingly yielding clues to its identity. A quick glance at the Hubble picture at top shows that this celestial body, called He2-90, looks like a young, dust-enshrouded star with narrow jets of material streaming from each side. But it's not. The object is classified as a planetary nebula, the glowing remains of a dying, lightweight star. But the Hubble observations suggest that it may not fit that classification, either. The Hubble astronomers now suspect that this enigmatic object may actually be a pair of aging stars masquerading as a single youngster. One member of the duo is a bloated red giant star shedding matter from its outer layers. This matter is then gravitationally captured in a rotating, pancake-shaped accretion disk around a compact partner, which is most likely a young white dwarf (the collapsed remnant of a sun-like star). The stars cannot be seen in the Hubble images because a lane of dust obscures them. The Hubble picture at top shows a centrally bright object with jets, appearing like strings of beads, emanating from both sides of center. (The other streaks of light running diagonally from He2-90 are artificial effects of the telescope's optical system.) Each jet possesses at least six bright clumps of gas, which are speeding along at rates estimated to be at least 375,000 miles an hour (600,000 kilometers an hour). These gaseous salvos are being ejected into space about every 100 years, and may be caused by periodic instabilities in He2-90's accretion disk. The jets from very young stars behave in a similar way. Deep images taken from terrestrial observatories show each jet extending at least 100,000 astronomical units (one astronomical unit equals the Earth-Sun distance, 93 million miles). The jets' relatively modest speed implies that one member of the duo is a white dwarf. Observations by the Compton Gamma-Ray Observatory, however, discovered a gamma-ray source in the vicinity of He2-90, suggesting that the companion may be a neutron star or a black hole (the compact corpses of dying, massive stars). But the jets from accretion disks around neutron stars or black holes travel at a few tenths the speed of light, much faster than the plodding pace of He2-90's jets. The Hubble astronomers are planning more observations to pinpoint the gamma-ray source to determine whether it is associated with He2-90. An accretion disk needs gravity to form. For gravity to create He2-90's disk, the pair of stars must reside at a cozy distance from each other: within about 10 astronomical units. Although the astronomers are uncertain about the details, they believe that magnetic fields associated with the accretion disk produce and constrict the pencil-thin jets seen in the Hubble image. The close-up Hubble photo at bottom shows a dark, flaring, disk-like structure [off-center] bisecting the bright light from the object. The disk is seen edge-on. Although too large to be an accretion disk, this dark, flaring disk may provide indirect proof of the other's existence. Most theories for producing jets require the presence of an accretion disk. The jets are seen streaming from both sides of the central object. The round, white objects at the lower left and upper right corners are two bright clumps of gas in the jets. The astronomers traced the jets to within 1,000 astronomical units of the central obscured star. The star ejected this jet material about 30 years ago. Scientists discovered this puzzling object while taking a census of planetary nebulae. They knew it had been classified as a dying, sun-like star. He2-90 is enshrouded in very hot (17,500 degrees Fahrenheit or 10,000 degrees Kelvin), glowing gas, a typical feature of planetary nebulae. And yet the disk and jets indicated the presence of an embryonic star. The mystified astronomers needed more information. Since embryonic stars are usually associated with cool, dense clouds of gas and dust, they used a ground-based radio telescope in Chile to look for evidence of such a cloud around He2-90. No such cloud was found, and He2-90's neighborhood showed no traces of developing stars. He2-90 lies about 8,000 light-years from Earth in the constellation Centaurus in the southern sky. The images were taken Sept 28, 1999 with the Wide Field and Planetary Camera 2. The images and results appear in the Aug. 1 issue of the Astrophysical Journal Letters. Credits: NASA, Raghvendra Sahai (NASA Jet Propulsion Laboratory), Lars-Ake Nyman (European Southern Observatory, Chile and Onsala Space Observatory, Sweden)

The Grism Lens-amplified Survey from Space (GLASS). X. Sub-kiloparsec Resolution Gas-phase Metallicity Maps at Cosmic Noon behind the Hubble Frontier Fields Cluster MACS1149.6+2223

NASA Astrophysics Data System (ADS)

Wang, Xin; Jones, Tucker A.; Treu, Tommaso; Morishita, Takahiro; Abramson, Louis E.; Brammer, Gabriel B.; Huang, Kuang-Han; Malkan, Matthew A.; Schmidt, Kasper B.; Fontana, Adriano; Grillo, Claudio; Henry, Alaina L.; Karman, Wouter; Kelly, Patrick L.; Mason, Charlotte A.; Mercurio, Amata; Rosati, Piero; Sharon, Keren; Trenti, Michele; Vulcani, Benedetta

2017-03-01

We combine deep Hubble Space Telescope grism spectroscopy with a new Bayesian method to derive maps of gas-phase metallicity for 10 star-forming galaxies at high redshift (1.2≲ z≲ 2.3). Exploiting lensing magnification by the foreground cluster MACS1149.6+2223, we reach sub-kiloparsec spatial resolution and push the limit of stellar mass associated with such high-z spatially resolved measurements below {10}8 {M}⊙ for the first time. Our maps exhibit diverse morphologies, indicative of various effects such as efficient radial mixing from tidal torques, rapid accretion of low-metallicity gas, and other physical processes that can affect the gas and metallicity distributions in individual galaxies. Based upon an exhaustive sample of all existing sub-kiloparesec resolution metallicity gradient measurements at high z, we find that predictions given by analytical chemical evolution models assuming a relatively extended star-formation profile in the early disk-formation phase can explain the majority of observed metallicity gradients, without involving galactic feedback or radial outflows. We observe a tentative correlation between stellar mass and metallicity gradients, consistent with the “downsizing” galaxy formation picture that more massive galaxies are more evolved into a later phase of disk growth, where they experience more coherent mass assembly at all radii and thus show shallower metallicity gradients. In addition to the spatially resolved analysis, we compile a sample of homogeneously cross-calibrated integrated metallicity measurements spanning three orders of magnitude in stellar mass at z ˜ 1.8. We use this sample to study the mass-metallicity relation (MZR) and find that the slope of the observed MZR can rule out the momentum-driven wind model at a 3σ confidence level.

Primordial perturbations in multi-scalar inflation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Abedi, Habib; Abbassi, Amir M., E-mail: h.abedi@ut.ac.ir, E-mail: amabasi@khayam.ut.ac.ir

2017-07-01

Multiple field models of inflation exhibit new features than single field models. In this work, we study the hierarchy of parameters based on Hubble expansion rate in curved field space and derive the system of flow equations that describe their evolutions. Then we focus on obtaining derivatives of number of e-folds with respect to scalar fields during inflation and at hypersurface of the end of inflation.

CHEERS Results from NGC 3393. II. Investigating the Extended Narrow-line Region Using Deep Chandra Observations and Hubble Space Telescope Narrow-line Imaging

DOE Office of Scientific and Technical Information (OSTI.GOV)

Maksym, W. Peter; Fabbiano, Giuseppina; Elvis, Martin

The CHandra Extended Emission Line Region Survey (CHEERS) is an X-ray study of nearby active galactic nuclei (AGNs) designed to take full advantage of Chandra 's unique angular resolution by spatially resolving feedback signatures and effects. In the second paper of a series on CHEERS target NGC 3393, we examine deep high-resolution Chandra images and compare them with Hubble Space Telescope narrow-line images of [O iii], [S ii], and H α , as well as previously unpublished mid-ultraviolet (MUV) images. The X-rays provide unprecedented evidence that the S-shaped arms that envelope the nuclear radio outflows extend only ≲0.″2 (≲50 pc)more » across. The high-resolution multiwavelength data suggest that the extended narrow-line region is a complex multiphase structure in the circumnuclear interstellar medium (ISM). Its ionization structure is highly stratified with respect to outflow-driven bubbles in the bicone and varies dramatically on scales of ∼10 pc. Multiple findings show likely contributions from shocks to the feedback in regions where radio outflows from the AGN most directly influence the ISM. These findings include H α evidence for gas compression and extended MUV emission and are in agreement with existing STIS kinematics. Extended filamentary structure in the X-rays and optical suggests the presence of an undetected plasma component, whose existence could be tested with deeper radio observations.« less

Hubble Observes a New Saturn Storm

NASA Technical Reports Server (NTRS)

1994-01-01

This NASA Hubble Space Telescope image of the ringed planet Saturn shows a rare storm that appears as a white arrowhead-shaped feature near the planet's equator. The storm is generated by an upwelling of warmer air, similar to a terrestrial thunderhead. The east-west extent of this storm is equal to the diameter of the Earth (about 7,900 miles). Hubble provides new details about the effects of Saturn's prevailing winds on the storm. The new image shows that the storm's motion and size have changed little since its discovery in September, 1994.

The storm was imaged with Hubble's Wide Field Planetary Camera 2 (WFPC2) in the wide field mode on December 1, 1994, when Saturn was 904 million miles from the Earth. The picture is a composite of images taken through different color filters within a 6 minute interval to create a 'true-color' rendition of the planet. The blue fringe on the right limb of the planet is an artifact of image processing used to compensate for the rotation of the planet between exposures.

The Hubble images are sharp enough to reveal that Saturn's prevailing winds shape a dark 'wedge' that eats into the western (left) side of the bright central cloud. The planet's strongest eastward winds (clocked at 1,000 miles per hour from analysis of Voyager spacecraft images taken in 1980-81) are at the latitude of the wedge.

To the north of this arrowhead-shaped feature, the winds decrease so that the storm center is moving eastward relative to the local flow. The clouds expanding north of the storm are swept westward by the winds at higher latitudes. The strong winds near the latitude of the dark wedge blow over the northern part of the storm, creating a secondary disturbance that generates the faint white clouds to the east (right) of the storm center.

The storm's white clouds are ammonia ice crystals that form when an upward flow of warmer gases shoves its way through Saturn's frigid cloud tops. This current storm is larger than the white clouds associated with minor storms that have been reported more frequently as bright cloud features.

Hubble observed a similar, though larger, storm in September 1990, which was one of three major Saturn storms seen over the past two centuries. Although these events were separated by about 57 years (approximately 2 Saturnian years) there is yet no explanation why they apparently follow a cycle -- occurring when it is summer in Saturn's northern hemisphere.

The Wide Field/Planetary Camera 2 was developed by the Jet Propulsion Laboratory and managed by the Goddard Spaced Flight Center for NASA's Office of Space Science.

This image and other images and data received from the Hubble Space Telescope are posted on the World Wide Web on the Space Telescope Science Institute home page at URL http://oposite.stsci.edu/pubinfo/

BUOYANCY INSTABILITIES IN A WEAKLY COLLISIONAL INTRACLUSTER MEDIUM

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kunz, Matthew W.; Stone, James M.; Bogdanovic, Tamara

2012-08-01

The intracluster medium (ICM) of galaxy clusters is a weakly collisional plasma in which the transport of heat and momentum occurs primarily along magnetic-field lines. Anisotropic heat conduction allows convective instabilities to be driven by temperature gradients of either sign: the magnetothermal instability (MTI) in the outskirts of clusters and the heat-flux buoyancy-driven instability (HBI) in their cooling cores. We employ the Athena magnetohydrodynamic code to investigate the nonlinear evolution of these instabilities, self-consistently including the effects of anisotropic viscosity (i.e., Braginskii pressure anisotropy), anisotropic conduction, and radiative cooling. We find that, in all but the innermost regions of cool-coremore » clusters, anisotropic viscosity significantly impairs the ability of the HBI to reorient magnetic-field lines orthogonal to the temperature gradient. Thus, while radio-mode feedback appears necessary in the central few Multiplication-Sign 10 kpc, heat conduction may be capable of offsetting radiative losses throughout most of a cool core over a significant fraction of the Hubble time. Magnetically aligned cold filaments are then able to form by local thermal instability. Viscous dissipation during cold filament formation produces accompanying hot filaments, which can be searched for in deep Chandra observations of cool-core clusters. In the case of MTI, anisotropic viscosity leads to a nonlinear state with a folded magnetic field structure in which field-line curvature and field strength are anti-correlated. These results demonstrate that, if the HBI and MTI are relevant for shaping the properties of the ICM, one must self-consistently include anisotropic viscosity in order to obtain even qualitatively correct results.« less

CLUES to the past: Local Group progenitors amongst high-redshift Lyman break galaxies

NASA Astrophysics Data System (ADS)

Dayal, Pratika; Libeskind, Noam I.; Dunlop, James S.

2013-06-01

We use state-of-the-art numerical simulations to explore the observability and the expected physical properties of the progenitors of the Local Group galaxies at z ≃ 6-8, within 1 billion years of the big bang. We find that the most massive progenitors of the Milky Way (MW) and Andromeda (M31) at z ≃ 6 and 7 are predicted to have absolute ultraviolet (UV) continuum magnitudes MUV ≃ -17 to -18, suggesting that their analogues lie close to the detection limits of the deepest near-infrared (IR) surveys conducted to date [i.e. Hubble Space Telescope Wide Field Camera 3/IR Ultra Deep Field (UDF)12]. This in turn confirms that the majority of currently known z ≃ 6-8 galaxies are expected to be the seeds of present-day galaxies which are more massive than L* spirals. We also discuss the properties of the Local Group progenitors at these early epochs, extending down to absolute magnitudes MUV ≃ -13. The most massive MW/M31 progenitors at z ≃ 7 have stellar masses M* ≃ 107.5-8 M⊙, stellar metallicities Z* ˜ 3-6 per cent Z⊙, and predicted observed UV continuum slopes β ≃ -2.4 to -2.5.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Skillman, Evan D.; Hidalgo, Sebastian L.; Monelli, Matteo

We present an analysis of the star formation history (SFH) of a field near the half-light radius in the Local Group dwarf irregular galaxy IC 1613 based on deep Hubble Space Telescope Advanced Camera for Surveys imaging. Our observations reach the oldest main sequence turn-off, allowing a time resolution at the oldest ages of ∼1 Gyr. Our analysis shows that the SFH of the observed field in IC 1613 is consistent with being constant over the entire lifetime of the galaxy. These observations rule out an early dominant episode of star formation in IC 1613. We compare the SFH ofmore » IC 1613 with expectations from cosmological models. Since most of the mass is in place at early times for low-mass halos, a naive expectation is that most of the star formation should have taken place at early times. Models in which star formation follows mass accretion result in too many stars formed early and gas mass fractions that are too low today (the 'over-cooling problem'). The depth of the present photometry of IC 1613 shows that, at a resolution of ∼1 Gyr, the star formation rate is consistent with being constant, at even the earliest times, which is difficult to achieve in models where star formation follows mass assembly.« less

VizieR Online Data Catalog: Galaxy candidates in the Hubble Frontier Fields (Laporte+, 2016)

NASA Astrophysics Data System (ADS)

Laporte, N.; Infante, L.; Troncoso Iribarren, P.; Zheng, W.; Molino, A.; Bauer, F. E.; Bina, D.; Broadhurst, T.; Chilingarian, I.; Garcia, S.; Kim, S.; Marques-Chaves, R.; Moustakas, J.; Pello, R.; Perez-Fournon, I.; Shu, X.; Streblyanska, A.; Zitrin, A.

2018-02-01

The Frontier Field (FF) project is carried out using HST Director's Discretionary Time and will use 840 orbits during Cycles 21, 22, and 23 with six strong-lensing galaxy clusters as the main targets. For each cluster, the final data set is composed of three images from ACS/HST (F435W, F606W, and F814W) and four images from WFC3/HST (F105W, F125W, F140W, and F160W) reaching depths of ~29 mag at 5σ in a 0.4" diameter aperture. In this study, we used the final data release on MACS J0717.5+3745 (z=0.551, Ebeling et al. 2004ApJ...609L..49E; Medezinski et al. 2013ApJ...777...43M) made public on 2015 April 1. This third cluster in the FF list has been observed by HST through several observing programs, mainly those related to CLASH (ID: 12103, PI: M. Postman) and the FFs (ID: 13498, PI: J. Lotz). We matched the HST data with deep Spitzer/IRAC images obtained from observations (ID: 90259) carried out from 2013 August to 2015 January combined with archival data from 2007 November to 2013 June. (6 data files).

Micrometeoroid Impacts on the Hubble Space Telescope Wide Field and Planetary Camera 2: Smaller Particle Impacts

NASA Technical Reports Server (NTRS)

Ross, D. K.; Anz-Meador, P.; Liou, J.C.; Opiela, J.; Kearsley, A. T.; Grime, G.; Webb, R.; Jeynes, C.; Palitsin, V.; Colaux, J.;

Hubble Sees Pinwheel of Star Birth

NASA Image and Video Library

2017-12-08

NASA image release October 19, 2010 Though the universe is chock full of spiral-shaped galaxies, no two look exactly the same. This face-on spiral galaxy, called NGC 3982, is striking for its rich tapestry of star birth, along with its winding arms. The arms are lined with pink star-forming regions of glowing hydrogen, newborn blue star clusters, and obscuring dust lanes that provide the raw material for future generations of stars. The bright nucleus is home to an older population of stars, which grow ever more densely packed toward the center. NGC 3982 is located about 68 million light-years away in the constellation Ursa Major. The galaxy spans about 30,000 light-years, one-third of the size of our Milky Way galaxy. This color image is composed of exposures taken by the Hubble Space Telescope's Wide Field Planetary Camera 2 (WFPC2), the Advanced Camera for Surveys (ACS), and the Wide Field Camera 3 (WFC3). The observations were taken between March 2000 and August 2009. The rich color range comes from the fact that the galaxy was photographed invisible and near-infrared light. Also used was a filter that isolates hydrogen emission that emanates from bright star-forming regions dotting the spiral arms. The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency. NASA's Goddard Space Flight Center manages the telescope. The Space Telescope Science Institute (STScI) conducts Hubble science operations. STScI is operated for NASA by the Association of Universities for Research in Astronomy, Inc. in Washington, D.C. Credit: NASA, ESA, and the Hubble Heritage Team (STScI/AURA) Acknowledgment: A. Riess (STScI) NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Join us on Facebook

Keck Spectroscopy of Redshift z ~ 3 Galaxies in the Hubble Deep Field

NASA Astrophysics Data System (ADS)

Lowenthal, James D.; Koo, David C.; Guzmán, Rafael; Gallego, Jesús; Phillips, Andrew C.; Faber, S. M.; Vogt, Nicole P.; Illingworth, Garth D.; Gronwall, Caryl

1997-05-01

We have obtained spectra with the 10 m Keck telescope of a sample of 24 galaxies having colors consistent with star-forming galaxies at redshifts 2 <~ z <~ 4.5 in the Hubble deep field (HDF). Eleven of these galaxies are confirmed to be at high redshift (zmed = 3.0), one is at z = 0.5, and the other 12 have uncertain redshifts but have spectra consistent with their being at z > 2. The spectra of the confirmed high-redshift galaxies show a diversity of features, including weak Lyα emission, strong Lyα breaks or damped Lyα absorption profiles, and the stellar and interstellar rest-UV absorption lines common to local starburst galaxies and high-redshift star-forming galaxies reported recently by others. The narrow profiles and low equivalent widths of C IV, Si IV, and N V absorption lines may imply low stellar metallicities. Combined with the five high-redshift galaxies in the HDF previously confirmed with Keck spectra by Steidel et al. (1996a), the 16 confirmed sources yield a comoving volume density of n >= 2.4 × 10-4 h350 Mpc-3 for q0 = 0.05, or n >= 1.1 × 10-3 h350 Mpc-3 for q0 = 0.5. These densities are 3-4 times higher than the recent estimates of Steidel et al. (1996b) based on ground-based photometry with slightly brighter limits and are comparable to estimates of the local volume density of galaxies brighter than L*. The high-redshift density measurement is only a lower limit and could be almost 3 times higher still if all 29 of the unconfirmed candidates in our original sample, including those not observed, are indeed also at high redshift. The galaxies are small but luminous, with half-light radii 1.8 < r1/2 < 6.5 h-150 kpc and absolute magnitudes -21.5 > MB > -23. The HST images show a wide range of morphologies, including several with very close, small knots of emission embedded in wispy extended structures. Using rest-frame UV continuum fluxes with no dust correction, we calculate star formation rates in the range 7-24 or 3-9 h-250 Msolar yr-1 for q0 = 0.05 and q0 = 0.5, respectively. These rates overlap those for local spiral and H II galaxies today, although they could be more than twice as high if dust extinction in the UV is significant. If the objects at z = 3 were simply to fade by 5 mag (assuming a 107 yr burst and passive evolution) without mergers in the 14 Gyr between then and now (for q0 = 0.05, h50 = 1.0), they would resemble average dwarf elliptical/spheroidal galaxies in both luminosity and size. However, the variety of morphologies and the high number density of z = 3 galaxies in the HDF suggest that they represent a range of physical processes and stages of galaxy formation and evolution, rather than any one class of object, such as massive ellipticals. A key issue remains the measurement of masses. These high-redshift objects are likely to be the low-mass, starbursting building blocks of more massive galaxies seen today. Based on observations obtained at the W. M. Keck Observatory, which is operated jointly by the University of California and the California Institute of Technology, and with the NASA/ESA Hubble Space Telescope, which is operated by AURA, Inc., under contract with NASA.

Whirlpool Galaxy

NASA Technical Reports Server (NTRS)

1999-01-01

Scientists are seeing unprecedented detail of the spiral arms and dust clouds in the nearby Whirlpool galaxy, thanks to a new Hubble Space Telescope image, available at http://www.jpl.nasa.gov/pictures/wfpc/wfpc.html. The image uses data collected January 15 and 24, 1995, and July 21, 1999, by Hubble's Wide Field and Planetary Camera 2, designed and built by JPL. Using the image, a research group led by Dr. Nick Scoville of the California Institute of Technology, Pasadena, clearly defined the structure of the galaxy's cold dust clouds and hot hydrogen, and they linked star clusters within the galaxy to their parent dust clouds.

The Whirlpool galaxy is one of the most photogenic galaxies. This celestial beauty is easily seen and photographed with smaller telescopes and studied extensively from large ground- and space-based observatories. The new composite image shows visible starlight and light from the emission of glowing hydrogen, which is associated with the most luminous young stars in the spiral arms.

The galaxy is having a close encounter with a nearby companion galaxy, NGC 5195, just off the upper edge of the image. The companion's gravitational pull is triggering star formation in the main galaxy, lit up by numerous clusters of young and energetic stars in brilliant detail. Luminous clusters are highlighted in red by their associated emission from glowing hydrogen gas.

This image was composed by the Hubble Heritage Team from Hubble archive data and was superimposed onto data taken by Dr. Travis Rector of the National Optical Astronomy Observatory at the .9-meter (35-inch) telescope at the National Science Foundation's Kitt Peak National Observatory, Tucson, Ariz. Scoville's team includes M. Polletta of the University of Geneva, Switzerland; S. Ewald and S. Stolovy of Caltech; and R. Thompson and M. Rieke of the University of Arizona, Tucson.

The Space Telescope Science Institute, Baltimore, Md., manages space operations for the Hubble Space Telescope for NASA's Office of Space Science, Washington, D.C. The institute is operated by the Association of Universities for Research in Astronomy, Inc., for NASA under contract with NASA's Goddard Space Flight Center, Greenbelt, Md. The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency. JPL is a division of Caltech.

Additional information about the Hubble Space Telescope is available at http://www.stsci.edu . More information about the Wide Field and Planetary Camera 2 is available at http://wfpc2.jpl.nasa.gov

HUBBLE SPIES A REALLY COOL STAR

NASA Technical Reports Server (NTRS)

2002-01-01

This is a Hubble Space Telescope picture of one of the least massive and coolest stars even seen (upper right). It is a diminutive companion to the K dwarf star called GL 105A (also known as HD 16160) seen at lower left. The binary pair is located 27 light-years away in the constellation Cetus. Based on the Hubble observation, astronomers calculate that the companion, called GL 105C, is 25,000 times fainter than GL 105A in visible light. If the dim companion were at the distance of our Sun, it would be only four times brighter than the full moon. The Hubble observations confirm the detection of GL 105C last year by David Golimowski and his collaborators at Palomar Observatory in California. Although GL 105C was identified before, the Hubble view allows a more precise measurement of the separation between the binary components. Future Hubble observations of the binary orbit will allow the masses of both stars to be determined accurately. The Palomar group estimates that the companion's mass is 8-9 percent of the Sun's mass, which places it near the theoretical lower limit for stable hydrogen burning. Objects below this limit, called brown dwarfs, still 'shine' -- not by thermonuclear energy, but by the energy released through gravitational contraction. Two pictures, taken with Hubble's Wide Field Planetary Camera 2 (in PC mode) through different filters (in visible and near-infrared light) show that GL 105C is redder, hence cooler than GL 105A. The surface temperature of GL 105C is not precisely known, but may be as low as 2,600 degrees Kelvin (4,200 degrees Fahrenheit). This image was taken in near-infrared light, on January 5, 1995. GL 105C is located 3.4 arc seconds to the west-northwest of the larger GL 105A. (One arc second equals 1/3600 of a degree.) The bright spikes are caused by diffraction of light within the telescope's optical system, and the brighter white bar is an artifact of the CCD camera, which bleeds along a CCD column when a relatively bright object is in the field of view. These observations are part of a Guaranteed Time Observing Program for which William Fastie (the Johns Hopkins University, Baltimore, MD) and Dan Schroeder (Beloit College, Beloit, WI) were co-principal investigators. Credit: D. Golimowski (Johns Hopkins University), and NASA Image files in GIF and JPEG format may be accessed on Internet via anonymous ftp from oposite.stsci.edu in /pubinfo:

Oscillatory attractors: a new cosmological phase

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bains, Jasdeep S.; Hertzberg, Mark P.; Wilczek, Frank, E-mail: bains@physics.harvard.edu, E-mail: mark.hertzberg@tufts.edu, E-mail: wilczek@mit.edu

2017-05-01

In expanding FRW spacetimes, it is usually the case that homogeneous scalar fields redshift and their amplitudes approach limiting values: Hubble friction usually ensures that the field relaxes to its minimum energy configuration, which is usually a static configuration. Here we discover a class of relativistic scalar field models in which the attractor behavior is the field oscillating indefinitely, with finite amplitude, in an expanding FRW spacetime, despite the presence of Hubble friction. This is an example of spontaneous breaking of time translation symmetry. We find that the effective equation of state of the field has average value ( wmore » )=−1, implying that the field itself could drive an inflationary or dark energy dominated phase. This behavior is reminiscent of ghost condensate models, but in the new models, unlike in the ghost condensate models, the energy-momentum tensor is time dependent, so that these new models embody a more definitive breaking of time translation symmetry. We explore (quantum) fluctuations around the homogeneous background solution, and find that low k -modes can be stable, while high k -modes are typically unstable. We discuss possible interpretations and implications of that instability.« less

KSC-2009-2982

NASA Image and Video Library

2009-05-08

CAPE CANAVERAL, Fla. – On Launch Pad 39A at NASA's Kennedy Space Center in Florida, space shuttle Atlantis' payload bay is filled with hardware for the STS-125 mission to service NASA's Hubble Space Telescope. From the bottom are the Flight Support System with the Soft Capture mechanism and Multi-Use Lightweight Equipment Carrier with the Science Instrument Command and Data Handling Unit, or SIC&DH; the Orbital Replacement Unit Carrier with the Cosmic Origins Spectrograph, or COS, and an IMAX 3D camera; and the Super Lightweight Interchangeable Carrier with the Wide Field Camera 3. Atlantis' crew will service NASA's Hubble Space Telescope for the fifth and final time. The flight will include five spacewalks during which astronauts will refurbish and upgrade the telescope with state-of-the-art science instruments. As a result, Hubble's capabilities will be expanded and its operational lifespan extended through at least 2014. Photo credit: NASA/Kim Shiflett

KSC-2009-2981

NASA Image and Video Library

2009-05-08

CAPE CANAVERAL, Fla. – On Launch Pad 39A at NASA's Kennedy Space Center in Florida, space shuttle Atlantis' payload bay is filled with hardware for the STS-125 mission to service NASA's Hubble Space Telescope. At the bottom are the Flight Support System with the Soft Capture mechanism and Multi-Use Lightweight Equipment Carrier with the Science Instrument Command and Data Handling Unit, or SIC&DH. At center is the Orbital Replacement Unit Carrier with the Cosmic Origins Spectrograph, or COS, and an IMAX 3D camera. At top is the Super Lightweight Interchangeable Carrier with the Wide Field Camera 3. Atlantis' crew will service NASA's Hubble Space Telescope for the fifth and final time. The flight will include five spacewalks during which astronauts will refurbish and upgrade the telescope with state-of-the-art science instruments. As a result, Hubble's capabilities will be expanded and its operational lifespan extended through at least 2014. Photo credit: NASA/Kim Shiflett

KSC-2009-2980

NASA Image and Video Library

2009-05-08

CAPE CANAVERAL, Fla. – On Launch Pad 39A at NASA's Kennedy Space Center in Florida, space shuttle Atlantis' payload bay is filled with hardware for the STS-125 mission to service NASA's Hubble Space Telescope. From the bottom are the Flight Support System with the Soft Capture mechanism and Multi-Use Lightweight Equipment Carrier with the Science Instrument Command and Data Handling Unit, or SIC&DH. At center is the Orbital Replacement Unit Carrier with the Cosmic Origins Spectrograph, or COS, and an IMAX 3D camera. At top is the Super Lightweight Interchangeable Carrier with the Wide Field Camera 3. Atlantis' crew will service NASA's Hubble Space Telescope for the fifth and final time. The flight will include five spacewalks during which astronauts will refurbish and upgrade the telescope with state-of-the-art science instruments. As a result, Hubble's capabilities will be expanded and its operational lifespan extended through at least 2014. Photo credit: NASA/Kim Shiflett

Hubble's Necklace

NASA Image and Video Library

2017-12-08

Image released 11 Aug 2011. The "Necklace Nebula" is located 15,000 light-years away in the constellation Sagitta (the Arrow). In this composite image, taken on July 2, 2011, Hubble's Wide Field Camera 3 captured the glow of hydrogen (blue), oxygen (green), and nitrogen (red). The object, aptly named the Necklace Nebula, is a recently discovered planetary nebula, the glowing remains of an ordinary, Sun-like star. The nebula consists of a bright ring, measuring 12 trillion miles wide, dotted with dense, bright knots of gas that resemble diamonds in a necklace. Credit: NASA, ESA, and the Hubble Heritage Team (STScI/AURA) NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Like us on Facebook Find us on Instagram

KSC-2009-3030

NASA Image and Video Library

2009-05-10

CAPE CANAVERAL, Fla. – The tools that will be used to service NASA's Hubble Space Telescope on the STS-125 mission are displayed in the NASA News Center at NASA's Kennedy Space Center in Florida. Being held in the foreground is the grid cutter tool, which will enable removal of the Electromagnetic Interference Grid from the Advanced Camera for Surveys access cover. On space shuttle Atlantis’ STS-125 mission, Hubble will be serviced for the fifth and final time. The flight will include five spacewalks during which astronauts will refurbish and upgrade the telescope with these state-of-the-art science instruments. As a result, Hubble's capabilities will be expanded and its operational lifespan extended through at least 2014. The payload includes a Wide Field Camera 3, fine guidance sensor and the Cosmic Origins Spectrograph. Launch is scheduled for 2:01 p.m. EDT May 11. Photo credit: NASA/Jack Pfaller

The Hubble Space Telescope: UV, Visible, and Near-Infrared Pursuits

NASA Technical Reports Server (NTRS)

Wiseman, Jennifer

2010-01-01

The Hubble Space Telescope continues to push the limits on world-class astrophysics. Cameras including the Advanced Camera for Surveys and the new panchromatic Wide Field Camera 3 which was installed nu last year's successful servicing mission S2N4,o{fer imaging from near-infrared through ultraviolet wavelengths. Spectroscopic studies of sources from black holes to exoplanet atmospheres are making great advances through the versatile use of STIS, the Space Telescope Imaging Spectrograph. The new Cosmic Origins Spectrograph, also installed last year, is the most sensitive UV spectrograph to fly io space and is uniquely suited to address particular scientific questions on galaxy halos, the intergalactic medium, and the cosmic web. With these outstanding capabilities on HST come complex needs for laboratory astrophysics support including atomic and line identification data. I will provide an overview of Hubble's current capabilities and the scientific programs and goals that particularly benefit from the studies of laboratory astrophysics.

Hubble Sees Material Ejected From Comet Hale-Bopp

NASA Technical Reports Server (NTRS)

1995-01-01

These NASA Hubble Space Telescope pictures of comet Hale-Bopp show a remarkable 'pinwheel' pattern and a blob of free-flying debris near the nucleus. The bright clump of light along the spiral (above the nucleus, which is near the center of the frame) may be a piece of the comet's icy crust that was ejected into space by a combination of ice evaporation and the comet's rotation, and which then disintegrated into a bright cloud of particles.

Although the 'blob' is about 3.5 times fainter than the brightest portion at the nucleus, the lump appears brighter because it covers a larger area. The debris follows a spiral pattern outward because the solid nucleus is rotating like a lawn sprinkler, completing a single rotation about once per week.

Ground-based observations conducted over the past two months have documented at least two separate episodes of jet and pinwheel formation and fading. By coincidence, the first Hubble images of Hale-Bopp, taken on September 26, 1995, immediately followed one of these outbursts and allow researchers to examine it at unprecedented detail. For the first time they see a clear separation between the nucleus and some of the debris being shed. By putting together information from the Hubble images and those taken during the recent outburst using the 82 cm telescope of the Teide Observatory (Tenerife, Canary Islands, Spain), astronomers find that the debris is moving away from the nucleus at a speed (projected on the sky) of about 68 miles per hour (109 kilometers per hour).

The Hubble observations will be used to determine if Hale-Bopp is really a giant comet or rather a more moderate-sized object whose current activity is driven by outgassing from a very volatile ice which will 'burn out' over the next year. Comet Hale-Bopp was discovered on July 23, 1995 by amateur astronomers Alan Hale and Thomas Bopp. Though this comet is still well outside the orbit of Jupiter (almost 600 million miles, or one billion kilometers from Earth) it looks surprisingly bright, fueling predictions that it could become the brightest comet of the century in early 1997.

The full-field picture on the left, taken with the Wide Field Planetary Camera 2 (in WF mode), shows the comet against a stellar backdrop in the constellation Sagittarius. The stars are streaked due to a combination of Hubble's orbital motion and its tracking of the nucleus, which is now falling toward the Sun at 33,800 miles per hour (54,000 km/hr). In the close-up picture on the right, the stars have been subtracted through image processing. Each picture element is nearly 300 miles (480 km) across at the comet's distance. In this false color scale the faintest regions are black, the brightest regions are white, and intermediate intensities are represented by different levels of red.

Even more detailed Hubble images will be taken with the Planetary Camera in late October to follow the further evolution of the spiral, look for more outbursts, place limits on the size of the nucleus, and use spectroscopy to study the enigmatic comet's chemical composition.

The Wide Field/Planetary Camera 2 was developed by the Jet Propulsion Laboratory and managed by the Goddard Spaced Flight Center for NASA's Office of Space Science.

This image and other images and data received from the Hubble Space Telescope are posted on the World Wide Web on the Space Telescope Science Institute home page at URL http://oposite.stsci.edu/pubinfo/

ASTRO-ENTOMOLOGY? ANT-LIKE SPACE STRUCTURE PREVIEWS DEATH OF OUR SUN

NASA Technical Reports Server (NTRS)

2002-01-01

From ground-based telescopes, the so-called 'ant nebula' (Menzel 3, or Mz 3) resembles the head and thorax of a garden-variety ant. This dramatic NASA/ESA Hubble Space Telescope image, showing 10 times more detail, reveals the 'ant's' body as a pair of fiery lobes protruding from a dying, Sun-like star. The Hubble images directly challenge old ideas about the last stages in the lives of stars. By observing Sun-like stars as they approach their deaths, the Hubble Heritage image of Mz 3 -- along with pictures of other planetary nebulae -- shows that our Sun's fate probably will be more interesting, complex, and striking than astronomers imagined just a few years ago. Though approaching the violence of an explosion, the ejection of gas from the dying star at the center of Mz 3 has intriguing symmetrical patterns unlike the chaotic patterns expected from an ordinary explosion. Scientists using Hubble would like to understand how a spherical star can produce such prominent, non-spherical symmetries in the gas that it ejects. One possibility is that the central star of Mz 3 has a closely orbiting companion that exerts strong gravitational tidal forces, which shape the outflowing gas. For this to work, the orbiting companion star would have to be close to the dying star, about the distance of the Earth from the Sun. At that distance the orbiting companion star wouldn't be far outside the hugely bloated hulk of the dying star. It's even possible that the dying star has consumed its companion, which now orbits inside of it, much like the duck in the wolf's belly in the story 'Peter and the Wolf.' (See http://oposite.stsci.edu/pubinfo/qt/ssudec.mov for an animation that shows how this might work.) A second possibility is that, as the dying star spins, its strong magnetic fields are wound up into complex shapes like spaghetti in an eggbeater. Charged winds moving at speeds up to 1000 kilometers per second from the star, much like those in our sun's solar wind but millions of times denser, are able to follow the twisted field lines on their way out into space. These dense winds can be rendered visible by ultraviolet light from the hot central star or from highly supersonic collisions with the ambient gas that excites the material into florescence. No other planetary nebula observed by Hubble resembles Mz 3 very closely. M2-9 comes close, but the outflow speeds in Mz 3 are up to 10 times larger than those of M2-9. (See http://oposite.stsci.edu/pubinfo/PR/97/38/content/9738aw.jpg). Interestingly, the very massive, young star, Eta Carinae, shows a very similar outflow pattern (see http://oposite.stsci.edu/pubinfo/PR/96/23.html). Astronomers Bruce Balick (University of Washington) and Vincent Icke (Leiden University) used Hubble to observe this planetary nebula, Mz 3, in July 1997 with the Wide Field Planetary 2 camera. One year later, astronomers Raghvendra Sahai and John Trauger of the Jet Propulsion Lab in California snapped pictures of Mz 3 using slightly different filters. This intriguing image, which is a composite of several filters from each of the two datasets, was created by the Hubble Heritage Team. Image credit: NASA, ESA and The Hubble Heritage Team (STScI/AURA) Acknowledgment: R. Sahai (Jet Propulsion Lab), B. Balick (University of Washington)

Faint source detection in ISOCAM images

NASA Astrophysics Data System (ADS)

Starck, J. L.; Aussel, H.; Elbaz, D.; Fadda, D.; Cesarsky, C.

1999-08-01

We present a tool adapted to the detection of faint mid-infrared sources within ISOCAM mosaics. This tool is based on a wavelet analysis which allows us to discriminate sources from cosmic ray impacts at the very limit of the instrument, four orders of magnitudes below IRAS. It is called PRETI for Pattern REcognition Technique for ISOCAM data, because glitches with transient behaviors are isolated in the wavelet space, i.e. frequency space, where they present peculiar signatures in the form of patterns automatically identified and then reconstructed. We have tested PRETI with Monte-Carlo simulations of fake ISOCAM data. These simulations allowed us to define the fraction of remaining false sources due to cosmic rays, the sensitivity and completeness limits as well as the photometric accuracy as a function of the observation parameters. Although the main scientific applications of this technique have appeared or will appear in separated papers, we present here an application to the ISOCAM-Hubble Deep Field image. This work completes and confirms the results already published (\\cite[Aussel et al. 1999]{starck:aussel99}).

Hubble confirms cosmic acceleration with weak lensing

NASA Image and Video Library

2017-12-08

NASA/ESA Hubble Release Date: March 25, 2010 This image shows a smoothed reconstruction of the total (mostly dark) matter distribution in the COSMOS field, created from data taken by the NASA/ESA Hubble Space Telescope and ground-based telescopes. It was inferred from the weak gravitational lensing distortions that are imprinted onto the shapes of background galaxies. The colour coding indicates the distance of the foreground mass concentrations as gathered from the weak lensing effect. Structures shown in white, cyan, and green are typically closer to us than those indicated in orange and red. To improve the resolution of the map, data from galaxies both with and without redshift information were used. The new study presents the most comprehensive analysis of data from the COSMOS survey. The researchers have, for the first time ever, used Hubble and the natural "weak lenses" in space to characterise the accelerated expansion of the Universe. Credit: NASA, ESA, P. Simon (University of Bonn) and T. Schrabback (Leiden Observatory) To learn more abou this image go to: www.spacetelescope.org/news/html/heic1005.html For more information about Goddard Space Flight Center go here: www.nasa.gov/centers/goddard/home/index.html

Precision Distances with the Tip of the Red Giant Branch Method

NASA Astrophysics Data System (ADS)

Beaton, Rachael Lynn; Carnegie-Chicago Hubble Program Team

2018-01-01

The Carnegie-Chicago Hubble Program aims to construct a distance ladder that utilizes old stellar populations in the outskirts of galaxies to produce a high precision measurement of the Hubble Constant that is independent of Cepheids. The CCHP uses the tip of the red giant branch (TRGB) method, which is a statistical measurement technique that utilizes the termination of the red giant branch. Two innovations combine to make the TRGB a competitive route to the Hubble Constant (i) the large-scale measurement of trigonometric parallax by the Gaia mission and (ii) the development of both precise and accurate means of determining the TRGB in both nearby (~1 Mpc) and distant (~20 Mpc) galaxies. Here I will summarize our progress in developing these standardized techniques, focusing on both our edge-detection algorithm and our field selection strategy. Using these methods, the CCHP has determined equally precise (~2%) distances to galaxies in the Local Group (< 1 Mpc) and across the Local Volume (< 20 Mpc). The TRGB is, thus, an incredibly powerful and straightforward means to determine distances to galaxies of any Hubble Type and, thus, has enormous potential for putting any number of astrophyiscal phenomena on absolute units.

The HST Frontier Fields: High-Level Science Data Products for the First 4 Completed Clusters, and Latest Data on the Remaining Clusters

NASA Astrophysics Data System (ADS)

Koekemoer, Anton M.; Mack, Jennifer; Lotz, Jennifer; Anderson, Jay; Avila, Roberto J.; Barker, Elizabeth A.; Borncamp, David; Gunning, Heather C.; Hilbert, Bryan; Khandrika, Harish G.; Lucas, Ray A.; Ogaz, Sara; Porterfield, Blair; Grogin, Norman A.; Robberto, Massimo; Flanagan, Kathryn; Mountain, Matt; HST Frontier Fields Team

2016-01-01

The Hubble Space Telescope Frontier Fields program is a large Director's Discretionary program of 840 orbits, to obtain ultra-deep observations of six strong lensing clusters of galaxies, together with parallel deep blank fields, making use of the strong lensing amplification by these clusters of distant background galaxies to detect the faintest galaxies currently observable in the high-redshift universe. The first four of these clusters are now complete, namely Abell 2744, MACS J0416.1-2403, MACS J0717.5+3745 and MACS J1149.5+2223, with each of these having been observed over two epochs, to a total depth of 140 orbits on the main cluster and an associated parallel field, using ACS (F435W, F606W, F814W) and WFC3/IR (F105W, F125W, F140W, F160W). The remaining two clusters, Abell 370 and Abell S1063, are currently in progress. Full sets of high-level science products have been generated for all these clusters by the team at STScI, including a total of 24 separate cumulative-depth data releases during each epoch, as well as full-depth version 1.0 releases at the end of each completed epoch. These products include all the full-depth distortion-corrected mosaics and associated products for each cluster, which are science-ready to facilitate the construction of lensing models as well as enabling a wide range of other science projects. Many improvements beyond default calibration for ACS and WFC3/IR are implemented in these data products, including corrections for persistence, time-variable sky, and low-level dark current residuals, as well as improvements in astrometric alignment to achieve milliarcsecond-level accuracy. The resulting high-level science products are delivered via the Mikulski Archive for Space Telescopes (MAST) to the community on a rapid timescale to enable the widest scientific use of these data, as well as ensuring a public legacy dataset of the highest possible quality that is of lasting value to the entire community.

The HST Frontier Fields: High-Level Science Data Products for the First 4 Completed Clusters, and for the Last 2 Clusters Currently in Progress

NASA Astrophysics Data System (ADS)

Koekemoer, Anton M.; Mack, Jennifer; Lotz, Jennifer M.; Anderson, Jay; Avila, Roberto J.; Barker, Elizabeth A.; Borncamp, David; Gunning, Heather C.; Hilbert, Bryan; Khandrika, Harish G.; Lucas, Ray A.; Ogaz, Sara; Porterfield, Blair; Sunnquist, Ben; Grogin, Norman A.; Robberto, Massimo; Sembach, Kenneth; Flanagan, Kathryn; Mountain, Matt; HST Frontier Fields Team

2016-06-01

The Hubble Space Telescope Frontier Fields program (PI: J. Lotz) is a large Director's Discretionary program of 840 orbits, to obtain ultra-deep observations of six strong lensing clusters of galaxies, together with parallel deep blank fields, making use of the strong lensing amplification by these clusters of distant background galaxies to detect the faintest galaxies currently observable in the high-redshift universe. The first four of these clusters are now complete, namely Abell 2744, MACS J0416.1-2403, MACS J0717.5+3745 and MACS J1149.5+2223, with each of these having been observed over two epochs, to a total depth of 140 orbits on the main cluster and an associated parallel field, using ACS (F435W, F606W, F814W) and WFC3/IR (F105W, F125W, F140W, F160W). The remaining two clusters, Abell 370 and Abell S1063, are currently in progress, with the first epoch for each having been completed. Full sets of high-level science products have been generated for all these clusters by the team at STScI, including cumulative-depth v0.5 data releases during each epoch, as well as full-depth version 1.0 releases after the completion of each epoch. These products include all the full-depth distortion-corrected mosaics and associated products for each cluster, which are science-ready to facilitate the construction of lensing models as well as enabling a wide range of other science projects. Many improvements beyond default calibration for ACS and WFC3/IR are implemented in these data products, including corrections for persistence, time-variable sky, and low-level dark current residuals, as well as improvements in astrometric alignment to achieve milliarcsecond-level accuracy. The full set of resulting high-level science products are publicly delivered to the community via the Mikulski Archive for Space Telescopes (MAST) to enable the widest scientific use of these data, as well as ensuring a public legacy dataset of the highest possible quality that is of lasting value to the entire community.

Firestorm Of Star Birth In The Active Galaxy Centaurus A

NASA Image and Video Library

2017-12-08

NASA image release June 16, 2011 Resembling looming rain clouds on a stormy day, dark lanes of dust crisscross the giant elliptical galaxy Centaurus A. Hubble's panchromatic vision, stretching from ultraviolet through near-infrared wavelengths, reveals the vibrant glow of young, blue star clusters and a glimpse into regions normally obscured by the dust. The warped shape of Centaurus A's disk of gas and dust is evidence for a past collision and merger with another galaxy. The resulting shockwaves cause hydrogen gas clouds to compress, triggering a firestorm of new star formation. These are visible in the red patches in this Hubble close-up. At a distance of just over 11 million light-years, Centaurus A contains the closest active galactic nucleus to Earth. The center is home for a supermassive black hole that ejects jets of high-speed gas into space, but neither the supermassive or the jets are visible in this image. This image was taken in July 2010 with Hubble's Wide Field Camera 3. The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency. NASA's Goddard Space Flight Center manages the telescope. The Space Telescope Science Institute (STScI) conducts Hubble science operations. STScI is operated for NASA by the Association of Universities for Research in Astronomy, Inc., in Washington, D.C. For images and more information about the findings, visit: www.nasa.gov/hubble and www.hubblesite.org/news/2011/18 Cheryl Gundy, STSCI NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Join us on Facebook Find us on Instagram

HUBBLE SEES A VAST 'CITY' OF STARS

NASA Technical Reports Server (NTRS)

2002-01-01

In these pictures, a 'city' of a million stars glitters like a New York City skyline. The images capture the globular cluster 47 Tucanae, located 15,000 light-years from Earth in the southern constellation Tucana. Using NASA's Hubble Space Telescope, astronomers went hunting in this large city for planetary companions: bloated gaseous planets that snuggle close to their parent stars, completing an orbit in a quick three to five days. To their surprise, they found none. This finding suggests that the cluster's environment is too hostile for breeding planets or that it lacks the necessary elements for making them. The picture at left, taken by a terrestrial telescope, shows most of the cluster, a tightly packed group of middle-aged stars held together by mutual gravitational attraction. The box near the center represents the Hubble telescope's view. The image at right shows the Hubble telescope's close-up look at a swarm of 35,000 stars near the cluster's central region. The stars are tightly packed together: They're much closer together than our Sun and its closest stars. The picture, taken by the Wide Field and Planetary Camera 2, depicts the stars' natural colors and tells scientists about their composition and age. For example, the red stars denote bright red giants nearing the end of their lives; the more common yellow stars are similar to our middle-aged Sun. Most of the stars in the cluster are believed to have formed about 10 billion years ago. The bright, blue stars -- thought to be remnants of stellar collisions and mergers -- provide a few rejuvenated, energetic stars in an otherwise old system. The Hubble picture was taken in July 1999. Credits for Hubble image: NASA and Ron Gilliland (Space Telescope Science Institute) Credits for ground-based image: David Malin, c Anglo-Australian Observatory

The interaction of the halo around the butterfly planetary nebula NGC 650-1 with the interstellar medium

NASA Astrophysics Data System (ADS)

Ramos-Larios, G.; Guerrero, M. A.; Nigoche-Netro, A.; Olguín, L.; Gómez-Muñoz, M. A.; Sabin, L.; Vázquez, R.; Akras, S.; Ramírez Vélez, J. C.; Chávez, M.

2018-03-01

With its bright and wide equatorial waist seen almost edge-on (`the butterfly body') and the faint and broad bipolar extensions (`the butterfly wings'), NGC 650-1 is the archetypical example of bipolar planetary nebula (PN) with butterfly morphology. We present here deep high-resolution broad- and narrow-band optical images that expose the rich and intricate fine structure of this bipolar PN, with small-scale bubble-like features and collimated outflows. A SHAPE spatio-kinematic model indicates that NGC 650-1 has a broad central torus with an inclination angle of 75° with respect to the line of sight, whereas that of the bipolar lobes, which are clearly seen in the position-velocity maps, is 85°. Large field of view deep images show, for first time, an arc-like diffuse envelope in low- and high-excitation emission lines located up to 180 arcsec towards the east-south-east of the central star, well outside the main nebula. This morphological component is confirmed by Spitzer MIPS and WISE infrared imaging, as well as by long-slit low- and high-dispersion optical spectroscopic observations. Hubble Space Telescope images of NGC 650-1 obtained at two different epochs ˜14 yr apart reveal the proper motion of the central star along this direction. We propose that this motion of the star through the interstellar medium compresses the remnant material of a slow asymptotic giant branch wind, producing this bow-shock-like feature.

A DEEP HUBBLE SPACE TELESCOPE SEARCH FOR ESCAPING LYMAN CONTINUUM FLUX AT z {approx} 1.3: EVIDENCE FOR AN EVOLVING IONIZING EMISSIVITY

DOE Office of Scientific and Technical Information (OSTI.GOV)

Siana, Brian; Bridge, Carrie R.; Teplitz, Harry I.

We have obtained deep Hubble Space Telescope far-UV images of 15 starburst galaxies at z {approx} 1.3 in the GOODS fields to search for escaping Lyman continuum (LyC) photons. These are the deepest far-UV images (m{sub AB} = 28.7, 3{sigma}, 1'' diameter) over this large an area (4.83 arcmin{sup 2}) and provide some of the best escape fraction constraints for any galaxies at any redshift. We do not detect any individual galaxies, with 3{sigma} limits to the LyC ({approx}700 A) flux 50-149 times fainter (in f{sub {nu}}) than the rest-frame UV (1500 A) continuum fluxes. Correcting for the mean intergalacticmore » medium (IGM) attenuation (factor {approx}2), as well as an intrinsic stellar Lyman break (factor {approx}3), these limits translate to relative escape fraction limits of f{sub esc,rel} < [0.03, 0.21]. The stacked limit is f{sub esc,rel}(3{sigma}) < 0.02. We use a Monte Carlo simulation to properly account for the expected distribution of line-of-sight IGM opacities. When including constraints from previous surveys at z {approx} 1.3 we find that, at the 95% confidence level, no more than 8% of star-forming galaxies at z {approx} 1.3 can have relative escape fractions greater than 0.50. Alternatively, if the majority of galaxies have low, but non-zero, escaping LyC, the escape fraction cannot be more than 0.04. In light of some evidence for strong LyC emission from UV-faint regions of Lyman break galaxies (LBGs) at z {approx} 3, we also stack sub-regions of our galaxies with different surface brightnesses and detect no significant LyC flux at the f{sub esc,rel} < 0.03 level. Both the stacked limits and the limits from the Monte Carlo simulation suggest that the average ionizing emissivity (relative to non-ionizing UV emissivity) at z {approx} 1.3 is significantly lower than has been observed in LBGs at z {approx} 3. If the ionizing emissivity of star-forming galaxies is in fact increasing with redshift, it would help to explain the high photoionization rates seen in the IGM at z>4 and reionization of the IGM at z>6.« less

Galaxy NGC 1512

NASA Technical Reports Server (NTRS)

1999-01-01

A rainbow of colors is captured in the center of a magnificent barred spiral galaxy, as witnessed by the three cameras of NASA's Hubble Space Telescope.

The color-composite image of the galaxy NGC 1512 was created from seven images taken with the JPL-designed and built Wide Field and Planetary Camera 2 (WFPC-2), along with the Faint Object Camera and the Near Infrared Camera and Multi-Object Spectrometer. Hubble's unique vantage point high above the atmosphere allows astronomers to see objects over a broad range of wavelengths from the ultraviolet to the infrared and to detect differences in the regions around newly born stars.

The new image is online at http://oposite.stsci.edu/pubinfo/pr/2001/16 and http://www.jpl.nasa.gov/images/wfpc .

The image reveals a stunning 2,400 light-year-wide circle of infant star clusters in the center of NGC 1512. Located 30 million light-years away in the southern constellation of Horologium, NGC 1512 is a neighbor of our Milky Way galaxy.

With the Hubble data, a team of Israeli and American astronomers performed one of the broadest, most detailed studies ever of such star-forming regions. Results will appear in the June issue of the Astronomical Journal. The team includes Dr. Dan Maoz, Tel-Aviv University, Israel and Columbia University, New York, N.Y.; Dr. Aaron J. Barth, Harvard-Smithsonian Center for Astrophysics, Cambridge, Mass.; Dr. Luis C. Ho, The Observatories of the Carnegie Institution of Washington; Dr. Amiel Sternberg, Tel-Aviv University, Israel; and Dr. Alexei V. Filippenko, University of California, Berkeley.

The Space Telescope Science Institute, Baltimore, Md., manages space operations for the Hubble Space Telescope for NASA's Office of Space Science, Washington, D.C. The Institute is operated by the Association of Universities for Research in Astronomy Inc., for NASA under contract with NASA's Goddard Space Flight Center, Greenbelt, Md. The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency. JPL is a division of the California Institute of Technology in Pasadena.

Additional information about the Hubble Space Telescope is online at http://www.stsci.edu . More information about the Wide Field and Planetary Camera 2 is at http://wfpc2.jpl.nasa.gov.

When can preheating affect the CMB?

NASA Astrophysics Data System (ADS)

Tsujikawa, Shinji; Bassett, Bruce A.

2002-05-01

We discuss the principles governing the selection of inflationary models for which preheating can affect the CMB. This is a (fairly small) subset of those models which have nonnegligible entropy/isocurvature perturbations on large scales during inflation. We study new models which belong to this class-two-field inflation with negative nonminimal coupling and hybrid/double/supernatural inflation models where the tachyonic growth of entropy perturbations can lead to the variation of the curvature perturbation, /R, on super-Hubble scales. Finally, we present evidence against recent claims for the variation of /R in the absence of substantial super-Hubble entropy perturbations.

Higgs field and cosmological parameters in the fractal quantum system

NASA Astrophysics Data System (ADS)

Abramov, Valeriy

2017-10-01

For the fractal model of the Universe the relations of cosmological parameters and the Higgs field are established. Estimates of the critical density, the expansion and speed-up parameters of the Universe (the Hubble constant and the cosmological redshift); temperature and anisotropy of the cosmic microwave background radiation were performed.

Wide Field Camera 3 Accommodations for HST Robotics Servicing Mission

NASA Technical Reports Server (NTRS)

Ginyard, Amani

2005-01-01

This slide presentation discusses the objectives of the Hubble Space Telescope (HST) Robotics Servicing and Deorbit Mission (HRSDM), reviews the Wide Field Camera 3 (WFC3), and also reviews the contamination accomodations for the WFC3. The objectives of the HRSDM are (1) to provide a disposal capability at the end of HST's useful life, (2) to upgrade the hardware by installing two new scientific instruments: replace the Corrective Optics Space Telescope Axial Replacement (COSTAR) with the Cosmic Origins Spectrograph (COS), and to replace the Wide Field/Planetary Camera-2 (WFPC2) with Wide Field Camera-3, and (3) Extend the Scientific life of HST for a minimum of 5 years after servicing. Included are slides showing the Hubble Robotic Vehicle (HRV) and slides describing what the HRV contains. There are also slides describing the WFC3. One of the mechanisms of the WFC3 is to serve partially as replacement gyroscopes for HST. There are also slides that discuss the contamination requirements for the Rate Sensor Units (RSUs), that are part of the Rate Gyroscope Assembly on the WFC3.

Rotten Egg Nebula

NASA Technical Reports Server (NTRS)

1999-01-01

Violent gas collisions that produced supersonic shock fronts in a dying star are seen in a new, detailed image from NASA's Hubble Space Telescope.

The picture, taken by Hubble's Wide Field and Planetary Camera 2, is online at http://www.jpl.nasa.gov/images/wfpc . The camera was designed and built by NASA's Jet Propulsion Laboratory, Pasadena, Calif.

Stars like our Sun will eventually die and expel most of their material outward into shells of gas and dust. These shells eventually form some of the most beautiful objects in the universe, called planetary nebulae.

'This new image gives us a rare view of the early death throes of stars like our Sun. For the first time, we can see phenomena leading to the formation of planetary nebulae. Until now, this had only been predicted by theory, but had never been seen directly,' said Dr. Raghvendra Sahai, research scientist and member of the science team at JPL for the Wide Field and Planetary Camera 2.

The object is sometimes called the Rotten Egg Nebula, because it contains a lot of sulphur, which would produce an awful odor if one could smell in space. The object is also known as the Calabash Nebula or by the technical name OH231.8+4.2.

The densest parts of the nebula are composed of material ejected recently by the central star and accelerated in opposite directions. This material, shown as yellow in the image, is zooming away at speeds up to one and a half million kilometers per hour (one million miles per hour). Most of the star's original mass is now contained in these bipolar gas structures.

A team of Spanish and American astronomers used NASA's Hubble Space Telescope to study how the gas stream rams into the surrounding material, shown in blue. They believe that such interactions dominate the formation process in planetary nebulae. Due to the high speed of the gas, shock-fronts are formed on impact and heat the surrounding gas. Although computer calculations have predicted the existence and structure of such shocks for some time, previous observations have not been able to prove the theory.

This new Hubble image used filters that only let through light from ionized hydrogen and nitrogen atoms. Astronomers were able to distinguish the warmest parts of the gas heated by the violent shocks and found that they form a complex double-bubble shape. The bright yellow-orange colors in the picture show how dense, high-speed gas is flowing from the star, like supersonic speeding bullets ripping through a medium in opposite directions. The central star itself is hidden in the dusty band at the center.

Much of the gas flow observed today seems to stem from a sudden acceleration that took place only about 800 years ago. The astronomers believe that 1,000 years from now, the Calabash Nebula will become a fully developed planetary nebula, like a butterfly emerging from its cocoon.

The Calabash Nebula is 1.4 light years (more than 8 trillion miles) long and located some 5,000 light years (2,900 trillion miles) from Earth in the constellation Puppis.

The image was taken in December 2000 by the Wide Field and Planetary Camera 2. The image was originally released by the Hubble European Space Agency Information Centre, with a website at http://sci.esa.int/hubble. Additional information about the Hubble Space Telescope is online at http://www.stsci.edu . More information about the Wide Field and Planetary Camera 2 is at http://wfpc2.jpl.nasa.gov .

Other scientists on the team include Valentin Bujarrabal and Javier Alcolea of Observatorio Astronomico Nacional, Spain, and Carmen Sanchez Contreras of JPL.

The Space Telescope Science Institute, Baltimore, Md., manages space operations for Hubble for NASA's Office of Space Science, Washington, D.C. The institute is operated by the Association of Universities for Research in Astronomy, Inc., for NASA, under contract with the Goddard Space Flight Center, Greenbelt, Md. The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency. JPL is a division of the California Institute of Technology in Pasadena.

Micrometeoroid Impacts on the Hubble Sace Telescope Wide Field and Planetary Camera 2: Ion Beam Analysis of Subtle Impactor Traces

NASA Technical Reports Server (NTRS)

Grime, G. W.; Webb, R. P.; Jeynes, C.; Palitsin, V. V.; Colaux, J. L.; Kearsley, A. T.; Ross, D. K.; Anz-Meador, P.; Liou, J. C.; Opiela, J.;

Galaxy evolution by color-log(n) type since redshift unity in the Hubble Ultra Deep Field

NASA Astrophysics Data System (ADS)

Cameron, E.; Driver, S. P.

2009-01-01

Aims: We explore the use of the color-log(n) (where n is the global Sérsic index) plane as a tool for subdividing the galaxy population in a physically-motivated manner out to redshift unity. We thereby aim to quantify surface brightness evolution by color-log(n) type, accounting separately for the specific selection and measurement biases against each. Methods: We construct (u-r) color-log(n) diagrams for distant galaxies in the Hubble Ultra Deep Field (UDF) within a series of volume-limited samples to z=1.5. The color-log(n) distributions of these high redshift galaxies are compared against that measured for nearby galaxies in the Millennium Galaxy Catalogue (MGC), as well as to the results of visual morphological classification. Based on this analysis we divide our sample into three color-structure classes. Namely, “red, compact”, “blue, diffuse” and “blue, compact”. Luminosity-size diagrams are constructed for members of the two largest classes (“red, compact” and “blue, diffuse”), both in the UDF and the MGC. Artificial galaxy simulations (for systems with exponential and de Vaucouleurs profile shapes alternately) are used to identify “bias-free” regions of the luminosity-size plane in which galaxies are detected with high completeness, and their fluxes and sizes recovered with minimal surface brightness-dependent biases. Galaxy evolution is quantified via comparison of the low and high redshift luminosity-size relations within these “bias-free” regions. Results: We confirm the correlation between color-log(n) plane position and visual morphological type observed locally and in other high redshift studies in the color and/or structure domain. The combined effects of observational uncertainties, the morphological K-correction and cosmic variance preclude a robust statistical comparison of the shape of the MGC and UDF color-log(n) distributions. However, in the interval 0.75 < z <1.0 where the UDF i-band samples close to rest-frame B-band light (i.e., the morphological K-correction between our samples is negligible) we are able to present tentative evidence of bimodality, albiet for a very small sample size (17 galaxies). Our unique approach to quantifying selection and measurement biases in the luminosity-size plane highlights the need to consider errors in the recovery of both magnitudes and sizes, and their dependence on profile shape. Motivated by these results we divide our sample into the three color-structure classes mentioned above and quantify luminosity-size evolution by galaxy type. Specifically, we detect decreases in B-band, surface brightness of 1.57 ± 0.22 mag arcsec-2 and 1.65 ± 0.22 mag arcsec-2 for our “blue, diffuse” and “red, compact” classes respectively between redshift unity and the present day.

The properties and evolution of a K-band selected sample of massive galaxies at z ~ 0.4-2 in the Palomar/DEEP2 survey

NASA Astrophysics Data System (ADS)

Conselice, C. J.; Bundy, K.; Trujillo, I.; Coil, A.; Eisenhardt, P.; Ellis, R. S.; Georgakakis, A.; Huang, J.; Lotz, J.; Nandra, K.; Newman, J.; Papovich, C.; Weiner, B.; Willmer, C.

2007-11-01

We present the results of a study on the properties and evolution of massive (M* > 1011Msolar) galaxies at z ~ 0.4-2 utilizing Keck spectroscopy, near-infrared Palomar imaging, and Hubble, Chandra and Spitzer data covering fields targeted by the DEEP2 galaxy spectroscopic survey. Our sample is K-band selected and stellar mass limited, based on wide-area near-infrared imaging from the Palomar Observatory Wide-Field Infrared Survey, which covers 1.53 deg2 to a 5σ depth of Ks,vega ~ 20.5. Our primary goal is to obtain a broad census of massive galaxies through measuring how their number and mass densities, morphology, as well as their star formation and active galactic nucleus content evolve from z ~ 0.4-2. Our major findings include: (i) statistically the mass and number densities of M* > 1011Msolar galaxies show little evolution between z = 0 and 1 and from z ~ 0 to 2 for M* > 1011.5Msolar galaxies. We however find significant evolution within 1 < z < 1.5 for 1011 Msolar < M* < 1011.5Msolar galaxies. (ii) After examining the structures of our galaxies using Hubble ACS imaging, we find that M* > 1011Msolar selected galaxies show a nearly constant elliptical fraction of ~70-90 per cent at all redshifts. The remaining objects tend to be peculiars possibly undergoing mergers at z > 0.8, while spirals dominate the remainder at lower redshifts. A significant fraction (~25 per cent) of these early-types contain minor structural anomalies. (iii) We find that only a fraction (~60 per cent) of massive galaxies with M* > 1011Msolar are on the red sequence at z ~ 1.4, while nearly 100 per cent evolve on to it by z ~ 0.4. (iv) By utilizing Spitzer MIPS imaging and [OII] line fluxes we argue that M* > 1011.5Msolar galaxies have a steeply declining star formation rate (SFR) density ~ (1 + z)6. By examining the contribution of star formation to the evolution of the mass function, as well as the merger history through the CAS parameters, we determine that M* > 1011Msolar galaxies undergo on average 0.9+0.7-0.5 major mergers at 0.4 < z < 1.4. (v) We find that a high (5 per cent) fraction of all M* > 1011Msolar galaxies are X-ray emitters. Roughly half of these are morphologically distorted ellipticals or peculiars. Finally, we compare our mass growth with semi-analytical models from the Millennium Simulation, finding relative good agreement at z < 2 for the M* < 1011.5Msolar systems, but that the number and mass densities of M* > 1011.5Msolar galaxies are underpredicted by a factor of >100.

Cosmological magnetic fields from inflation in extended electromagnetism

DOE Office of Scientific and Technical Information (OSTI.GOV)

Beltran Jimenez, Jose; Maroto, Antonio L.

2011-01-15

In this work we consider an extended electromagnetic theory in which the scalar state which is usually eliminated by means of the Lorenz condition is allowed to propagate. This state has been shown to generate a small cosmological constant in the context of standard inflationary cosmology. Here we show that the usual Lorenz gauge-breaking term now plays the role of an effective electromagnetic current. Such a current is generated during inflation from quantum fluctuations and gives rise to a stochastic effective charge density distribution. Because of the high electric conductivity of the cosmic plasma after inflation, the electric charge densitymore » generates currents which give rise to both vorticity and magnetic fields on sub-Hubble scales. Present upper limits on vorticity coming from temperature anisotropies of the CMB are translated into lower limits on the present value of cosmic magnetic fields. We find that, for a nearly scale invariant vorticity spectrum, magnetic fields B{sub {lambda}>}10{sup -12} G are typically generated with coherence lengths ranging from subgalactic scales up to the present Hubble radius. Those fields could act as seeds for a galactic dynamo or even account for observations just by collapse and differential rotation of the protogalactic cloud.« less

Relaxion: A landscape without anthropics

NASA Astrophysics Data System (ADS)

Nelson, Ann; Prescod-Weinstein, Chanda

2017-12-01

The relaxion mechanism provides a potentially elegant solution to the hierarchy problem without resorting to anthropic or other fine-tuning arguments. This mechanism introduces an axion-like field, dubbed the relaxion, whose expectation value determines the electroweak hierarchy as well as the QCD strong C P -violating θ ¯ parameter. During an inflationary period, the Higgs mass squared is selected to be negative and hierarchically small in a theory which is consistent with 't Hooft's technical naturalness criteria. However, in the original model proposed by Graham, Kaplan, and Rajendran [Phys. Rev. Lett. 115, 221801 (2015), 10.1103/PhysRevLett.115.221801], the relaxion does not solve the strong C P problem, and in fact contributes to it, as the coupling of the relaxion to the Higgs field and the introduction of a linear potential for the relaxion produces large strong C P violation. We resolve this tension by considering inflation with a Hubble scale which is above the QCD scale but below the weak scale, and estimating the Hubble temperature dependence of the axion mass. The relaxion potential is thus very different during inflation than it is today. We find that provided the inflationary Hubble scale is between the weak scale and about 3 GeV, the relaxion resolves the hierarchy, strong C P , and dark matter problems in a way that is technically natural.

Galaxy Evolution in the Reddest Possible Filter

NASA Astrophysics Data System (ADS)

Richards, E. A.

We describe an observational programme aimed at understanding the radio emission from distant, rapidly evolving galaxy populations. These observations were carried out at 1.4 and 8.5 GHz with the VLA, centred on the Hubble Deep Field, obtaining limiting flux densities of 40 and 8 μJy respectively. The differential count of the radio sources is marginally sub-Euclidean to the completeness limits (γ = - 2.4 +/- 0.1) and fluctuation analysis suggests nearly 60 sources per arcmin^2 at the 1 μJy level. Using high-resolution 1.4 GHz observations obtained with MERLIN, we resolve all radio sources detected in the VLA complete sample and measure a median angular size for the microjansky radio population of 1-2``. This clue, coupled with the steep spectral index of the 1.4 GHz selected sample, suggests diffuse synchrotron radiation in z ~ 1 galactic discs. The wide-field HST and ground-based optical exposures show that the radio sources are identified primarily with disc systems composed of irregulars, peculiars, interacting/merging galaxies and a few isolated field spirals. Only 20% of the radio sources can be attributed to AGN - the majority are probably associated with starburst activity. The available redshifts range from 0.1 to 3, with a mean of about 0.8. We are plrobably witnessing a major episode of starburst activity in these luminous (L > L_*) systems, occasionally accompanied by an embedded AGN. About 20% of the radio sources remain unidentified to I = 26-28 in the HDF and flanking fields. Several of these objects have extremely red counterparts. We suggest that these are high-redshift dusty protogalaxies.

THE CLUSTER LENSING AND SUPERNOVA SURVEY WITH HUBBLE (CLASH): STRONG-LENSING ANALYSIS OF A383 FROM 16-BAND HST/WFC3/ACS IMAGING

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zitrin, A.; Broadhurst, T.; Coe, D.

2011-12-01

We examine the inner mass distribution of the relaxed galaxy cluster A383 (z = 0.189), in deep 16 band Hubble Space Telescope/ACS+WFC3 imaging taken as part of the Cluster Lensing And Supernova survey with Hubble (CLASH) multi-cycle treasury program. Our program is designed to study the dark matter distribution in 25 massive clusters, and balances depth with a wide wavelength coverage, 2000-16000 A, to better identify lensed systems and generate precise photometric redshifts. This photometric information together with the predictive strength of our strong-lensing analysis method identifies 13 new multiply lensed images and candidates, so that a total of 27more » multiple images of nine systems are used to tightly constrain the inner mass profile gradient, dlog {Sigma}/dlog r {approx_equal} -0.6 {+-} 0.1 (r < 160 kpc). We find consistency with the standard distance-redshift relation for the full range spanned by the lensed images, 1.01 < z < 6.03, with the higher-redshift sources deflected through larger angles as expected. The inner mass profile derived here is consistent with the results of our independent weak-lensing analysis of wide-field Subaru images, with good agreement in the region of overlap ({approx}0.7-1 arcmin). Combining weak and strong lensing, the overall mass profile is well fitted by a Navarro-Frenk-White profile with M{sub vir} = (5.37{sup +0.70}{sub -0.63} {+-} 0.26) Multiplication-Sign 10{sup 14} M{sub Sun} h{sup -1} and a relatively high concentration, c{sub vir} = 8.77{sup +0.44}{sub -0.42} {+-} 0.23, which lies above the standard c-M relation similar to other well-studied clusters. The critical radius of A383 is modest by the standards of other lensing clusters, r{sub E} {approx_equal} 16 {+-} 2'' (for z{sub s} = 2.55), so the relatively large number of lensed images uncovered here with precise photometric redshifts validates our imaging strategy for the CLASH survey. In total we aim to provide similarly high-quality lensing data for 25 clusters, 20 of which are X-ray-selected relaxed clusters, enabling a precise determination of the representative mass profile free from lensing bias.« less

The Enigmatic Local Hubble Flow: Probing the Nearby Peculiar Velocity Field with Consistent Distances to Neighboring Galaxies.

NASA Astrophysics Data System (ADS)

Mendez, B.; Davis, M.; Newman, J.; Madore, B. F.; Freedman, W. L.; Moustakas, J.

2002-12-01

The properties of the velocity field in the local volume (cz < 550 km s-1) have been difficult to constrain due to a lack of a consistent set of galaxy distances. The sparse observations available to date suggest a remarkably quiet flow, with little deviation from a pure Hubble law. However, velocity field models based on the distribution of galaxies in the 1.2 Jy IRAS redshift survey, predict a quadrupolar flow pattern locally with strong infall at the poles of the local Supergalactic plane. In an attempt to resolve this discrepency, we probe the local velocity field and begin to establish a consistent set of galactic distances. We have obtained images of nearby galaxies in I, V, and B bands from the W.M. Keck Observatory and in F814W and F555W filters from the Hubble Space Telescope. Where these galaxies are well resolved into stars we can use the Tip of the Red Giant Branch (TRGB) as a distance indicator. Using a maximum likelihood analysis to quantitatively measure the I magnitude of the TRGB we determine precise distances to several nearby galaxies. We supplement that dataset with published distances to local galaxies measured using Cepheids, Surface Brightness Fluctuations, and the TRGB. With these data we find that the amplitude of the local flow is roughly half that expected in linear theory and N-body simulations; thus the enigma of cold local flows persists. This work was supported in part by NASA through a grant from the Space Telescope Science Institute and a Predoctoral Fellowship for Minorities from the Ford Foundation.

A Butterfly in the Making: Revealing the Near-Infrared Structure of Hubble 12

NASA Technical Reports Server (NTRS)

Hora, Joseph L.; Latter, William B.

1996-01-01

We present deep narrowband near-IR images and moderate resolution spectra of the young planetary nebula Hubble 12. These data are the first to show clearly the complex structure for this important planetary nebula. Images were obtained at lambda = 2.12, 2.16, and 2.26 micron. The lambda = 2.12 Am image reveals the bipolar nature of the nebula, as well as complex structure near the central star in the equatorial region. The images show an elliptical region of emission, which may indicate a ring or a cylindrical source structure. This structure is possibly related to the mechanism that is producing the bipolar flow. The spectra show the nature of several distinct components. The central object is dominated by recombination lines of H I and He I. The core is not a significant source of molecular hydrogen emission. The east position in the equatorial region is rich in lines of ultraviolet-excited fluorescent H2. A spectrum of part of the central region shows strong [Fe II] emission, which might indicate the presence of shocks.

HUBBLE VIEWS THE GALILEO PROBE ENTRY SITE ON JUPITER

NASA Technical Reports Server (NTRS)

2002-01-01

[left] - This Hubble Space Telescope image of Jupiter was taken on Oct. 5, 1995, when the giant planet was at a distance of 534 million miles (854 million kilometers) from Earth. The arrow points to the predicted site at which the Galileo Probe will enter Jupiter's atmosphere on December 7, 1995. At this latitude, the eastward winds have speeds of about 250 miles per hour (110 meters per second). The white oval to the north of the probe site drifts westward at 13 miles per hour (6 meters per second), rolling in the winds which increase sharply toward the equator. The Jupiter image was obtained with the high resolution mode of Hubble's Wide Field Planetary Camera 2 (WFPC2). Because the disk of the planet is larger than the field of view of the camera, image processing was used to combine overlapping images from three consecutive orbits to produce this full disk view of the planet. [right] - These four enlarged Hubble images of Jupiter's equatorial region show clouds sweeping across the predicted Galileo probe entry site, which is at the exact center of each frame (a small white dot has been inserted at the centered at the predicted entry site). The first image (upper left quadrant) was obtained with the WFPC2 on Oct. 4, 1995 at (18 hours UT). The second, third and fourth images (from upper right to lower right) were obtained 10, 20 and 60 hours later, respectively. The maps extend +/- 15 degrees in latitude and longitude. The distance across one of the images is about three Earth diameters (37,433 kilometers). During the intervening time between the first and fourth maps, the winds have swept the clouds 15,000 miles (24,000 kilometers) eastward. Credit: Reta Beebe (New Mexico State University), and NASA

Hubble Catches a Galaxy Duo by the "Hare"

NASA Image and Video Library

2017-12-08

This image from the NASA/ESA Hubble Space Telescope shows the unusual galaxy IRAS 06076-2139, found in the constellation Lepus (The Hare). Hubble’s Wide Field Camera 3 (WFC3) and Advanced Camera for Surveys (ACS) instruments observed the galaxy from a distance of 500 million light-years. This particular object stands out from the crowd by actually being composed of two separate galaxies rushing past each other at about 2 million kilometers (1,243,000 miles) per hour. This speed is most likely too fast for them to merge and form a single galaxy. However, because of their small separation of only about 20,000 light-years, the galaxies will distort one another through the force of gravity while passing each other, changing their structures on a grand scale. Such galactic interactions are a common sight for Hubble, and have long been a field of study for astronomers. The intriguing behaviors of interacting galaxies take many forms; galactic cannibalism, galaxy harassment and even galaxy collisions. The Milky Way itself will eventually fall victim to the latter, merging with the Andromeda Galaxy in about 4.5 billion years. The fate of our galaxy shouldn’t be alarming though: while galaxies are populated by billions of stars, the distances between individual stars are so large that hardly any stellar collisions will occur. Credit: ESA/Hubble & NASA NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Like us on Facebook Find us on Instagram

S-COSMOS: The Spitzer Legacy Survey of the Hubble Space Telescope ACS 2 deg2 COSMOS Field I: Survey Strategy and First Analysis

NASA Astrophysics Data System (ADS)

Sanders, D. B.; Salvato, M.; Aussel, H.; Ilbert, O.; Scoville, N.; Surace, J. A.; Frayer, D. T.; Sheth, K.; Helou, G.; Brooke, T.; Bhattacharya, B.; Yan, L.; Kartaltepe, J. S.; Barnes, J. E.; Blain, A. W.; Calzetti, D.; Capak, P.; Carilli, C.; Carollo, C. M.; Comastri, A.; Daddi, E.; Ellis, R. S.; Elvis, M.; Fall, S. M.; Franceschini, A.; Giavalisco, M.; Hasinger, G.; Impey, C.; Koekemoer, A.; Le Fèvre, O.; Lilly, S.; Liu, M. C.; McCracken, H. J.; Mobasher, B.; Renzini, A.; Rich, M.; Schinnerer, E.; Shopbell, P. L.; Taniguchi, Y.; Thompson, D. J.; Urry, C. M.; Williams, J. P.

2007-09-01

The COSMOS Spitzer survey (S-COSMOS) is a Legacy program (Cycles 2+3) designed to carry out a uniform deep survey of the full 2 deg2 COSMOS field in all seven Spitzer bands (3.6, 4.5, 5.6, 8.0, 24.0, 70.0, and 160.0 μm). This paper describes the survey parameters, mapping strategy, data reduction procedures, achieved sensitivities to date, and the complete data set for future reference. We show that the observed infrared backgrounds in the S-COSMOS field are within 10% of the predicted background levels. The fluctuations in the background at 24 μm have been measured and do not show any significant contribution from cirrus, as expected. In addition, we report on the number of asteroid detections in the low Galactic latitude COSMOS field. We use the Cycle 2 S-COSMOS data to determine preliminary number counts, and compare our results with those from previous Spitzer Legacy surveys (e.g., SWIRE, GOODS). The results from this ``first analysis'' confirm that the S-COSMOS survey will have sufficient sensitivity with IRAC to detect ~L* disks and spheroids out to z>~3, and with MIPS to detect ultraluminous starbursts and AGNs out to z~3 at 24 μm and out to z~1.5-2 at 70 and 160 μm. Based on observations with the NASA/ESA Hubble Space Telescope obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy (AURA), Inc., under NASA contract NAS 5-26555 also based on data collected at the Subaru Telescope, which is operated by the National Astronomical Observatory of Japan; the XMM-Newton, an ESA science mission with instruments and contributions directly funded by ESA Member States and NASA; the European Southern Observatory under Large Program 175.A-0839, Chile; Kitt Peak National Observatory, Cerro Tololo Inter-American Observatory, and the National Optical Astronomy Observatory, which are operated by AURA under cooperative agreement with the National Science Foundation; the National Radio Astronomy Observatory, which is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc.; and the Canada-France-Hawaii Telescope (CFHT) with MegaPrime/MegaCam operated as a joint project by the CFHT Corporation, CEA/DAPNIA, the National Research Council of Canada, the Canadian Astronomy Data Centre, the Centre National de la Recherche Scientifique de France, TERAPIX, and the University of Hawaii.

Discovery of bright z ≃ 7 galaxies in the UltraVISTA survey

NASA Astrophysics Data System (ADS)

Bowler, R. A. A.; Dunlop, J. S.; McLure, R. J.; McCracken, H. J.; Milvang-Jensen, B.; Furusawa, H.; Fynbo, J. P. U.; Le Fèvre, O.; Holt, J.; Ideue, Y.; Ihara, Y.; Rogers, A. B.; Taniguchi, Y.

2012-11-01

We have exploited the new, deep, near-infrared UltraVISTA imaging of the Cosmological Evolution Survey (COSMOS) field, in tandem with deep optical and mid-infrared imaging, to conduct a new search for luminous galaxies at redshifts z ≃ 7. The year-one UltraVISTA data provide contiguous Y, J, H, Ks imaging over 1.5 deg2, reaching a 5σ detection limit of Y + J ≃ 25 (AB mag, 2-arcsec-diameter aperture). The central ≃1 deg2 of this imaging coincides with the final deep optical (u*, g, r, i) data provided by the Canada-France-Hawaii Telescope (CFHT) Legacy Survey and new deep Subaru/Suprime-Cam z'-band imaging obtained specifically to enable full exploitation of UltraVISTA. It also lies within the Hubble Space Telescope (HST) I814 band and Spitzer/Infrared Array Camera imaging obtained as part of the COSMOS survey. We have utilized this unique multiwavelength dataset to select galaxy candidates at redshifts z > 6.5 by searching first for Y + J-detected objects which are undetected in the CFHT and HST optical data. This sample was then refined using a photometric redshift fitting code, enabling the rejection of lower redshift galaxy contaminants and cool galactic M, L, T dwarf stars. The final result of this process is a small sample of (at most) 10 credible galaxy candidates at z > 6.5 (from over 200 000 galaxies detected in the year-one UltraVISTA data) which we present in this paper. The first four of these appear to be robust galaxies at z > 6.5, and fitting to their stacked spectral energy distribution yields zphot = 6.98 ± 0.05 with a stellar mass M* ≃ 5 × 109 M⊙ and rest-frame ultraviolet (UV) spectral slope β ≃ -2.0 ± 0.2 (where fλ ∝ λβ). The next three are also good candidates for z > 6.5 galaxies, but the possibility that they are dwarf stars cannot be completely excluded. Our final subset of three additional candidates is afflicted not only by potential dwarf star contamination, but also contains objects likely to lie at redshifts just below z = 6.5. We show that the three even-brighter z ≳ 7 galaxy candidates reported in the COSMOS field by Capak et al. are in fact all lower redshift galaxies at z ≃ 1.5-3.5. Consequently the new z ≃ 7 galaxies reported here are the first credible z ≃ 7 Lyman-break galaxies discovered in the COSMOS field and, as the most UV luminous discovered to date at these redshifts, are prime targets for deep follow-up spectroscopy. We explore their physical properties, and briefly consider the implications of their inferred number density for the form of the galaxy luminosity function at z ≃ 7.

Edge-on Galaxy

NASA Technical Reports Server (NTRS)

1999-01-01

NASA's Hubble Space Telescope has imaged an unusual edge-on galaxy, revealing remarkable details of its warped dusty disc and showing how colliding galaxies trigger the birth of new stars.

The image, taken by Hubble's Wide Field and Planetary Camera 2 (WFPC2), is online at http://heritage.stsci.edu and http://www.jpl.nasa.gov/images/wfpc. The camera was designed and built by NASA's Jet Propulsion Laboratory, Pasadena, Calif. During observations of the galaxy, the camera passed a milestone, taking its 100,000th image since shuttle astronauts installed it in Hubble in 1993.

The dust and spiral arms of normal spiral galaxies, like our Milky Way, look flat when seen edge- on. The new image of the galaxy ESO 510-G13 shows an unusual twisted disc structure, first seen in ground-based photographs taken at the European Southern Observatory in Chile. ESO 510-G13 lies in the southern constellation Hydra, some 150 million light-years from Earth. Details of the galaxy's structure are visible because interstellar dust clouds that trace its disc are silhouetted from behind by light from the galaxy's bright, smooth central bulge.

The strong warping of the disc indicates that ESO 510-G13 has recently collided with a nearby galaxy and is in the process of swallowing it. Gravitational forces distort galaxies as their stars, gas, and dust merge over millions of years. When the disturbances die out, ESO 510-G13 will be a single galaxy.

The galaxy's outer regions, especially on the right side of the image, show dark dust and bright clouds of blue stars. This indicates that hot, young stars are forming in the twisted disc. Astronomers believe star formation may be triggered when galaxies collide and their interstellar clouds are compressed.

The Hubble Heritage Team used WFPC2 to observe ESO 510-G13 in April 2001. Pictures obtained through blue, green, and red filters were combined to make this color-composite image, which emphasizes the contrast between the dusty spiral arms, the bright bulge, and the blue star-forming regions. Additional information about the Hubble Space Telescope is online at http://www.stsci.edu. More information about the Wide Field and Planetary Camera 2 is at http://wfpc2.jpl.nasa.gov.

The Space Telescope Science Institute, Baltimore, Md., manages space operations for Hubble for NASA's Office of Space Science, Washington, D.C. The institute is operated by the Association of Universities for Research in Astronomy, Inc., for NASA, under contract with the Goddard Space Flight Center, Greenbelt, Md. Hubble is a project of international cooperation between NASA and the European Space Agency. JPL is a division of the California Institute of Technology in Pasadena.

Linear: A Novel Algorithm for Reconstructing Slitless Spectroscopy from HST/WFC3

NASA Astrophysics Data System (ADS)

Ryan, R. E., Jr.; Casertano, S.; Pirzkal, N.

2018-03-01

We present a grism extraction package (LINEAR) designed to reconstruct 1D spectra from a collection of slitless spectroscopic images, ideally taken at a variety of orientations, dispersion directions, and/or dither positions. Our approach is to enumerate every transformation between all direct image positions (i.e., a potential source) and the collection of grism images at all relevant wavelengths. This leads to solving a large, sparse system of linear equations, which we invert using the standard LSQR algorithm. We implement a number of color and geometric corrections (such as flat field, pixel-area map, source morphology, and spectral bandwidth), but assume many effects have been calibrated out (such as basic reductions, background subtraction, and astrometric refinement). We demonstrate the power of our approach with several Monte Carlo simulations and the analysis of archival data. The simulations include astrometric and photometric uncertainties, sky-background estimation, and signal-to-noise calculations. The data are G141 observations obtained with the Wide-Field Camera 3 of the Hubble Ultra-Deep Field, and show the power of our formalism by improving the spectral resolution without sacrificing the signal-to-noise (a tradeoff that is often made by current approaches). Additionally, our approach naturally accounts for source contamination, which is only handled heuristically by present softwares. We conclude with a discussion of various observations where our approach will provide much improved spectral 1D spectra, such as crowded fields (star or galaxy clusters), spatially resolved spectroscopy, or surveys with strict completeness requirements. At present our software is heavily geared for Wide-Field Camera 3 IR, however we plan extend the codebase for additional instruments.

Can dark matter be a scalar field?

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jesus, J.F.; Malatrasi, J.L.G.; Pereira, S.H.

2016-08-01

In this paper we study a real scalar field as a possible candidate to explain the dark matter in the universe. In the context of a free scalar field with quadratic potential, we have used Union 2.1 SN Ia observational data jointly with a Planck prior over the dark matter density parameter to set a lower limit on the dark matter mass as m ≥0.12 H {sub 0}{sup -1} eV ( c = h-bar =1). For the recent value of the Hubble constant indicated by the Hubble Space Telescope, namely H {sub 0}=73±1.8 km s{sup -1}Mpc{sup -1}, this leads tomore » m ≥1.56×10{sup -33} eV at 99.7% c.l. Such value is much smaller than m ∼ 10{sup -22} eV previously estimated for some models. Nevertheless, it is still in agreement with them once we have not found evidences for a upper limit on the scalar field dark matter mass from SN Ia analysis. In practice, it confirms free real scalar field as a viable candidate for dark matter in agreement with previous studies in the context of density perturbations, which include scalar field self interaction.« less

Electroweak vacuum instability and renormalized Higgs field vacuum fluctuations in the inflationary universe

NASA Astrophysics Data System (ADS)

Kohri, Kazunori; Matsui, Hiroki

2017-08-01

In this work, we investigated the electroweak vacuum instability during or after inflation. In the inflationary Universe, i.e., de Sitter space, the vacuum field fluctuations < δ phi 2 > enlarge in proportion to the Hubble scale H2. Therefore, the large inflationary vacuum fluctuations of the Higgs field < δ phi 2 > are potentially catastrophic to trigger the vacuum transition to the negative-energy Planck-scale vacuum state and cause an immediate collapse of the Universe. However, the vacuum field fluctuations < δ phi 2 >, i.e., the vacuum expectation values have an ultraviolet divergence, and therefore a renormalization is necessary to estimate the physical effects of the vacuum transition. Thus, in this paper, we revisit the electroweak vacuum instability from the perspective of quantum field theory (QFT) in curved space-time, and discuss the dynamical behavior of the homogeneous Higgs field phi determined by the effective potential V eff( phi ) in curved space-time and the renormalized vacuum fluctuations < δ phi 2 >ren via adiabatic regularization and point-splitting regularization. We simply suppose that the Higgs field only couples the gravity via the non-minimal Higgs-gravity coupling ξ(μ). In this scenario, the electroweak vacuum stability is inevitably threatened by the dynamical behavior of the homogeneous Higgs field phi, or the formations of AdS domains or bubbles unless the Hubble scale is small enough H< ΛI .

Fun House Mirror in Space

NASA Image and Video Library

2010-08-19

NASA Hubble Space Telescope shows the inner region of Abell 1689, an immense cluster of galaxies located 2.2 billion light-years away. The cluster gravitational field is warping light from background galaxies, causing them to appear as arcs.

Hubble View of a Dying Star

NASA Image and Video Library

2003-05-21

This image of a dying star, protoplanetary nebula IRAS22036+5306, containing strange, complex structures may help explain the death throes of stars and defy our current understanding of physics. Taken by NASA Wide Field and Planetary Camera 2.

A New Spin on Vesta

NASA Image and Video Library

2010-10-08

Hubble Wide Field Camera 3 observed the potato-shaped asteroid in preparation for the visit by NASA Dawn spacecraft in 2011. This is one frame from a movie showing the difference in brightness and color on the asteroid surface.

Bianchi Type-II String Cosmological Model with Magnetic Field in f ( R, T) Gravity

NASA Astrophysics Data System (ADS)

Sharma, N. K.; Singh, J. K.

2014-09-01

The spatially homogeneous and totally anisotropic Bianchi type-II cosmological solutions of massive strings have been investigated in the presence of the magnetic field in the framework of f( R, T) gravity proposed by Harko et al. (Phys Rev D 84:024020, 2011). With the help of special law of variation for Hubble's parameter proposed by Berman (Nuovo Cimento B 74:182, 1983) cosmological model is obtained in this theory. We consider f( R, T) model and investigate the modification R+ f( T) in Bianchi type-II cosmology with an appropriate choice of a function f( T)= μ T. We use the power law relation between average Hubble parameter H and average scale factor R to find the solution. The assumption of constant deceleration parameter leads to two models of universe, i.e. power law model and exponential model. Some physical and kinematical properties of the model are also discussed.

The 2008 Passage of Jupiter's Great Red Spot and Oval BA as Observed from Hubble/WFPC2

NASA Technical Reports Server (NTRS)

Simon-Miller, Amy A.; Chanover, N. J.; Orton, G. S.; Tsavaris, I.

2008-01-01

Hubble Space Telescope data of the passage of Jupiter's Great Red Spot (GRS) and Oval BA were acquired on May 15, June 28 (near closest approach), and July 8. Wind fields were measured from Wide Field Planetary Camera 2 (WFPC2) data with 10-hour separations before and after closest approach, and within the GRS with 40-minute separations on all three dates. Color information was also derived using 8 narrowband WFPC2 filters from 343 to 673-nm on all three dates. We will present the results of principal components and wind analyses and discuss unique features seen in this data set. In addition, we will highlight any changes observed in the GRS, Oval BA and their surroundings as a result of the passage, including the movement of a smaller red anticyclone from west of the GRS, around its southern periphery, and to the east of the GRS.

KSC-2009-3087

NASA Image and Video Library

2009-05-11

CAPE CANAVERAL, Fla. – On Launch Pad 39A at NASA's Kennedy Space Center in Florida, space shuttle Atlantis rises past the fixed service structure as it races toward space on the STS-125 mission. Atlantis will rendezvous with NASA's Hubble Space Telescope on the STS-125 mission. Liftoff was on time at 2:01 p.m. EDT. Atlantis' 11-day flight will include five spacewalks to refurbish and upgrade the telescope with state-of-the-art science instruments that will expand Hubble's capabilities and extend its operational lifespan through at least 2014. The payload includes a Wide Field Camera 3, fine guidance sensor and the Cosmic Origins Spectrograph. Photo credit: NASA/Michael Gayle-Rusty Backer

Outer layers of a carbon star: The view from the Hubble Space Telescope

NASA Technical Reports Server (NTRS)

Johnson, H. R.; Ensman, Lisa M.; Alexander, D. R.; Avrett, E. H.; Brown, A.; Carpenter, K. G.; Eriksson, K.; Gustafsson, B.; Jorgensen, U. G.; Judge, Philip D.

1995-01-01

To advance our understanding of the relationship between stellar chromospheres and mass loss, which is a common property of carbon stars and other asymptotic giant branch stars, we have obtained ultraviolet spectra of the nearby N-type carbon star UU Aur using the Hubble Space Telescope (HST). In this paper we describe the HST observations, identify spectral features in both absorption and emission, and attempt to infer the velocity field in the chromosphere, upper troposphere, and circumstellar envelope from spectral line shifts. A mechanism for producing fluoresced emission to explain a previously unobserved emission line is proposed. Some related ground-based observations are also described.

Super-Hubble de Sitter fluctuations and the dynamical RG

NASA Astrophysics Data System (ADS)

Burgess, C. P.; Leblond, L.; Holman, R.; Shandera, S.

2010-03-01

Perturbative corrections to correlation functions for interacting theories in de Sitter spacetime often grow secularly with time, due to the properties of fluctuations on super-Hubble scales. This growth can lead to a breakdown of perturbation theory at late times. We argue that Dynamical Renormalization Group (DRG) techniques provide a convenient framework for interpreting and resumming these secularly growing terms. In the case of a massless scalar field in de Sitter with quartic self-interaction, the resummed result is also less singular in the infrared, in precisely the manner expected if a dynamical mass is generated. We compare this improved infrared behavior with large-N expansions when applicable.

Theoretical colours and isochrones for some Hubble Space Telescope colour systems

NASA Technical Reports Server (NTRS)

Edvardsson, B.; Bell, R. A.

1989-01-01

Synthetic spectra for effective temperatures of 4000-7250 K, logarithmic surface gravities typical of dwarfs and subgiants, and metallicities from solar values to 0.001 of the solar metallicity were used to derive a grid of synthetic surface brightness magnitudes for 21 of the Hubble Space Telescope Wide Field Camera (WFC) band passes. The absolute magnitudes of these 21 band passes are also obtained for a set of globular cluster isochrones with different helium abundances, metallicities, oxygen abundances, and ages. The usefulness and efficiency of different sets of broad and intermediate bandwidth WFC colors for determining ages and metallicities for globular clusters are evaluated.

Hubble Space Telescope Discovery of a Probable Caustic-Crossing Event in the MACS1149 Galaxy Cluster Field

NASA Astrophysics Data System (ADS)

Kelly, Patrick L.; Rodney, Steven; Diego, Jose Maria; Zitrin, Adi; Broadhurst, Tom; Selsing, Jonatan; Balestra, Italo; Benito, Alberto Molino; Bradac, Marusa; Bradley, Larry; Brammer, Gabriel; Cenko, Brad; Christensen, Lise; Coe, Dan; Filippenko, Alexei V.; Foley, Ryan; Frye, Brenda; Graham, Melissa; Graur, Or; Grillo, Claudio; Hjorth, Jens; Howell, Andy; Jauzac, Mathilde; Jha, Saurabh; Kaiser, Nick; Kawamata, Ryota; Kneib, Jean-Paul; Lotz, Jennifer; Matheson, Thomas; McCully, Curtis; Merten, Julian; Nonino, Mario; Oguri, Masamune; Richard, Johan; Riess, Adam; Rosati, Piero; Schmidt, Kasper Borello; Sharon, Keren; Smith, Nathan; Strolger, Lou; Treu, Tommaso; Wang, Xin; Weiner, Ben; Williams, Liliya; Zheng, Weikang

2016-05-01

While monitoring the MACS1149 (z = 0.54) galaxy cluster as part of the RefsdalRedux program (PID 14199; PI Kelly) with the Hubble Space Telescope (HST) WFC3 IR camera, we have detected a rising transient that appears to be coincident ( Target-of-opportunity optical follow-up imaging in several ACS and WFC3 bands with the FrontierSN program (PID 14208; PI Rodney) has revealed that its rest-frame ultraviolet through optical spectrum may be reasonably well fit with that of a B star at z=1.49 exhibiting a strong Balmer break.

Perkinelmer Lamda 950 Measurements in Support of Nasa's Hubble Space Telescope

NASA Technical Reports Server (NTRS)

Miller, Kevin H.; Quijada, Manuel A.

2014-01-01

We present visible spectroscopy measurements using the PerkinElmer Lambda 950 grating monochromator in support of two projects at NASA Goddard Space Flight Center. The first and primary project to be discussed is the Wide Field Planetary Camera 2 as an upgrade to the Hubble Space Telescope. Numerous optical filters were measured in the visible and near-infrared regions to experimentally vet the theoretical prediction upon which the filters were engineered. The second topic of our presentation will cover the measurement of SNAP prototype filters from three venders (ASAHI, BARR and JDSU) with applications towards NASAs the Joint Dark Energy Mission (JDEM).

Jupiter After the 2009 Impact: Hubble Space Telescope Imaging of the Impact-Generated Debris and Its Temporal Evolution

NASA Technical Reports Server (NTRS)

Hammel, H. B.; Wong, M. H.; Clarke, J. T.; de Pater, I.; Fletcher, L. N.; Hueso, R.; Noll, K.; Orton, G. S.; Perez-Hoyos, S.; Sanchez-Lavega, A.;

NASA's Hubble Shows Milky Way is Destined for Head-On Collision

NASA Image and Video Library

2017-12-08

NASA image release Thursday, May 31, 2012 To view a video from this Hubble release go to: www.flickr.com/photos/gsfc/7309212940 Caption: This illustration shows a stage in the predicted merger between our Milky Way galaxy and the neighboring Andromeda galaxy, as it will unfold over the next several billion years. In this image, representing Earth's night sky in 3.75 billion years, Andromeda (left) fills the field of view and begins to distort the Milky Way with tidal pull. Credit: NASA; ESA; Z. Levay and R. van der Marel, STScI; T. Hallas; and A. Mellinger To read more go to: www.nasa.gov/mission_pages/hubble/science/milky-way-colli... NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Like us on Facebook Find us on Instagram

Hubble Views Two Galaxies Merging

NASA Image and Video Library

2017-12-08

This image, taken with the Wide Field Planetary Camera 2 on board the NASA/ESA Hubble Space Telescope, shows the galaxy NGC 6052, located around 230 million light-years away in the constellation of Hercules. It would be reasonable to think of this as a single abnormal galaxy, and it was originally classified as such. However, it is in fact a “new” galaxy in the process of forming. Two separate galaxies have been gradually drawn together, attracted by gravity, and have collided. We now see them merging into a single structure. As the merging process continues, individual stars are thrown out of their original orbits and placed onto entirely new paths, some very distant from the region of the collision itself. Since the stars produce the light we see, the “galaxy” now appears to have a highly chaotic shape. Eventually, this new galaxy will settle down into a stable shape, which may not resemble either of the two original galaxies. Image credit: ESA/Hubble & NASA, Acknowledgement: Judy Schmidt

Opening up a Colourful Cosmic Jewel Box

NASA Astrophysics Data System (ADS)

2009-10-01

The combination of images taken by three exceptional telescopes, the ESO Very Large Telescope on Cerro Paranal , the MPG/ESO 2.2-metre telescope at ESO's La Silla observatory and the NASA/ESA Hubble Space Telescope, has allowed the stunning Jewel Box star cluster to be seen in a whole new light. Star clusters are among the most visually alluring and astrophysically fascinating objects in the sky. One of the most spectacular nestles deep in the southern skies near the Southern Cross in the constellation of Crux. The Kappa Crucis Cluster, also known as NGC 4755 or simply the "Jewel Box" is just bright enough to be seen with the unaided eye. It was given its nickname by the English astronomer John Herschel in the 1830s because the striking colour contrasts of its pale blue and orange stars seen through a telescope reminded Herschel of a piece of exotic jewellery. Open clusters [1] such as NGC 4755 typically contain anything from a few to thousands of stars that are loosely bound together by gravity. Because the stars all formed together from the same cloud of gas and dust their ages and chemical makeup are similar, which makes them ideal laboratories for studying how stars evolve. The position of the cluster amongst the rich star fields and dust clouds of the southern Milky Way is shown in the very wide field view generated from the Digitized Sky Survey 2 data. This image also includes one of the stars of the Southern Cross as well as part of the huge dark cloud of the Coal Sack [2]. A new image taken with the Wide Field Imager (WFI) on the MPG/ESO 2.2-metre telescope at ESO's La Silla Observatory in Chile shows the cluster and its rich surroundings in all their multicoloured glory. The large field of view of the WFI shows a vast number of stars. Many are located behind the dusty clouds of the Milky Way and therefore appear red [3]. The FORS1 instrument on the ESO Very Large Telescope (VLT) allows a much closer look at the cluster itself. The telescope's huge mirror and exquisite image quality have resulted in a brand-new, very sharp view despite a total exposure time of just 5 seconds. This new image is one of the best ever taken of this cluster from the ground. The Jewel Box may be visually colourful in images taken on Earth, but observing from space allows the NASA/ESA Hubble Space Telescope to capture light of shorter wavelengths than can not be seen by telescopes on the ground. This new Hubble image of the core of the cluster represents the first comprehensive far ultraviolet to near-infrared image of an open galactic cluster. It was created from images taken through seven filters, allowing viewers to see details never seen before. It was taken near the end of the long life of the Wide Field Planetary Camera 2 ― Hubble's workhorse camera up until the recent Servicing Mission, when it was removed and brought back to Earth. Several very bright, pale blue supergiant stars, a solitary ruby-red supergiant and a variety of other brilliantly coloured stars are visible in the Hubble image, as well as many much fainter ones. The intriguing colours of many of the stars result from their differing intensities at different ultraviolet wavelengths. The huge variety in brightness of the stars in the cluster exists because the brighter stars are 15 to 20 times the mass of the Sun, while the dimmest stars in the Hubble image are less than half the mass of the Sun. More massive stars shine much more brilliantly. They also age faster and make the transition to giant stars much more quickly than their faint, less-massive siblings. The Jewel Box cluster is about 6400 light-years away and is approximately 16 million years old. Notes [1] Open, or galactic, star clusters are not to be confused with globular clusters ― huge balls of tens of thousands of ancient stars in orbit around our galaxy and others. It seems that most stars, including our Sun, formed in open clusters. [2] The Coal Sack is a dark nebula in the Southern Hemisphere, near the Southern Cross, that can be seen with the unaided eye. A dark nebula is not the complete absence of light, but an interstellar cloud of thick dust that obscures most background light in the visible. [3] If the light from a distant star passes through dust clouds in space the blue light is scattered and absorbed more than the red. As a result the starlight looks redder when it arrives on Earth. The same effect creates the glorious red colours of terrestrial sunsets. More information ESO, the European Southern Observatory, is the foremost intergovernmental astronomy organisation in Europe and the world's most productive astronomical observatory. It is supported by 14 countries: Austria, Belgium, the Czech Republic, Denmark, France, Finland, Germany, Italy, the Netherlands, Portugal, Spain, Sweden, Switzerland and the United Kingdom. ESO carries out an ambitious programme focused on the design, construction and operation of powerful ground-based observing facilities enabling astronomers to make important scientific discoveries. ESO also plays a leading role in promoting and organising cooperation in astronomical research. ESO operates three unique world-class observing sites in Chile: La Silla, Paranal and Chajnantor. At Paranal, ESO operates the Very Large Telescope, the world's most advanced visible-light astronomical observatory. ESO is the European partner of a revolutionary astronomical telescope ALMA, the largest astronomical project in existence. ESO is currently planning a 42-metre European Extremely Large optical/near-infrared Telescope, the E-ELT, which will become "the world's biggest eye on the sky". The Hubble Space Telescope is a project of international cooperation between ESA and NASA.

The research and development program for the SNAP dark energy experiment

NASA Astrophysics Data System (ADS)

Levi, Michael E.

2007-03-01

The SNAP mission includes two surveys to study dark energy. In the deep survey, we detect more than 2000 matched Type Ia supernovae within a 7.5 deg2 field, with redshifts covering the range z=0.1 1.7. This uniform and high-quality set of “standard candles” will provide the most precise mapping of the expansion of the universe through the magnitude-redshift relation (Hubble diagram) ever constructed. The SNAP wide survey maps 1000 deg2/year in nine passbands to 28th magnitude. A weak-lensing study of the wide survey data traces the growth of structure and provides completely independent constraints on dark energy parameters. SNAP utilizes a 2 m class rigid light-weight telescope with a three-mirror anastigmatic design for a large, diffraction-limited field of view. The telescope feeds an instrumented ˜0.7 deg2 focal plane with ˜600 million pixels sensitive to wavelengths from 400 to 1700 nm. Full-depletion, high-purity silicon CCDs detect visible wavelengths, and 1700 nm cutoff HgCdTe detector arrays detect the near-IR. Passive cooling of the focal plane, fixed solar panels, fixed filters, and fixed antenna for telemetry simplify the mission. Room temperature operation of the telescope facilitates preflight testing. The satellite is placed in orbit about the second Earth Sun Lagrange point (L2).

Novel optical designs for consumer astronomical telescopes and their application to professional imaging

NASA Astrophysics Data System (ADS)

Wise, Peter; Hodgson, Alan

2006-06-01

Since the launch of the Hubble Space Telescope there has been widespread popular interest in astronomy. A further series of events, most notably the recent Deep Impact mission and Mars oppositions have served to fuel further interest. As a result more and more amateurs are coming into astronomy as a practical hobby. At the same time more sophisticated optical equipment is becoming available as the price to performance ratio become more favourable. As a result larger and better optical telescopes are now in use by amateurs. We also have the explosive growth in digital imaging technologies. In addition to displacing photographic film as the preferred image capture modality it has made the capture of high quality astronomical imagery more accessible to a wider segment of the astronomy community. However, this customer requirement has also had an impact on telescope design. There has become a greater imperative for wide flat image fields in these telescopes to take advantage of the ongoing advances in CCD imaging technology. As a result of these market drivers designers of consumer astronomical telescopes are now producing state of the art designs that result in wide, flat fields with optimal spatial and chromatic aberrations. Whilst some of these designs are not scalable to the larger apertures required for professional ground and airborne telescope use there are some that are eminently suited to make this transition.

Weak Lensing : Ground vs. Space in the Cosmos Field

NASA Astrophysics Data System (ADS)

Kasliwal, Mansi M.; Massey, R. J.; Ellis, R. S.; Rhodes, J.

2006-12-01

Weak lensing statistics are best for large numbers wide surveys with greater number of galaxies and deep surveys with a higher number density of galaxies. Although space-based surveys are unparalleled in their depth, ground-based surveys are the more cost-effective way to survey wide regions of the sky. We assess the relative merits of the two observing platforms, by using premier, multi-band, ground-based Subaru SuprimeCam data and space-based Hubble ACS data, in the 2 sq. degree COSMOS field in three ways. First, we compare shear measurements of individual galaxies and identify the relative calibration of the two datasets in terms of the largest subset in magnitude and size that is consistent. Second, we compare spaceand ground-based mass maps to quantify the relative completeness and contamination of the resulting cluster catalogs. We find that more clusters with XMM catalog counterparts are detected from space than ground and some ground-based clusters are possibly spurious detections. Third, we perform a detailed comparison of the precision with which it is possible to reconstruct the mass and size of four clusters at various redshifts identified from both ground and space. We find that the noise is much lower from space in all three investigations, but find no evidence for systematic overestimation or underestimation of the individual cluster properties by either survey.

Intracluster light at the Frontier - II. The Frontier Fields Clusters

NASA Astrophysics Data System (ADS)

Montes, Mireia; Trujillo, Ignacio

2018-02-01

Multiwavelength deep observations are a key tool to understand the origin of the diffuse light in clusters of galaxies: the intracluster light (ICL). For this reason, we take advantage of the Hubble Frontier Fields (HFF) survey to investigate the properties of the stellar populations of the ICL of its six massive intermediate redshift (0.3 < z < 0.6) clusters. We carry on this analysis down to a radial distance of ˜120 kpc from the brightest cluster galaxy. We found that the average metallicity of the ICL is [Fe/H]ICL ˜ -0.5, compatible with the value of the outskirts of the Milky Way. The mean stellar ages of the ICL are between 2 and 6 Gyr younger than the most massive galaxies of the clusters. Those results suggest that the ICL of these massive (>1015 M⊙) clusters is formed by the stripping of MW-like objects that have been accreted at z < 1, in agreement with current simulations. We do not find any significant increase in the fraction of light of the ICL with cosmic time, although the redshift range explored is narrow to derive any strong conclusion. When exploring the slope of the stellar mass density profile, we found that the ICL of the HFF clusters follows the shape of their underlying dark matter haloes, in agreement with the idea that the ICL is the result of the stripping of galaxies at recent times.

Astronauts Greg Harbaugh and Joe Tanner suit up for training in WETF

NASA Image and Video Library

1996-06-11

S96-12830 (10 June 1996) --- Astronaut Joseph R. Tanner, STS-82 mission specialist assigned to extravehicular activity (EVA) involved with the servicing of the Hubble Space Telescope (HST), dons the gloves for his extravehicular mobility unit (EMU) space suit. He is about to be submerged in a 25-ft. deep pool at the Johnson Space Center's weightless environment training facility (WET-F) to participate in simulations for some of the EVA work. Out of frame, astronaut Gregory J. Harbaugh was on the other side of the platform, waiting to join Tanner in the spacewalk rehearsal.

NASA's Hubble Sees Asteroid Spout Six Comet-like Tails

NASA Image and Video Library

2013-11-13

This NASA Hubble Space Telescope set of images reveals a never-before-seen set of six comet-like tails radiating from a body in the asteroid belt, designated P/2013 P5. The asteroid was discovered as an unusually fuzzy-looking object with the Panoramic Survey Telescope and Rapid Response System (Pan-STARRS) survey telescope in Hawaii. The multiple tails were discovered in Hubble images taken on Sept. 10, 2013. When Hubble returned to the asteroid on Sept. 23, the asteroid's appearance had totally changed. It looked as if the entire structure had swung around. One interpretation is that the asteroid's rotation rate has been increased to the point where dust is falling off the surface and escaping into space where the pressure of sunlight sweeps out fingerlike tails. According to this theory, the asteroid's spin has been accelerated by the gentle push of sunlight. The object, estimated to be no more than 1,400 feet across, has ejected dust for at least five months, based on analysis of the tail structure. These visible-light, false-color images were taken with Hubble's Wide Field Camera 3. Object Name: P/2013 P5 Image Type: Astronomical/Annotated Credit: NASA, ESA, and D. Jewitt (UCLA) NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Like us on Facebook Find us on Instagram

NASA's Hubble Sees Asteroid Spout Six Comet-like Tails

NASA Image and Video Library

2013-11-13

P/2013 P5 on September 23, 2013. --- This NASA Hubble Space Telescope set of images reveals a never-before-seen set of six comet-like tails radiating from a body in the asteroid belt, designated P/2013 P5. The asteroid was discovered as an unusually fuzzy-looking object with the Panoramic Survey Telescope and Rapid Response System (Pan-STARRS) survey telescope in Hawaii. The multiple tails were discovered in Hubble images taken on Sept. 10, 2013. When Hubble returned to the asteroid on Sept. 23, the asteroid's appearance had totally changed. It looked as if the entire structure had swung around. One interpretation is that the asteroid's rotation rate has been increased to the point where dust is falling off the surface and escaping into space where the pressure of sunlight sweeps out fingerlike tails. According to this theory, the asteroid's spin has been accelerated by the gentle push of sunlight. The object, estimated to be no more than 1,400 feet across, has ejected dust for at least five months, based on analysis of the tail structure. These visible-light, false-color images were taken with Hubble's Wide Field Camera 3. Object Name: P/2013 P5 Image Type: Astronomical/Annotated Credit: NASA, ESA, and D. Jewitt (UCLA) NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Like us on Facebook Find us on Instagram

NASA's Hubble Sees Asteroid Spout Six Comet-like Tails

NASA Image and Video Library

2013-11-13

P/2013 P5 on September 10, 2013. --- This NASA Hubble Space Telescope set of images reveals a never-before-seen set of six comet-like tails radiating from a body in the asteroid belt, designated P/2013 P5. The asteroid was discovered as an unusually fuzzy-looking object with the Panoramic Survey Telescope and Rapid Response System (Pan-STARRS) survey telescope in Hawaii. The multiple tails were discovered in Hubble images taken on Sept. 10, 2013. When Hubble returned to the asteroid on Sept. 23, the asteroid's appearance had totally changed. It looked as if the entire structure had swung around. One interpretation is that the asteroid's rotation rate has been increased to the point where dust is falling off the surface and escaping into space where the pressure of sunlight sweeps out fingerlike tails. According to this theory, the asteroid's spin has been accelerated by the gentle push of sunlight. The object, estimated to be no more than 1,400 feet across, has ejected dust for at least five months, based on analysis of the tail structure. These visible-light, false-color images were taken with Hubble's Wide Field Camera 3. Object Name: P/2013 P5 Image Type: Astronomical/Annotated Credit: NASA, ESA, and D. Jewitt (UCLA) NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Like us on Facebook Find us on Instagram

HUBBLE TRACKS 'PERFECT STORM' ON MARS

NASA Technical Reports Server (NTRS)

2002-01-01

Two dramatically different faces of our Red Planet neighbor appear in these comparison images showing how a global dust storm engulfed Mars with the onset of Martian spring in the Southern Hemisphere. When NASA's Hubble Space Telescope imaged Mars in June, the seeds of the storm were caught brewing in the giant Hellas Basin (oval at 4 o'clock position on disk) and in another storm at the northern polar cap. When Hubble photographed Mars in early September, the storm had already been raging across the planet for nearly two months obscuring all surface features. The fine airborne dust blocks a significant amount of sunlight from reaching the Martian surface. Because the airborne dust is absorbing this sunlight, it heats the upper atmosphere. Seasonal global Mars dust storms have been observed from telescopes for over a century, but this is the biggest storm ever seen in the past several decades. Mars looks gibbous in the right photograph because it is 26 million miles farther from Earth than in the left photo (though the pictures have been scaled to the same angular size), and our viewing angle has changed. The left picture was taken when Mars was near its closest approach to Earth for 2001 (an event called opposition); at that point the disk of Mars was fully illuminated as seen from Earth because Mars was exactly opposite the Sun. Both images are in natural color, taken with Hubble's Wide Field Planetary Camera 2. Credit: NASA, James Bell (Cornell Univ.), Michael Wolff (Space Science Inst.), and the Hubble Heritage Team (STScI/AURA)

Hubble Observes the Planet Uranus

NASA Technical Reports Server (NTRS)

1994-01-01

This NASA Hubble Space Telescope image of the planet Uranus reveals the planet's rings and bright clouds and a high altitude haze above the planet's south pole.

Hubble's new view was obtained on August 14, 1994, when Uranus was 1.7 billion miles (2.8 billion kilometers) from Earth. These details, as imaged by the Wide Field Planetary Camera 2, were only previously seen by the Voyager 2 spacecraft, which flew by Uranus in 1986. Since then, none of these inner satellites has been further observed, and detailed observations of the rings have not been possible.

Though Uranus' rings were discovered indirectly in 1977 (through stellar occultation observations), they have never before been seen in visible light through a ground-based telescope.

Hubble resolves several of Uranus' rings, including the outermost Epsilon ring. The planet has a total of 11 concentric rings of dark dust. Uranus is tipped such that its rotation axis lies in the plane of its orbit, so the rings appear nearly face-on.

Three of Uranus' inner moons each appear as a string of three dots at the bottom of the picture. This is because the picture is a composite of three images, taken about six minutes apart, and then combined to show the moons' orbital motions. The satellites are, from left to right, Cressida, Juliet, and Portia. The moons move much more rapidly than our own Moon does as it moves around the Earth, so they noticeably change position over only a few minutes.

One of the four gas giant planets of our solar system, Uranus is largely featureless. HST does resolve a high altitude haze which appears as a bright 'cap' above the planet's south pole, along with clouds at southern latitudes (similar structures were observed by Voyager). Unlike Earth, Uranus' south pole points toward the Sun during part of the planet's 84-year orbit. Thanks to its high resolution and ability to make observations over many years, Hubble can follow seasonal changes in Uranus's atmosphere, which should be unusual given the planet's large tilt.

The Wide Field/Planetary Camera 2 was developed by the Jet Propulsion Laboratory and managed by the Goddard Spaced Flight Center for NASA's Office of Space Science.

This image and other images and data received from the Hubble Space Telescope are posted on the World Wide Web on the Space Telescope Science Institute home page at URL http://oposite.stsci.edu/pubinfo/

Horsehead nebula

NASA Technical Reports Server (NTRS)

1999-01-01

Rising from a sea of dust and gas like a giant seahorse, the Horsehead nebula is one of the most photographed objects in the sky. NASA's Hubble Space Telescope took a close-up look at this heavenly icon, revealing the cloud's intricate structure. This detailed view of the horse's head is being released to celebrate the orbiting observatory's eleventh anniversary. Produced by the Hubble Heritage Project, this picture is a testament to the Horsehead's popularity. Internet voters selected this object for the orbiting telescope to view.

The Horsehead, also known as Barnard 33, is a cold, dark cloud of gas and dust, silhouetted against the bright nebula, IC 434. The bright area at the top left edge is a young star still embedded in its nursery of gas and dust. But radiation from this hot star is eroding the stellar nursery. The top of the nebula also is being sculpted by radiation from a massive star located out of Hubble's field of view.

Only by chance does the nebula roughly resemble the head of a horse. Its unusual shape was first discovered on a photographic plate in the late 1800s. Located in the constellation Orion, the Horsehead is a cousin of the famous pillars of dust and gas known as the Eagle nebula. Both tower-like nebulas are cocoons of young stars.

The Horsehead nebula lies just south of the bright star Zeta Orionis, which is easily visible to the unaided eye as the left-hand star in the line of three that form Orion's Belt. Amateur astronomers often use the Horsehead as a test of their observing skills; it is known as one of the more difficult objects to see visually in an amateur-sized telescope.

The magnificent extent of the Horsehead is best appreciated in a new wide-field image of the nebula being released today by the National Optical Astronomy Observatory, taken by Travis Rector with the National Science Foundation's 0.9 meter telescope at Kitt Peak National Observatory near Tucson, AZ.

This popular celestial target was the clear winner among more than 5,000 Internet voters, who were asked last year to select an astronomical target for the Hubble telescope to observe. The voters included students, teachers, and professional and amateur astronomers.

This 11th anniversary release image was composed by the Hubble Heritage Team, which superimposed Hubble data onto ground-based data (limited to small triangular regions around the outer edge of the image). Ground-based image courtesy of Nigel A. Sharp (NOAO/AURA/NSF) taken at the 0.9-meter telescope on Kitt Peak.

Probing the z > 6 Universe with the First Hubble Frontier Fields Cluster A2744

NASA Astrophysics Data System (ADS)

Atek, Hakim; Richard, Johan; Kneib, Jean-Paul; Clement, Benjamin; Egami, Eiichi; Ebeling, Harald; Jauzac, Mathilde; Jullo, Eric; Laporte, Nicolas; Limousin, Marceau; Natarajan, Priyamvada

2014-05-01

The Hubble Frontier Fields program combines the capabilities of the Hubble Space Telescope (HST) with the gravitational lensing of massive galaxy clusters to probe the distant universe to an unprecedented depth. Here, we present the results of the first combined HST and Spitzer observations of the cluster A-2744. We combine the full near-infrared data with ancillary optical images to search for gravitationally lensed high-redshift (z >~ 6) galaxies. We report the detection of 15 I 814 dropout candidates at z ~ 6-7 and one Y 105 dropout at z ~ 8 in a total survey area of 1.43 arcmin2 in the source plane. The predictions of our lens model also allow us to identify five multiply imaged systems lying at redshifts between z ~ 6 and z ~ 8. Thanks to constraints from the mass distribution in the cluster, we were able to estimate the effective survey volume corrected for completeness and magnification effects. This was in turn used to estimate the rest-frame ultraviolet luminosity function (LF) at z ~ 6-8. Our LF results are generally in agreement with the most recent blank field estimates, confirming the feasibility of surveys through lensing clusters. Although based on a shallower observations than what will be achieved in the final data set including the full Advanced Camera for Survey observations, the LF presented here goes down to M UV ~-18.5, corresponding to 0.2L sstarf at z ~ 7 with one identified object at M UV ~-15 thanks to the highly magnified survey areas. This early study forecasts the power of using massive galaxy clusters as cosmic telescopes and its complementarity to blank fields. Based on observations made with the NASA/ESA Hubble Space Telescope (HST), which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555. These observations are associated with programs 13495 and 11689. Based in part on observations made with the Spitzer Space Telescope, which is operated by the Jet Propulsion Laboratory, California Institute of Technology under a contract with NASA. This work utilizes gravitational lensing models produced by PIs Ebeling, Merten, and Zitrin, and Sharon funded as part of the HST Frontier Fields program conducted by STScI. STScI is operated by the Association of Universities for Research in Astronomy, Inc. under NASA contract NAS 5-26555. The lens models were obtained from the Mikulski Archive for Space Telescopes (MAST).

Reheating signature in the gravitational wave spectrum from self-ordering scalar fields

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kuroyanagi, Sachiko; Hiramatsu, Takashi; Yokoyama, Jun'ichi, E-mail: skuro@nagoya-u.jp, E-mail: hiramatz@yukawa.kyoto-u.ac.jp, E-mail: yokoyama@resceu.s.u-tokyo.ac.jp

2016-02-01

We investigate the imprint of reheating on the gravitational wave spectrum produced by self-ordering of multi-component scalar fields after a global phase transition. The equation of state of the Universe during reheating, which usually has different behaviour from that of a radiation-dominated Universe, affects the evolution of gravitational waves through the Hubble expansion term in the equations of motion. This gives rise to a different power-law behavior of frequency in the gravitational wave spectrum. The reheating history is therefore imprinted in the shape of the spectrum. We perform 512{sup 3} lattice simulations to investigate how the ordering scalar field reactsmore » to the change of the Hubble expansion and how the reheating effect arises in the spectrum. We also compare the result with inflation-produced gravitational waves, which has a similar spectral shape, and discuss whether it is possible to distinguish the origin between inflation and global phase transition by detecting the shape with future direct detection gravitational wave experiments such as DECIGO.« less

Hubble Sees the Remains of a Star Gone Supernova

NASA Image and Video Library

2017-12-08

These delicate wisps of gas make up an object known as SNR B0519-69.0, or SNR 0519 for short. The thin, blood-red shells are actually the remnants from when an unstable progenitor star exploded violently as a supernova around 600 years ago. There are several types of supernovae, but for SNR 0519 the star that exploded is known to have been a white dwarf star — a Sun-like star in the final stages of its life. SNR 0519 is located over 150 000 light-years from Earth in the southern constellation of Dorado (The Dolphinfish), a constellation that also contains most of our neighboring galaxy the Large Magellanic Cloud (LMC). Because of this, this region of the sky is full of intriguing and beautiful deep sky objects. The LMC orbits the Milky Way galaxy as a satellite and is the fourth largest in our group of galaxies, the Local Group. SNR 0519 is not alone in the LMC; the NASA/ESA Hubble Space Telescope also came across a similar bauble a few years ago in SNR B0509-67.5, a supernova of the same type as SNR 0519 with a strikingly similar appearance. European Space Agency/NASA Hubble NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Like us on Facebook Find us on Instagram

H0LiCOW – IV. Lens mass model of HE 0435-1223 and blind measurement of its time-delay distance for cosmology

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wong, Kenneth C.; Suyu, Sherry H.; Auger, Matthew W.

Strong gravitational lenses with measured time delays between the multiple images allow a direct measurement of the time-delay distance to the lens, and thus a measure of cosmological parameters, particularly the Hubble constant, H0. We present a blind lens model analysis of the quadruply imaged quasar lens HE 0435-1223 using deep Hubble Space Telescope imaging, updated time-delay measurements from the COSmological MOnitoring of GRAvItational Lenses (COSMOGRAIL), a measurement of the velocity dispersion of the lens galaxy based on Keck data, and a characterization of the mass distribution along the line of sight. HE 0435-1223 is the third lens analysed as a part of the H0 Lenses in COSMOGRAIL's Wellspring (H0LiCOW) project. We account for various sources of systematic uncertainty, including the detailed treatment of nearby perturbers, the parametrization of the galaxy light and mass profile, and the regions used for lens modelling. We constrain the effective time-delay distance to be D Δt=2612more » $$+208\\atop{-191}$$Mpc, a precision of 7.6 per cent. From HE 0435-1223 alone, we infer a Hubble constant of H 0=73.1$$+5.7\\atop{-6.0}$$kms -1Mpc -1 assuming a flat ΛCDM cosmology. Lastly, the cosmographic inference based on the three lenses analysed by H0LiCOW to date is presented in a companion paper (H0LiCOW Paper V).« less

H0LiCOW – IV. Lens mass model of HE 0435-1223 and blind measurement of its time-delay distance for cosmology

DOE PAGES

Wong, Kenneth C.; Suyu, Sherry H.; Auger, Matthew W.; ...

2016-11-29

Strong gravitational lenses with measured time delays between the multiple images allow a direct measurement of the time-delay distance to the lens, and thus a measure of cosmological parameters, particularly the Hubble constant, H0. We present a blind lens model analysis of the quadruply imaged quasar lens HE 0435-1223 using deep Hubble Space Telescope imaging, updated time-delay measurements from the COSmological MOnitoring of GRAvItational Lenses (COSMOGRAIL), a measurement of the velocity dispersion of the lens galaxy based on Keck data, and a characterization of the mass distribution along the line of sight. HE 0435-1223 is the third lens analysed as a part of the H0 Lenses in COSMOGRAIL's Wellspring (H0LiCOW) project. We account for various sources of systematic uncertainty, including the detailed treatment of nearby perturbers, the parametrization of the galaxy light and mass profile, and the regions used for lens modelling. We constrain the effective time-delay distance to be D Δt=2612more » $$+208\\atop{-191}$$Mpc, a precision of 7.6 per cent. From HE 0435-1223 alone, we infer a Hubble constant of H 0=73.1$$+5.7\\atop{-6.0}$$kms -1Mpc -1 assuming a flat ΛCDM cosmology. Lastly, the cosmographic inference based on the three lenses analysed by H0LiCOW to date is presented in a companion paper (H0LiCOW Paper V).« less

Cluster Mass Calibration at High Redshift: HST Weak Lensing Analysis of 13 Distant Galaxy Clusters from the South Pole Telescope Sunyaev-Zel’dovich Survey

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schrabback, T.; Applegate, D.; Dietrich, J. P.

Here we present an HST/Advanced Camera for Surveys (ACS) weak gravitational lensing analysis of 13 massive high-redshift (z median = 0.88) galaxy clusters discovered in the South Pole Telescope (SPT) Sunyaev–Zel'dovich Survey. This study is part of a larger campaign that aims to robustly calibrate mass–observable scaling relations over a wide range in redshift to enable improved cosmological constraints from the SPT cluster sample. We introduce new strategies to ensure that systematics in the lensing analysis do not degrade constraints on cluster scaling relations significantly. First, we efficiently remove cluster members from the source sample by selecting very blue galaxies in V-I colour. Our estimate of the source redshift distribution is based on Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey (CANDELS) data, where we carefully mimic the source selection criteria of the cluster fields. We apply a statistical correction for systematic photometric redshift errors as derived from Hubble Ultra Deep Field data and verified through spatial cross-correlations. We account for the impact of lensing magnification on the source redshift distribution, finding that this is particularly relevant for shallower surveys. Finally, we account for biases in the mass modelling caused by miscentring and uncertainties in the concentration–mass relation using simulations. In combination with temperature estimates from Chandra we constrain the normalization of the mass–temperature scaling relation ln (E(z)M 500c/10 14 M ⊙) = A + 1.5ln (kT/7.2 keV) to A=1.81more » $$+0.24\\atop{-0.14}$$(stat.)±0.09(sys.), consistent with self-similar redshift evolution when compared to lower redshift samples. Additionally, the lensing data constrain the average concentration of the clusters to c 200c=5.6$$+3.7\\atop{-1.8}$$.« less

Cluster Mass Calibration at High Redshift: HST Weak Lensing Analysis of 13 Distant Galaxy Clusters from the South Pole Telescope Sunyaev-Zel’dovich Survey

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schrabback, T.; Applegate, D.; Dietrich, J. P.

We present an HST/Advanced Camera for Surveys (ACS) weak gravitational lensing analysis of 13 massive high-redshift (z(median) = 0.88) galaxy clusters discovered in the South Pole Telescope (SPT) Sunyaev-Zel'dovich Survey. This study is part of a larger campaign that aims to robustly calibrate mass-observable scaling relations over a wide range in redshift to enable improved cosmological constraints from the SPT cluster sample. We introduce new strategies to ensure that systematics in the lensing analysis do not degrade constraints on cluster scaling relations significantly. First, we efficiently remove cluster members from the source sample by selecting very blue galaxies in Vmore » - I colour. Our estimate of the source redshift distribution is based on Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey (CANDELS) data, where we carefully mimic the source selection criteria of the cluster fields. We apply a statistical correction for systematic photometric redshift errors as derived from Hubble Ultra Deep Field data and verified through spatial cross-correlations. We account for the impact of lensing magnification on the source redshift distribution, finding that this is particularly relevant for shallower surveys. Finally, we account for biases in the mass modelling caused by miscentring and uncertainties in the concentration-mass relation using simulations. In combination with temperature estimates from Chandra we constrain the normalization of the mass-temperature scaling relation ln (E(z) M-500c/10(14)M(circle dot)) = A + 1.5ln (kT/7.2 keV) to A = 1.81(-0.14)(+0.24)(stat.)+/- 0.09(sys.), consistent with self-similar redshift evolution when compared to lower redshift samples. Additionally, the lensing data constrain the average concentration of the clusters to c(200c) = 5.6(-1.8)(+3.7).« less

Cluster Mass Calibration at High Redshift: HST Weak Lensing Analysis of 13 Distant Galaxy Clusters from the South Pole Telescope Sunyaev-Zel’dovich Survey

DOE PAGES

Schrabback, T.; Applegate, D.; Dietrich, J. P.; ...

2017-10-14

Here we present an HST/Advanced Camera for Surveys (ACS) weak gravitational lensing analysis of 13 massive high-redshift (z median = 0.88) galaxy clusters discovered in the South Pole Telescope (SPT) Sunyaev–Zel'dovich Survey. This study is part of a larger campaign that aims to robustly calibrate mass–observable scaling relations over a wide range in redshift to enable improved cosmological constraints from the SPT cluster sample. We introduce new strategies to ensure that systematics in the lensing analysis do not degrade constraints on cluster scaling relations significantly. First, we efficiently remove cluster members from the source sample by selecting very blue galaxies in V-I colour. Our estimate of the source redshift distribution is based on Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey (CANDELS) data, where we carefully mimic the source selection criteria of the cluster fields. We apply a statistical correction for systematic photometric redshift errors as derived from Hubble Ultra Deep Field data and verified through spatial cross-correlations. We account for the impact of lensing magnification on the source redshift distribution, finding that this is particularly relevant for shallower surveys. Finally, we account for biases in the mass modelling caused by miscentring and uncertainties in the concentration–mass relation using simulations. In combination with temperature estimates from Chandra we constrain the normalization of the mass–temperature scaling relation ln (E(z)M 500c/10 14 M ⊙) = A + 1.5ln (kT/7.2 keV) to A=1.81more » $$+0.24\\atop{-0.14}$$(stat.)±0.09(sys.), consistent with self-similar redshift evolution when compared to lower redshift samples. Additionally, the lensing data constrain the average concentration of the clusters to c 200c=5.6$$+3.7\\atop{-1.8}$$.« less

VizieR Online Data Catalog: Bgri light curves of PTF11kmb and PTF12bho (Lunnan+, 2017)

NASA Astrophysics Data System (ADS)

Lunnan, R.; Kasliwal, M. M.; Cao, Y.; Hangard, L.; Yaron, O.; Parrent, J. T.; McCully, C.; Gal-Yam, A.; Mulchaey, J. S.; Ben-Ami, S.; Filippenko, A. V.; Fremling, C.; Fruchter, A. S.; Howell, D. A.; Koda, J.; Kupfer, T.; Kulkarni, S. R.; Laher, R.; Masci, F.; Nugent, P. E.; Ofek, E. O.; Yagi, M.; Yan, L.

2017-09-01

The objects PTF11kmb and PTF12bho were found as part of the Palomar Transient Factory (PTF). PTF11kmb was discovered in data taken with the 48 inch Samuel Oschin Telescope at Palomar Observatory (P48) on 2011 August 16.25 at a magnitude r=19.8mag. A spectrum was taken with the Low Resolution Imaging Spectrometer (LRIS) on the 10m Keck I telescope on 2011 August 28, showing SN features consistent with a SN Ib at a redshift z=0.017. The source PTF12bho was discovered in P48 data on 2012 February 25.25 at a magnitude of r=20.52mag. A spectrum taken with LRIS on 2012 March 15 yields z=0.023 based on the SN features. We obtained R- and g-band photometry of PTF11kmb and PTF12bho with the P48 CFH12K camera. Additional follow-up photometry was conducted with the automated 60-inch telescope at Palomar (P60) in the Bgri bands, and with the Las Cumbres Observatory (LCO) Faulkes Telescope North in gri. PTF12bho was also observed with the Swift Ultra-Violet/Optical Telescope (UVOT) and the Swift X-ray telescope (XRT) on 2012 March 17.8 for 3ks. We obtained a sequence of spectra for both PTF11kmb and PTF12bho using LRIS on Keck I, the DEep Imaging Multi-Object Spectrograph (DEIMOS) on the 10m Keck II telescope, and the Double Spectrograph (DPSP) on the 200-inch Hale telescope at Palomar Observatory (P200) spanning 2011 Aug 28.5 to 2014 Jul 2.5. We obtained deep imaging of the fields of PTF11kmb using WFC3/UVIS on the Hubble Space Telescope (HST) through program GO-13864 (PI Kasliwal) in 2015 Jul 12. This program also covered the field of SN 2005E (2014 Dec 10). (1 data file).

FORTY-SEVEN MILKY WAY-SIZED, EXTREMELY DIFFUSE GALAXIES IN THE COMA CLUSTER

DOE Office of Scientific and Technical Information (OSTI.GOV)

Van Dokkum, Pieter G.; Merritt, Allison; Geha, Marla

2015-01-10

We report the discovery of 47 low surface brightness objects in deep images of a 3° × 3° field centered on the Coma cluster, obtained with the Dragonfly Telephoto Array. The objects have central surface brightness μ(g, 0) ranging from 24-26 mag arcsec{sup –2} and effective radii r {sub eff} = 3''-10'', as measured from archival Canada-France-Hawaii Telescope images. From their spatial distribution we infer that most or all of the objects are galaxies in the Coma cluster. This relatively large distance is surprising as it implies that the galaxies are very large: with r {sub eff} = 1.5-4.6 kpcmore » their sizes are similar to those of L {sub *} galaxies even though their median stellar mass is only ∼6 × 10{sup 7} M {sub ☉}. The galaxies are relatively red and round, with (g – i) = 0.8 and (b/a) = 0.74. One of the 47 galaxies is fortuitously covered by a deep Hubble Space Telescope Advanced Camera for Surveys (ACS) observation. The ACS imaging shows a large spheroidal object with a central surface brightness μ{sub 475} = 25.8 mag arcsec{sup –2}, a Sérsic index n = 0.6, and an effective radius of 7'', corresponding to 3.4 kpc at the distance of Coma. The galaxy is not resolved into stars, consistent with expectations for a Coma cluster object. We speculate that these ''ultra-diffuse galaxies'' may have lost their gas supply at early times, possibly resulting in very high dark matter fractions.« less

The Host Galaxies of X-Ray Selected Active Galactic Nuclei to z - 2.5: Structure, Star-Formation and Their Relationships from CANDELS and Herschel/Pacs

NASA Technical Reports Server (NTRS)

Rosario, D.J.; McIntosh, D. H.; van der Wel, A.; Kartaltepe, J.; Lang, P.; Santini, P.; Wuyts, S.; Lutz, D.; Rafelski, M.; Villforth, C.;

Witnessing The Onset Of Environmental Quenching At Z 1-2

NASA Astrophysics Data System (ADS)

Fossati, Matteo

2017-06-01

During the last decade observations of galaxies across cosmic times coupled with cosmological simulations have provided an increasingly clear description of galaxy evolution. In particular we have a fairly detailed phenomenological picture of how galaxies transition from star forming to passive (or quenched) as a function of their internal properties (e.g. stellar mass) and the external environment (e.g. local density). By exploiting the highly complete coverage of grism and spectroscopic redshifts from the 3D-HST survey, we derive the local environment for a deep and complete sample of galaxies in the five 3D-HST deep fields at 0.5 < z < 2.5. A robust definition of environment also requires accurate calibrations obtained using the most up to date semi-analytic model derived from the Millennium simulation. By combining observational data and models we have devised a robust statistical framework within which we link observables to physical quantities (e.g. halo mass and central/satellite status). In this talk I will present our latest results on the environmental quenching of satellites up to z 2.5 in the range of haloes commonly included in our sample Mhalo < 10^14. We find evidences that the quenching timescales for satellites are almost independent on halo mass but have a significant stellar mass dependence. In contrast to local observations we found that for low mass galaxies at z>1 this timescale approaches the Hubble time. I will discuss the physical motivation of these results in terms of quenching mechanisms and gas content of the satellites at the epoch of infall.

A candidate redshift z ≈ 10 galaxy and rapid changes in that population at an age of 500 Myr.

PubMed

Bouwens, R J; Illingworth, G D; Labbe, I; Oesch, P A; Trenti, M; Carollo, C M; van Dokkum, P G; Franx, M; Stiavelli, M; González, V; Magee, D; Bradley, L

2011-01-27

Searches for very-high-redshift galaxies over the past decade have yielded a large sample of more than 6,000 galaxies existing just 900-2,000 million years (Myr) after the Big Bang (redshifts 6 > z > 3; ref. 1). The Hubble Ultra Deep Field (HUDF09) data have yielded the first reliable detections of z ≈ 8 galaxies that, together with reports of a γ-ray burst at z ≈ 8.2 (refs 10, 11), constitute the earliest objects reliably reported to date. Observations of z ≈ 7-8 galaxies suggest substantial star formation at z > 9-10 (refs 12, 13). Here we use the full two-year HUDF09 data to conduct an ultra-deep search for z ≈ 10 galaxies in the heart of the reionization epoch, only 500 Myr after the Big Bang. Not only do we find one possible z ≈ 10 galaxy candidate, but we show that, regardless of source detections, the star formation rate density is much smaller (∼10%) at this time than it is just ∼200 Myr later at z ≈ 8. This demonstrates how rapid galaxy build-up was at z ≈ 10, as galaxies increased in both luminosity density and volume density from z ≈ 10 to z ≈ 8. The 100-200 Myr before z ≈ 10 is clearly a crucial phase in the assembly of the earliest galaxies.

Deep 1.1 mm-wavelength imaging of the GOODS-S field by AzTEC/ASTE - II. Redshift distribution and nature of the submillimetre galaxy population

NASA Astrophysics Data System (ADS)

Yun, Min S.; Scott, K. S.; Guo, Yicheng; Aretxaga, I.; Giavalisco, M.; Austermann, J. E.; Capak, P.; Chen, Yuxi; Ezawa, H.; Hatsukade, B.; Hughes, D. H.; Iono, D.; Johnson, S.; Kawabe, R.; Kohno, K.; Lowenthal, J.; Miller, N.; Morrison, G.; Oshima, T.; Perera, T. A.; Salvato, M.; Silverman, J.; Tamura, Y.; Williams, C. C.; Wilson, G. W.

2012-02-01

We report the results of the counterpart identification and a detailed analysis of the physical properties of the 48 sources discovered in our deep 1.1-mm wavelength imaging survey of the Great Observatories Origins Deep Survey-South (GOODS-S) field using the AzTEC instrument on the Atacama Submillimeter Telescope Experiment. One or more robust or tentative counterpart candidate is found for 27 and 14 AzTEC sources, respectively, by employing deep radio continuum, Spitzer/Multiband Imaging Photometer for Spitzer and Infrared Array Camera, and Large APEX Bolometer Camera 870 μm data. Five of the sources (10 per cent) have two robust counterparts each, supporting the idea that these galaxies are strongly clustered and/or heavily confused. Photometric redshifts and star formation rates (SFRs) are derived by analysing ultraviolet(UV)-to-optical and infrared(IR)-to-radio spectral energy distributions (SEDs). The median redshift of zmed˜ 2.6 is similar to other earlier estimates, but we show that 80 per cent of the AzTEC-GOODS sources are at z≥ 2, with a significant high-redshift tail (20 per cent at z≥ 3.3). Rest-frame UV and optical properties of AzTEC sources are extremely diverse, spanning 10 mag in the i- and K-band photometry (a factor of 104 in flux density) with median values of i= 25.3 and K= 22.6 and a broad range of red colour (i-K= 0-6) with an average value of i-K≈ 3. These AzTEC sources are some of the most luminous galaxies in the rest-frame optical bands at z≥ 2, with inferred stellar masses M*= (1-30) × 1010 M⊙ and UV-derived SFRs of SFRUV≳ 101-3 M⊙ yr-1. The IR-derived SFR, 200-2000 M⊙ yr-1, is independent of z or M*. The resulting specific star formation rates, SSFR ≈ 1-100 Gyr-1, are 10-100 times higher than similar mass galaxies at z= 0, and they extend the previously observed rapid rise in the SSFR with redshift to z= 2-5. These galaxies have a SFR high enough to have built up their entire stellar mass within their Hubble time. We find only marginal evidence for an active galactic nucleus (AGN) contribution to the near-IR and mid-IR SEDs, even among the X-ray detected sources, and the derived M* and SFR show little dependence on the presence of an X-ray bright AGN.

Stellar Populations of Lyα Emitters at z ~ 6-7: Constraints on the Escape Fraction of Ionizing Photons from Galaxy Building Blocks

NASA Astrophysics Data System (ADS)

Ono, Yoshiaki; Ouchi, Masami; Shimasaku, Kazuhiro; Dunlop, James; Farrah, Duncan; McLure, Ross; Okamura, Sadanori

2010-12-01

We investigate the stellar populations of Lyα emitters (LAEs) at z = 5.7 and 6.6 in a 0.65 deg2 sky of the Subaru/XMM-Newton Deep Survey (SXDS) Field, using deep images taken with the Subaru/Suprime-Cam, United Kingdom Infrared Telescope/Wide Field Infrared Camera, and Spitzer/Infrared Array Camera (IRAC). We produce stacked multiband images at each redshift from 165 (z = 5.7) and 91 (z = 6.6) IRAC-undetected objects to derive typical spectral energy distributions (SEDs) of z ~ 6-7 LAEs for the first time. The stacked LAEs have as blue UV continua as the Hubble Space Telescope (HST)/Wide Field Camera 3 (WFC3) z-dropout galaxies of similar M UV, with a spectral slope β ~ -3, but at the same time they have red UV-to-optical colors with detection in the 3.6 μm band. Using SED fitting we find that the stacked LAEs have low stellar masses of ~(3-10) × 107 M sun, very young ages of ~1-3 Myr, negligible dust extinction, and strong nebular emission from the ionized interstellar medium, although the z = 6.6 object is fitted similarly well with high-mass models without nebular emission; inclusion of nebular emission reproduces the red UV-to-optical colors while keeping the UV colors sufficiently blue. We infer that typical LAEs at z ~ 6-7 are building blocks of galaxies seen at lower redshifts. We find a tentative decrease in the Lyα escape fraction from z = 5.7 to 6.6, which may imply an increase in the intergalactic medium neutral fraction. From the minimum contribution of nebular emission required to fit the observed SEDs, we place an upper limit on the escape fraction of ionizing photons of f ion esc ~ 0.6 at z = 5.7 and ~0.9 at z = 6.6. We also compare the stellar populations of our LAEs with those of stacked HST/WFC3 z-dropout galaxies. Based on data collected at the Subaru Telescope, which is operated by the National Astronomical Observatory of Japan.

Peering Through the Muck: Notes on the the Influence of the Galactic Interstellar Medium on Extragalactic Observations

NASA Astrophysics Data System (ADS)

Lockman, Felix J.

This paper considers some effects of foreground Galactic gas on radiation received from extragalactic objects, with an emphasis on the use of the 21cm line to determine the total N(HI). In general, the opacity of the 21cm line makes it impossible to derive an accurate value of N(HI) by simply applying a formula to the observed emission, except in directions where there is very little interstellar matter. The 21cm line can be used to estimate the likelihood that there is significant molecular hydrogen in a particular direction, but carries little or no information on the amount of ionized gas, which can be a major source of foreground effects. Considerable discussion is devoted to the importance of small-scale angular structure in HI, with the conclusion that it will rarely contribute significantly to the total error compared to other factors (such as the effects of ionized gas) for extragalactic sight lines at high Galactic latitude. The direction of the Hubble/Chandra Deep Field North is used as an example of the complexities that might occur even in the absence of opacity or molecular gas.

Inflation model selection meets dark radiation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tram, Thomas; Vallance, Robert; Vennin, Vincent, E-mail: thomas.tram@port.ac.uk, E-mail: robert.vallance@student.manchester.ac.uk, E-mail: vincent.vennin@port.ac.uk

2017-01-01

We investigate how inflation model selection is affected by the presence of additional free-streaming relativistic degrees of freedom, i.e. dark radiation. We perform a full Bayesian analysis of both inflation parameters and cosmological parameters taking reheating into account self-consistently. We compute the Bayesian evidence for a few representative inflation scenarios in both the standard ΛCDM model and an extension including dark radiation parametrised by its effective number of relativistic species N {sub eff}. Using a minimal dataset (Planck low-ℓ polarisation, temperature power spectrum and lensing reconstruction), we find that the observational status of most inflationary models is unchanged. The exceptionsmore » are potentials such as power-law inflation that predict large values for the scalar spectral index that can only be realised when N {sub eff} is allowed to vary. Adding baryon acoustic oscillations data and the B-mode data from BICEP2/Keck makes power-law inflation disfavoured, while adding local measurements of the Hubble constant H {sub 0} makes power-law inflation slightly favoured compared to the best single-field plateau potentials. This illustrates how the dark radiation solution to the H {sub 0} tension would have deep consequences for inflation model selection.« less

VizieR Online Data Catalog: A deep Chandra ACIS survey of M83 (Long+, 2014)

NASA Astrophysics Data System (ADS)

Long, K. S.; Kuntz, K. D.; Blair, W. P.; Godfrey, L.; Plucinsky, P. P.; Soria, R.; Stockdale, C.; Winkler, P. F.

2014-07-01

X-ray observations of M83 were all carried out with Chandra/ACIS-S in the "very faint" mode and spaced over a period of one year from 2010 December to 2011 December. We included in our analysis earlier Chandra observations of M83 in 2000 and 2001 totaling 61ks obtained by G. Rieke (Prop ID. 1600489; ObsID 73) and by A. Prestwich (Prop ID. 267005758; ObsID 2064). To support and extend our X-ray study of M83, we have been carrying out a number of other studies of M83, including optical broadband and narrowband imaging with the IMACS camera on Magellan (Blair et al. 2012, Cat. J/ApJS/203/8), optical imaging with the Wide Field Camera 3 (WFC3) on the Hubble Space Telescope (HST; W. P. Blair PI, Prop. ID. 12513, Blair et al. 2014ApJ...788...55B), and radio imaging with the Jansky Very Large Array (JVLA; C. Stockdale PI, Prog. ID. 12A-335). Here we describe new 6 and 3cm radio imaging we have obtained from ATCA (Australia Telescope Compact Array) on 2011 April 28, 29, and 30 (table 2). (4 data files).

Electroweak vacuum instability and renormalized Higgs field vacuum fluctuations in the inflationary universe

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kohri, Kazunori; Matsui, Hiroki, E-mail: kohri@post.kek.jp, E-mail: matshiro@post.kek.jp

In this work, we investigated the electroweak vacuum instability during or after inflation. In the inflationary Universe, i.e., de Sitter space, the vacuum field fluctuations < δ φ {sup 2} > enlarge in proportion to the Hubble scale H {sup 2}. Therefore, the large inflationary vacuum fluctuations of the Higgs field < δ φ {sup 2} > are potentially catastrophic to trigger the vacuum transition to the negative-energy Planck-scale vacuum state and cause an immediate collapse of the Universe. However, the vacuum field fluctuations < δ φ {sup 2} >, i.e., the vacuum expectation values have an ultraviolet divergence, andmore » therefore a renormalization is necessary to estimate the physical effects of the vacuum transition. Thus, in this paper, we revisit the electroweak vacuum instability from the perspective of quantum field theory (QFT) in curved space-time, and discuss the dynamical behavior of the homogeneous Higgs field φ determined by the effective potential V {sub eff}( φ ) in curved space-time and the renormalized vacuum fluctuations < δ φ {sup 2} >{sub ren} via adiabatic regularization and point-splitting regularization. We simply suppose that the Higgs field only couples the gravity via the non-minimal Higgs-gravity coupling ξ(μ). In this scenario, the electroweak vacuum stability is inevitably threatened by the dynamical behavior of the homogeneous Higgs field φ, or the formations of AdS domains or bubbles unless the Hubble scale is small enough H < Λ {sub I} .« less

Hubble Observes the Moons and Rings of Uranus

NASA Technical Reports Server (NTRS)

1994-01-01

This NASA Hubble Space Telescope image of the planet Uranus reveals the planet's rings, at least five of the inner moons, and bright clouds in the planet's southern hemisphere. Hubble now allows astronomers to revisit the planet at a level of detail not possible since the Voyager 2 spacecraft flew by the planet briefly, nearly a decade ago.

Hubble's new view was obtained on August 14, 1994, when Uranus was 1.7 billion miles (2.8 billion kilometers) from Earth. Similar details, as imaged by the Wide Field Planetary Camera 2, were only previously seen by the Voyager 2 spacecraft that flew by Uranus in 1986 (the rings were discovered by stellar occultation experiments in 1977, but not seen directly until Voyager flew to Uranus). Since the flyby, none of these inner satellites has been observed further, and detailed observations of the rings and Uranus' atmosphere have not been possible, because the rings are lost in the planet's glare as seen through ground-based optical telescopes.

Each of the inner moons appears as a string of three dots in this picture because it is a composite of three images, taken about six minutes apart. When these images are combined, they show the motion of the moons compared with the sky background. Because the moons move much more rapidly than our own Moon, they change position noticeably over only a few minutes. (These multiple images also help to distinguish the moons from stars and imaging detector artifacts, i.e., cosmic rays and electronic noise).

Thanks to Hubble's capabilities, astronomers will now be able to determine the orbits more precisely. With this increase in accuracy, astronomers can better probe the unusual dynamics of Uranus' complicated satellite system. Measuring the moons' brightness in several colors might offer clues to the satellites' origin by providing new information on their mineralogical composition. Similar measurements of the rings should yield new insights into their composition and origin.

One of the four gas giant planets of our solar system, Uranus is largely featureless. HST does reveal a high altitude haze which appears as a bright 'cap' above the planet's south pole, along with clouds at southern latitudes (similar structures were observed by Voyager). Unlike Earth, Uranus' south pole points toward the Sun during part of the planet's 84- year orbit. Thanks to its high resolution and ability to make observations over many years, Hubble can follow seasonal changes in Uranus' atmosphere, which should be unusual given the planet's large tilt.

The Wide Field/Planetary Camera 2 was developed by the Jet Propulsion Laboratory and managed by the Goddard Spaced Flight Center for NASA's Office of Space Science.

This image and other images and data received from the Hubble Space Telescope are posted on the World Wide Web on the Space Telescope Science Institute home page at URL http://oposite.stsci.edu/pubinfo/

Deep HST Imaging in 47 Tucanae: A Global Dynamical Model

NASA Astrophysics Data System (ADS)

Heyl, J.; Caiazzo, I.; Richer, H.; Anderson, J.; Kalirai, J.; Parada, J.

2017-12-01

Multi-epoch observations with the Advanced Camera Survey and WFC3 on the Hubble Space Telescope provide a unique and comprehensive probe of stellar dynamics within 47 Tucanae. We confront analytic models of the globular cluster with the observed stellar proper motions that probe along the main sequence from just above 0.8-0.1M ⊙ as well as white dwarfs younger than 1 Gyr. One field lies just beyond the half-light radius where dynamical models (e.g., lowered Maxwellian distributions) make robust predictions for the stellar proper motions. The observed proper motions in this outer field show evidence for anisotropy in the velocity distribution as well as skewness; the latter is evidence of rotation. The measured velocity dispersions and surface brightness distributions agree in detail with a rotating anisotropic model of the stellar distribution function with mild dependence of the proper-motion dispersion on mass. However, the best-fitting models underpredict the rotation and skewness of the stellar velocities. In the second field, centered on the core of the cluster, the mass segregation in proper motion is much stronger. Nevertheless the model developed in the outer field can be extended inward by taking this mass segregation into account in a heuristic fashion. The proper motions of the main-sequence stars yield a mass estimate of the cluster of 1.31+/- 0.02× {10}6{M}⊙ at a distance of 4.7 kpc. By comparing the proper motions of a sample of giant and subgiant stars with the observed radial velocities we estimate the distance to the cluster kinematically to be 4.29 ± 0.47 kpc.

Unveiling the Galaxy Population at 1.3 < z < 4: the HUDF05 NICMOS Parallel Fields

NASA Technical Reports Server (NTRS)

Petty, Sara M.; deMello, Duilia F.; Wiklind, Tomy; Gardner, Jonathan P.; Mountain, Matt

2010-01-01

Using the Hubble Ultra Deep Field Near Infrared Camera and Multi-Object Spectrometer (HUDF-NICMOS) UDF05 parallel fields, we cross-matched 301 out of 630 galaxies with the ACS filters V606 and z850, NICMOS filters J110 and H160, and Spitzer IRAC filters at 3.6, 4.5, 5.8 , and 8.0 (mu)m. We modeled the spectral energy distributions (SEDs) to estimate: photometric redshifts, dust extinction, stellar mass, bolometric luminosity, starburst age and metallicity. To validate the photometric redshifts, comparisons with 16 spectroscopic redshifts give 75% within Delta < 0.2, which agrees with the sensitivities expected from the Balmer-break in our dataset. Five parallel fields observed by NICMOS have sensitivities in the H160-band of 80% at mAB = 25.4 and 50% at mAB = 26.7. Because the sample is H160-band selected, it is sensitive to stellar mass rather than UV luminosities. We also use Monte Carlo simulations to determine that the parameters from the best-fit SEDs are robust for the redshift ranges z > or approx. 1.3. Based on the robustness of the photometric redshifts, we analyze a subsample of the 301 galaxies at 1.3 < or = z < or = 2 (35 objects) and 3 < or = z < or = 4 (31 objects) and determine that L(BoI) and the star formation rate increase significantly from z approx. 1.5 to 4. The Balmer decrement is indicative of more evolved galaxies, and at high redshifts, they serve as records of some of the first galaxies. Therefore, the galaxies in this sample are great candidates for future surveys with the James Webb Space Telescope and Atacama Large Millimeter Array.

Scalar-tensor extension of the ΛCDM model

DOE Office of Scientific and Technical Information (OSTI.GOV)

Algoner, W.C.; Velten, H.E.S.; Zimdahl, W., E-mail: w.algoner@cosmo-ufes.org, E-mail: velten@pq.cnpq.br, E-mail: winfried.zimdahl@pq.cnpq.br

2016-11-01

We construct a cosmological scalar-tensor-theory model in which the Brans-Dicke type scalar Φ enters the effective (Jordan-frame) Hubble rate as a simple modification of the Hubble rate of the ΛCDM model. This allows us to quantify differences between the background dynamics of scalar-tensor theories and general relativity (GR) in a transparent and observationally testable manner in terms of one single parameter. Problems of the mapping of the scalar-field degrees of freedom on an effective fluid description in a GR context are discused. Data from supernovae, the differential age of old galaxies and baryon acoustic oscillations are shown to strongly limitmore » potential deviations from the standard model.« less

Resolution of massive compact clusters in the 30 Doradus periphery with the Hubble Space Telescope

NASA Technical Reports Server (NTRS)

Walborn, Nolan R.; Mackenty, John W.; Saha, Abhijit; White, Richard L.; Parker, Joel WM.

1995-01-01

Hubble Space Telescope Wide Field/Planetary Camera UBV images of three massive, compact multiple systems with the SNR 30 Dor B/NGC 2060 and 30 Dor C/NGC 2044 are discussed and illustrated. In two cases, WN+OB objects have been resolved into additional components to those previously known from ground-based observations, substantially reducing the luminosities of the WN stars and rendering them currently unidentified; in the third case, the components of a B+K composite-spectrum object have been clearly identified. The results are of significance for evolutionary interpretations of these massive stars and for determinations of the upper IMF in extragalactic systems.

Hubble Space Telescope electrical power system

NASA Technical Reports Server (NTRS)

Whitt, Thomas H.; Bush, John R., Jr.

1990-01-01

The Hubble Space Telescope (HST) electrical power system (EPS) is supplying between 2000 and 2400 W of continuous power to the electrical loads. The major components of the EPS are the 5000-W back surface field reflector solar array, the six nickel-hydrogen (NiH2) 22-cell 88-Ah batteries, and the charge current controllers, which, in conjunction with the flight computer, control battery charging. The operation of the HST EPS and the results of the HST NiH2 six-battery test are discussed, and preliminary flight data are reviewed. The HST NiH2 six-battery test is a breadboard of the HST EPS on test at Marshall Space Flight Center.

MULTIPLE GALAXY COLLISIONS

NASA Technical Reports Server (NTRS)

2002-01-01

Here is a sampling of 15 ultraluminous infrared galaxies viewed by NASA's Hubble Space Telescope. Hubble's sharp vision reveals more complexity within these galaxies, which astronomers are interpreting as evidence of a multiple-galaxy pileup. These images, taken by the Wide Field and Planetary Camera 2, are part of a three-year study of 123 galaxies within 3 billion light-years of Earth. The study was conducted in 1996, 1997, and 1999. False colors were assigned to these photos to enhance fine details within these coalescing galaxies. Credits: NASA, Kirk Borne (Raytheon and NASA Goddard Space Flight Center, Greenbelt, Md.), Luis Colina (Instituto de Fisica de Cantabria, Spain), and Howard Bushouse and Ray Lucas (Space Telescope Science Institute, Baltimore, Md.)

The Capodimonte Deep Field

NASA Astrophysics Data System (ADS)

2001-04-01

A Window towards the Distant Universe Summary The Osservatorio Astronomico Capodimonte Deep Field (OACDF) is a multi-colour imaging survey project that is opening a new window towards the distant universe. It is conducted with the ESO Wide Field Imager (WFI) , a 67-million pixel advanced camera attached to the MPG/ESO 2.2-m telescope at the La Silla Observatory (Chile). As a pilot project at the Osservatorio Astronomico di Capodimonte (OAC) [1], the OACDF aims at providing a large photometric database for deep extragalactic studies, with important by-products for galactic and planetary research. Moreover, it also serves to gather experience in the proper and efficient handling of very large data sets, preparing for the arrival of the VLT Survey Telescope (VST) with the 1 x 1 degree 2 OmegaCam facility. PR Photo 15a/01 : Colour composite of the OACDF2 field . PR Photo 15b/01 : Interacting galaxies in the OACDF2 field. PR Photo 15c/01 : Spiral galaxy and nebulous object in the OACDF2 field. PR Photo 15d/01 : A galaxy cluster in the OACDF2 field. PR Photo 15e/01 : Another galaxy cluster in the OACDF2 field. PR Photo 15f/01 : An elliptical galaxy in the OACDF2 field. The Capodimonte Deep Field ESO PR Photo 15a/01 ESO PR Photo 15a/01 [Preview - JPEG: 400 x 426 pix - 73k] [Normal - JPEG: 800 x 851 pix - 736k] [Hi-Res - JPEG: 3000 x 3190 pix - 7.3M] Caption : This three-colour image of about 1/4 of the Capodimonte Deep Field (OACDF) was obtained with the Wide-Field Imager (WFI) on the MPG/ESO 2.2-m telescope at the la Silla Observatory. It covers "OACDF Subfield no. 2 (OACDF2)" with an area of about 35 x 32 arcmin 2 (about the size of the full moon), and it is one of the "deepest" wide-field images ever obtained. Technical information about this photo is available below. With the comparatively few large telescopes available in the world, it is not possible to study the Universe to its outmost limits in all directions. Instead, astronomers try to obtain the most detailed information possible in selected viewing directions, assuming that what they find there is representative for the Universe as a whole. This is the philosophy behind the so-called "deep-field" projects that subject small areas of the sky to intensive observations with different telescopes and methods. The astronomers determine the properties of the objects seen, as well as their distances and are then able to obtain a map of the space within the corresponding cone-of-view (the "pencil beam"). Recent, successful examples of this technique are the "Hubble Deep Field" (cf. ESO PR Photo 26/98 ) and the "Chandra Deep Field" ( ESO PR 05/01 ). In this context, the Capodimonte Deep Field (OACDF) is a pilot research project, now underway at the Osservatorio Astronomico di Capodimonte (OAC) in Napoli (Italy). It is a multi-colour imaging survey performed with the Wide Field Imager (WFI) , a 67-million pixel (8k x 8k) digital camera that is installed at the 2.2-m MPG/ESO Telescope at ESO's La Silla Observatory in Chile. The scientific goal of the OACDF is to provide an important database for subsequent extragalactic, galactic and planetary studies. It will allow the astronomers at OAC - who are involved in the VLT Survey Telescope (VST) project - to gain insight into the processing (and use) of the large data flow from a camera similar to, but four times smaller than the OmegaCam wide-field camera that will be installed at the VST. The field selection for the OACDF was based on the following criteria: * There must be no stars brighter than about 9th magnitude in the field, in order to avoid saturation of the CCD detector and effects from straylight in the telescope and camera. No Solar System planets should be near the field during the observations; * It must be located far from the Milky Way plane (at high galactic latitude) in order to reduce the number of galactic stars seen in this direction; * It must be located in the southern sky in order to optimize observing conditions (in particular, the altitude of the field above the horizon), as seen from the La Silla and Paranal sites; * There should be little interstellar material in this direction that may obscure the view towards the distant Universe; * Observations in this field should have been made with the Hubble Space Telescope (HST) that may serve for comparison and calibration purposes. Based on these criteria, the astronomers selected a field measuring about 1 x 1 deg 2 in the southern constellation of Corvus (The Raven). This is now known as the Capodimonte Deep Field (OACDF) . The above photo ( PR Photo 15a/01 ) covers one-quarter of the full field (Subfield No. 2 - OACDF2) - some of the objects seen in this area are shown below in more detail. More than 35,000 objects have been found in this area; the faintest are nearly 100 million fainter than what can be perceived with the unaided eye in the dark sky. Selected objects in the Capodimonte Deep Field ESO PR Photo 15b/01 ESO PR Photo 15b/01 [Preview - JPEG: 400 x 435 pix - 60k] [Normal - JPEG: 800 x 870 pix - 738k] [Hi-Res - JPEG: 3000 x 3261 pix - 5.1M] Caption : Enlargement of the interacting galaxies that are seen in the upper left corner of the OACDF2 field shown in PR Photo 15a/01 . The enlargement covers 1250 x 1130 WFI pixels (1 pixel = 0.24 arcsec), or about 5.0 x 4.5 arcmin 2 in the sky. The lower spiral is itself an interactive double. ESO PR Photo 15c/01 ESO PR Photo 15c/01 [Preview - JPEG: 557 x 400 pix - 93k] [Normal - JPEG: 1113 x 800 pix - 937k] [Hi-Res - JPEG: 3000 x 2156 pix - 4.0M] Caption : Enlargement of a spiral galaxy and a nebulous object in this area. The field shown covers 1250 x 750 pixels, or about 5 x 3 arcmin 2 in the sky. Note the very red objects next to the two bright stars in the lower-right corner. The colours of these objects are consistent with those of spheroidal galaxies at intermediate distances (redshifts). ESO PR Photo 15d/01 ESO PR Photo 15d/01 [Preview - JPEG: 400 x 530 pix - 68k] [Normal - JPEG: 800 x 1060 pix - 870k] [Hi-Res - JPEG: 2768 x 3668 pix - 6.2M] Caption : A further enlargement of a galaxy cluster of which most members are located in the north-east quadrant (upper left) and have a reddish colour. The nebulous object to the upper left is a dwarf galaxy of spheroidal shape. The red object, located near the centre of the field and resembling a double star, is very likely a gravitational lens [2]. Some of the very red, point-like objects in the field may be distant quasars, very-low mass stars or, possibly, relatively nearby brown dwarf stars. The field shown covers 1380 x 1630 pixels, or 5.5 x 6.5 arcmin 2. ESO PR Photo 15e/01 ESO PR Photo 15e/01 [Preview - JPEG: 400 x 418 pix - 56k] [Normal - JPEG: 800 x 835 pix - 700k] [Hi-Res - JPEG: 3000 x 3131 pix - 5.0M] Caption : Enlargement of a moderately distant galaxy cluster in the south-east quadrant (lower left) of the OACDF2 field. The field measures 1380 x 1260 pixels, or about 5.5 x 5.0 arcmin 2 in the sky. ESO PR Photo 15f/01 ESO PR Photo 15f/01 [Preview - JPEG: 449 x 400 pix - 68k] [Normal - JPEG: 897 x 800 pix - 799k] [Hi-Res - JPEG: 3000 x 2675 pix - 5.6M] Caption : Enlargement of the elliptical galaxy that is located to the west (right) in the OACDF2 field. The numerous tiny objects surrounding the galaxy may be globular clusters. The fuzzy object on the right edge of the field may be a dwarf spheroidal galaxy. The size of the field is about 6 x 5 arcmin 2. Technical Information about the OACDF Survey The observations for the OACDF project were performed in three different ESO periods (18-22 April 1999, 7-12 March 2000 and 26-30 April 2000). Some 100 Gbyte of raw data were collected during each of the three observing runs. The first OACDF run was done just after the commissioning of the ESO-WFI. The observational strategy was to perform a 1 x 1 deg 2 short-exposure ("shallow") survey and then a 0.5 x 1 deg 2 "deep" survey. The shallow survey was performed in the B, V, R and I broad-band filters. Four adjacent 30 x 30 arcmin 2 fields, together covering a 1 x 1 deg 2 field in the sky, were observed for the shallow survey. Two of these fields were chosen for the 0.5 x 1 deg 2 deep survey; OACDF2 shown above is one of these. The deep survey was performed in the B, V, R broad-bands and in other intermediate-band filters. The OACDF data are fully reduced and the catalogue extraction has started. A two-processor (500 Mhz each) DS20 machine with 100 Gbyte of hard disk, specifically acquired at the OAC for WFI data reduction, was used. The detailed guidelines of the data reduction, as well as the catalogue extraction, are reported in a research paper that will appear in the European research journal Astronomy & Astrophysics . Notes [1]: The team members are: Massimo Capaccioli, Juan M. Alcala', Roberto Silvotti, Magda Arnaboldi, Vincenzo Ripepi, Emanuella Puddu, Massimo Dall'Ora, Giuseppe Longo and Roberto Scaramella . [2]: This is a preliminary result by Juan Alcala', Massimo Capaccioli, Giuseppe Longo, Mikhail Sazhin, Roberto Silvotti and Vincenzo Testa , based on recent observations with the Telescopio Nazionale Galileo (TNG) which show that the spectra of the two objects are identical. Technical information about the photos PR Photo 15a/01 has been obtained by the combination of the B, V, and R stacked images of the OACDF2 field. The total exposure times in the three bands are 2 hours in B and V (12 ditherings of 10 min each were stacked to produce the B and V images) and 3 hours in R (13 ditherings of 15 min each). The mosaic images in the B and V bands were aligned relative to the R-band image and adjusted to a logarithmic intensity scale prior to the combination. The typical seeing was of the order of 1 arcsec in each of the three bands. Preliminary estimates of the three-sigma limiting magnitudes in B, V and R indicate 25.5, 25.0 and 25.0, respectively. More than 35,000 objects are detected above the three-sigma level. PR Photos 15b-f/01 display selected areas of the field shown in PR Photo 15a/01 at the original WFI scale, hereby also demonstrating the enormous amount of information contained in these wide-field images. In all photos, North is up and East is left.

Hubble Sees Stars and a Stripe in Celestial Fireworks

NASA Image and Video Library

2017-12-08

Release date: July 1, 2008 SN 1006 Supernova Remnant (Hubble) A delicate ribbon of gas floats eerily in our galaxy. A contrail from an alien spaceship? A jet from a black-hole? Actually this image, taken by NASA's Hubble Space Telescope, is a very thin section of a supernova remnant caused by a stellar explosion that occurred more than 1,000 years ago. On or around May 1, 1006 A.D., observers from Africa to Europe to the Far East witnessed and recorded the arrival of light from what is now called SN 1006, a tremendous supernova explosion caused by the final death throes of a white dwarf star nearly 7,000 light-years away. The supernova was probably the brightest star ever seen by humans, and surpassed Venus as the brightest object in the night time sky, only to be surpassed by the moon. It was visible even during the day for weeks, and remained visible to the naked eye for at least two and a half years before fading away. It wasn't until the mid-1960s that radio astronomers first detected a nearly circular ring of material at the recorded position of the supernova. The ring was almost 30 arcminutes across, the same angular diameter as the full moon. The size of the remnant implied that the blast wave from the supernova had expanded at nearly 20 million miles per hour over the nearly 1,000 years since the explosion occurred. In 1976, the first detection of exceedingly faint optical emission of the supernova remnant was reported, but only for a filament located on the northwest edge of the radio ring. A tiny portion of this filament is revealed in detail by the Hubble observation. The twisting ribbon of light seen by Hubble corresponds to locations where the expanding blast wave from the supernova is now sweeping into very tenuous surrounding gas. The hydrogen gas heated by this fast shock wave emits radiation in visible light. Hence, the optical emission provides astronomers with a detailed "snapshot" of the actual position and geometry of the shock front at any given time. Bright edges within the ribbon correspond to places where the shock wave is seen exactly edge on to our line of sight. Today we know that SN 1006 has a diameter of nearly 60 light-years, and it is still expanding at roughly 6 million miles per hour. Even at this tremendous speed, however, it takes observations typically separated by years to see significant outward motion of the shock wave against the grid of background stars. In the Hubble image as displayed, the supernova would have occurred far off the lower right corner of the image, and the motion would be toward the upper left. SN 1006 resides within our Milky Way Galaxy. Located more than 14 degrees off the plane of the galaxy's disk, there is relatively little confusion with other foreground and background objects in the field when trying to study this object. In the Hubble image, many background galaxies (orange extended objects) far off in the distant universe can be seen dotting the image. Most of the white dots are foreground or background stars in our Milky Way galaxy. This image is a composite of hydrogen-light observations taken with Hubble's Advanced Camera for Surveys in February 2006 and Wide Field Planetary Camera 2 observations in blue, yellow-green, and near-infrared light taken in April 2008. The supernova remnant, visible only in the hydrogen-light filter was assigned a red hue in the Heritage color image. Credit: NASA, ESA, and the Hubble Heritage Team (STScI/AURA) Acknowledgment: W. Blair (Johns Hopkins University) To learn more about the Hubble Space Telescope go here: www.nasa.gov/mission_pages/hubble/main/index.html NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Like us on Facebook Find us on Instagram

Revisiting Abell 2744: a powerful synergy of the GLASS spectroscopy and the HFF photometry.

NASA Astrophysics Data System (ADS)

Wang, Xin; Borello Schmidt, Kasper; Treu, Tommaso

2015-08-01

We present new emission line identifications and improve the strong lensing reconstruction of the massive cluster Abell 2744 using the Grism Lens-Amplified Survey from Space (GLASS) observations and the full depth of the Hubble Frontier Fields (HFF) imaging. We performed a blind and targeted search for emission lines in objects within the full field of view (FoV) of the GLASS prime pointings, including all the previously known multiple arc images. We report over 50 high quality spectroscopic redshifts, 4 of which are for the arc images. We also present an extensive analysis based on the HFF photometry, measuring the colors and photometric redshifts of all objects within the FoV, and comparing the spectroscopic and photometric results of the same ensemble of sources. In order to improve the lens model of Abell 2744, we develop a rigorous alogorithm to screen arc images, based on their colors and morphology, and selecting the most reliable ones to use. As a result, 21 systems (corresponding to 59 images) pass the screening process and are used to reconstruct the gravitational potential of the cluster pixellated on an adaptive mesh. The resulting total mass distribution is compared with a stellar mass map obtained from the deep Spitzer Frontier Fields data in a fashion very similar to the reduction of the Spitzer UltRa Faint SUrvey Program (SURFS UP) clusters, in order to study the relative distribution of stars and dark matter in the cluster. The maps of convergence, shear, and magnification are made publicly available in the standard HFF format.

The nature of radio emission from distant galaxies

NASA Astrophysics Data System (ADS)

Richards, Eric A.

I describe an observational program aimed at understanding the radio emission from distant, rapidly evolving galaxy populations. These observations were carried out at 1.4 and 8.5 GHz with the VLA centered on the Hubble Deep Field. Further MERLIN observations of the HDF region at 1.4 GHz provided an angular resolution of 0.2'' and when combined with the VLA data produced an image with an unprecedented rms noise of 4 μJy. All radio sources detected in the VLA complete sample are resolved with a median angular size of 1-2''. The differential count of the radio sources is marginally sub-Euclidean (γ = -2.4 +/- 0.1) and fluctuation analysis suggests nearly 60 sources per armin2 are present at the 1 μJy level. A correlation analysis indicates spatial clustering among the 371 radio sources on angular scales of 1-40 arcmin. Optical identifications are made primarily with bright (I = 22) disk systems composed of irregulars, peculiars, interacting/merging galaxies, and a few isolated field spirals. Available redshifts span the range 0.2-3. These clues coupled with the steep spectral index of the 1.4 GHz selected sample are indicative of diffuse synchrotron radiation in distant galactic disks. Thus the evolution in the microjansky radio population is driven principally by star-formation. I have isolated a number of optically faint radio sources (about 25% of the overall sample) which remain unidentified to I = 26-28 in the HDF and flanking optical fields. Several of these objects have extremely red counterparts and constitute a new class of radio sources which are candidate high redshift dusty protogalaxies.

Morphology and Structure of Ultraluminous Infrared Galaxies at z ∼ 2 in the EGS Field

NASA Astrophysics Data System (ADS)

Fang, Guan-Wen; Ma, Zhong-Yang; Chen, Yang; Kong, Xu

2015-04-01

Using the high-resolution F160W images observed by the HST WFC3 (Hubble Space Telescope Wide Field Camera 3) in the CANDELS-EGS (Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey-Extended Groth Strip) field, we have studied the morphological and structural features of 9 ultraluminous infrared galaxies (ULIRGs) at z ∼ 2. We find a wide range of morphological diversity for these ULIRGs, from ellipsoids to multiple bright nuclei or diffuse structures, e.g., the double nuclei, gaseous bridges, dual asym- metries, irregular or elliptical structures. In order to study the morphology of these ULIRGs quantitatively, their morphological parameters (the Gini coeffcient G and moment index M20) are measured in the rest-frame optical wave- band. Compared with the low-redshift counterparts, the high-redshift ULIRGs show a smaller value of G and a larger value of M20, indicating a less concen- tricity and a larger asymmetry of the stellar population distribution in these ULIRGs. Based on a 2-D fitting of the brightness profiles of these ULIRGs, we have derived their effective radii, which are distributed in a range from 2.4 to kpc, with a mean value of (3.9 ± 1.1) kpc. Moreover, we find that in average the sizes of the high-redshift ULIRGs are one to two times smaller than those of the nearby star-forming galaxies of analogous stellar mass. Our results are consistent with those of other studies under the similar conditions of redshift and infrared luminosity.

The Kormendy relation of galaxies in the Frontier Fields clusters: Abell S1063 and MACS J1149.5+2223

NASA Astrophysics Data System (ADS)

Tortorelli, Luca; Mercurio, Amata; Paolillo, Maurizio; Rosati, Piero; Gargiulo, Adriana; Gobat, Raphael; Balestra, Italo; Caminha, G. B.; Annunziatella, Marianna; Grillo, Claudio; Lombardi, Marco; Nonino, Mario; Rettura, Alessandro; Sartoris, Barbara; Strazzullo, Veronica

2018-06-01

We analyse the Kormendy relations (KRs) of the two Frontier Fields clusters, Abell S1063, at z = 0.348, and MACS J1149.5+2223, at z = 0.542, exploiting very deep Hubble Space Telescope photometry and Very Large Telescope (VLT)/Multi Unit Spectroscopic Explorer (MUSE) integral field spectroscopy. With this novel data set, we are able to investigate how the KR parameters depend on the cluster galaxy sample selection and how this affects studies of galaxy evolution based on the KR. We define and compare four different galaxy samples according to (a) Sérsic indices: early-type (`ETG'), (b) visual inspection: `ellipticals', (c) colours: `red', (d) spectral properties: `passive'. The classification is performed for a complete sample of galaxies with mF814W ≤ 22.5 ABmag (M* ≳ 1010.0 M⊙). To derive robust galaxy structural parameters, we use two methods: (1) an iterative estimate of structural parameters using images of increasing size, in order to deal with closely separated galaxies and (2) different background estimations, to deal with the intracluster light contamination. The comparison between the KRs obtained from the different samples suggests that the sample selection could affect the estimate of the best-fitting KR parameters. The KR built with ETGs is fully consistent with the one obtained for ellipticals and passive. On the other hand, the KR slope built on the red sample is only marginally consistent with those obtained with the other samples. We also release the photometric catalogue with structural parameters for the galaxies included in the present analysis.

Discovery of a z = 7.452 High Equivalent Width Lyα Emitter from the Hubble Space Telescope  Faint Infrared Grism Survey

NASA Astrophysics Data System (ADS)

Larson, Rebecca L.; Finkelstein, Steven L.; Pirzkal, Norbert; Ryan, Russell; Tilvi, Vithal; Malhotra, Sangeeta; Rhoads, James; Finkelstein, Keely; Jung, Intae; Christensen, Lise; Cimatti, Andrea; Ferreras, Ignacio; Grogin, Norman; Koekemoer, Anton M.; Hathi, Nimish; O’Connell, Robert; Östlin, Göran; Pasquali, Anna; Pharo, John; Rothberg, Barry; Windhorst, Rogier A.; The FIGS Team

2018-05-01

We present the results of an unbiased search for Lyα emission from continuum-selected 5.6 < z < 8.7 galaxies. Our data set consists of 160 orbits of G102 slitless grism spectroscopy obtained with the Hubble Space Telescope(HST)/WFC3 as part of the Faint Infrared Grism Survey (FIGS; PI: Malhotra), which obtains deep slitless spectra of all sources in four fields, and was designed to minimize contamination in observations of previously identified high-redshift galaxy candidates. The FIGS data can potentially spectroscopically confirm the redshifts of galaxies, and as Lyα emission is resonantly scattered by neutral gas, FIGS can also constrain the ionization state of the intergalactic medium during the epoch of reionization. These data have sufficient depth to detect Lyα emission in this epoch, as Tilvi et al. have published the FIGS detection of previously known Lyα emission at z = 7.51. The FIGS data use five separate roll angles of HST to mitigate the contamination by nearby galaxies. We created a method that accounts for and removes the contamination from surrounding galaxies and also removes any dispersed continuum light from each individual spectrum. We searched for significant (>4σ) emission lines using two different automated detection methods, free of any visual inspection biases. Applying these methods on photometrically selected high-redshift candidates between 5.6 < z < 8.7, we find two emission lines, one previously published by Tilvi et al., (2016) and a new line at 1.028 μm, which we identify as Lyα at z = 7.452 ± 0.003. This newly spectroscopically confirmed galaxy has the highest Lyα rest-frame equivalent width (EWLyα ) yet published at z > 7 (140.3 ± 19.0 Å).

DOE Office of Scientific and Technical Information (OSTI.GOV)

Konstantopoulos, I. S.; Charlton, J. C.; Gronwall, C.

The environment where galaxies are found heavily influences their evolution. Close groupings, like the ones in the cores of galaxy clusters or compact groups, evolve in ways far more dramatic than their isolated counterparts. We have conducted a multi-wavelength study of Hickson Compact Group 7 (HCG 7), consisting of four giant galaxies: three spirals and one lenticular. We use Hubble Space Telescope (HST) imaging to identify and characterize the young and old star cluster populations. We find young massive clusters (YMCs) mostly in the three spirals, while the lenticular features a large, unimodal population of globular clusters (GCs) but nomore » detectable clusters with ages less than a few Gyr. The spatial and approximate age distributions of the {approx}300 YMCs and {approx}150 GCs thus hint at a regular star formation history in the group over a Hubble time. While at first glance the HST data show the galaxies as undisturbed, our deep ground-based, wide-field imaging that extends the HST coverage reveals faint signatures of stellar material in the intragroup medium (IGM). We do not, however, detect the IGM in H I or Chandra X-ray observations, signatures that would be expected to arise from major mergers. Despite this fact, we find that the H I gas content of the individual galaxies and the group as a whole are a third of the expected abundance. The appearance of quiescence is challenged by spectroscopy that reveals an intense ionization continuum in one galaxy nucleus, and post-burst characteristics in another. Our spectroscopic survey of dwarf galaxy members yields a single dwarf elliptical galaxy in an apparent stellar tidal feature. Based on all this information, we suggest an evolutionary scenario for HCG 7, whereby the galaxies convert most of their available gas into stars without the influence of major mergers and ultimately result in a dry merger. As the conditions governing compact groups are reminiscent of galaxies at intermediate redshift, we propose that HCGs are appropriate for studying galaxy evolution at z {approx} 1-2.« less

Evidence of a Non-universal Stellar Initial Mass Function. Insights from HST Optical Imaging of Six Ultra-faint Dwarf Milky Way Satellites

NASA Astrophysics Data System (ADS)

Gennaro, Mario; Tchernyshyov, Kirill; Brown, Thomas M.; Geha, Marla; Avila, Roberto J.; Guhathakurta, Puragra; Kalirai, Jason S.; Kirby, Evan N.; Renzini, Alvio; Simon, Joshua D.; Tumlinson, Jason; Vargas, Luis C.

2018-03-01

Using deep observations obtained with the Advanced Camera for Surveys (ACS) on board the Hubble Space Telescope (HST), we demonstrate that the sub-solar stellar initial mass function (IMF) of six ultra-faint dwarf Milky Way satellites (UFDs) is more bottom light than the IMF of the Milky Way disk. Our data have a lower-mass limit of ∼0.45 M ⊙, while the upper limit is ∼0.8 M ⊙, set by the turnoff mass of these old, metal-poor systems. If formulated as a single power law, we obtain a shallower IMF slope than the Salpeter value of ‑2.3, ranging from ‑1.01 for Leo IV to ‑1.87 for Boötes I. The significance of these deviations depends on the galaxy and is typically 95% or more. When modeled as a log-normal, the IMF fit results in a higher peak mass than in the Milky Way disk, but a Milky Way disk value for the characteristic system mass (∼0.22 M ⊙) is excluded at only 68% significance, and only for some UFDs in the sample. We find that the IMF slope correlates well with the galaxy mean metallicity, and to a lesser degree, with the velocity dispersion and the total mass. The strength of the observed correlations is limited by shot noise in the number of observed stars, but future space-based missions like the James Webb Space Telescope (JWST) and the Wide-Field Infrared Survey Telescope ( WFIRST) will enhance both the number of dwarf Milky Way satellites that can be studied in such detail and the observation depth for individual galaxies. Based on observations made with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555. These observations are associated with program GO-12549.

Type Ia Supernova Rate Measurements to Redshift 2.5 from Candles: Searching for Prompt Explosions in the Early Universe

NASA Technical Reports Server (NTRS)

Rodney, Steven A.; Riess, Adam G.; Strogler, Louis-Gregory; Dahlen, Tomas; Graur, Or; Casertano, Stefano; Dickinson, Mark E.; Ferguson, Henry C.; Garnavich, Peter; Cenko, Stephen Bradley

2014-01-01

The Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey (CANDELS) was a multi-cycle treasury program on the Hubble Space Telescope(HST) that surveyed a total area of approx. 0.25 deg(sup 2) with approx.900 HST orbits spread across five fields over three years. Within these survey images we discovered 65 supernovae (SNe) of all types, out to z approx. 2.5. We classify approx. 24 of these as Type Ia SNe (SNe Ia) based on host galaxy redshifts and SN photometry (supplemented by grism spectroscopy of six SNe). Here we present a measurement of the volumetric SN Ia rate as a function of redshift, reaching for the first time beyond z = 2 and putting new constraints on SN Ia progenitor models. Our highest redshift bin includes detections of SNe that exploded when the universe was only approx. 3 Gyr old and near the peak of the cosmic star formation history. This gives the CANDELS high redshift sample unique leverage for evaluating the fraction of SNe Ia that explode promptly after formation (500 Myr). Combining the CANDELS rates with all available SN Ia rate measurements in the literature we find that this prompt SN Ia fraction isfP0.530.09stat0.100.10sys0.26, consistent with a delay time distribution that follows a simplet1power law for all timest40 Myr. However, mild tension is apparent between ground-based low-z surveys and space-based high-z surveys. In both CANDELS and the sister HST program CLASH (Cluster Lensing And Supernova Survey with Hubble), we find a low rate of SNe Ia at z > 1. This could be a hint that prompt progenitors are in fact relatively rare, accounting for only 20 of all SN Ia explosions though further analysis and larger samples will be needed to examine that suggestion.

Type Ia Supernova Rate Measurements to Redshift 2.5 from CANDELS: Searching for Prompt Explosions in the Early Universe

NASA Astrophysics Data System (ADS)

Rodney, Steven A.; Riess, Adam G.; Strolger, Louis-Gregory; Dahlen, Tomas; Graur, Or; Casertano, Stefano; Dickinson, Mark E.; Ferguson, Henry C.; Garnavich, Peter; Hayden, Brian; Jha, Saurabh W.; Jones, David O.; Kirshner, Robert P.; Koekemoer, Anton M.; McCully, Curtis; Mobasher, Bahram; Patel, Brandon; Weiner, Benjamin J.; Cenko, S. Bradley; Clubb, Kelsey I.; Cooper, Michael; Filippenko, Alexei V.; Frederiksen, Teddy F.; Hjorth, Jens; Leibundgut, Bruno; Matheson, Thomas; Nayyeri, Hooshang; Penner, Kyle; Trump, Jonathan; Silverman, Jeffrey M.; U, Vivian; Azalee Bostroem, K.; Challis, Peter; Rajan, Abhijith; Wolff, Schuyler; Faber, S. M.; Grogin, Norman A.; Kocevski, Dale

2014-07-01

The Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey (CANDELS) was a multi-cycle treasury program on the Hubble Space Telescope (HST) that surveyed a total area of ~0.25 deg2 with ~900 HST orbits spread across five fields over three years. Within these survey images we discovered 65 supernovae (SNe) of all types, out to z ~ 2.5. We classify ~24 of these as Type Ia SNe (SNe Ia) based on host galaxy redshifts and SN photometry (supplemented by grism spectroscopy of six SNe). Here we present a measurement of the volumetric SN Ia rate as a function of redshift, reaching for the first time beyond z = 2 and putting new constraints on SN Ia progenitor models. Our highest redshift bin includes detections of SNe that exploded when the universe was only ~3 Gyr old and near the peak of the cosmic star formation history. This gives the CANDELS high redshift sample unique leverage for evaluating the fraction of SNe Ia that explode promptly after formation (<500 Myr). Combining the CANDELS rates with all available SN Ia rate measurements in the literature we find that this prompt SN Ia fraction is f_{P}\\,{=}\\,0.53^{\\ \\,\\, +/- 0.09}_{stat0.10} {}^{\\ \\, +/- 0.10}_{sys 0.26}, consistent with a delay time distribution that follows a simple t -1 power law for all times t > 40 Myr. However, mild tension is apparent between ground-based low-z surveys and space-based high-z surveys. In both CANDELS and the sister HST program CLASH (Cluster Lensing And Supernova Survey with Hubble), we find a low rate of SNe Ia at z > 1. This could be a hint that prompt progenitors are in fact relatively rare, accounting for only 20% of all SN Ia explosions—though further analysis and larger samples will be needed to examine that suggestion.

Hubble views a spectacular supernova with interstellar material over 160,000 light-years away

NASA Image and Video Library

2017-12-08

This NASA/ESA Hubble Space Telescope image captures the remnants of a long-dead star. These rippling wisps of ionized gas, named DEM L316A, are located some 160,000 light-years away within one of the Milky Way’s closest galactic neighbors — the Large Magellanic Cloud (LMC). The explosion that formed DEM L316A was an example of an especially energetic and bright variety of supernova, known as a Type Ia. Such supernova events are thought to occur when a white dwarf star steals more material than it can handle from a nearby companion, and becomes unbalanced. The result is a spectacular release of energy in the form of a bright, violent explosion, which ejects the star’s outer layers into the surrounding space at immense speeds. As this expelled gas travels through the interstellar material, it heats up and ionizes it, producing the faint glow that Hubble’s Wide Field Camera 3 has captured here. The LMC orbits the Milky Way as a satellite galaxy and is the fourth largest in our group of galaxies, the Local Group. DEM L316A is not the only supernova remnant in the LMC; Hubble came across another one in 2010 with SNR 0509, and in 2013 it snapped SNR 0519. Image credit: ESA (European Space Agency)/Hubble & NASA, Y. Chu