A new detection of an UFO in the X-ray spectrum of a lensed QSO

NASA Astrophysics Data System (ADS)

Dadina, M.

2017-10-01

The discovery of the "M_{SMBH}-σ relation" indicated that a connection between the central black-hole and the hosting galaxies acted during the cosmic time. With the discovery in X-rays of the ultra-fast outflows in nearby AGN, we have most probably probed one of the ingredients that are needed to build-up this mechanism. At high-z, however, such measurements were possible only in an handful of objects and this was possible mainly for the presence of gravitational lenses that magnified otherwise X-ray weak QSO. Following this, we proposed a program to use XMM-Newton and gravitational lenses as telescopes to point bright, lensed and distant QSO to characterize in detail their X-ray spectrum and to detect blushifted absorption lines at E˜7-10 keV (rest frame). Here we present the preliminary results obtained for the z=2.64 QSO MG J0414+0534.

WEAVE-QSO: A Massive Intergalactic Medium Survey for the William Herschel Telescope

NASA Astrophysics Data System (ADS)

Pieri, M. M.; Bonoli, S.; Chaves-Montero, J.; Pâris, I.; Fumagalli, M.; Bolton, J. S.; Viel, M.; Noterdaeme, P.; Miralda-Escudé, J.; Busca, N. G.; Rahmani, H.; Peroux, C.; Font-Ribera, A.; Trager, S. C.

2016-12-01

In these proceedings we describe the WEAVE-QSO survey, which will observe around 400,000 high redshift quasars starting in 2018. This survey is part of a broader WEAVE survey to be conducted at the 4.2m William Herschel Telescope. We will focus on chiefly on the science goals, but will also briefly summarise the target selection methods anticipated and the expected survey plan. Understanding the apparent acceleration in the expansion of the Universe is one of the key scientific challenges of our time. Many experiments have been proposed to study this expansion, using a variety of techniques. Here we describe a survey that can measure this acceleration and therefore help elucidate the nature of dark energy: a survey of the Lyα forest (and quasar absorption in general) in spectra towards z>2 quasars (QSOs). Further constraints on neutrino masses and warm dark matter are also anticipated. The same data will also shed light on galaxy formation via study of the properties of inflowing/outflowing gas associated with nearby galaxies and in a cosmic web context. Gas properties are sensitive to density, temperature, UV radiation, metallicity and abundance pattern, and so constraint galaxy formation in a variety of ways. WEAVE-QSO will study absorbers with a dynamic range spanning more than 8 orders of magnitude in column density, their thermal broadening, and a host of elements and ionization species. A core principal of the WEAVE-QSO survey is the targeting of QSOs with near 100% efficiency principally through use of the J-PAS (r < 23.2) and Gaia (r ≲ 20) data.

ALMA Reveals a Compact Starburst Around a Hidden QSO at z˜5

NASA Astrophysics Data System (ADS)

Gilli, R.; Norman, C. A.; Vignali, C.

2015-12-01

We present ALMA 1.3mm observations of XID403, an SMG at z=4.75 in the Chandra Deep Field South hosting a heavily obscured, Compton-thick QSO. The ALMA data show that the dust heated by star formation is distributed within ˜0.9 kpc from the nucleus (effective radius). The SFR and dust temperature obtained from the Herschel+ALMA far-IR SED, reveal a warm and compact starburst with surface density of 200 M⊙ yr-1 kpc-2. Our analysis suggest that, besides the mass, SFR and gas consumption timescale, objects like XID403 have also the right size to be the progenitors of the compact quiescent massive galaxies seen at z˜3. It is finally shown that the density of the gas co-spatial with the dust provides a substantial contribution to the absorbing column density towards the QSO as measured from the X-rays.

Galaxies Probing Galaxies in PRIMUS. I. Sample, Spectroscopy, and Characteristics of the z\\sim 0.5 Mg II–absorbing Circumgalactic Medium

NASA Astrophysics Data System (ADS)

Rubin, Kate H. R.; Diamond-Stanic, Aleksandar M.; Coil, Alison L.; Crighton, Neil H. M.; Moustakas, John

2018-01-01

The spectroscopy of background QSO sightlines passing close to foreground galaxies is a potent technique for studying the circumgalactic medium (CGM). However, QSOs are effectively point sources, limiting their potential to constrain the size of circumgalactic gaseous structures. Here we present the first large Keck/Low-resolution Imaging Spectrometer (LRIS) and Very Large Telescope (VLT)/Focal Reducer/Low-dispersion Spectrograph 2 (FORS2) spectroscopic survey of bright ({B}{AB}< 22.3) background galaxies whose lines of sight probe Mg II λ λ 2796,2803 absorption from the CGM around close projected foreground galaxies at transverse distances 10 {kpc}< {R}\\perp < 150 {kpc}. Our sample of 72 projected pairs, drawn from the PRIsm MUlti-object Survey, includes 48 background galaxies that do not host bright active galactic nuclei, and both star-forming and quiescent foreground galaxies with stellar masses of 9.0< {log}{M}* /{M}ȯ < 11.2 at redshifts of 0.35< {z}{{f}/{{g}}}< 0.8. We detect Mg II absorption associated with these foreground galaxies with equivalent widths of 0.25 \\mathring{{A}} < {W}2796< 2.6 \\mathring{{A}} at > 2σ significance in 20 individual background sightlines passing within {R}\\perp < 50 {kpc} and place 2σ upper limits on W 2796 of ≲ 0.5 \\mathring{{A}} in an additional 11 close sightlines. Within {R}\\perp < 50 {kpc}, W 2796 is anticorrelated with R ⊥, consistent with analyses of Mg II absorption detected along background QSO sightlines. Subsamples of these foreground hosts divided at {log}{M}* /{M}ȯ =9.9 exhibit statistically inconsistent W 2796 distributions at 30 {kpc}< {R}\\perp < 50 {kpc}, with the higher-M * galaxies yielding a larger median W 2796 by 0.9 \\mathring{{A}} . Finally, we demonstrate that foreground galaxies with similar stellar masses exhibit the same median W 2796 at a given R ⊥ to within < 0.2 \\mathring{{A}} toward both background galaxies and toward QSO sightlines drawn from the literature. Analysis of these

The Co-evolution of QSOs and Galaxies

NASA Astrophysics Data System (ADS)

Coziol, R.; Torres-Papaqui, J. P.; Andernach, H.

2015-07-01

Using two large samples of QSOs detected in the mid-infrared (MIR) with WISE, we find that the change of W2-W3 colors with redshift suggests that star formation in their host galaxies increases by a factor of 3 from z = 0 to 2.7, then stays constant up to z = 4, and decreases above z=4. This behavior is slightly different from the best fits for the star formation history of field galaxies as deduced from the Optical-UV and IR, but is consistent with what is observed for sub-mm galaxies at high z. Our results constitute the clearest evidence, so far, that QSO host galaxies form their stars before field galaxies, and are in good agreement with the hierarchical biased structure formation paradigm.

Host galaxy identification for supernova surveys

DOE PAGES

Gupta, Ravi R.; Kuhlmann, Steve; Kovacs, Eve; ...

2016-11-08

Host galaxy identification is a crucial step for modern supernova (SN) surveys such as the Dark Energy Survey (DES) and the Large Synoptic Survey Telescope (LSST), which will discover SNe by the thousands. Spectroscopic resources are limited, so in the absence of real-time SN spectra these surveys must rely on host galaxy spectra to obtain accurate redshifts for the Hubble diagram and to improve photometric classification of SNe. In addition, SN luminosities are known to correlate with host-galaxy properties. Therefore, reliable identification of host galaxies is essential for cosmology and SN science. We simulate SN events and their locations withinmore » their host galaxies to develop and test methods for matching SNe to their hosts. We use both real and simulated galaxy catalog data from the Advanced Camera for Surveys General Catalog and MICECATv2.0, respectively. We also incorporate "hostless" SNe residing in undetected faint hosts into our analysis, with an assumed hostless rate of 5%. Our fully automated algorithm is run on catalog data and matches SNe to their hosts with 91% accuracy. We find that including a machine learning component, run after the initial matching algorithm, improves the accuracy (purity) of the matching to 97% with a 2% cost in efficiency (true positive rate). Although the exact results are dependent on the details of the survey and the galaxy catalogs used, the method of identifying host galaxies we outline here can be applied to any transient survey.« less

HOST GALAXY IDENTIFICATION FOR SUPERNOVA SURVEYS

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

Gupta, Ravi R.; Kuhlmann, Steve; Kovacs, Eve

Host galaxy identification is a crucial step for modern supernova (SN) surveys such as the Dark Energy Survey and the Large Synoptic Survey Telescope, which will discover SNe by the thousands. Spectroscopic resources are limited, and so in the absence of real-time SN spectra these surveys must rely on host galaxy spectra to obtain accurate redshifts for the Hubble diagram and to improve photometric classification of SNe. In addition, SN luminosities are known to correlate with host-galaxy properties. Therefore, reliable identification of host galaxies is essential for cosmology and SN science. We simulate SN events and their locations within theirmore » host galaxies to develop and test methods for matching SNe to their hosts. We use both real and simulated galaxy catalog data from the Advanced Camera for Surveys General Catalog and MICECATv2.0, respectively. We also incorporate “hostless” SNe residing in undetected faint hosts into our analysis, with an assumed hostless rate of 5%. Our fully automated algorithm is run on catalog data and matches SNe to their hosts with 91% accuracy. We find that including a machine learning component, run after the initial matching algorithm, improves the accuracy (purity) of the matching to 97% with a 2% cost in efficiency (true positive rate). Although the exact results are dependent on the details of the survey and the galaxy catalogs used, the method of identifying host galaxies we outline here can be applied to any transient survey.« less

Host galaxy identification for supernova surveys

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

Gupta, Ravi R.; Kuhlmann, Steve; Kovacs, Eve

Host galaxy identification is a crucial step for modern supernova (SN) surveys such as the Dark Energy Survey (DES) and the Large Synoptic Survey Telescope (LSST), which will discover SNe by the thousands. Spectroscopic resources are limited, so in the absence of real-time SN spectra these surveys must rely on host galaxy spectra to obtain accurate redshifts for the Hubble diagram and to improve photometric classification of SNe. In addition, SN luminosities are known to correlate with host-galaxy properties. Therefore, reliable identification of host galaxies is essential for cosmology and SN science. We simulate SN events and their locations withinmore » their host galaxies to develop and test methods for matching SNe to their hosts. We use both real and simulated galaxy catalog data from the Advanced Camera for Surveys General Catalog and MICECATv2.0, respectively. We also incorporate "hostless" SNe residing in undetected faint hosts into our analysis, with an assumed hostless rate of 5%. Our fully automated algorithm is run on catalog data and matches SNe to their hosts with 91% accuracy. We find that including a machine learning component, run after the initial matching algorithm, improves the accuracy (purity) of the matching to 97% with a 2% cost in efficiency (true positive rate). Although the exact results are dependent on the details of the survey and the galaxy catalogs used, the method of identifying host galaxies we outline here can be applied to any transient survey.« less

HOST GALAXY IDENTIFICATION FOR SUPERNOVA SURVEYS

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

Gupta, Ravi R.; Kuhlmann, Steve; Kovacs, Eve

Host galaxy identification is a crucial step for modern supernova (SN) surveys such as the Dark Energy Survey and the Large Synoptic Survey Telescope, which will discover SNe by the thousands. Spectroscopic resources are limited, and so in the absence of real-time SN spectra these surveys must rely on host galaxy spectra to obtain accurate redshifts for the Hubble diagram and to improve photometric classification of SNe. In addition, SN luminosities are known to correlate with host-galaxy properties. Therefore, reliable identification of host galaxies is essential for cosmology and SN science. We simulate SN events and their locations within theirmore » host galaxies to develop and test methods for matching SNe to their hosts. We use both real and simulated galaxy catalog data from the Advanced Camera for Surveys General Catalog and MICECATv2.0, respectively. We also incorporate "hostless" SNe residing in undetected faint hosts into our analysis, with an assumed hostless rate of 5%. Our fully automated algorithm is run on catalog data and matches SNe to their hosts with 91% accuracy. We find that including a machine learning component, run after the initial matching algorithm, improves the accuracy (purity) of the matching to 97% with a 2% cost in efficiency (true positive rate). Although the exact results are dependent on the details of the survey and the galaxy catalogs used, the method of identifying host galaxies we outline here can be applied to any transient survey.« less

Measuring BAO and non-Gaussianity via QSO clustering

NASA Astrophysics Data System (ADS)

Sawangwit, U.; Shanks, T.; Croom, S. M.; Drinkwater, M. J.; Fine, S.; Parkinson, D.; Ross, Nicholas P.

2012-03-01

Our goals are (i) to search for BAO and large-scale structure in current quasi-stellar object (QSO) survey data and (ii) to use these and simulation/forecast results to assess the science case for a new, ≳10 times larger, QSO survey. We first combine the Sloan Digital Sky Survey (SDSS), 2dF QSO Redshift Survey (2QZ) and 2dF-SDSS LRG and QSO (2SLAQ) surveys to form a survey of ≈60 000 QSOs. We find a hint of a peak in the QSO two-point correlation function, ξ(s), at the same scale (≈105 h-1 Mpc) as detected by Eisenstein et al. in their sample of Data Release 5 (DR5) Luminous Red Galaxies (LRGs) but only at low statistical significance. We then compare these data with QSO mock catalogues from the Hubble Volume N-body light-cone simulation used by Hoyle et al. and find that both routes give statistical error estimates that are consistent at ≈100 h-1 Mpc scales. Mock catalogues are then used to estimate the nominal survey size needed for a 3-4σ detection of the Baryon Acoustic Oscillations (BAO) peak. We find that a redshift survey of ≈250 000 z < 2.2 QSOs is required over ≈3000 deg2. This is further confirmed by static lognormal simulations where the BAO are clearly detectable in the QSO power spectrum and correlation function. The nominal survey would on its own produce the first detection of, for example, discontinuous dark energy evolution in the so far uncharted 1 < z < 2.2 redshift range. We further find that a survey with ≈50 per cent higher QSO sky densities and 50 per cent bigger area will give an ≈6σ BAO detection, leading to an error ≈60 per cent of the size of the BOSS error on the dark energy evolution parameter, wa. Another important aim of a QSO survey is to place new limits on primordial non-Gaussianity at large scales. In particular, it is important to test tentative evidence we have found for the evolution of the linear form of the combined SDSS+2QZ+2SLAQ QSO ξ(s) at z≈ 1.6, which may be caused by the existence of non

The puzzling case of the radio-loud QSO 3C 186: a gravitational wave recoiling black hole in a young radio source?

NASA Astrophysics Data System (ADS)

Chiaberge, M.; Ely, J. C.; Meyer, E. T.; Georganopoulos, M.; Marinucci, A.; Bianchi, S.; Tremblay, G. R.; Hilbert, B.; Kotyla, J. P.; Capetti, A.; Baum, S. A.; Macchetto, F. D.; Miley, G.; O'Dea, C. P.; Perlman, E. S.; Sparks, W. B.; Norman, C.

2017-04-01

Context. Radio-loud active galactic nuclei with powerful relativistic jets are thought to be associated with rapidly spinning black holes (BHs). BH spin-up may result from a number of processes, including accretion of matter onto the BH itself, and catastrophic events such as BH-BH mergers. Aims: We study the intriguing properties of the powerful (Lbol 1047 erg s-1) radio-loud quasar 3C 186. This object shows peculiar features both in the images and in the spectra. Methods: We utilize near-IR Hubble Space Telescope (HST) images to study the properties of the host galaxy, and HST UV and Sloan Digital Sky Survey optical spectra to study the kinematics of the source. Chandra X-ray data are also used to better constrain the physical interpretation. Results: HST imaging shows that the active nucleus is offset by 1.3 ± 0.1 arcsec (I.e. 11 kpc) with respect to the center of the host galaxy. Spectroscopic data show that the broad emission lines are offset by -2140 ± 390 km s-1 with respect to the narrow lines. Velocity shifts are often seen in QSO spectra, in particular in high-ionization broad emission lines. The host galaxy of the quasar displays a distorted morphology with possible tidal features that are typical of the late stages of a galaxy merger. Conclusions: A number of scenarios can be envisaged to account for the observed features. While the presence of a peculiar outflow cannot be completely ruled out, all of the observed features are consistent with those expected if the QSO is associated with a gravitational wave (GW) recoiling BH. Future detailed studies of this object will allow us to confirm this type of scenario and will enable a better understanding of both the physics of BH-BH mergers and the phenomena associated with the emission of GW from astrophysical sources.

Large-scale Environment of a z = 6.61 Luminous Quasar Probed by Lyα Emitters and Lyman Break Galaxies

NASA Astrophysics Data System (ADS)

Ota, Kazuaki; Venemans, Bram P.; Taniguchi, Yoshiaki; Kashikawa, Nobunari; Nakata, Fumiaki; Harikane, Yuichi; Bañados, Eduardo; Overzier, Roderik; Riechers, Dominik A.; Walter, Fabian; Toshikawa, Jun; Shibuya, Takatoshi; Jiang, Linhua

2018-04-01

Quasars (QSOs) hosting supermassive black holes are believed to reside in massive halos harboring galaxy overdensities. However, many observations revealed average or low galaxy densities around z ≳ 6 QSOs. This could be partly because they measured galaxy densities in only tens of arcmin2 around QSOs and might have overlooked potential larger-scale galaxy overdensities. Some previous studies also observed only Lyman break galaxies (LBGs; massive older galaxies) and missed low-mass young galaxies, like Lyα emitters (LAEs), around QSOs. Here we present observations of LAE and LBG candidates in ∼700 arcmin2 around a z = 6.61 luminous QSO using the Subaru Telescope Suprime-Cam with narrowband/broadband. We compare their sky distributions, number densities, and angular correlation functions with those of LAEs/LBGs detected in the same manner and comparable data quality in our control blank field. In the QSO field, LAEs and LBGs are clustering in 4–20 comoving Mpc angular scales, but LAEs show mostly underdensity over the field while LBGs are forming 30 × 60 comoving Mpc2 large-scale structure containing 3σ–7σ high-density clumps. The highest-density clump includes a bright (23.78 mag in the narrowband) extended (≳16 kpc) Lyα blob candidate, indicative of a dense environment. The QSO could be part of the structure but is not located exactly at any of the high-density peaks. Near the QSO, LAEs show underdensity while LBGs average to 4σ excess densities compared to the control field. If these environments reflect halo mass, the QSO may not be in the most massive halo but still in a moderately massive one. Based on data collected at Subaru Telescope, which is operated by the National Astronomical Observatory of Japan.

Mapping the Lyα Emission around a z ˜ 6.6 QSO with MUSE: Extended Emission and a Companion at a Close Separation

NASA Astrophysics Data System (ADS)

Farina, Emanuele P.; Venemans, Bram P.; Decarli, Roberto; Hennawi, Joseph F.; Walter, Fabian; Bañados, Eduardo; Mazzucchelli, Chiara; Cantalupo, Sebastiano; Arrigoni-Battaia, Fabrizio; McGreer, Ian D.

2017-10-01

We utilize the Multi Unit Spectroscopic Explorer (MUSE) on the Very Large Telescope to search for extended Lyα emission around the z ˜ 6.6 QSO J0305-3150. After carefully subtracting the point spread function, we reach a nominal 5σ surface-brightness limit of SB5σ = 1.9 × 10-18 erg s-1 cm-2 arcsec-2 over a 1 arcsec2 aperture, collapsing five wavelength slices centered at the expected location of the redshifted Lyα emission (I.e., at 9256 Å). Current data suggest the presence (5σ accounting for systematics) of a Lyα nebula that extends for 9 kpc around the QSO. This emission is displaced and redshifted by 155 km s-1 with respect to the location of the QSO host galaxy traced by the [{{C}} {{II}}] 158 μm emission line. The total luminosity is L({Ly}α ) = (3.0 ± 0.4) × 1042 erg s-1. Our analysis suggests that this emission is unlikely to rise from optically thick clouds illuminated by the ionizing radiation of the QSO. It is more plausible that the Lyα emission is due to the fluorescence of the highly ionized optically thin gas. This scenario implies a high hydrogen volume density of {n}{{H}}˜ 6 cm-3. In addition, we detect a Lyα emitter (LAE) in the immediate vicinity of the QSO, I.e., with a projected separation of ˜12.5 kpc and a line-of-sight velocity difference of 560 km s-1. The luminosity of the LAE is L({Ly}α ) = (2.1 ± 0.2) × 1042 erg s-1 and its inferred star-formation rate is SFR ˜ 1.3 M ⊙ yr-1. The probability of finding such a close LAE is one order of magnitude above the expectations based on the QSO-galaxy cross-correlation function. This discovery is in agreement with a scenario where dissipative interactions favor the rapid build-up of supermassive black holes at early cosmic times.

Tidal Disruption Event Host Galaxies in the Context of the Local Galaxy Population

NASA Astrophysics Data System (ADS)

Law-Smith, Jamie; Ramirez-Ruiz, Enrico; Ellison, Sara L.; Foley, Ryan J.

2017-11-01

We study the properties of tidal disruption event (TDE) host galaxies in the context of a catalog of ˜500,000 galaxies from the Sloan Digital Sky Survey. We explore whether selection effects can account for the overrepresentation of TDEs in E+A/post-starburst galaxies by creating matched galaxy samples. Accounting for possible selection effects due to black hole (BH) mass, redshift completeness, strong active galactic nucleus presence, bulge colors, and surface brightness can reduce the apparent overrepresentation of TDEs in E+A host galaxies by a factor of ˜4 (from ˜×100-190 to ˜×25-48), but cannot fully explain the preference. We find that TDE host galaxies have atypical photometric properties compared to similar, “typical” galaxies. In particular, TDE host galaxies tend to live in or near the “green valley” between star-forming and passive galaxies, and have bluer bulge colors ({{Δ }}(g-r)≈ 0.3 mag), lower half-light surface brightnesses (by ˜1 mag/arcsec2), higher Sérsic indices ({{Δ }}{n}{{g}}≈ 3), and higher bulge-to-total-light ratios ({{Δ }}B/T≈ 0.5) than galaxies with matched BH masses. We find that TDE host galaxies appear more centrally concentrated and that all have high galaxy Sérsic indices and B/T fractions—on average in the top 10% of galaxies of the same BH mass—suggesting a higher nuclear stellar density. We identify a region in the Sérsic index and BH mass parameter space that contains ˜2% of our reference catalog galaxies but ≥slant 60 % of TDE host galaxies. The unique photometric properties of TDE host galaxies may be useful for selecting candidate TDEs for spectroscopic follow-up observations in large transient surveys.

Extent of warm haloes around medium-redshift galaxies

NASA Technical Reports Server (NTRS)

Burbidge, E. M.; Barlow, T. A.; Cohen, R. D.; Junkkarinen, V. T.; Womble, D. S.

1989-01-01

The properties of low-to-medium ionization gaseous haloes around galaxies are briefly reviewed. New observations concerning such haloes are presented. For the galaxy-QSO pair in the field of the radio source 3C303, the higher-redshift QSO has been found to show Mg II absorption at the lower redshift of the faint nearby galaxy. Secondly, new data are presented on one of the galaxies in the environment of the well-known BL Lac object AO 0235 + 164.

Cosmic dance at z 3: Detecting the host galaxies of the dual AGN system LBQS 0302-0019 and Jil with HAWK-I+GRAAL

NASA Astrophysics Data System (ADS)

Husemann, B.; Bielby, R.; Jahnke, K.; Arrigoni-Battaia, F.; Worseck, G.; Shanks, T.; Wardlow, J.; Scholtz, J.

2018-06-01

We recently discovered that the luminous radio-quiet quasi-stellar objects (QSO) LBQS 0302-0019 at z = 3.286 is likely accompanied by an obscured AGN at 20 kpc projected distance, which we dubbed Jil. It represents the tightest candidate system of an obscured and unobscured dual AGN at z > 3. To verify the dual AGN scenario, we obtained deep Ks band (rest-frame V band) imaging with the VLT/HAWK-I+GRAAL instrument at 0.″4 resolution during science verification in January 2018. We detect the individual host galaxies of the QSO and Jil with estimated stellar masses of log(M⋆/M⊙) = 11.4 ± 0.5 and log(M⋆/M⊙) = 0.9 ± 0.5, respectively. Near-IR spectra obtained with Very Large Telescope-K-band Multi Object Spectrograph (VLT-KMOS) reveal a clear [O III] λ5007 line detection at the location of Jil that does not contribute significantly to the Ks band flux. Both observations therefore corroborate the dual AGN scenario. A comparison to Illustris simulations suggests a parent halo mass of log(Mhalo/M⊙) = 13.2 ± 0.5 for this interacting galaxy system, corresponding to a massive dark matter halo at that epoch. Based on observations collected at the European Organisation for Astronomical Research in the Southern Hemisphere under ESO programme(s) 60.A-9471(A) and 100.A-0134(B).

Study of GRBs Hosts Galaxies Vicinity Properties

NASA Astrophysics Data System (ADS)

Bernal, S.; Vasquez, N.; Hoyle, F.

2017-07-01

The study of GRBs host galaxies and its vicinity could provide constrains on the progenitor and an opportunity to use these violent explosions to characterize the nature of the highredshift universe. Studies of GRB host galaxies reveal a population of starforming galaxies with great diversity, spanning a wide range of masses, star formation rate, and redshifts. In order to study the galactic ambient of GRBs we used the S. Savaglio catalog from 2015 where 245 GRBs are listed with RA-Dec position and z. We choose 22 GRBs Hosts galaxies from Savaglio catalog and SDSS DR12, with z range 0galaxies, in a local vicinity of 10 h-1 Mpc radius to determine some photometric and population characteristics. We calculate the volumetric density populatation of glalaxies around the GRB Hosts within a volume of an sphere whit radius of 10 h-1 Mpc and find a low density compared with a typical group of galaxies. In order to know the galaxies stellar formation state, in regions where GRBs are formed, we made an analysis of color index using SDSS data of μ [λ 3543], r[λ 6231] and calculate the indexes μ-r. We find a value μ-r=2.63, it means that the galactic ambient of GRBs Host regions are statistically redder than void and wall regions on a indirect way (Voids:μ-r=2.043; Walls:μ-r=2.162). Futhermore, we used a inverse concentration index analysis, ICI=R50/R90 and find that galaxies in GRBs Hosts vicinity are also of slightly early type than void and wall galaxies. With this work we provide characteristics on the regions for future works related with highredsift universe that using the GRBs.

The concerted impact of galaxies and QSOs on the ionization and thermal state of the intergalactic medium

NASA Astrophysics Data System (ADS)

Kakiichi, Koki; Graziani, Luca; Ciardi, Benedetta; Meiksin, Avery; Compostella, Michele; Eide, Marius B.; Zaroubi, Saleem

2017-07-01

We present a detailed analysis of the ionization and thermal structure of the intergalactic medium (IGM) around a high-redshift (z = 10) QSO, using a large suite of cosmological, multifrequency radiative transfer simulations, exploring the contribution from galaxies as well as the QSO, and the effect of X-rays and secondary ionization. We show that in high-z QSO environments both the central QSO and the surrounding galaxies concertedly control the reionization morphology of hydrogen and helium and have a non-linear impact on the thermal structure of the IGM. A QSO imprints a distinctive morphology on H II regions if its total ionizing photon budget exceeds that of the surrounding galaxies since the onset of hydrogen reionization; otherwise, the morphology shows little difference from that of H II regions produced only by galaxies. In addition, the spectral shape of the collective radiation field from galaxies and QSOs controls the thickness of the I-fronts. While a UV-obscured QSO can broaden the I-front, the contribution from other UV sources, either galaxies or unobscured QSOs, is sufficient to maintain a sharp I-front. X-ray photons from the QSO are responsible for a prominent extended tail of partial ionization ahead of the I-front. QSOs leave a unique imprint on the morphology of He II/He III regions. We suggest that, while the physical state of the IGM is modified by QSOs, the most direct test to understand the role of galaxies and QSOs during reionization is to perform galaxy surveys in a region of sky imaged by 21 cm tomography.

Multiwavelength Characterization of an ACT-selected, Lensed Dusty Star-forming Galaxy at z = 2.64

NASA Astrophysics Data System (ADS)

Roberts-Borsani, G. W.; Jiménez-Donaire, M. J.; Daprà, M.; Alatalo, K.; Aretxaga, I.; Álvarez-Márquez, J.; Baker, A. J.; Fujimoto, S.; Gallardo, P. A.; Gralla, M.; Hilton, M.; Hughes, J. P.; Jiménez, C.; Laporte, N.; Marriage, T. A.; Nati, F.; Rivera, J.; Sievers, A.; Weiß, A.; Wilson, G. W.; Wollack, E. J.; Yun, M. S.

2017-08-01

We present C I(2-1) and multi-transition 12CO observations of a dusty star-forming galaxy, ACT J2029+0120, which we spectroscopically confirm to lie at z = 2.64. We detect CO(3-2), CO(5-4), CO(7-6), CO(8-7), and C I(2-1) at high significance, tentatively detect HCO+(4-3), and place strong upper limits on the integrated strength of dense gas tracers (HCN(4-3) and CS(7-6)). Multi-transition CO observations and dense gas tracers can provide valuable constraints on the molecular gas content and excitation conditions in high-redshift galaxies. We therefore use this unique data set to construct a CO spectral line energy distribution (SLED) of the source, which is most consistent with that of a ULIRG/Seyfert or QSO host object in the taxonomy of the Herschel Comprehensive ULIRG Emission Survey. We employ RADEX models to fit the peak of the CO SLED, inferring a temperature of T ˜ 117 K and {n}{{{H}}2}˜ {10}5 cm-3, most consistent with a ULIRG/QSO object and the presence of high-density tracers. We also find that the velocity width of the C I line is potentially larger than seen in all CO transitions for this object, and that the {L}{{C} {{I}}(2-1)}\\prime /{L}{CO(3-2)}\\prime ratio is also larger than seen in other lensed and unlensed submillimeter galaxies and QSO hosts; if confirmed, this anomaly could be an effect of differential lensing of a shocked molecular outflow.

Star formation quenching in quasar host galaxies

NASA Astrophysics Data System (ADS)

Carniani, Stefano

2017-10-01

Galaxy evolution is likely to be shaped by negative feedback from active galactic nuclei (AGN). In the whole range of redshifts and luminosities studied so far, galaxies hosting an AGN frequently show fast and extended outflows consisting in both ionised and molecular gas. Such outflows could potentially quench the start formation within the host galaxy, but a clear evidence of negative feedback in action is still missing. Hereby I will analyse integral-field spectroscopic data for six quasars at z ˜2.4 obtained with SINFONI in the H- and K-band. All the quasars show [OIII]λ5007 line detection of fast, extended outflows. Also, the high signal-to-noise SINFONI observations allow the identification of faint narrow Hα emission (FWHM < 500 km/s), which is spatially extended and associated with star formation in the host galaxy. On paper fast outflows are spatially anti-correlated with star-formation powered emission, i.e. star formation is suppressed in the area affected by the outflow. Nonetheless as narrow, spatially-extended Hα emission, indicating star formation rates of at least 50 - 100 M⊙/yr, has been detected, either AGN feedback is not affecting the whole host galaxy, or star formation is completely quenched only by several feedback episodes. On the other hand, a positive feedback scenario, supported by narrow emission in Hα extending along the edges of the outflow cone, suggests that galaxy-wide outflows could also have a twofold role in the evolution of the host galaxy. Finally, I will present CO(3-2) ALMA data for three out of the six QSOs observed with SINFONI. Flux maps obtained for the CO(3-2) transition suggest that molecular gas within the host galaxy is swept away by fast winds. A negative-feedback scenario is supported by the inferred molecular gas mass in all three objects, which is significantly below what observed in non-active main-sequence galaxies at high-z.

Gas-rich galaxy pair unveiled in the lensed quasar 0957+561

PubMed

Planesas; Martin-Pintado; Neri; Colina

1999-12-24

Molecular gas in the host galaxy of the lensed quasar 0957+561 (QSO 0957+561) at the redshift of 1.41 has been detected in the carbon monoxide (CO) line. This detection shows the extended nature of the molecular gas distribution in the host galaxy and the pronounced lensing effects due to the differentially magnified CO luminosity at different velocities. The estimated mass of molecular gas is about 4 x 10(9) solar masses, a molecular gas mass typical of a spiral galaxy like the Milky Way. A second, weaker component of CO is interpreted as arising from a close companion galaxy that is rich in molecular gas and has remained undetected so far. Its estimated molecular gas mass is 1.4 x 10(9) solar masses, and its velocity relative to the main galaxy is 660 kilometers per second. The ability to probe the molecular gas distribution and kinematics of galaxies associated with high-redshift lensed quasars can be used to improve the determination of the Hubble constant H(0).

Associating Fast Radio Bursts with Their Host Galaxies

NASA Astrophysics Data System (ADS)

Eftekhari, T.; Berger, E.

2017-11-01

The first precise localization of a fast radio burst (FRB) sheds light on the nature of these mysterious bursts and the physical mechanisms that power them. Increasing the sample of FRBs with robust host galaxy associations is the key impetus behind ongoing and upcoming searches and facilities. Here, we quantify the robustness of FRB host galaxy associations as a function of localization area and galaxy apparent magnitude. We also explore the use of FRB dispersion measures to constrain the source redshift, thereby reducing the number of candidate hosts. We use these results to demonstrate that even in the absence of a unique association, a constraint can be placed on the maximum luminosity of a host galaxy as a function of localization and dispersion measure (DM). We find that localizations of ≲ 0.5\\text{'}\\text{'} are required for a chance coincidence probability of ≲ 1 % for dwarf galaxies at z≳ 0.1; if some hosts have luminosities of ˜ {L}\\ast , then localizations of up to ≈ 5\\prime\\prime may suffice at z˜ 0.1. Constraints on the redshift from the DM only marginally improve the association probability unless the DM is low, ≲ 400 pc cm-3. This approach also relies on the determination of galaxy redshifts, which is challenging at z≳ 0.5 if the hosts are dwarf galaxies. Finally, interesting limits on the maximum host luminosity require localizations of ≲ 5\\prime\\prime at z≳ 0.1. Even a few such localizations will explain the nature of FRB progenitors, their possible diversity, and their use as cosmological tools.

Galaxy Zoo: evidence for rapid, recent quenching within a population of AGN host galaxies

NASA Astrophysics Data System (ADS)

Smethurst, R. J.; Lintott, C. J.; Simmons, B. D.; Schawinski, K.; Bamford, S. P.; Cardamone, C. N.; Kruk, S. J.; Masters, K. L.; Urry, C. M.; Willett, K. W.; Wong, O. I.

2016-12-01

We present a population study of the star formation history of 1244 Type 2 active galactic nuclei (AGN) host galaxies, compared to 6107 inactive galaxies. A Bayesian method is used to determine individual galaxy star formation histories, which are then collated to visualize the distribution for quenching and quenched galaxies within each population. We find evidence for some of the Type 2 AGN host galaxies having undergone a rapid drop in their star formation rate within the last 2 Gyr. AGN feedback is therefore important at least for this population of galaxies. This result is not seen for the quenching and quenched inactive galaxies whose star formation histories are dominated by the effects of downsizing at earlier epochs, a secondary effect for the AGN host galaxies. We show that histories of rapid quenching cannot account fully for the quenching of all the star formation in a galaxy's lifetime across the population of quenched AGN host galaxies, and that histories of slower quenching, attributed to secular (non-violent) evolution, are also key in their evolution. This is in agreement with recent results showing that both merger-driven and non-merger processes are contributing to the co-evolution of galaxies and supermassive black holes. The availability of gas in the reservoirs of a galaxy, and its ability to be replenished, appear to be the key drivers behind this co-evolution.

Yet another UFO in the X-ray spectrum of a high-z lensed QSO

NASA Astrophysics Data System (ADS)

Dadina, M.; Vignali, C.; Cappi, M.; Lanzuisi, G.; Ponti, G.; Torresi, E.; De Marco, B.; Chartas, G.; Giustini, M.

2018-02-01

Aim. Ultra-fast outflows (UFO) appear to be common in local active galactic nuclei (AGN) and may be powerful enough (Ėkin ≥ 1% of Lbol) to effectively quench the star formation in their host galaxies. To test feedback models based on AGN outflows, it is mandatory to investigate UFOs near the peak of AGN activity, that is, at high-z where only a few studies are available to date. Methods: UFOs produce Fe resonant absorption lines measured above ≈7 keV. The most critical problem in detecting such features in distant objects is the difficulty in obtaining X-ray data with sufficient signal-to-noise. We therefore selected a distant QSO that gravitational lensing made bright enough for these purposes, the z = 2.64 QSO MG J0414+0534, and observed it with XMM-Newton for ≈78 ks. Results: The X-ray spectrum of MG J0414+0534 is complex and shows signatures of cold absorption (NH ≈ 4 × 1022 cm-2) and of the presence of an iron emission line (E ≈ 6.4 keV, EW = 95 ± 53 eV) consistent with it originating in the cold absorber. Our main result, however, is the robust detection (more than 5σ) of an absorption line at Eint ≈ 9.2 keV (Eobs ≈ 2.5 keV observer frame). If interpreted as due to FeXXVI, it implies gas outflowing at vout ≈ 0.3c. To our knowledge, this is the first detection of an UFO in a radio-loud quasar at z ≥ 1.5. We estimated that the UFO mechanical output is Ėkin ≈ 2.5Lbol with ṗout/ṗrad ≈ 17 indicating that it is capable of installing significant feedback between the super-massive black hole and the bulge of the host galaxy. We argue that this also suggests a magnetic driving origin of the UFO.

Gamma-Ray Burst Host Galaxies Have "Normal" Luminosities.

PubMed

Schaefer

2000-04-10

The galactic environment of gamma-ray bursts can provide good evidence about the nature of the progenitor system, with two old arguments implying that the burst host galaxies are significantly subluminous. New data and new analysis have now reversed this picture: (1) Even though the first two known host galaxies are indeed greatly subluminous, the next eight hosts have absolute magnitudes typical for a population of field galaxies. A detailed analysis of the 16 known hosts (10 with redshifts) shows them to be consistent with a Schechter luminosity function with R*=-21.8+/-1.0, as expected for normal galaxies. (2) Bright bursts from the Interplanetary Network are typically 18 times brighter than the faint bursts with redshifts; however, the bright bursts do not have galaxies inside their error boxes to limits deeper than expected based on the luminosities for the two samples being identical. A new solution to this dilemma is that a broad burst luminosity function along with a burst number density varying as the star formation rate will require the average luminosity of the bright sample (>6x1058 photons s-1 or>1.7x1052 ergs s-1) to be much greater than the average luminosity of the faint sample ( approximately 1058 photons s-1 or approximately 3x1051 ergs s-1). This places the bright bursts at distances for which host galaxies with a normal luminosity will not violate the observed limits. In conclusion, all current evidence points to gamma-ray burst host galaxies being normal in luminosity.

Active Galactic Nucleus Host Galaxy Morphologies in COSMOS

NASA Astrophysics Data System (ADS)

Gabor, J. M.; Impey, C. D.; Jahnke, K.; Simmons, B. D.; Trump, J. R.; Koekemoer, A. M.; Brusa, M.; Cappelluti, N.; Schinnerer, E.; Smolčić, V.; Salvato, M.; Rhodes, J. D.; Mobasher, B.; Capak, P.; Massey, R.; Leauthaud, A.; Scoville, N.

2009-01-01

We use Hubble Space Telescope/Advanced Camera for Surveys images and a photometric catalog of the Cosmic Evolution Survey (COSMOS) field to analyze morphologies of the host galaxies of ~400 active galactic nucleus (AGN) candidates at redshifts 0.3 < z < 1.0. We compare the AGN hosts with a sample of nonactive galaxies drawn from the COSMOS field to match the magnitude and redshift distribution of the AGN hosts. We perform two-dimensional surface brightness modeling with GALFIT to yield host galaxy and nuclear point source magnitudes. X-ray-selected AGN host galaxy morphologies span a substantial range that peaks between those of early-type, bulge-dominated and late-type, disk-dominated systems. We also measure the asymmetry and concentration of the host galaxies. Unaccounted for, the nuclear point source can significantly bias results of these measured structural parameters, so we subtract the best-fit point source component to obtain images of the underlying host galaxies. Our concentration measurements reinforce the findings of our two-dimensional morphology fits, placing X-ray AGN hosts between early- and late-type inactive galaxies. AGN host asymmetry distributions are consistent with those of control galaxies. Combined with a lack of excess companion galaxies around AGN, the asymmetry distributions indicate that strong interactions are no more prevalent among AGN than normal galaxies. In light of recent work, these results suggest that the host galaxies of AGN at these X-ray luminosities may be in a transition from disk-dominated to bulge-dominated, but that this transition is not typically triggered by major mergers. Based on observations with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by 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

Spatially Resolved Spectroscopy of Narrow-line Seyfert 1 Host Galaxies

NASA Astrophysics Data System (ADS)

Scharwächter, J.; Husemann, B.; Busch, G.; Komossa, S.; Dopita, M. A.

2017-10-01

We present optical integral field spectroscopy for five z< 0.062 narrow-line Seyfert 1 (NLS1) galaxies, probing their host galaxies at ≳ 2{--}3 {kpc} scales. Emission lines from the active galactic nucleus (AGN) and the large-scale host galaxy are analyzed separately, based on an AGN-host decomposition technique. The host galaxy gas kinematics indicates large-scale gas rotation in all five sources. At the probed scales of ≳ 2{--}3 {kpc}, the host galaxy gas is found to be predominantly ionized by star formation without any evidence of a strong AGN contribution. None of the five objects shows specific star formation rates (SFRs) exceeding the main sequence of low-redshift star-forming galaxies. The specific SFRs for MCG-05-01-013 and WPVS 007 are roughly consistent with the main sequence, while ESO 399-IG20, MS 22549-3712, and TON S180 show lower specific SFRs, intermediate to the main sequence and the red quiescent galaxies. The host galaxy metallicities, derived for the two sources with sufficient data quality (ESO 399-IG20 and MCG-05-01-013), indicate central oxygen abundances just below the low-redshift mass-metallicity relation. Based on this initial case study, we outline a comparison of AGN and host galaxy parameters as a starting point for future extended NLS1 studies with similar methods.

AGN feedback through UFO and galaxy-wide winds in the early Universe

NASA Astrophysics Data System (ADS)

Feruglio, C.; Piconcelli, E.; Bischetti, M.; Zappacosta, L.; Fiore, F.

2017-10-01

AGN feedback through massive molecular winds is today routinely observed in local AGN host galaxies, but not as such in the early universe. I will present the first evidence for a massive, AGN-driven molecular wind in the z 4 QSO APM08279, which also hosts the most well studied and persistent nuclear semi-raltivistic wind (UFO). This observation directly probes the expansion mechanism of a nuclear wind into the ISM on galaxy wide scales, that so far was constrained by a couple of other objects only (Feruglio et al. 2015, Tombesi et al. 2015). This result also opens the path toward the exploration of molecular AGN-driven winds at early epochs, close after the end of the Epoch of Reionisation (EoR).

Cosmic evolution and metal aversion in superluminous supernova host galaxies

NASA Astrophysics Data System (ADS)

Schulze, S.; Krühler, T.; Leloudas, G.; Gorosabel, J.; Mehner, A.; Buchner, J.; Kim, S.; Ibar, E.; Amorín, R.; Herrero-Illana, R.; Anderson, J. P.; Bauer, F. E.; Christensen, L.; de Pasquale, M.; de Ugarte Postigo, A.; Gallazzi, A.; Hjorth, J.; Morrell, N.; Malesani, D.; Sparre, M.; Stalder, B.; Stark, A. A.; Thöne, C. C.; Wheeler, J. C.

2018-01-01

The SUperluminous Supernova Host galaxIES survey aims to provide strong new constraints on the progenitors of superluminous supernovae (SLSNe) by understanding the relationship to their host galaxies. We present the photometric properties of 53 H-poor and 16 H-rich SLSN host galaxies out to z ∼ 4. We model their spectral energy distributions to derive physical properties, which we compare with other galaxy populations. At low redshift, H-poor SLSNe are preferentially found in very blue, low-mass galaxies with high average specific star formation rates. As redshift increases, the host population follows the general evolution of star-forming galaxies towards more luminous galaxies. After accounting for secular evolution, we find evidence for differential evolution in galaxy mass, but not in the B band and the far-ultraviolet luminosity (3σ confidence). Most remarkable is the scarcity of hosts with stellar masses above 1010 M⊙ for both classes of SLSNe. In case of H-poor SLSNe, we attribute this to a stifled production efficiency above ∼0.4 solar metallicity. However, we argue that, in addition to low metallicity, a short-lived stellar population is also required to regulate the SLSN production. H-rich SLSNe are found in a very diverse population of star-forming galaxies. Still, the scarcity of massive hosts suggests a stifled production efficiency above ∼0.8 solar metallicity. The large dispersion of the H-rich SLSNe host properties is in stark contrast to those of gamma-ray burst, regular core-collapse SN, and H-poor SLSNe host galaxies. We propose that multiple progenitor channels give rise to this subclass.

First neutral atomic hydrogen images of quasar host galaxies.

NASA Astrophysics Data System (ADS)

Lim, J.; Ho, P. T. P.

1999-12-01

Violent galactic encounters or mergers are the leading contenders for triggering luminous quasar activity at low redshifts: such interactions can lead to the concentration of gas in the host galactic nucleus, thus fueling the suspected central supermassive black hole. Here the authors image quasar host galaxies in the redshifted 21-cm line emission of neutral atomic hydrogen (H I) gas, which in nearby galaxies has proven to be a particularly sensitive as well as enduring tracer of tidal interactions. The three quasars studied have different optical environments normally seen around low-redshift quasars, ranging from a perhaps mildly interacting system to a relatively undisturbed host with a projected neighbouring galaxy to an isolated and apparently serene host galaxy. By contrast with their optical appearences, all three quasar host galaxies exhibit ongoing or remnant tidal H I disruptions tracing galactic encounters or mergers. These observations provide a better understanding of the likely stage of their interaction.

Do Low Surface Brightness Galaxies Host Stellar Bars?

NASA Astrophysics Data System (ADS)

Cervantes Sodi, Bernardo; Sánchez García, Osbaldo

2017-09-01

With the aim of assessing if low surface brightness galaxies host stellar bars and by studying the dependence of the occurrence of bars as a function of surface brightness, we use the Galaxy Zoo 2 data set to construct a large volume-limited sample of galaxies and then segregate these galaxies as having low or high surface brightness in terms of their central surface brightness. We find that the fraction of low surface brightness galaxies hosting strong bars is systematically lower than that found for high surface brightness galaxies. The dependence of the bar fraction on the central surface brightness is mostly driven by a correlation of the surface brightness with the spin and the gas richness of the galaxies, showing only a minor dependence on the surface brightness. We also find that the length of the bars is strongly dependent on the surface brightness, and although some of this dependence is attributed to the gas content, even at a fixed gas-to-stellar mass ratio, high surface brightness galaxies host longer bars than their low surface brightness counterparts, which we attribute to an anticorrelation of the surface brightness with the spin.

Do Low Surface Brightness Galaxies Host Stellar Bars?

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

Cervantes Sodi, Bernardo; Sánchez García, Osbaldo, E-mail: b.cervantes@irya.unam.mx, E-mail: o.sanchez@irya.unam.mx

With the aim of assessing if low surface brightness galaxies host stellar bars and by studying the dependence of the occurrence of bars as a function of surface brightness, we use the Galaxy Zoo 2 data set to construct a large volume-limited sample of galaxies and then segregate these galaxies as having low or high surface brightness in terms of their central surface brightness. We find that the fraction of low surface brightness galaxies hosting strong bars is systematically lower than that found for high surface brightness galaxies. The dependence of the bar fraction on the central surface brightness ismore » mostly driven by a correlation of the surface brightness with the spin and the gas richness of the galaxies, showing only a minor dependence on the surface brightness. We also find that the length of the bars is strongly dependent on the surface brightness, and although some of this dependence is attributed to the gas content, even at a fixed gas-to-stellar mass ratio, high surface brightness galaxies host longer bars than their low surface brightness counterparts, which we attribute to an anticorrelation of the surface brightness with the spin.« less

The Chemical Evolution of QSO Absorbers

NASA Astrophysics Data System (ADS)

Ellison, Sara L.

2000-06-01

The chemical evolution of the high redshift intergalactic and interstellar media of galaxies is studied using QSO absorption lines. The redshift evolution of damped Lyman alpha (DLA) system metallicity is studied down to z=0.5, and no significant increase in metals is found. The CIV/HI ratio in the Lyman alpha forest is investigated at z approximately 3 and traces of are metals found in the low density HI gas with optical depth of around 1. Finally, a new survey for DLAs in a radio-selected sample of QSOs is presented, with the aim of determining whether a significant dust bias may have affected previous surveys.

Type II supernovae in low luminosity host galaxies

NASA Astrophysics Data System (ADS)

Gutiérrez, C. P.; Anderson, J. P.; Sullivan, M.; Dessart, L.; González-Gaitan, S.; Galbany, L.; Dimitriadis, G.; Arcavi, I.; Bufano, F.; Chen, T.-W.; Dennefeld, M.; Gromadzki, M.; Haislip, J. B.; Hosseinzadeh, G.; Howell, D. A.; Inserra, C.; Kankare, E.; Leloudas, G.; Maguire, K.; McCully, C.; Morrell, N.; E, F. Olivares; Pignata, G.; Reichart, D. E.; Reynolds, T.; Smartt, S. J.; Sollerman, J.; Taddia, F.; Takáts, K.; Terreran, G.; Valenti, S.; Young, D. R.

2018-06-01

We present an analysis of a new sample of type II core-collapse supernovae (SNe II) occurring within low-luminosity galaxies, comparing these with a sample of events in brighter hosts. Our analysis is performed comparing SN II spectral and photometric parameters and estimating the influence of metallicity (inferred from host luminosity differences) on SN II transient properties. We measure the SN absolute magnitude at maximum, the light-curve plateau duration, the optically thick duration, and the plateau decline rate in the V -band, together with expansion velocities and pseudo-equivalent-widths (pEWs) of several absorption lines in the SN spectra. For the SN host galaxies, we estimate the absolute magnitude and the stellar mass, a proxy for the metallicity of the host galaxy. SNe II exploding in low luminosity galaxies display weaker pEWs of Fe II λ5018, confirming the theoretical prediction that metal lines in SN II spectra should correlate with metallicity. We also find that SNe II in low-luminosity hosts have generally slower declining light curves and display weaker absorption lines. We find no relationship between the plateau duration or the expansion velocities with SN environment, suggesting that the hydrogen envelope mass and the explosion energy are not correlated with the metallicity of the host galaxy. This result supports recent predictions that mass-loss for red supergiants is independent of metallicity.

Galaxy Clustering Around Nearby Luminous Quasars

NASA Technical Reports Server (NTRS)

Fisher, Karl B.; Bahcall, John N.; Kirhakos, Sofia; Schneider, Donald P.

1996-01-01

We examine the clustering of galaxies around a sample of 20 luminous low redshift (z approx. less than 0.30) quasars observed with the Wide Field Camera-2 on the Hubble Space Telescope (HST). The HST resolution makes possible galaxy identification brighter than V = 24.5 and as close as 1 min or 2 min to the quasar. We find a significant enhancement of galaxies within a projected separation of approx. less than 100 1/h kpc of the quasars. If we model the QSO/galaxy correlation function as a power law with a slope given by the galaxy/galaxy correlation function, we find that the ratio of the QSO/galaxy to galaxy/galaxy correlation functions is 3.8 +/- 0.8. The galaxy counts within r less than 15 1/h kpc of the quasars are too high for the density profile to have an appreciable core radius (approx. greater than 100 1/h kpc). Our results reinforce the idea that low redshift quasars are located preferentially in groups of 10-20 galaxies rather than in rich clusters. We see no significant difference in the clustering amplitudes derived from radio-loud and radio-quiet subsamples.

A Spatially Resolved Study of the GRB 020903 Host Galaxy

NASA Astrophysics Data System (ADS)

Thorp, Mallory D.; Levesque, Emily M.

2018-03-01

GRB 020903 is a long-duration gamma-ray burst with a host galaxy close enough and extended enough for spatially resolved observations, making it one of less than a dozen GRBs where such host studies are possible. GRB 020903 lies in a galaxy host complex that appears to consist of four interacting components. Here we present the results of spatially resolved spectroscopic observations of the GRB 020903 host. By taking observations at two different position angles, we were able to obtain optical spectra (3600–9000 Å) of multiple regions in the galaxy. We confirm redshifts for three regions of the host galaxy that match that of GRB 020903. We measure the metallicity of these regions, and find that the explosion site and the nearby star-forming regions both have comparable subsolar metallicities. We conclude that, in agreement with past spatially resolved studies of GRBs, the GRB explosion site is representative of the host galaxy as a whole rather than localized in a metal-poor region of the galaxy.

Circumnuclear Structures in Megamaser Host Galaxies

NASA Astrophysics Data System (ADS)

Pjanka, Patryk; Greene, Jenny E.; Seth, Anil C.; Braatz, James A.; Henkel, Christian; Lo, Fred K. Y.; Läsker, Ronald

2017-08-01

Using the Hubble Space Telescope, we identify circumnuclear (100-500 pc scale) structures in nine new H2O megamaser host galaxies to understand the flow of matter from kpc-scale galactic structures down to the supermassive black holes (SMBHs) at galactic centers. We double the sample analyzed in a similar way by Greene et al. and consider the properties of the combined sample of 18 sources. We find that disk-like structure is virtually ubiquitous when we can resolve <200 pc scales, in support of the notion that non-axisymmetries on these scales are a necessary condition for SMBH fueling. We perform an analysis of the orientation of our identified nuclear regions and compare it with the orientation of megamaser disks and the kpc-scale disks of the hosts. We find marginal evidence that the disk-like nuclear structures show increasing misalignment from the kpc-scale host galaxy disk as the scale of the structure decreases. In turn, we find that the orientation of both the ˜100 pc scale nuclear structures and their host galaxy large-scale disks is consistent with random with respect to the orientation of their respective megamaser disks.

The Swift GRB Host Galaxy Legacy Survey

NASA Astrophysics Data System (ADS)

Perley, Daniel A.

2015-01-01

I introduce the Swift Host Galaxy Legacy Survey (SHOALS), a comprehensive multiwavelength program to characterize the demographics of the GRB host population across its entire redshift range. Using unbiased selection criteria we have designated a subset of 130 Swift gamma-ray bursts which are now being targeted with intensive observational follow-up. Deep Spitzer imaging of every field has already been obtained and analyzed, with major programs ongoing at Keck, GTC, and Gemini to obtain complementary optical/NIR photometry to enable full SED modeling and derivation of fundamental physical parameters such as mass, extinction, and star-formation rate. Using these data I will present an unbiased measurement of the GRB host-galaxy luminosity and mass functions and their evolution with redshift between z=0 and z=5, compare GRB hosts to other star-forming galaxy populations, and discuss implications for the nature of the GRB progenitor and the ability of GRBs to probe cosmic star-formation.

Near-infrared properties of quasar and Seyfert host galaxies

NASA Astrophysics Data System (ADS)

McLeod, Kim Katris

1994-01-01

We present near-infrared images of nearly 100 host galaxies of Active Galactic Nuclei (AGN). Our quasar sample is comprised of the 50 quasars from the Palomar Green Bright Quasar Survey with redshifts z less than or equal to 0.3. We have restricted the redshift range to ensure adequate spatial resolution, galaxy detectability, and minimal distance-dependent effects, while still giving a large sample of objects. For lower-luminosity AGN we have chosen to image the CfA Seyfert sample. This sample is composed of 48 Seyferts, roughly equally divided among types 1, 1.5-1.9, and 2. This sample was spectroscopically selected, and, therefore, is not biased towards Seyferts with significant star formation. Taken together, these samples allow a statistical look at the continuity of host galaxy properties over a factor of 10,000 in nuclear luminosity. We find the near-infrared light to be a good tracer of luminous mass in these galaxies. The Seyferts are found in galaxies of type SO to Sc. The radio quiet quasars live in similar kinds of galaxies spanning the same range of mass centered around L(*). However, for the most luminous quasars, there is a correlation between the minimum host galaxy mass and the luminosity of the active nucleus. Radio-loud quasars are generally found in hosts more massive than an L(*) galaxy. We also detect a population of low mass host galaxies with very low luminosity Seyfert nuclei. The low luminosity quasars and the Seyferts both tend to lie in host galaxies seen preferentially face-on, which suggests there is a substantial amount of obscuration coplanar with the galaxian disk. The obscuration must be geometrically thick (thickness-to-radius approximately 1) and must cover a significant fraction of the narrow line region (r greater than 100 pc). We have examined our images for signs of perturbations that could drive fuel toward the galaxy nucleus, but there are none we can identify at a significant level. The critical element for fueling is

Near-Infrared Properties of Quasar and Seyfert Host Galaxies

NASA Astrophysics Data System (ADS)

McLeod, Kim Katris

1995-01-01

We present near-infrared images of nearly 100 host galaxies of Active Galactic Nuclei (AGN). Our quasar sample is comprised of the 50 quasars from the Palomar Green Bright Quasar Survey with redshifts z\\<= 0.3. We have restricted the redshift range to ensure adequate spatial resolution, galaxy detectability, and minimal distance-dependent effects, while still giving a large sample of objects. For lower-luminosity AGN we have chosen to image the CfA Seyfert sample. This sample is composed of 48 Seyferts, roughly equally divided among types 1, 1.5-1.9, and 2. This sample was spectroscopically selected, and, therefore, is not biased towards Seyferts with significant star formation. Taken together, these samples allow a statistical look at the continuity of host-galaxy properties over a factor of 10,000 in nuclear luminosity. We find the near-infrared light to be a good tracer of luminous mass in these galaxies. The Seyferts are found in galaxies of type S0 to Sc. The radio quiet quasars live in similar kinds of galaxies spanning the same range of mass centered around L*. However, for the most luminous quasars, there is a correlation between the minimum host-galaxy mass and the luminosity of the active nucleus. Radio-loud quasars are generally found in hosts more massive than an L* galaxy. We also detect a population of low-mass host galaxies with very low-luminosity Seyfert nuclei. The low luminosity quasars and the Seyferts both tend to lie in host galaxies seen preferentially face-on, which suggests there is a substantial amount of obscuration coplanar with the galaxian disk. The obscuration must be geometrically thick (thickness-to-radius ~1) and must cover a significant fraction of the narrow line region (r>100 pc). We have examined our images for signs of perturbations that could drive fuel toward the galaxy nucleus, but there are none we can identify at a significant level. The critical element for fueling is evidently not reflected clearly in the large scale

THE EXTREMELY RED HOST GALAXY OF GRB 080207

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

Hunt, Leslie; Cresci, Giovanni; Palazzi, Eliana

2011-08-01

We present optical, near-infrared, and Spitzer IRAC and MIPS observations of the host galaxy of the dark Swift gamma-ray burst GRB 080207. The host is faint, with extremely red optical-infrared colors (R - K = 6.3, 24 {mu}m/R-band flux {approx}1000) making it an extremely red object (ERO) and a dust-obscured galaxy (DOG). The spectral energy distribution (SED) shows the clear signature of the 1.6 {mu}m photometric 'bump', typical of evolved stellar populations. We use this bump to establish the photometric redshift z{sub phot} as 2.2{sup +0.2}{sub -0.3}, using a vast library of SED templates, including M 82. The star formationmore » rate (SFR) inferred from the SED fitting is {approx}119 M{sub sun} yr{sup -1}, the stellar mass 3 x 10{sup 11} M{sub sun}, and A{sub V} extinction from 1 to 2 mag. The ERO and DOG nature of the host galaxy of the dark GRB 080207 may be emblematic of a distinct class of dark GRB hosts, with high SFRs, evolved and metal-rich stellar populations, and significant dust extinction within the host galaxy.« less

The Star Formation Reference Survey - II. Activity demographics and host-galaxy properties for infrared-selected galaxies

NASA Astrophysics Data System (ADS)

Maragkoudakis, A.; Zezas, A.; Ashby, M. L. N.; Willner, S. P.

2018-04-01

We present activity demographics and host-galaxy properties of infrared-selected galaxies in the local Universe, using the representative Star Formation Reference Survey (SFRS). Our classification scheme is based on a combination of optical emission-line diagrams (BPT) and infrared (IR)-colour diagnostics. Using the weights assigned to the SFRS galaxies based on its parent sample, a far-IR-selected sample comprises 71 per cent H II galaxies, 13 per cent Seyferts, 3 per cent transition objects (TOs), and 13 per cent low-ionization nuclear emission-line regions (LINERs). For the SFRS H II galaxies, we derive nuclear star formation rates and gas-phase metallicities. We measure host-galaxy metallicities for all galaxies with available long-slit spectroscopy and abundance gradients for a subset of 12 face-on galaxies. The majority of H II galaxies show a narrow range of metallicities, close to solar, and flat metallicity profiles. Based on their host-galaxy and nuclear properties, the dominant ionizing source in the far-infrared selected TOs is star-forming activity. LINERs are found mostly in massive hosts (median of 1010.5 M⊙), median L(60 μm) = 109 L⊙, median dust temperatures of F60/F100 = 0.36, and median LH α surface density of 1040.2 erg s-1kpc-2, indicating older stellar populations as their main ionizing source rather than active galactic nucleus activity.

Long-Duration Gamma-Ray Burst Host Galaxies in Emission and Absorption

NASA Astrophysics Data System (ADS)

Perley, Daniel A.; Niino, Yuu; Tanvir, Nial R.; Vergani, Susanna D.; Fynbo, Johan P. U.

2016-12-01

The galaxy population hosting long-duration GRBs provides a means to constrain the progenitor and an opportunity to use these violent explosions to characterize the nature of the high-redshift universe. Studies of GRB host galaxies in emission reveal a population of star-forming galaxies with great diversity, spanning a wide range of masses, metallicities, and redshifts. However, as a population GRB hosts are significantly less massive and poorer in metals than the hosts of other core-collapse transients, suggesting that GRB production is only efficient at metallicities significantly below Solar. GRBs may also prefer compact galaxies, and dense and/or central regions of galaxies, more than other types of core-collapse explosion. Meanwhile, studies of hosts in absorption against the luminous GRB optical afterglow provide a unique means of unveiling properties of the ISM in even the faintest and most distant galaxies; these observations are helping to constrain the chemical evolution of galaxies and the properties of interstellar dust out to very high redshifts. New ground- and space-based instrumentation, and the accumulation of larger and more carefully-selected samples, are continually enhancing our view of the GRB host population.

The Swift GRB Host Galaxy Legacy Survey

NASA Astrophysics Data System (ADS)

Perley, Daniel

2015-08-01

I will describe the Swift Host Galaxy Legacy Survey (SHOALS), a comprehensive multiwavelength program to characterize the demographics of the GRB host population and its redshift evolution from z=0 to z=7. Using unbiased selection criteria we have designated a subset of 119 Swift gamma-ray bursts which are now being targeted with intensive observational follow-up. Deep Spitzer imaging of every field has already been obtained and analyzed, with major programs ongoing at Keck, GTC, Gemini, VLT, and Magellan to obtain complementary optical/NIR photometry and spectroscopy to enable full SED modeling and derivation of fundamental physical parameters such as mass, extinction, and star-formation rate. Using these data I will present an unbiased measurement of the GRB host-galaxy luminosity and mass distributions and their evolution with redshift, compare GRB hosts to other star-forming galaxy populations, and discuss implications for the nature of the GRB progenitor and the ability of GRBs to serve as tools for measuring and studying cosmic star-formation in the distant universe.

Morphologies of mid-IR variability-selected AGN host galaxies

NASA Astrophysics Data System (ADS)

Polimera, Mugdha; Sarajedini, Vicki; Ashby, Matthew L. N.; Willner, S. P.; Fazio, Giovanni G.

2018-05-01

We use multi-epoch 3.6 and 4.5 μm data from the Spitzer Extended Deep Survey (SEDS) to probe the AGN population among galaxies to redshifts ˜3 via their mid-IR variability. About 1 per cent of all galaxies in our survey contain varying nuclei, 80 per cent of which are likely to be AGN. Twenty-three per cent of mid-IR variables are also X-ray sources. The mid-IR variables have a slightly greater fraction of weakly disturbed morphologies compared to a control sample of normal galaxies. The increased fraction of weakly distorted hosts becomes more significant when we remove the X-ray emitting AGN, while the frequency of strongly disturbed hosts remains similar to the control galaxy sample. These results suggest that mid-IR variability identifies a unique population of obscured, Compton-thick AGN revealing elevated levels of weak distortion among their host galaxies.

The SEDs and Host Galaxies of the Dustiest GRB Afterglows

NASA Technical Reports Server (NTRS)

Kruhler, T.; Greiner, J.; Schady, P.; Savaglio, S.; Afonso, P. M. J.; Clemens, C.; Elliott, J.; Filgas, R.; Gruber, D.; Kann, D. A.;

Detection of emission lines from z ˜ 3 DLAs towards the QSO J2358+0149

NASA Astrophysics Data System (ADS)

Srianand, Raghunathan; Hussain, Tanvir; Noterdaeme, Pasquier; Petitjean, Patrick; Krühler, Thomas; Japelj, Jure; Pâris, Isabelle; Kashikawa, Nobunari

2016-07-01

Using VLT/X-shooter, we searched for emission line galaxies associated with four damped Lyman α systems (DLAs) and one sub-DLA at 2.73 ≤z ≤3.25 towards QSO J2358+0149. We detect [O III] emission from a `low-cool' DLA at zabs = 2.9791 (having log N(H I) = 21.69 ± 0.10, [Zn/H] = -1.83 ± 0.18) at an impact parameter of, ρ ˜ 12 kpc. The associated galaxy is compact with a dynamical mass of (1-6) × 109 M⊙, very high excitation ([O III]/[O II] and [O III]/[Hβ] both greater than 10), 12+[O/H]≤8.5 and moderate star formation rate (SFR ≤2 M⊙ yr-1). Such properties are typically seen in the low-z extreme blue compact dwarf galaxies. The kinematics of the gas is inconsistent with that of an extended disc and the gas is part of either a large scale wind or cold accretion. We detect Lyα emission from the zabs = 3.2477 DLA [having log N(H I) = 21.12 ± 0.10 and [Zn/H] = -0.97 ± 0.13]. The Lyα emission is redshifted with respect to the metal absorption lines by 320 km s-1, consistent with the location of the red hump expected in radiative transport models. We derive SFR ˜0.2-1.7 M⊙ yr-1 and Lyα escape fraction of ≥10 per cent. No other emission line is detected from this system. Because the DLA has a small velocity separation from the quasar (˜500 km s-1) and the DLA emission is located within a small projected distance (ρ < 5 kpc), we also explore the possibility that the Lyα emission is being induced by the QSO itself. QSO-induced Lyα fluorescence is possible if the DLA is within a physical separation of 340 kpc to the QSO. Detection of stellar continuum light and/or the oxygen emission lines would disfavour this possibility. We do not detect any emission line from the remaining three systems.

Deficiency of ''Thin'' Stellar Bars in Seyfert Host Galaxies

NASA Technical Reports Server (NTRS)

Shlosman, Isaac; Peletier, Reynier F.; Knapen, Johan

1999-01-01

Using all available major samples of Seyfert galaxies and their corresponding control samples of closely matched non-active galaxies, we find that the bar ellipticities (or axial ratios) in Seyfert galaxies are systematically different from those in non-active galaxies. Overall, there is a deficiency of bars with large ellipticities (i.e., 'fat' or 'weak' bars) in Seyferts, compared to non-active galaxies. Accompanied with a large dispersion due to small number statistics, this effect is strictly speaking at the 2 sigma level. To obtain this result, the active galaxy samples of near-infrared surface photometry were matched to those of normal galaxies in type, host galaxy ellipticity, absolute magnitude, and, to some extent, in redshift. We discuss possible theoretical explanations of this phenomenon within the framework of galactic evolution, and, in particular, of radial gas redistribution in barred galaxies. Our conclusions provide further evidence that Seyfert hosts differ systematically from their non-active counterparts on scales of a few kpc.

Violent Tidal Disruptions of Atomic Hydrogen Gas in Quasar Host Galaxies

NASA Astrophysics Data System (ADS)

Lim, Jeremy; Ho, Paul T. P.

1999-01-01

Violent galactic encounters or mergers are the leading contenders for triggering luminous quasar activity at low redshifts: such interactions can lead to the concentration of gas in the host galactic nucleus, thus fueling the suspected central supermassive black hole. Although optical images show a number of violently interacting systems, in many cases, the evidence for such interactions is only circumstantial (e.g., asymmetric optical morphologies, projected nearby companion galaxies) or not at all apparent. Here we image quasar host galaxies for the first time in the redshifted 21 cm line emission of neutral atomic hydrogen (H I) gas, which, in nearby galaxies, has proved to be a particularly sensitive as well as enduring tracer of tidal interactions. The three quasars studied have different optical environments that are normally seen around low-redshift quasars, ranging from a perhaps mildly interacting system to a relatively undisturbed host with a projected neighboring galaxy to an isolated and apparently serene host galaxy. By contrast with their optical appearances, all three quasar host galaxies exhibit ongoing or remnant tidal H I disruptions tracing galactic encounters or mergers. These observations demonstrate the utility of H I at revealing tidal interactions in quasar host galaxies and, combined with optical studies, provide a fuller understanding of the likely stage of the interaction.

Host galaxies of type ia supernovae from the nearby supernova factory

NASA Astrophysics Data System (ADS)

Childress, Michael Joseph

Type Ia Supernovae (SNe Ia) are excellent distance indicators, yet the full details of the underlying physical mechanism giving rise to these dramatic stellar deaths remain unclear. As large samples of cosmological SNe Ia continue to be collected, the scatter in brightnesses of these events is equally affected by systematic errors as statistical. Thus we need to understand the physics of SNe Ia better, and in particular we must know more about the progenitors of these SNe so that we can derive better estimates for their true intrinsic brightnesses. The host galaxies of SNe Ia provide important indirect clues as to the nature of SN Ia progenitors. In this Thesis we utilize the host galaxies of SNe Ia discovered by the Nearby Supernova Factory (SNfactory) to pursue several key investigations into the nature of SN Ia progenitors and their effects on SN Ia brightnesses. We first examine the host galaxy of SN 2007if, an important member of the subclass of SNe Ia whose extreme brightnesses indicate a progenitor that exceeded the canonical Chandrasekhar-mass value presumed for normal SNe Ia, and show that the host galaxy of this SN is composed of very young stars and has extremely low metallicity, providing important constraints on progenitor scenarios for this SN. We then utilize the full sample of SNfactory host galaxy masses (measured from photometry) and metallicities (derived from optical spectroscopy) to examine several global properties of SN Ia progenitors: (i) we show that SN Ia hosts show tight agreement with the normal galaxy mass-metallicity relation; (ii) comparing the observed distribution of SN Ia host galaxy masses to a theoretical model that couples galaxy physics to the SN Ia delay time distribution (DTD), we show the power of the SN Ia host mass distribution in constraining the SN Ia DTD; and (iii) we show that the lack of ultra-low metallicities in the SNfactory SN Ia host sample gives provisional support for the theorized low-metallicity inhibition of

Tidal Disruption Events Prefer Unusual Host Galaxies

NASA Astrophysics Data System (ADS)

Arcavi, Iair; French, K. Decker; Zabludoff, Ann I.

2016-06-01

A star passing close to a supermassive black hole (SMBH) can be torn apart in a Tidal Disruption Events (TDE). TDEs that are accompanied by observable flares are now being discovered in transient surveys and are revealing the presence and the properties of otherwise-quiescent SMBHs. Recently, it was discovered that TDEs show a strong preference for rare post-starburst galaxies, (i.e. galaxies that have undergone intense star formation but are no longer forming stars today). We quantify this preference and find that TDEs are approximately 30-200 times more likely to occur in post-starburst hosts (compared to the general SDSS galaxy population), with the enhancement factor depending on the star formation history of the galaxy. This surprising host-galaxy preference connects the until-now disparate TDE subclasses of UV/optical-dominated TDEs and X-ray-dominated TDEs, and serves as the basis for TDE-targeted transient surveys. Post-starburst galaxies may be post-mergers, with binary SMBH systems that are still spiraling in. Such systems could enhance the TDE rate, but it is not yet clear if models can quantitatively reproduce the observed enhancement. Alternative explanations for enhanced TDE rate in post-starbursts include non-spherical post-merger central potentials and enhanced rates of giant stars.

Strong Clustering of Lyman Break Galaxies around Luminous Quasars at Z ˜ 4

NASA Astrophysics Data System (ADS)

García-Vergara, Cristina; Hennawi, Joseph F.; Barrientos, L. Felipe; Rix, Hans-Walter

2017-10-01

In the standard picture of structure formation, the first massive galaxies are expected to form at the highest peaks of the density field, which constitute the cores of massive proto-clusters. Luminous quasars (QSOs) at z ˜ 4 are the most strongly clustered population known, and should thus reside in massive dark matter halos surrounded by large overdensities of galaxies, implying a strong QSO-galaxy cross-correlation function. We observed six z ˜ 4 QSO fields with VLT/FORS, exploiting a novel set of narrow-band filters custom designed to select Lyman Break Galaxies (LBGs) in a thin redshift slice of {{Δ }}z˜ 0.3, mitigating the projection effects that have limited the sensitivity of previous searches for galaxies around z≳ 4 QSOs. We find that LBGs are strongly clustered around QSOs, and present the first measurement of the QSO-LBG cross-correlation function at z ˜ 4, on scales of 0.1≲ R≲ 9 {h}-1 {Mpc} (comoving). Assuming a power-law form for the cross-correlation function ξ ={(r/{r}0{QG})}γ , we measure {r}0{QG}={8.83}-1.51+1.39 {h}-1 {Mpc} for a fixed slope of γ =2.0. This result is in agreement with the expected cross-correlation length deduced from measurements of the QSO and LBG auto-correlation function, and assuming a deterministic bias model. We also measure a strong auto-correlation of LBGs in our QSO fields, finding {r}0{GG}={21.59}-1.69+1.72 {h}-1 {Mpc} for a fixed slope of γ =1.5, which is ˜4 times larger than the LBG auto-correlation length in blank fields, providing further evidence that QSOs reside in overdensities of LBGs. Our results qualitatively support a picture where luminous QSOs inhabit exceptionally massive ({M}{halo}> {10}12 {M}⊙ ) dark matter halos at z ˜ 4.

The host galaxy/AGN connection in nearby early-type galaxies. Is there a miniature radio-galaxy in every "core" galaxy?

NASA Astrophysics Data System (ADS)

Balmaverde, B.; Capetti, A.

2006-02-01

This is the second of a series of three papers exploring the connection between the multiwavelength properties of AGN in nearby early-type galaxies and the characteristics of their hosts. We selected two samples with 5 GHz VLA radio flux measurements down to 1 mJy, reaching levels of radio luminosity as low as 1036 erg s-1. In Paper I we presented a study of the surface brightness profiles for the 65 objects with available archival HST images out of the 116 radio-detected galaxies. We classified early-type galaxies into "core" and "power-law" galaxies, discriminating on the basis of the slope of their nuclear brightness profiles, following the Nukers scheme. Here we focus on the 29 core galaxies (hereafter CoreG). We used HST and Chandra data to isolate their optical and X-ray nuclear emission. The CoreG invariably host radio-loud nuclei, with an average radio-loudness parameter of Log R = L5 {GHz} / LB ˜ 3.6. The optical and X-ray nuclear luminosities correlate with the radio-core power, smoothly extending the analogous correlations already found for low luminosity radio-galaxies (LLRG) toward even lower power, by a factor of ˜ 1000, covering a combined range of 6 orders of magnitude. This supports the interpretation of a common non-thermal origin of the nuclear emission also for CoreG. The luminosities of the nuclear sources, most likely dominated by jet emission, set firm upper limits, as low as L/L_Edd ˜ 10-9 in both the optical and X-ray band, on any emission from the accretion process. The similarity of CoreG and LLRG when considering the distributions host galaxies luminosities and black hole masses, as well as of the surface brightness profiles, indicates that they are drawn from the same population of early-type galaxies. LLRG represent only the tip of the iceberg associated with (relatively) high activity levels, with CoreG forming the bulk of the population. We do not find any relationship between radio-power and black hole mass. A minimum black hole

Multiwavelength Characterization of an ACT-Selected, Lensed Dusty Star-Forming Galaxy at zeta 2.64

NASA Technical Reports Server (NTRS)

Roberts-Borsani, G. W.; Jimenez-Donaire, M. J.; Dapra, M.; Alatalo, K.; Aretxaga, I.; Alvarez-Marquez, J.; Baker, A. J.; Fujimoto, S.; Gallardo, P. A.; Gralla, M.;

Host Galaxies of Dust-Reddened QSOs

NASA Astrophysics Data System (ADS)

Urrutia, T.; Lacy, M.; Becker, R.; Gregg, M.; Helfand, D.; White, R.

2005-12-01

We present Hubble/ACS observations of 13 dust-reddened Type 1 quasars to study the properties of their host galaxies. The quasars have a mean reddening of E(B-V) = 0.8 and lie at moderate redshifts (0.4 < z < 1.0). Images were taken in I and g' band during one or two Hubble orbits. After correcting for absorption the absolute magnitudes of the quasars lie around MV = -27. We are just probing the tip of the luminosity iceberg and there must be many more obscured quasars at these redshifts. The images show extensive merger activity such as tidal tails and various compact halos even before subtracting the quasar contribution. The red quasar phenomenon is likely to be an evolutionary effect. The young quasar is obscured while the dust of the merging galaxies is still settling in. None of the quasars fit a perfect elliptical profile after subtracting the PSF as all of them show many irregularities. The host galaxies also seem to be having bluer colors that typical galaxies, although there is a large scatter in the data. This would argue for recent star-formation most likely triggered my the merger, in concordance with models arguing the emergence of AGN from dusty Starburst galaxies. This work was partly performed under the auspices of the US Department of Energy, National Nuclear Security Administration by the University of California, Lawrence Livermore National Laboratory under contract No. W-7405-Eng-48.

GALAXY CLUSTERS IN THE LINE OF SIGHT TO BACKGROUND QUASARS. III. MULTI-OBJECT SPECTROSCOPY

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

Andrews, H.; Barrientos, L. F.; Padilla, N.

2013-09-01

We present Gemini/GMOS-S multi-object spectroscopy of 31 galaxy cluster candidates at redshifts between 0.2 and 1.0 and centered on QSO sight lines taken from Lopez et al. The targets were selected based on the presence of an intervening Mg II absorption system at a similar redshift to that of a galaxy cluster candidate lying at a projected distance <2 h{sub 71}{sup -1} Mpc from the QSO sight line (a {sup p}hotometric hit{sup )}. The absorption systems span rest-frame equivalent widths between 0.015 and 2.028 A. Our aim was three-fold: (1) to identify the absorbing galaxies and determine their impact parameters,more » (2) to confirm the galaxy cluster candidates in the vicinity of each quasar sightline, and (3) to determine whether the absorbing galaxies reside in galaxy clusters. In this way, we are able to characterize the absorption systems associated with cluster members. Our main findings are as follows. (1) We identified 10 out of 24 absorbing galaxies with redshifts between 0.2509 {<=} z{sub gal} {<=} 1.0955, up to an impact parameter of 142 h{sub 71}{sup -1} kpc and a maximum velocity difference of 280 km s{sup -1}. (2) We spectroscopically confirmed 20 out of 31 cluster/group candidates, with most of the confirmed clusters/groups at z < 0.7. This relatively low efficiency results from the fact that we centered our observations on the QSO location, and thus occasionally some of the cluster centers were outside the instrument field of view. (3) Following from the results above, we spectroscopically confirmed of 10 out of 14 photometric hits within {approx}650 km s{sup -1} from galaxy clusters/groups, in addition to two new ones related to galaxy group environments. These numbers imply efficiencies of 71% in finding such systems with MOS spectroscopy. This is a remarkable result since we defined a photometric hit as those cluster-absorber pairs having a redshift difference {Delta}z = 0.1. The general population of our confirmed absorbing galaxies have

ON THE HOST GALAXY OF GRB 150101B AND THE ASSOCIATED ACTIVE GALACTIC NUCLEUS

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

Xie, Chen; Fang, Taotao; Wang, Junfeng

We present a multi-wavelength analysis of the host galaxy of short-duration gamma-ray burst (GRB) 150101B. Follow-up optical and X-ray observations suggested that the host galaxy, 2MASX J12320498-1056010, likely harbors low-luminosity active galactic nuclei (AGNs). Our modeling of the spectral energy distribution has confirmed the nature of the AGN, making it the first reported GRB host that contains an AGN. We have also found the host galaxy is a massive elliptical galaxy with stellar population of ∼5.7 Gyr, one of the oldest among the short-duration GRB hosts. Our analysis suggests that the host galaxy can be classified as an X-ray bright,more » optically normal galaxy, and the central AGN is likely dominated by a radiatively inefficient accretion flow. Our work explores an interesting connection that may exist between GRB and AGN activities of the host galaxy, which can help in understanding the host environment of the GRB events and the roles of AGN feedback.« less

The environment of x ray selected BL Lacs: Host galaxies and galaxy clustering

NASA Technical Reports Server (NTRS)

Wurtz, Ron; Stocke, John T.; Ellingson, Erica; Yee, Howard K. C.

1993-01-01

Using the Canada-France-Hawaii Telescope, we have imaged a complete, flux-limited sample of Einstein Medium Sensitivity Survey BL Lacertae objects in order to study the properties of BL Lac host galaxies and to use quantitative methods to determine the richness of their galaxy cluster environments.

A Bayesian approach to multi-messenger astronomy: identification of gravitational-wave host galaxies

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

Fan, XiLong; Messenger, Christopher; Heng, Ik Siong

We present a general framework for incorporating astrophysical information into Bayesian parameter estimation techniques used by gravitational wave data analysis to facilitate multi-messenger astronomy. Since the progenitors of transient gravitational wave events, such as compact binary coalescences, are likely to be associated with a host galaxy, improvements to the source sky location estimates through the use of host galaxy information are explored. To demonstrate how host galaxy properties can be included, we simulate a population of compact binary coalescences and show that for ∼8.5% of simulations within 200 Mpc, the top 10 most likely galaxies account for a ∼50% ofmore » the total probability of hosting a gravitational wave source. The true gravitational wave source host galaxy is in the top 10 galaxy candidates ∼10% of the time. Furthermore, we show that by including host galaxy information, a better estimate of the inclination angle of a compact binary gravitational wave source can be obtained. We also demonstrate the flexibility of our method by incorporating the use of either the B or K band into our analysis.« less

The Host Galaxies of Type Ia Supernovae Discovered by the Palomar Transient Factory

NASA Technical Reports Server (NTRS)

Pan, Y.-C.; Sullivan, M.; McGuire, K.; Hook, I. M.; Nugent, P. E.; Howell, D. A.; Arcavi, I.; Botyanszki, J.; Cenko, Stephen Bradley; DeRose, J.

2013-01-01

We present spectroscopic observations of the host galaxies of 82 low-redshift type Ia supernovae (SNe Ia) discovered by the Palomar Transient Factory (PTF). We determine star-formation rates, gas-phase stellar metallicities, and stellar masses and ages of these objects. As expected, strong correlations between the SN Ia light-curve width (stretch) and the host age mass metallicity are found: fainter, faster-declining events tend to be hosted by older massive metal-rich galaxies. There is some evidence that redder SNe Ia explode in higher metallicity galaxies, but we found no relation between the SN colour and host galaxy extinction based on the Balmer decrement, suggesting that the colour variation of these SNe does not primarily arise from this source. SNe Ia in higher-mass metallicity galaxies also appear brighter after stretch colour corrections than their counterparts in lower mass hosts, and the stronger correlation is with gas-phase metallicity suggesting this may be the more important variable. We also compared the host stellar mass distribution to that in galaxy targeted SN surveys and the high-redshift untargeted Supernova Legacy Survey (SNLS). SNLS has many more low mass galaxies, while the targeted searches have fewer. This can be explained by an evolution in the galaxy stellar mass function, coupled with a SN delay-time distribution proportional to t1. Finally, we found no significant difference in the mass--metallicity relation of our SN Ia hosts compared to field galaxies, suggesting any metallicity effect on the SN Ia rate is small.

Quasar Host Galaxies/Neptune Rotation/Galaxy Building Blocks/Hubble Deep Field/Saturn Storm

NASA Technical Reports Server (NTRS)

2001-01-01

Computerized animations simulate a quasar erupting in the core of a normal spiral galaxy, the collision of two interacting galaxies, and the evolution of the universe. Hubble Space Telescope (HST) images show six quasars' host galaxies (including spirals, ellipticals, and colliding galaxies) and six clumps of galaxies approximately 11 billion light years away. A false color time lapse movie of Neptune displays the planet's 16-hour rotation, and the evolution of a storm on Saturn is seen though a video of the planet's rotation. A zoom sequence starts with a ground-based image of the constellation Ursa major and ends with the Hubble Deep Field through progressively narrower and deeper views.

Type Ia supernova host galaxies as seen with IFU spectroscopy

NASA Astrophysics Data System (ADS)

Stanishev, V.; Rodrigues, M.; Mourão, A.; Flores, H.

2012-09-01

Context. Type Ia supernovae (SNe Ia) have been widely used in cosmology as distance indicators. However, to fully exploit their potential in cosmology, a better control over systematic uncertainties is required. Some of the uncertainties are related to the unknown nature of the SN Ia progenitors. Aims: We aim to test the use of integral field unit (IFU) spectroscopy for correlating the properties of nearby SNe Ia with the properties of their host galaxies at the location of the SNe. The results are to be compared with those obtained from an analysis of the total host spectrum. The goal is to explore this path of constraining the nature of the SN Ia progenitors and further improve the use of SNe Ia in cosmology. Methods: We used the wide-field IFU spectrograph PMAS/PPAK at the 3.5 m telescope of Calar Alto Observatory to observe six nearby spiral galaxies that hosted SNe Ia. Spatially resolved 2D maps of the properties of the ionized gas and the stellar populations were derived. Results: Five of the observed galaxies have an ongoing star formation rate of 1-5 M⊙ yr-1 and mean stellar population ages ~5 Gyr. The sixth galaxy shows no star formation and has an about 12 Gyr old stellar population. All galaxies have stellar masses larger than 2 × 1010 M⊙ and metallicities above solar. Four galaxies show negative radial metallicity gradients of the ionized gas up to -0.058 dex kpc-1 and one has nearly uniform metallicity with a possible shallow positive slope. The stellar components show shallower negative metallicity gradients up to -0.03 dex kpc-1. We find no clear correlation between the properties of the galaxy and those of the supernovae, which may be because of the small ranges spanned by the galaxy parameters. However, we note that the Hubble residuals are on average positive while negative Hubble residuals are expected for SNe Ia in massive hosts such as the galaxies in our sample. Conclusions: The IFU spectroscopy on 4-m telescopes is a viable technique for

Starburst-driven Superwinds in Quasar Host Galaxies

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

Barthel, Peter; Podigachoski, Pece; Wilkes, Belinda

2017-07-01

During the past five decades astronomers have been puzzled by the presence of strong absorption features including metal lines, observed in the optical and ultraviolet spectra of quasars, signaling inflowing and outflowing gas winds with relative velocities up to several thousands of km s{sup −1}. In particular, the location of these winds—close to the quasar, further out in its host galaxy, or in its direct environment—and the possible impact on their surroundings have been issues of intense discussion and uncertainty. Using our Herschel Space Observatory data, we report a tendency for this so-called associated metal absorption to occur along withmore » prodigious star formation in the quasar host galaxy, indicating that the two phenomena are likely to be interrelated, that the gas winds likely occur on the kiloparsec scale and would then have a strong impact on the interstellar medium of the galaxy. This correlation moreover would imply that the unusually high cold dust luminosities in these quasars are connected with ongoing star formation. Given that we find no correlation with the AGN strength, the wind feedback that we establish in these radio-loud objects is most likely associated with their host star formation rather than with their black hole accretion.« less

Einstein observations of active galaxies and quasars

NASA Technical Reports Server (NTRS)

Schreier, E. J.

1979-01-01

The radio galaxies Centaurus A and Signus B are discussed. In both these sources, a comparison of the radio and imaged X-ray flux is allowed for the measurement of the magnetic fields. Einstein observations of quasars are discussed. The number of known X-ray emitting QSO's was increased from 3 to 22 and the distances where these QSO's were seen to correspond to an age of 15 billion years. It was shown that these quasars contributed significantly to the X-ray background.

DEMOGRAPHICS OF THE GALAXIES HOSTING SHORT-DURATION GAMMA-RAY BURSTS

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

Fong, W.; Berger, E.; Chornock, R.

We present observations of the afterglows and host galaxies of three short-duration gamma-ray bursts (GRBs): 100625A, 101219A, and 110112A. We find that GRB 100625A occurred in a z = 0.452 early-type galaxy with a stellar mass of Almost-Equal-To 4.6 Multiplication-Sign 10{sup 9} M{sub Sun} and a stellar population age of Almost-Equal-To 0.7 Gyr, and GRB 101219A originated in a star-forming galaxy at z = 0.718 with a stellar mass of Almost-Equal-To 1.4 Multiplication-Sign 10{sup 9} M{sub Sun }, a star formation rate of Almost-Equal-To 16 M{sub Sun} yr{sup -1}, and a stellar population age of Almost-Equal-To 50 Myr. We alsomore » report the discovery of the optical afterglow of GRB 110112A, which lacks a coincident host galaxy to i {approx}> 26 mag, and we cannot conclusively identify any field galaxy as a possible host. From afterglow modeling, the bursts have inferred circumburst densities of Almost-Equal-To 10{sup -4}-1 cm{sup -3} and isotropic-equivalent gamma-ray and kinetic energies of Almost-Equal-To 10{sup 50}-10{sup 51} erg. These three events highlight the diversity of galactic environments that host short GRBs. To quantify this diversity, we use the sample of 36 Swift short GRBs with robust associations to an environment ({approx}1/2 of 68 short bursts detected by Swift to 2012 May) and classify bursts originating from four types of environments: late-type ( Almost-Equal-To 50%), early-type ( Almost-Equal-To 15%), inconclusive ( Almost-Equal-To 20%), and ''host-less'' (lacking a coincident host galaxy to limits of {approx}> 26 mag; Almost-Equal-To 15%). To find likely ranges for the true late- and early-type fractions, we assign each of the host-less bursts to either the late- or early-type category using probabilistic arguments and consider the scenario that all hosts in the inconclusive category are early-type galaxies to set an upper bound on the early-type fraction. We calculate most likely ranges for the late- and early-type fractions of Almost

A Hubble Space Telescope imaging study of four FeLoBAL quasar host galaxies

NASA Astrophysics Data System (ADS)

Lawther, D.; Vestergaard, M.; Fan, X.

2018-04-01

We study the host galaxies of four Iron Low-Ionization Broad Absorption-line Quasars (FeLoBALs), using Hubble Space Telescope imaging data, investigating the possibility that they represent a transition between an obscured active galactic nucleus (AGN) and an ordinary optical quasar. In this scenario, the FeLoBALs represent the early stage of merger-triggered accretion, in which case their host galaxies are expected to show signs of an ongoing or recent merger. Using PSF subtraction techniques, we decompose the images into host galaxy and AGN components at rest-frame ultraviolet and optical wavelengths. The ultraviolet is sensitive to young stars, while the optical probes stellar mass. In the ultraviolet we image at the BAL absorption trough wavelengths so as to decrease the contrast between the quasar and host galaxy emission. We securely detect an extended source for two of the four FeLoBALs in the rest-frame optical; a third host galaxy is marginally detected. In the rest-frame UV we detect no host emission; this constrains the level of unobscured star formation. Thus, the host galaxies have observed properties that are consistent with those of non-BAL quasars with the same nuclear luminosity, i.e. quiescent or moderately star-forming elliptical galaxies. However, we cannot exclude starbursting hosts that have the stellar UV emission obscured by modest amounts of dust reddening. Thus, our findings also allow the merger-induced young quasar scenario. For three objects, we identify possible close companion galaxies that may be gravitationally interacting with the quasar hosts.

Investigating a population of infrared-bright gamma-ray burst host galaxies

NASA Astrophysics Data System (ADS)

Chrimes, Ashley A.; Stanway, Elizabeth R.; Levan, Andrew J.; Davies, Luke J. M.; Angus, Charlotte R.; Greis, Stephanie M. L.

2018-07-01

We identify and explore the properties of an infrared-bright gamma-ray burst (GRB) host population. Candidate hosts are selected by coincidence with sources in WISE, with matching to random coordinates and a false alarm probability analysis showing that the contamination fraction is ˜0.5. This methodology has already identified the host galaxy of GRB 080517. We combine survey photometry from Pan-STARRS, SDSS, APASS, 2MASS, GALEX, and WISE with our own WHT/ACAM and VLT/X-shooter observations to classify the candidates and identify interlopers. Galaxy SED fitting is performed using MAGPHYS, in addition to stellar template fitting, yielding 13 possible IR-bright hosts. A further seven candidates are identified from the previously published work. We report a candidate host for GRB 061002, previously unidentified as such. The remainder of the galaxies have already been noted as potential hosts. Comparing the IR-bright population properties including redshift z, stellar mass M⋆, star formation rate SFR, and V-band attenuation AV to GRB host catalogues in the literature, we find that the infrared-bright population is biased towards low z, high M⋆, and high AV. This naturally arises from their initial selection - local and dusty galaxies are more likely to have the required IR flux to be detected in WISE. We conclude that while IR-bright GRB hosts are not a physically distinct class, they are useful for constraining existing GRB host populations, particularly for long GRBs.

Investigating a population of infrared-bright gamma-ray burst host galaxies

NASA Astrophysics Data System (ADS)

Chrimes, Ashley A.; Stanway, Elizabeth R.; Levan, Andrew J.; Davies, Luke J. M.; Angus, Charlotte R.; Greis, Stephanie M. L.

2018-04-01

We identify and explore the properties of an infrared-bright gamma-ray burst (GRB) host population. Candidate hosts are selected by coincidence with sources in WISE, with matching to random coordinates and a false alarm probability analysis showing that the contamination fraction is ˜ 0.5. This methodology has already identified the host galaxy of GRB 080517. We combine survey photometry from Pan-STARRS, SDSS, APASS, 2MASS, GALEX and WISE with our own WHT/ACAM and VLT/X-shooter observations to classify the candidates and identify interlopers. Galaxy SED fitting is performed using MAGPHYS, in addition to stellar template fitting, yielding 13 possible IR-bright hosts. A further 7 candidates are identified from previously published work. We report a candidate host for GRB 061002, previously unidentified as such. The remainder of the galaxies have already been noted as potential hosts. Comparing the IR-bright population properties including redshift z, stellar mass M⋆, star formation rate SFR and V-band attenuation AV to GRB host catalogues in the literature, we find that the infrared-bright population is biased toward low z, high M⋆ and high AV. This naturally arises from their initial selection - local and dusty galaxies are more likely to have the required IR flux to be detected in WISE. We conclude that while IR-bright GRB hosts are not a physically distinct class, they are useful for constraining existing GRB host populations, particularly for long GRBs.

Discovery of a bright quasar without a massive host galaxy.

PubMed

Magain, Pierre; Letawe, Géraldine; Courbin, Frédéric; Jablonka, Pascale; Jahnke, Knud; Meylan, Georges; Wisotzki, Lutz

2005-09-15

A quasar is thought to be powered by the infall of matter onto a supermassive black hole at the centre of a massive galaxy. Because the optical luminosity of quasars exceeds that of their host galaxy, disentangling the two components can be difficult. This led in the 1990s to the controversial claim of the discovery of 'naked' quasars. Since then, the connection between quasars and galaxies has been well established. Here we report the discovery of a quasar lying at the edge of a gas cloud, whose size is comparable to that of a small galaxy, but whose spectrum shows no evidence for stars. The gas in the cloud is excited by the quasar itself. If a host galaxy is present, it is at least six times fainter than would normally be expected for such a bright quasar. The quasar is interacting dynamically with a neighbouring galaxy, whose gas might be feeding the black hole.

A VLT/MUSE galaxy survey towards QSO Q1410: looking for a WHIM traced by BLAs in inter-cluster filaments

NASA Astrophysics Data System (ADS)

Pessa, Ismael; Tejos, Nicolas; Barrientos, L. Felipe; Werk, Jessica; Bielby, Richard; Padilla, Nelson; Morris, Simon L.; Prochaska, J. Xavier; Lopez, Sebastian; Hummels, Cameron

2018-07-01

Cosmological simulations predict that a significant fraction of the low-z baryon budget resides in large-scale filaments in the form of a diffuse plasma at temperatures T ˜ 105 - 107 K. However, direct observation of this so-called warm-hot intergalactic medium (WHIM) has been elusive. In the Λcold dark matter paradigm, galaxy clusters correspond to the nodes of the cosmic web at the intersection of several large-scale filamentary threads. In previous work, we used HST/COS data to conduct the first survey of broad H I Lyα absorbers (BLAs) potentially produced by WHIM in inter-cluster filaments. We targeted a single QSO, namely Q1410, whose sightline intersects seven independent inter-cluster axes at impact parameters <3 Mpc (comoving), and found a tentative excess of a factor of ˜4 with respect to the field. Here, we further investigate the origin of these BLAs by performing a blind galaxy survey within the Q1410 field using VLT/MUSE. We identified 77 sources and obtained the redshifts for 52 of them. Out of the total sample of seven BLAs in inter-cluster axes, we found three without any galaxy counterpart to stringent luminosity limits (˜4 × 108 L⊙ ˜0.01 L*), providing further evidence that these BLAs may represent genuine WHIM detections. We combined this sample with other suitable BLAs from the literature and inferred the corresponding baryon mean density for these filaments in the range Ω ^fil_bar= 0.02-0.04. Our rough estimates are consistent with the predictions from numerical simulations but still subject to large systematic uncertainties, mostly from the adopted geometry, ionization corrections, and density profile.

SDSS IV MaNGA - Properties of AGN Host Galaxies

NASA Astrophysics Data System (ADS)

Sánchez, S. F.; Avila-Reese, V.; Hernandez-Toledo, H.; Cortes-Suárez, E.; Rodríguez-Puebla, A.; Ibarra-Medel, H.; Cano-Díaz, M.; Barrera-Ballesteros, J. K.; Negrete, C. A.; Calette, A. R.; de Lorenzo-Cáceres, A.; Ortega-Minakata, R. A.; Aquino, E.; Valenzuela, O.; Clemente, J. C.; Storchi-Bergmann, T.; Riffel, R.; Schimoia, J.; Riffel, R. A.; Rembold, S. B.; Brownstein, J. R.; Pan, K.; Yates, R.; Mallmann, N.; Bitsakis, T.

2018-04-01

We present the characterization of the main properties of a sample of 98 AGN host galaxies, both type-II and type-I, in comparison with those of ≍2700 non-active galaxies observed by the MaNGA survey. We found that AGN hosts are morphologically early-type or early-spirals. AGN hosts are, on average, more massive, more compact, more centrally peaked and more pressure-supported systems. They are located in the intermediate/transition region between starforming and non-star-forming galaxies (i.e., the so-called green valley). We consider that they are in the process of halting/quenching the star formation. The analysis of the radial distributions of different properties shows that the quenching happens from inside-out involving both a decrease of the effciency of the star formation and a deficit of molecular gas. The data-products of the current analysis are distributed as a Value Added Catalog within the SDSS-DR14.

The clustering of QSOs and the dark matter halos that host them

NASA Astrophysics Data System (ADS)

Zhao, Dong-Yao; Yan, Chang-Shuo; Lu, Youjun

2013-10-01

The spatial clustering of QSOs is an important measurable quantity which can be used to infer the properties of dark matter halos that host them. We construct a simple QSO model to explain the linear bias of QSOs measured by recent observations and explore the properties of dark matter halos that host a QSO. We assume that major mergers of dark matter halos can lead to the triggering of QSO phenomena, and the evolution of luminosity for a QSO generally shows two accretion phases, i.e., initially having a constant Eddington ratio due to the self-regulation of the accretion process when supply is sufficient, and then declining in rate with time as a power law due to either diminished supply or long term disk evolution. Using a Markov Chain Monte Carlo method, the model parameters are constrained by fitting the observationally determined QSO luminosity functions (LFs) in the hard X-ray and in the optical band simultaneously. Adopting the model parameters that best fit the QSO LFs, the linear bias of QSOs can be predicted and then compared with the observational measurements by accounting for various selection effects in different QSO surveys. We find that the latest measurements of the linear bias of QSOs from both the SDSS and BOSS QSO surveys can be well reproduced. The typical mass of SDSS QSOs at redshift 1.5 < z < 4.5 is ~ (3 - 6) × 1012 h-1 Msolar and the typical mass of BOSS QSOs at z ~ 2.4 is ~ 2 × 1012 h-1 Msolar. For relatively faint QSOs, the mass distribution of their host dark matter halos is wider than that of bright QSOs because faint QSOs can be hosted in both big halos and smaller halos, but bright QSOs are only hosted in big halos, which is part of the reason for the predicted weak dependence of the linear biases on the QSO luminosity.

QSO Lyalpha Absorption Lines in Galaxy Superclusters and Voids

NASA Astrophysics Data System (ADS)

Stocke, J. T.; Shull, J. M.; Penton, S.; Burks, G.; Donahue, M.

1993-12-01

We have used the Hubble Space Telescope (HST) Goddard High Resolution Spectrograph (GHRS) to search for Lyalpha absorption clouds in nearby galaxy voids (cz <= 10,000 km s(-1) ). Thus far, we have obtained GHRS spectra (G160M, 1225 -- 1255 Angstroms, 0.25 Angstroms resolution) of three very bright Active Galactic Nuclei, Mrk 501, I Zw I, and Mrk 335, at V <= 14.5. We find 4 probable (4.0 sigma - 4.5 sigma ) and 4 definite (5 sigma - 16 sigma ) Lyalpha absorption lines, with equivalent widths W_λ = 50 - 200 m Angstroms, corresponding to column densities N(H I) = 10(13) -- 10(14) cm(-2) , assuming a typical Doppler parameter of b = 25 km s(-1) . Based on an updated version of the CfA redshift survey (Huchra and Clemens, private communication), most of these Lyalpha systems appear to be associated with supercluster - sized ``strings'' of galaxies similar to the ``Great Wall''. Toward Mrk 501, the nearest bright galaxy at the redshift of the strongest (200 m Angstroms) Lyalpha cloud lies 500 h75(-1) kpc off the line of sight. Models of H I disks exposed to the intergalactic ionizing radiation field (Dove & Shull 1994, ApJ, 423, in press) show that the N(H I) = 10(13) cm(-2) contour in a typical spiral galaxy is reached at 100 kpc radial extent. Thus, the Lyalpha absorbers associated with galaxy-string systems may be the result of H I in an extended halo, in dwarf satellite galaxies (M_B > -15), or in tidally-stripped gas. Most importantly for cosmological origins of baryons, one (4.3 sigma ) Lyalpha absorption line in the spectrum of Mrk 501 lies within the galaxy void in the foreground of the ``Great Wall''. The nearest bright galaxy, to a level M_B <= -18.5 for H_0 = 75 km s(-1) Mpc(-1) , is more than 5 Mpc away. A pencil-beam survey of faint galaxies to M_B = -16.0 finds no galaxy within 100 h75(-1) kpc of the line of sight, at or near the absorber redshift.

QSO Emission Lines and the Black Hole-Galaxy Bulge Relation

NASA Astrophysics Data System (ADS)

Shields, G. A.; Gebhardt, K.; Salviander, S.; Wills, B. J.; Yuan, M.; Xie, B.; Dietrich, M.

2002-05-01

Supermassive black holes in galactic nuclei have masses closely related to the properties of the host galaxy bulge. In particular, MBH varies as the fourth power of σ , the stellar velocity dispersion (Tremaine et al. 2002, ApJ in press, and references therein). The origin of the black hole-bulge relation is unknown, although theoretical suggestions abound. An important clue would be provided by knowledge of how the relation has evolved over cosmic time. This requires measurement of black hole masses and galactic potentials at large look-back times, which is difficult to do directly. However, black hole masses may be derived from the continuum luminosity and the widths of the broad Balmer lines of QSOs (e.g., Kaspi et al. 2000, ApJ 533, 631), and σ may be derived from the widths of the narrow [O III] lines (Nelson 2000, ApJ, 544, L91). We have carried out this program for a set of published and unpublished observations of Seyfert galaxies and QSOs. Results for low redshift objects support the use of this method to derive MBH and σ . The few available measurements of high redshift QSOs are consistent little or no change in the MBH-σ relation between the present and redshifts up to z = 3.3, when the universe was only two billion years old. This material is based in part upon work supported by the Texas Advanced Research Program under Grant No. 003658-0177-2001.

The Host Galaxies of Fast-Ejecta Core-Collapse Supernovae

NASA Technical Reports Server (NTRS)

Kelly, Patrick L.; Filippenko, Alexei V.; Modjaz, Maryam; Kocevski, Daniel

2014-01-01

Spectra of broad-lined Type Ic supernovae (SN Ic-BL), the only kind of SN observed at the locations of long-duration gamma-ray bursts (LGRBs), exhibit wide features indicative of high ejecta velocities ((is) approximately 0.1c). We study the host galaxies of a sample of 245 low-redshift (z (is) less than 0.2) core-collapse SN, including 17 SN Ic-BL, discovered by galaxy-untargeted searches, and 15 optically luminous and dust-obscured z (is) less than 1.2 LGRBs. We show that, in comparison with SDSS galaxies having similar stellar masses, the hosts of low-redshift SN Ic- BL and z (is) is less than 1.2 LGRBs have high stellar-mass and star-formation-rate densities. Core-collapse SN having typical ejecta velocities, in contrast, show no preference for such galaxies. Moreover, we find that the hosts of SN Ic-BL, unlike those of SN Ib/Ic and SN II, exhibit high gas velocity dispersions for their stellar masses. The patterns likely reflect variations among star-forming environments, and suggest that LGRBs can be used as probes of conditions in high-redshift galaxies. They may be caused by efficient formation of massive binary progenitors systems in densely star-forming regions, or, less probably, a higher fraction of stars created with the initial masses required for a SN Ic-BL or LGRB. Finally, we show that the preference of SN Ic-BL and LGRBs for galaxies with high stellar-mass and star-formation-rate densities cannot be attributed to a preference for low metal abundances but must reflect the influence of a separate environmental factor.

The MUSE view of the host galaxy of GRB 100316D

NASA Astrophysics Data System (ADS)

Izzo, L.; Thöne, C. C.; Schulze, S.; Mehner, A.; Flores, H.; Cano, Z.; de Ugarte Postigo, A.; Kann, D. A.; Amorín, R.; Anderson, J. P.; Bauer, F. E.; Bensch, K.; Christensen, L.; Covino, S.; Della Valle, M.; Fynbo, J. P. U.; Jakobsson, P.; Klose, S.; Kuncarayakti, H.; Leloudas, G.; Milvang-Jensen, B.; Møller, P.; Puech, M.; Rossi, A.; Sánchez-Ramírez, R.; Vergani, S. D.

2017-12-01

The low distance, z = 0.0591, of GRB 100316D and its association with SN 2010bh represent two important motivations for studying this host galaxy and the GRB's immediate environment with the integral field spectrographs like Very Large Telescope/Multi-Unit Spectroscopic Explorer. Its large field of view allows us to create 2D maps of gas metallicity, ionization level and the star formation rate (SFR) distribution maps, as well as to investigate the presence of possible host companions. The host is a late-type dwarf irregular galaxy with multiple star-forming regions and an extended central region with signatures of on-going shock interactions. The gamma-ray burst (GRB) site is characterized by the lowest metallicity, the highest SFR and the youngest (∼20-30 Myr) stellar population in the galaxy, which suggest a GRB progenitor stellar population with masses up to 20-40 M⊙. We note that the GRB site has an offset of ∼660 pc from the most luminous SF region in the host. The observed SF activity in this galaxy may have been triggered by a relatively recent gravitational encounter between the host and a small undetected (LH α ≤ 1036 erg s-1) companion.

The Relation between Luminous AGNs and Star Formation in Their Host Galaxies

NASA Astrophysics Data System (ADS)

Xu, Lei; Rieke, G. H.; Egami, E.; Haines, C. P.; Pereira, M. J.; Smith, G. P.

2015-08-01

We study the relation of active galactic nuclei (AGNs) to star formation in their host galaxies. Our sample includes 205 Type-1 and 85 Type-2 AGNs, 162 detected with Herschel, from fields surrounding 30 galaxy clusters in the Local Cluster Substructure Survey. The sample is identified by optical line widths and ratios after selection to be brighter than 1 mJy at 24 μm. We show that Type-2 AGN [O iii]λ5007 line fluxes at high z can be contaminated by their host galaxies with typical spectrograph entrance apertures (but our sample is not compromised in this way). We use spectral energy distribution (SED) templates to decompose the galaxy SEDs and estimate star formation rates (SFRs), AGN luminosities, and host galaxy stellar masses (described in an accompanying paper). The AGNs arise from massive black holes (˜ 3× {10}8{M}⊙ ) accreting at ˜10% of the Eddington rate and residing in galaxies with stellar mass \\gt 3× {10}10{M}⊙ ; those detected with Herschel have IR luminosity from star formation in the range of {L}{SF,{IR}}˜ {10}10-{10}12{L}⊙ . We find that (1) the specific SFRs in the host galaxies are generally consistent with those of normal star-forming (main sequence) galaxies; (2) there is a strong correlation between the luminosities from star formation and the AGN; and (3) the correlation may not result from a causal connection, but could arise because the black hole mass (and hence AGN Eddington luminosity) and star formation are both correlated with the galaxy mass.

Is QSO 1146 + 111B,C due to lensing by a cosmic string?

NASA Technical Reports Server (NTRS)

Gott, J. R., III

1986-01-01

A newly discovered lens candidate, QSO 1146 + 111B,C, is discussed which appears to consist of two images of equal brightness of a quasar at redshift 1.01 separated by 2.6 arcmin. If this is produced by a cosmic string, its mass per unit length is about 4.0 x 10 to the 23rd g/cm or more. This value is large enough to be interesting for string-assisted galaxy formation and near the upper limits implied by the isotropy of the cosmic microwave background and constraints on gravitational radiation.

A molecular Einstein ring: imaging a starburst disk surrounding a quasi-stellar object.

PubMed

Carilli, C L; Lewis, G F; Djorgovski, S G; Mahabal, A; Cox, P; Bertoldi, F; Omont, A

2003-05-02

Images of the molecular CO 2-1 line emission and the radio continuum emission from the redshift 4.12 gravitationally lensed quasi-stellar object (QSO) PSS J2322+1944 reveal an Einstein ring with a diameter of 1.5". These observations are modeled as a star-forming disk surrounding the QSO nucleus with a radius of 2 kiloparsecs. The implied massive star formation rate is 900 solar masses per year. At this rate, a substantial fraction of the stars in a large elliptical galaxy could form on a dynamical time scale of 108 years. The observation of active star formation in the host galaxy of a high-redshift QSO supports the hypothesis of coeval formation of supermassive black holes and stars in spheroidal galaxies.

Globular cluster systems and their host galaxies: comparison of spatial distributions and colors

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

Hargis, Jonathan R.; Rhode, Katherine L., E-mail: jhargis@haverford.edu

2014-11-20

We present a study of the spatial and color distributions of four early-type galaxies and their globular cluster (GC) systems observed as part of our ongoing wide-field imaging survey. We use BVR KPNO 4 m+MOSAIC imaging data to characterize the galaxies' GC populations, perform surface photometry of the galaxies, and compare the projected two-dimensional shape of the host galaxy light to that of the GC population. The GC systems of the ellipticals NGC 4406 and NGC 5813 both show an elliptical distribution consistent with that of the host galaxy light. Our analysis suggests a similar result for the giant ellipticalmore » NGC 4472, but a smaller GC candidate sample precludes a definite conclusion. For the S0 galaxy NGC 4594, the GCs have a circular projected distribution, in contrast to the host galaxy light, which is flattened in the inner regions. For NGC 4406 and NGC 5813, we also examine the projected shapes of the metal-poor and metal-rich GC subpopulations and find that both subpopulations have elliptical shapes that are consistent with those of the host galaxy light. Lastly, we use integrated colors and color profiles to compare the stellar populations of the galaxies to their GC systems. For each galaxy, we explore the possibility of color gradients in the individual metal-rich and metal-poor GC subpopulations. We find statistically significant color gradients in both GC subpopulations of NGC 4594 over the inner ∼5 effective radii (∼20 kpc). We compare our results to scenarios for the formation and evolution of giant galaxies and their GC systems.« less

Revisiting The First Galaxies: The effects of Population III stars on their host galaxies

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

Muratov, Alexander L.; Gnedin, Oleg Y.; Gnedin, Nickolay Y.

2013-07-12

We revisit the formation and evolution of the first galaxies using new hydrodynamic cosmological simulations with the adaptive refinement tree code. Our simulations feature a recently developed model for H 2 formation and dissociation, and a star formation recipe that is based on molecular rather than atomic gas. Here, we develop and implement a recipe for the formation of metal-free Population III (Pop III) stars in galaxy-scale simulations that resolve primordial clouds with sufficiently high density. We base our recipe on the results of prior zoom-in simulations that resolved the protostellar collapse in pre-galactic objects. We find the epoch duringmore » which Pop III stars dominated the energy and metal budget of the first galaxies to be short-lived. Galaxies that host Pop III stars do not retain dynamical signatures of their thermal and radiative feedback for more than 10 8 years after the lives of the stars end in pair-instability supernovae, even when we consider the maximum reasonable efficiency of the feedback. Though metals ejected by the supernovae can travel well beyond the virial radius of the host galaxy, they typically begin to fall back quickly, and do not enrich a large fraction of the intergalactic medium. Galaxies with a total mass in excess of 3 × 10 6 M ⊙ re-accrete most of their baryons and transition to metal-enriched Pop II star formation.« less

REVISITING THE FIRST GALAXIES: THE EFFECTS OF POPULATION III STARS ON THEIR HOST GALAXIES

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

Muratov, Alexander L.; Gnedin, Oleg Y.; Zemp, Marcel

2013-08-01

We revisit the formation and evolution of the first galaxies using new hydrodynamic cosmological simulations with the adaptive refinement tree code. Our simulations feature a recently developed model for H{sub 2} formation and dissociation, and a star formation recipe that is based on molecular rather than atomic gas. Here, we develop and implement a recipe for the formation of metal-free Population III (Pop III) stars in galaxy-scale simulations that resolve primordial clouds with sufficiently high density. We base our recipe on the results of prior zoom-in simulations that resolved the protostellar collapse in pre-galactic objects. We find the epoch duringmore » which Pop III stars dominated the energy and metal budget of the first galaxies to be short-lived. Galaxies that host Pop III stars do not retain dynamical signatures of their thermal and radiative feedback for more than 10{sup 8} years after the lives of the stars end in pair-instability supernovae, even when we consider the maximum reasonable efficiency of the feedback. Though metals ejected by the supernovae can travel well beyond the virial radius of the host galaxy, they typically begin to fall back quickly, and do not enrich a large fraction of the intergalactic medium. Galaxies with a total mass in excess of 3 Multiplication-Sign 10{sup 6} M{sub Sun} re-accrete most of their baryons and transition to metal-enriched Pop II star formation.« less

ALMA [N ii] 205 μ m Imaging Spectroscopy of the Interacting Galaxy System BRI 1202-0725 at Redshift 4.7

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

Lu, Nanyao; Xu, C. Kevin; Zhu, Lei

We present the results from Atacama Large Millimeter/submillimeter Array imaging in the [N ii] 205 μ m fine-structure line (hereafter [N ii]) and the underlying continuum of BRI 1202-0725, an interacting galaxy system at z = 4.7, consisting of a quasi-stellar object (QSO), a submillimeter galaxy (SMG), and two Ly α emitters, all within ∼25 kpc of the QSO. We detect the QSO and SMG in both [N ii] and continuum. At the ∼1″ (or 6.6 kpc) resolution, both the QSO and SMG are resolved in [N ii], with the de-convolved major axes of ∼9 and ∼14 kpc, respectively. Inmore » contrast, their continuum emissions are much more compact and unresolved even at an enhanced resolution of ∼0.″7. The ratio of the [N ii] flux to the existing CO(7−6) flux is used to constrain the dust temperature ( T {sub dust}) for a more accurate determination of the FIR luminosity L {sub FIR}. Our best estimated T {sub dust} equals 43 (±2) K for both galaxies (assuming an emissivity index β = 1.8). The resulting L {sub CO(7−6)}/ L {sub FIR} ratios are statistically consistent with that of local luminous infrared galaxies, confirming that L {sub CO(7−6)} traces the star formation (SF) rate (SFR) in these galaxies. We estimate that the ongoing SF of the QSO (SMG) has an SFR of 5.1 (6.9) × 10{sup 3} M {sub ⊙} yr{sup −1} (±30%) assuming Chabrier initial mass function, takes place within a diameter (at half maximum) of 1.3 (1.5) kpc, and will consume the existing 5 (5) × 10{sup 11} M {sub ⊙} of molecular gas in 10 (7) × 10{sup 7} years.« less

Host Galaxy Properties of the Swift BAT Ultra Hard X-Ray Selected AGN

NASA Technical Reports Server (NTRS)

Koss, Michael; Mushotzky, Richard; Veilleux, Sylvain; Winter, Lisa M.; Baumgartner, Wayne; Tueller, Jack; Gehrels, Neil; Valencic, Lynne

2011-01-01

We have assembled the largest sample of ultra hard X-ray selected (14-195 keV) AGN with host galaxy optical data to date, with 185 nearby (z<0.05), moderate luminosity AGN from the Swift Burst Alert Telescope (BAT) sample. The BAT AGN host galaxies have intermediate optical colors (u -- r and g -- r) that are bluer than a comparison sample of inactive galaxies and optically selected AGN from the Sloan Digital Sky Survey (SDSS) which are chosen to have the same stellar mass. Based on morphological classifications from the RC3 and the Galaxy Zoo, the bluer colors of BAT AGN are mainly due to a higher fraction of mergers and massive spirals than in the comparison samples. BAT AGN in massive galaxies (log Stellar Mass >10.5) have a 5 to 10 times higher rate of spiral morphologies than in SDSS AGN or inactive galaxies. We also see enhanced far-IR emission in BAT AGN suggestive of higher levels of star formation compared to the comparison samples. BAT AGN are preferentially found in the most massive host galaxies with high concentration indexes indicative of large bulge-to-disk ratios and large supermassive black holes. The narrow-line (NL) BAT AGN have similar intrinsic luminosities as the SDSS NL Seyferts based on measurements of [O III] Lambda 5007. There is also a correlation between the stellar mass and X-ray emission. The BAT AGN in mergers have bluer colors and greater ultra hard X-ray emission compared to the BAT sample as whole. In agreement with the Unified Model of AGN, and the relatively unbiased nature of the BAT sources, the host galaxy colors and morphologies are independent of measures of obscuration such as X-ray column density or Seyfert type. The high fraction of massive spiral galaxies and galaxy mergers in BAT AGN suggest that host galaxy morphology is related to the activation and fueling of local AGN.

The Spitzer/Swift Gamma-Ray Burst Host Galaxy Extended Legacy Survey

NASA Astrophysics Data System (ADS)

Perley, Daniel; Berger, Edo; Butler, Nathaniel; Cenko, S. Bradley; Chary, Ranga-Ram; Cucchiara, Antonino; Ellis, Richard; Fong, Wen-fai; Fruchter, Andrew; Fynbo, Johan; Gehrels, Neil; Graham, John; Greiner, Jochen; Hjorth, Jens; Hunt, Leslie; Jakobsson, Pall; Kruehler, Thomas; Laskar, Tanmoy; Le Floc'h, Emerich; Levan, Andrew; Levesque, Emily; Littlejohns, Owen; Malesani, Daniele; Michalowski, Michal; Prochaska, J. Xavier; Salvaterra, Ruben; Schulze, Steve; Schady, Patricia; Tanvir, Nial; de Ugarte Postigo, Antonio; Vergani, Susanna

2014-12-01

Long-duration gamma-ray bursts act as beacons to the sites of star-formation in the distant universe. GRBs reveal galaxies too faint and star-forming regions too dusty to characterize in detail using any other method, and provide a powerful independent constraint on the evolution of the cosmic star-formation rate density at high-redshift. However, a full understanding of the GRB phenomenon and its relation to cosmic star-formation requires connecting the observations obtained from GRBs to the properties of the galaxies hosting them. The large majority of GRBs originate at moderate to high redshift (z>1) and Spitzer has proven crucial for understanding the host population, given its unique ability to observe the rest-frame NIR and its unrivaled sensitivity and efficiency. We propose to complete a comprehensive public legacy survey of the Swift GRB host population to build on our earlier successes and push beyond the statistical limits of previous, smaller efforts. Our survey will enable a diverse range of GRB and galaxy science including: (1) to quantitatively and robustly map the connection between GRBs and cosmic star-formation to constrain the GRB progenitor and calibrate GRB rate-based measurements of the high-z cosmic star-formation rate; (2) to constrain the luminosity function of star-forming galaxies at the faint end and at high redshift; (3) to understand how the ISM properties seen in absorption in high-redshift galaxies unveiled by GRBs - metallicity, dust column, dust properties - connect to global properties of the host galaxies such as mass and age. Building on a decade of experience at both observatories, our observations will create an enduring joint Swift-Spitzer legacy sample and provide the definitive resource with which to examine all aspects of the GRB/galaxy connection for years and possibly decades to come.

A molecular gas-rich GRB host galaxy at the peak of cosmic star formation

NASA Astrophysics Data System (ADS)

Arabsalmani, M.; Le Floc'h, E.; Dannerbauer, H.; Feruglio, C.; Daddi, E.; Ciesla, L.; Charmandaris, V.; Japelj, J.; Vergani, S. D.; Duc, P.-A.; Basa, S.; Bournaud, F.; Elbaz, D.

2018-05-01

We report the detection of the CO(3-2) emission line from the host galaxy of gamma-ray burst (GRB) 080207 at z = 2.086. This is the first detection of molecular gas in emission from a GRB host galaxy beyond redshift 1. We find this galaxy to be rich in molecular gas with a mass of 1.1 × 10^{11} M_{{\\odot }} assuming αCO = 4.36 M_{{\\odot }} (K km s^{-1} pc^2)^{-1}. The molecular gas mass fraction of the galaxy is ˜0.5, typical of star-forming galaxies (SFGs) with similar stellar masses and redshifts. With an SFR_{FIR} of 260 M_{{\\odot }} yr^{-1}, we measure a molecular gas depletion time-scale of 0.43 Gyr, near the peak of the depletion time-scale distribution of SFGs at similar redshifts. Our findings are therefore in contradiction with the proposed molecular gas deficiency in GRB host galaxies. We argue that the reported molecular gas deficiency for GRB hosts could be the artefact of improper comparisons or neglecting the effect of the typical low metallicities of GRB hosts on the CO-to-molecular-gas conversion factor. We also compare the kinematics of the CO(3-2) emission line to that of the H α emission line from the host galaxy. We find the H α emission to have contributions from two separate components, a narrow and a broad one. The narrow component matches the CO emission well in velocity space. The broad component, with a full width at half-maximum of ˜1100 km s^{-1}, is separated by +390 km s^{-1} in velocity space from the narrow component. We speculate this broad component to be associated with a powerful outflow in the host galaxy or in an interacting system.

Galaxy Clusters in the Line of Sight to Background Quasars. III. Multi-object Spectroscopy

NASA Astrophysics Data System (ADS)

Andrews, H.; Barrientos, L. F.; López, S.; Lira, P.; Padilla, N.; Gilbank, D. G.; Lacerna, I.; Maureira, M. J.; Ellingson, E.; Gladders, M. D.; Yee, H. K. C.

2013-09-01

We present Gemini/GMOS-S multi-object spectroscopy of 31 galaxy cluster candidates at redshifts between 0.2 and 1.0 and centered on QSO sight lines taken from López et al. The targets were selected based on the presence of an intervening Mg II absorption system at a similar redshift to that of a galaxy cluster candidate lying at a projected distance <2 h_{71}^{-1} Mpc from the QSO sight line (a "photometric hit"). The absorption systems span rest-frame equivalent widths between 0.015 and 2.028 Å. Our aim was three-fold: (1) to identify the absorbing galaxies and determine their impact parameters, (2) to confirm the galaxy cluster candidates in the vicinity of each quasar sightline, and (3) to determine whether the absorbing galaxies reside in galaxy clusters. In this way, we are able to characterize the absorption systems associated with cluster members. Our main findings are as follows. (1) We identified 10 out of 24 absorbing galaxies with redshifts between 0.2509 <= z gal <= 1.0955, up to an impact parameter of 142\\ h_{71}^{-1} kpc and a maximum velocity difference of 280 km s-1. (2) We spectroscopically confirmed 20 out of 31 cluster/group candidates, with most of the confirmed clusters/groups at z < 0.7. This relatively low efficiency results from the fact that we centered our observations on the QSO location, and thus occasionally some of the cluster centers were outside the instrument field of view. (3) Following from the results above, we spectroscopically confirmed of 10 out of 14 photometric hits within ~650 km s-1 from galaxy clusters/groups, in addition to two new ones related to galaxy group environments. These numbers imply efficiencies of 71% in finding such systems with MOS spectroscopy. This is a remarkable result since we defined a photometric hit as those cluster-absorber pairs having a redshift difference Δz = 0.1. The general population of our confirmed absorbing galaxies have luminosities L_{B} \\sim L_{B}^{\\ast } and mean rest

Accreting SMBH in the COSMOS field: the connection to their host galaxies .

NASA Astrophysics Data System (ADS)

Merloni, A.; Bongiorno, A.

Using the rich multi-band photometry in the COSMOS field we explore the host galaxy properties of a large, complete, sample of X-ray and spectroscopically selected AGN. Based on a two-components fit to their Spectral Energy Distribution (SED) we derive rest-frame magnitudes, colours, stellar masses and star formation rates up to z˜ 3. The probability for a galaxy to host a black hole growing at any given specific accretion rate (the ratio of X-ray luminosity to the host stellar mass) is independent of the galaxy mass and follows a power-law distribution in L_X/M. By looking at the normalisation of such a probability distribution, we show how the incidence of AGN increases with redshift as rapidly as (1+z)4.2, in close resemblance with the overall evolution of the specific star formation rate. Although AGN activity and star formation appear to have a common triggering mechanism, we do not find any 'smoking gun' signalling powerful AGN influence on the global properties of their host galaxies.

Hubble Space Telescope Images and Spectra of Objects Around an Optically Violent Variable QSO

NASA Astrophysics Data System (ADS)

Burbidge, E. M.; Beaver, E. A.; Cohen, R. D.; Hamann, F.; Junkkarinen, V. T.; Lyons, R. W.; Zuo, L.

1995-12-01

The Arecibo Occultation radio source AO 0235+164 is a rapidly and violently variable QSO with ze = 0.94. It was originally designated as a BL Lac object since no emission lines were detected in its spectrum; two absorption redshifts at 0.524 and 0.851 were measured some years before weak emission lines at z = 0.94 were detected by Cohen et al. (ApJ,318,577,1987). A point-like companion (Smith et al., ApJ,218,611,1977) was found 2 arc sec south with an emission line redshift at 0.524. It was designated object A by Yanny et al. (ApJ,338,735,1989). This object has sometimes been called a ``normal'' galaxy, presumably giving rise to the absorption at 0.524 in the QSO. Recent observations of the surrounding field, using the post-repair WFPC 2 on the Hubble Space Telescope, have been analyzed and the nature of the companion object 2 arc sec south, and of a second companion 1.3 arc sec east of AO, have been studied. Spectra of companion object A have been obtained with the Faint Object Spectrograph with gratings G160L and G270H, and 1.0 arc sec aperture, and these show that it is an AGN or QSO with BAL-type broad absorption lines shortward of CIVlambda 1549, SiIVlambda 1397, and NVlambda 1240, also broad CIII]lambda 1909 emission. The second object, A1, 1.3 arc sec east of the QSO, originally identified by Yanny et al. (1989) and shown to have [0II]lambda 3727 at z=0.524, is slightly extended. The physical properties and nature of this remarkable configuration will be discussed. This research has been supported in part by NASA NAS5-29293 and NAG5-1630.

Spatially resolved analysis of superluminous supernovae PTF 11hrq and PTF 12dam host galaxies

NASA Astrophysics Data System (ADS)

Cikota, Aleksandar; De Cia, Annalisa; Schulze, Steve; Vreeswijk, Paul M.; Leloudas, Giorgos; Gal-Yam, Avishay; Perley, Daniel A.; Cikota, Stefan; Kim, Sam; Patat, Ferdinando; Lunnan, Ragnhild; Quimby, Robert; Yaron, Ofer; Yan, Lin; Mazzali, Paolo A.

2017-08-01

Superluminous supernovae (SLSNe) are the most luminous supernovae in the Universe. They are found in extreme star-forming galaxies and are probably connected with the death of massive stars. One hallmark of very massive progenitors would be a tendency to explode in very dense, UV-bright and blue regions. In this paper, we investigate the resolved host galaxy properties of two nearby hydrogen-poor SLSNe, PTF 11hrq and PTF 12dam. For both galaxies Hubble Space Telescope multifilter images were obtained. Additionally, we perform integral field spectroscopy of the host galaxy of PTF 11hrq using the Very Large Telescope Multi Unit Spectroscopic Explorer (VLT/MUSE), and investigate the line strength, metallicity and kinematics. Neither PTF 11hrq nor PTF 12dam occurred in the bluest part of their host galaxies, although both galaxies have overall blue UV-to-optical colours. The MUSE data reveal a bright starbursting region in the host of PTF 11hrq, although far from the SN location. The SN exploded close to a region with disturbed kinematics, bluer colour, stronger [O III] and lower metallicity. The host galaxy is likely interacting with a companion. PTF 12dam occurred in one of the brightest pixels, in a starbursting galaxy with a complex morphology and a tidal tail, where interaction is also very likely. We speculate that SLSN explosions may originate from stars generated during star formation episodes triggered by interaction. High-resolution imaging and integral field spectroscopy are fundamental for a better understanding of SLSNe explosion sites and how star formation varies across their host galaxies.

THE HOST GALAXY PROPERTIES OF VARIABILITY SELECTED AGN IN THE PAN-STARRS1 MEDIUM DEEP SURVEY

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

Heinis, S.; Gezari, S.; Kumar, S.

2016-07-20

We study the properties of 975 active galactic nuclei (AGNs) selected by variability in the Pan-STARRS1 Medium deep Survey. Using complementary multi-wavelength data from the ultraviolet to the far-infrared, we use spectral energy distribution fitting to determine the AGN and host properties at z < 1 and compare to a well-matched control sample. We confirm the trend previously observed: that the variability amplitude decreases with AGN luminosity, but we also observe that the slope of this relation steepens with wavelength, resulting in a “redder when brighter” trend at low luminosities. Our results show that AGNs are hosted by more massivemore » hosts than control sample galaxies, while the rest frame dust-corrected NUV r color distribution of AGN hosts is similar to control galaxies. We find a positive correlation between the AGN luminosity and star formation rate (SFR), independent of redshift. AGN hosts populate the entire range of SFRs within and outside of the Main Sequence of star-forming galaxies. Comparing the distribution of AGN hosts and control galaxies, we show that AGN hosts are less likely to be hosted by quiescent galaxies and more likely to be hosted by Main Sequence or starburst galaxies.« less

XMM-Newton reveals a Seyfert-like X-ray spectrum in the z = 3.6 QSO B1422+231

NASA Astrophysics Data System (ADS)

Dadina, M.; Vignali, C.; Cappi, M.; Lanzuisi, G.; Ponti, G.; De Marco, B.; Chartas, G.; Giustini, M.

2016-08-01

Context. Matter flows from the central regions of quasi-stellar objects (QSOs) during their active phases are probably responsible for the properties of the super-massive black holes and those of the bulges of host galaxies. To understand how this mechanism works, we need to characterize the geometry and the physical state of the accreting matter at cosmological redshifts, when QSO activity is at its peak. Aims: We aim to use X-ray data to probe the matter inflow at the very center of a QSO at z = 3.62. While complex absorption, the iron K emission line, reflection hump, and high-energy cutoff are known to be almost ubiquitous in nearby active galactic nuclei (AGN), only a few distant objects are known to exhibit some of them. Methods: The few high-quality spectra of distant QSO were collected by adding sparse pointings of single objects obtained during X-ray monitoring campaigns. This could have introduced spurious spectral features due to source variability and/or microlensing. To avoid such problems, we decided to collect a single-epoch and high-quality X-ray spectrum of a distant AGN. We thus picked up the z = 3.62 QSO B1422+231, whose flux, enhanced by gravitationally lensing, is proven to be among the brightest lensed QSOs in X-rays (F2-10 keV ~ 10-12 erg s-1 cm-2). Results: The X-ray spectrum of B1422+231 is found to be very similar to the one of a typical nearby Seyfert galaxy. Neutral absorption is clearly detected (NH ~ 5 × 1021 cm-2 at the redshift of the source), while a strong absorption edge is measured at E ~ 7.5 keV with an optical depth of τ ~ 0.14. We also find hints of the FeKα line in emission at E ~ 6.4 keV line (EW ≲ 70 eV), and a hump is detected in the E ~ 15 - 20 keV energy band (rest frame) in excess of what is predicted by a simple absorbed power-law. Conclusions: The spectrum can best be modeled with two rather complex models; one assumes ionized and partially covering matter along the line of sight, the other is characterized by a

The role of host galaxy for the environmental dependence of active nuclei in local galaxies

NASA Astrophysics Data System (ADS)

Davies, Richard I.; Hicks, E. K. S.; Erwin, P.; Burtscher, L.; Contursi, A.; Genzel, R.; Janssen, A.; Koss, M.; Lin, M.-Y.; Lutz, D.; Maciejewski, W.; Müller-Sánchez, F.; Orban de Xivry, G.; Ricci, C.; Riffel, R.; Riffel, R. A.; Rosario, D.; Schartmann, M.; Schnorr-Müller, A.; Shimizu, T.; Sternberg, A.; Sturm, E.; Storchi-Bergmann, T.; Tacconi, L.; Veilleux, S.

2017-04-01

We discuss the environment of local hard X-ray selected active galaxies, with reference to two independent group catalogues. We find that the fraction of these AGN in S0 host galaxies decreases strongly as a function of galaxy group size (halo mass) - which contrasts with the increasing fraction of galaxies of S0 type in denser environments. However, there is no evidence for an environmental dependence of AGN in spiral galaxies. Because most AGN are found in spiral galaxies, this dilutes the signature of environmental dependence for the population as a whole. We argue that the differing results for AGN in disc-dominated and bulge-dominated galaxies are related to the source of the gas fuelling the AGN, and so may also impact the luminosity function, duty cycle and obscuration. We find that there is a significant difference in the luminosity function for AGN in spiral and S0 galaxies, and tentative evidence for some difference in the fraction of obscured AGN.

Galaxies and Their Host Dark Matter Structures

NASA Astrophysics Data System (ADS)

Hahn, ChangHoon

Through their connection with dark matter structures, galaxies act as tracers of the underlying matter distribution in the Universe. Their observed spatial distribution allows us to precisely measure large scale structure and effectively test cosmological models that explain the content, geometry, and history of the Universe. Current observations from galaxy surveys such as the Baryon Oscillation Spectroscopic Survey have already probed vast cosmic volumes with millions of galaxies and ushered in an era of precision cosmology. The next surveys will probe over an order of magnitude more. With this unprecedented statistical power, the bottleneck of scientific discovery is in the methodology. In this dissertation, I address major methodological challenges in constraining cosmology with the large-scale distribution of galaxies. I develop a robust framework for treating systematic effects, which significantly bias galaxy clustering measurements. I apply new innovative approaches to probabilistic parameter inference that challenge and test the in- correct assumptions of the standard approach. Furthermore, I use precise predictions of structure formation from cosmology and observations of galaxies during the last eight billion years to develop detailed models of how galaxies are impacted by their host dark matter structures. These models provide key insight into the galaxy-halo connection, which bridges the gap between cosmology theory and observations. They also answer crucial questions of how galaxies form and evolve. The developments in this dissertation will help unlock the full potential of future observations and allow us to precisely test cosmological models, General Relativity and modified gravity scenarios, and even particle physics theory beyond the Standard Model.

DUST-CORRECTED COLORS REVEAL BIMODALITY IN THE HOST-GALAXY COLORS OF ACTIVE GALACTIC NUCLEI AT z {approx} 1

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

Cardamone, Carolin N.; Megan Urry, C.; Brammer, Gabriel

2010-09-20

Using new, highly accurate photometric redshifts from the MUSYC medium-band survey in the Extended Chandra Deep Field-South (ECDF-S), we fit synthetic stellar population models to compare active galactic nucleus (AGN) host galaxies to inactive galaxies at 0.8 {<=} z {<=} 1.2. We find that AGN host galaxies are predominantly massive galaxies on the red sequence and in the green valley of the color-mass diagram. Because both passive and dusty galaxies can appear red in optical colors, we use rest-frame near-infrared colors to separate passively evolving stellar populations from galaxies that are reddened by dust. As with the overall galaxy population,more » {approx}25% of the 'red' AGN host galaxies and {approx}75% of the 'green' AGN host galaxies have colors consistent with young stellar populations reddened by dust. The dust-corrected rest-frame optical colors are the blue colors of star-forming galaxies, which imply that these AGN hosts are not passively aging to the red sequence. At z {approx} 1, AGN activity is roughly evenly split between two modes of black hole growth: the first in passively evolving host galaxies, which may be heating up the galaxy's gas and preventing future episodes of star formation, and the second in dust-reddened young galaxies, which may be ionizing the galaxy's interstellar medium and shutting down star formation.« less

UV-luminous, star-forming hosts of z ˜ 2 reddened quasars in the Dark Energy Survey

NASA Astrophysics Data System (ADS)

Wethers, C. F.; Banerji, M.; Hewett, P. C.; Lemon, C. A.; McMahon, R. G.; Reed, S. L.; Shen, Y.; Abdalla, F. B.; Benoit-Lévy, A.; Brooks, D.; Buckley-Geer, E.; Capozzi, D.; Carnero Rosell, A.; CarrascoKind, M.; Carretero, J.; Cunha, C. E.; D'Andrea, C. B.; da Costa, L. N.; DePoy, D. L.; Desai, S.; Doel, P.; Flaugher, B.; Fosalba, P.; Frieman, J.; García-Bellido, J.; Gerdes, D. W.; Gruen, D.; Gruendl, R. A.; Gschwend, J.; Gutierrez, G.; Honscheid, K.; James, D. J.; Jeltema, T.; Kuehn, K.; Kuhlmann, S.; Kuropatkin, N.; Lima, M.; Maia, M. A. G.; Marshall, J. L.; Martini, P.; Menanteau, F.; Miquel, R.; Nichol, R. C.; Nord, B.; Plazas, A. A.; Romer, A. K.; Sanchez, E.; Scarpine, V.; Schindler, R.; Schubnell, M.; Sevilla-Noarbe, I.; Smith, M.; Smith, R. C.; Soares-Santos, M.; Sobreira, F.; Suchyta, E.; Tarle, G.; Walker, A. R.

2018-04-01

We present the first rest-frame UV population study of 17 heavily reddened, high-luminosity [E(B - V)QSO ≳ 0.5; Lbol > 1046 erg s-1] broad-line quasars at 1.5 < z < 2.7. We combine the first year of deep, optical, ground-based observations from the Dark Energy Survey (DES) with the near-infrared VISTA Hemisphere Survey and UKIDSS Large Area Survey data, from which the reddened quasars were initially identified. We demonstrate that the significant dust reddening towards the quasar in our sample allows host galaxy emission to be detected at the rest-frame UV wavelengths probed by the DES photometry. By exploiting this reddening effect, we disentangle the quasar emission from that of the host galaxy via spectral energy distribution fitting. We find evidence for a relatively unobscured, star-forming host galaxy in at least 10 quasars, with a further three quasars exhibiting emission consistent with either star formation or scattered light. From the rest-frame UV emission, we derive instantaneous, dust-corrected star formation rates (SFRs) in the range 25 < SFRUV < 365 M⊙ yr-1, with an average SFRUV = 130 ± 95 M⊙ yr-1. We find a broad correlation between SFRUV and the bolometric quasar luminosity. Overall, our results show evidence for coeval star formation and black hole accretion occurring in luminous, reddened quasars at the peak epoch of galaxy formation.

Discovery of a Damped Lyα Absorber at z = 3.3 along a Galaxy Sight-line in the SSA22 Field

NASA Astrophysics Data System (ADS)

Mawatari, K.; Inoue, A. K.; Kousai, K.; Hayashino, T.; Cooke, R.; Prochaska, J. X.; Yamada, T.; Matsuda, Y.

2016-02-01

Using galaxies as background light sources to map the Lyα absorption lines is a novel approach to study Damped Lyα Absorbers (DLAs). We report the discovery of an intervening z = 3.335 ± 0.007 DLA along a galaxy sight-line identified among 80 Lyman Break Galaxy (LBG) spectra obtained with our Very Large Telescope/Visible Multi-Object Spectrograph survey in the SSA22 field. The measured DLA neutral hydrogen (H I) column density is log(NH I/cm-2) = 21.68 ± 0.17. The DLA covering fraction over the extended background LBG is >70% (2σ), yielding a conservative constraint on the DLA area of ≳1 kpc2. Our search for a counterpart galaxy hosting this DLA concludes that there is no counterpart galaxy with star formation rate larger than a few M⊙ yr-1, ruling out an unobscured violent star formation in the DLA gas cloud. We also rule out the possibility that the host galaxy of the DLA is a passive galaxy with M* ≳ 5 × 1010M⊙ or a heavily dust-obscured galaxy with E(B - V) ≳ 2. The DLA may coincide with a large-scale overdensity of the spectroscopic LBGs. The occurrence rate of the DLA is compatible with that of DLAs found in QSO sight-lines.

Do Nuclear Star Clusters and Supermassive Black Holes Follow the Same Host-Galaxy Correlations?

DOE PAGES

Erwin, Peter; Gadotti, Dimitri Alexei

2012-01-01

Smore » tudies have suggested that there is a strong correlation between the masses of nuclear star clusters (NCs) and their host galaxies, a correlation which is said to be an extension of the well-known correlations between supermassive black holes (MBHs) and their host galaxies. But careful analysis of disk galaxies—including 2D bulge/disk/bar decompositions—shows that while MBHs correlate with the stellar mass of the bulge component of galaxies, the masses of NCs correlate much better with the total galaxy stellar mass. In addition, the mass ratio M NC / M ⋆ ,  tot for NCs in spirals (at least those with Hubble types c and later) is typically an order of magnitude smaller than the mass ratio M BH / M ⋆ ,  bul of MBHs. The absence of a universal “central massive object” correlation argues against common formation and growth mechanisms for both MBHs and NCs. We also discuss evidence for a break in the NC-host galaxy correlation, galaxies with Hubble types earlier than bc appear to host systematically more massive NCs than do types c and later.« less

GALAXY ZOO: THE FUNDAMENTALLY DIFFERENT CO-EVOLUTION OF SUPERMASSIVE BLACK HOLES AND THEIR EARLY- AND LATE-TYPE HOST GALAXIES

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

Schawinski, Kevin; Urry, C. Megan; Virani, Shanil

We use data from the Sloan Digital Sky Survey and visual classifications of morphology from the Galaxy Zoo project to study black hole growth in the nearby universe (z < 0.05) and to break down the active galactic nucleus (AGN) host galaxy population by color, stellar mass, and morphology. We find that the black hole growth at luminosities L[O{sub III}]>10{sup 40} erg s{sup -1} in early- and late-type galaxies is fundamentally different. AGN host galaxies as a population have a broad range of stellar masses (10{sup 10}-10{sup 11} M{sub sun}), reside in the green valley of the color-mass diagram andmore » their central black holes have median masses around 10{sup 6.5} M{sub sun}. However, by comparing early- and late-type AGN host galaxies to their non-active counterparts, we find several key differences: in early-type galaxies, it is preferentially the galaxies with the least massive black holes that are growing, while in late-type galaxies, it is preferentially the most massive black holes that are growing. The duty cycle of AGNs in early-type galaxies is strongly peaked in the green valley below the low-mass end (10{sup 10} M{sub sun}) of the red sequence at stellar masses where there is a steady supply of blue cloud progenitors. The duty cycle of AGNs in late-type galaxies on the other hand peaks in massive (10{sup 11} M{sub sun}) green and red late-types which generally do not have a corresponding blue cloud population of similar mass. At high-Eddington ratios (L/L{sub Edd}>0.1), the only population with a substantial fraction of AGNs are the low-mass green valley early-type galaxies. Finally, the Milky Way likely resides in the 'sweet spot' on the color-mass diagram where the AGN duty cycle of late-type galaxies is highest. We discuss the implications of these results for our understanding of the role of AGNs in the evolution of galaxies.« less

AGN host galaxy mass function in COSMOS. Is AGN feedback responsible for the mass-quenching of galaxies?

NASA Astrophysics Data System (ADS)

Bongiorno, A.; Schulze, A.; Merloni, A.; Zamorani, G.; Ilbert, O.; La Franca, F.; Peng, Y.; Piconcelli, E.; Mainieri, V.; Silverman, J. D.; Brusa, M.; Fiore, F.; Salvato, M.; Scoville, N.

2016-04-01

We investigate the role of supermassive black holes in the global context of galaxy evolution by measuring the host galaxy stellar mass function (HGMF) and the specific accretion rate, that is, λSAR, the distribution function (SARDF), up to z ~ 2.5 with ~1000 X-ray selected AGN from XMM-COSMOS. Using a maximum likelihood approach, we jointly fit the stellar mass function and specific accretion rate distribution function, with the X-ray luminosity function as an additional constraint. Our best-fit model characterizes the SARDF as a double power-law with mass-dependent but redshift-independent break, whose low λSAR slope flattens with increasing redshift while the normalization increases. This implies that for a given stellar mass, higher λSAR objects have a peak in their space density at earlier epoch than the lower λSAR objects, following and mimicking the well-known AGN cosmic downsizing as observed in the AGN luminosity function. The mass function of active galaxies is described by a Schechter function with an almost constant M∗⋆ and a low-mass slope α that flattens with redshift. Compared to the stellar mass function, we find that the HGMF has a similar shape and that up to log (M⋆/M⊙) ~ 11.5, the ratio of AGN host galaxies to star-forming galaxies is basically constant (~10%). Finally, the comparison of the AGN HGMF for different luminosity and specific accretion rate subclasses with a previously published phenomenological model prediction for the "transient" population, which are galaxies in the process of being mass-quenched, reveals that low-luminosity AGN do not appear to be able to contribute significantly to the quenching and that at least at high masses, that is, M⋆ > 1010.7 M⊙, feedback from luminous AGN (log Lbol ≳ 46 [erg/s]) may be responsible for the quenching of star formation in the host galaxy.

The Host Galaxies Of UV-selected AGNs At z 2-3

NASA Astrophysics Data System (ADS)

Hainline, Kevin; Shapley, A.; Greene, J.; Steidel, C.

2012-01-01

An important goal for studies of galaxy formation consists of tracing a direct evolutionary connection between the growth of supermassive black holes powering active galactic nuclei (AGNs) and the build-up of stellar mass in their host galaxies. In the local universe, AGNs are preferentially found in bulge-dominated galaxies, but the AGN demographics at earlier epochs are not as well understood. We present a rest-frame UV composite spectrum for a sample of 33 z 2-3 AGNs drawn from the UV-selected Lyman Break Galaxy (LBG) survey. This spectrum shows many emission and absorption features, such as HI Lyman-alpha, NV 1240, NIV] 1483, 1486, CIV 1548, 1550, HeII 1640, and CIII] 1907, 1909. Redshifted SiIV 1394 absorption provides evidence for outflowing high-ionization gas in these objects at speeds of 103 km/s. Finally, using optical, near-IR, and mid-IR photometry, which cover the rest-frame UV to near-IR portions of the galaxies' spectral energy distributions, we perform stellar population synthesis modeling of the sample. Based on these results, we explore the relationship in the host galaxy between AGN activity, maturity of the stellar population, and regulation of star formation.

The Luminosity Function of the Host Galaxies of QSOs and BL Lac Objects

NASA Astrophysics Data System (ADS)

Carangelo, Nicoletta; Falomo, Renato; Treves, Aldo

A clear insight of the galaxies hosting active galactic nuclei is of fundamental importance for understanding the processes of galaxies and nuclei formation and their cosmic evolution. A good characterization of the host galaxies properties requires images of excellent quality in order to disentangle the light of the galaxy from that of the bright nucleus. To this aim HST has provided a major improvement of data on QSOs (Disney et al. 1995; Bahcall et al. 1996,1997; Boyce et al. 1998; McLure et al. 1999; Hamilton et al. 2000; Kukula et al. 2001) and BL Lacs (Scarpa et al. 2000, Urry et al. 2000).

GRB host galaxies with VLT/X-Shooter: properties at 0.8 < z < 1.3

NASA Astrophysics Data System (ADS)

Piranomonte, S.; Japelj, J.; Vergani, S. D.; Savaglio, S.; Palazzi, E.; Covino, S.; Flores, H.; Goldoni, P.; Cupani, G.; Krühler, T.; Mannucci, F.; Onori, F.; Rossi, A.; D'Elia, V.; Pian, E.; D'Avanzo, P.; Gomboc, A.; Hammer, F.; Randich, S.; Fiore, F.; Stella, L.; Tagliaferri, G.

2015-10-01

Long gamma-ray bursts (LGRBs) are associated with the death of massive stars. Their host galaxies therefore represent a unique class of objects tracing star formation across the observable Universe. Indeed, recently accumulated evidence shows that GRB hosts do not differ substantially from general population of galaxies at high (z > 2) redshifts. However, it has been long recognized that the properties of z < 1.5 hosts, compared to general star-forming population, are unusual. To better understand the reasons for the supposed difference in LGRB hosts properties at z < 1.5, we obtained Very Large Telescope (VLT)/X-Shooter spectra of six hosts lying in the redshift range of 0.8 < z < 1.3. Some of these hosts have been observed before, yet we still lack well-constrained information on their characteristics such as metallicity, dust extinction and star formation rate (SFR). We search for emission lines in the VLT/X-Shooter spectra of the hosts and measure their fluxes. We perform a detailed analysis, estimating host average extinction, SFRs, metallicities and electron densities where possible. Measured quantities of our hosts are compared to a larger sample of previously observed GRB hosts at z < 2. SFRs and metallicities are measured for all the hosts analysed in this paper and metallicities are well determined for four hosts. The mass-metallicity relation, the fundamental metallicity relation and SFRs derived from our hosts occupy similar parameter space as other host galaxies investigated so far at the same redshift. We therefore conclude that GRB hosts in our sample support the found discrepancy between the properties of low-redshift GRB hosts and the general population of star-forming galaxies.

Resolving the host galaxy of a distant blazar with LBT/LUCI 1 + ARGOS

NASA Astrophysics Data System (ADS)

Farina, E. P.; Georgiev, I. Y.; Decarli, R.; Terzić, T.; Busoni, L.; Gässler, W.; Mazzoni, T.; Borelli, J.; Rosensteiner, M.; Ziegleder, J.; Bonaglia, M.; Rabien, S.; Buschkamp, P.; Orban de Xivry, G.; Rahmer, G.; Kulas, M.; Peter, D.

2018-05-01

BL Lac objects emitting in the very high energy (VHE) regime are unique tools to peer into the properties of the extragalactic background light (EBL). However, due to the typical absence of features in their spectra, the determination of their redshifts has proven challenging. In this work, we exploit the superb spatial resolution delivered by the new Advanced Rayleigh guided Ground layer adaptive Optics System (ARGOS) at the Large Binocular Telescope to detect the host galaxy of HESS J1943+213, a VHE emitting BL Lac shining through the Galaxy. Deep H-band imaging collected during the ARGOS commissioning allowed us to separate the contribution of the nuclear emission and to unveil the properties of the host galaxy with unprecedented detail. The host galaxy is well fitted by a Sérsic profile with index of n ˜ 2 and total magnitude of HHost ˜ 16.15 mag. Under the assumption that BL Lac host galaxies are standard candles, we infer a redshift of z ˜ 0.21. In the framework of the current model for the EBL, this value is in agreement with the observed dimming of the VHE spectrum due to the annihilation of energetic photons on the EBL

A low-luminosity type-1 QSO sample . IV. Molecular gas contents and conditions of star formation in three nearby Seyfert galaxies

NASA Astrophysics Data System (ADS)

Moser, Lydia; Krips, Melanie; Busch, Gerold; Scharwächter, Julia; König, Sabine; Eckart, Andreas; Smajić, Semir; García-Marin, Macarena; Valencia-S., Mónica; Fischer, Sebastian; Dierkes, Jens

2016-03-01

We present a pilot study of ~3'' resolution observations of low CO transitions with the Submillimeter Array in three nearby Seyfert galaxies, which are part of the low-luminosity quasi-stellar object (LLQSOs) sample consisting of 99 nearby (z = 0.06) type-1 active galactic nuclei (AGN) taken from the Hamburg/ESO quasi-stellar object (QSO) survey. Two sources were observed in 12CO(2-1) and 13CO(2-1) and the third in 12CO(3-2) and HCO+(4-3). None of the sources is detected in continuum emission. More than 80% of the 12CO detected molecular gas is concentrated within a diameter (FWHM) < 1.8 kpc. 13CO is tentatively detected, while HCO+ emission could not be detected. All three objects show indications of a kinematically decoupled central unresolved molecular gas component. The molecular gas masses of the three galaxies are in the range Mmol = (0.7-8.7) × 109M⊙. We give lower limits for the dynamical masses of Mdyn> 1.5 × 109M⊙ and for the dust masses of Mdust> 1.6 × 106M⊙. The R21 = 12CO/13CO(2-1) line luminosity ratios show Galactic values of R21 ~ 5-7 in the outskirts and R21 ≳ 20 in the central region, similar to starbursts and (ultra)luminous infrared galaxies ((U)LIRGs; I.e. LIRGs and ULIRGs), implying higher temperatures and stronger turbulence. All three sources show indications of 12CO(2-1)/12CO(1-0) ratios of ~0.5, suggesting a cold or diffuse gas phase. Strikingly, the 12CO(3-2)/(1-0) ratio of ~1 also indicates a higher excited phase. Since these galaxies have high infrared luminosities of LIR ≥ 1011L⊙ and seem to contain a circumnuclear starburst with minimum surface densities of gas and star formation rate (SFR) around Σmol = 50-550 M⊙pc-2 and ΣSFR = 1.1-3.1 M⊙ kpc-2 yr-1, we conclude that the interstellar medium in the centers of these LIRG Seyferts is strongly affected by violent star formation and better described by the ULIRG mass conversion factor.

Using diffusion k-means for simple stellar population modeling of low S/N quasar host galaxy spectra

NASA Astrophysics Data System (ADS)

Mosby, Gregory; Tremonti, Christina A.; Hooper, Eric; Wolf, Marsha J.; Sheinis, Andrew; Richards, Joseph

2016-01-01

Quasar host galaxies (QHGs) represent a unique stage in galaxy evolution that can provide a glimpse into the relationship between an active supermassive black hole (SMBH) and its host galaxy. However, observing the hosts of high luminosity, unobscured quasars in the optical is complicated by the large ratio of quasar to host galaxy light. One strategy in optical spectroscopy is to use offset longslit observations of the host galaxy. This method allows the centers of QHGs to be analyzed apart from other regions of their host galaxies. But light from the accreting black hole's point spread function still enters the host galaxy observations, and where the contrast between the host and intervening quasar light is favorable, the host galaxy is faint, producing low signal-to-noise (S/N) data. This stymies traditional stellar population methods that might rely on high S/N features in galaxy spectra to recover key galaxy properties like its star formation history (SFH). In response to this challenge, we have developed a method of stellar population modeling using diffusion k-means (DFK) that can recover SFHs from rest frame optical data with S/N ~ 5 Å^-1. Specifically, we use DFK to cultivate a reduced stellar population basis set. This DFK basis set of four broad age bins is able to recover a range of SFHs. With an analytic description of the seeing, we can use this DFK basis set to simultaneously model the SFHs and the intervening quasar light of QHGs as well. We compare the results of this method with previous techniques using synthetic data and find that our new method has a clear advantage in recovering SFHs from QHGs. On average, the DFK basis set is just as accurate and decisively more precise. This new technique could be used to analyze other low S/N galaxy spectra like those from higher redshift or integral field spectroscopy surveys.This material is based upon work supported by the National Science Foundation under grant no. DGE -0718123 and the Advanced

HOST GALAXY PROPERTIES OF THE SWIFT BAT ULTRA HARD X-RAY SELECTED ACTIVE GALACTIC NUCLEUS

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

Koss, Michael; Mushotzky, Richard; Veilleux, Sylvain

We have assembled the largest sample of ultra hard X-ray selected (14-195 keV) active galactic nucleus (AGN) with host galaxy optical data to date, with 185 nearby (z < 0.05), moderate luminosity AGNs from the Swift BAT sample. The BAT AGN host galaxies have intermediate optical colors (u - r and g - r) that are bluer than a comparison sample of inactive galaxies and optically selected AGNs from the Sloan Digital Sky Survey (SDSS) which are chosen to have the same stellar mass. Based on morphological classifications from the RC3 and the Galaxy Zoo, the bluer colors of BATmore » AGNs are mainly due to a higher fraction of mergers and massive spirals than in the comparison samples. BAT AGNs in massive galaxies (log M{sub *} >10.5) have a 5-10 times higher rate of spiral morphologies than in SDSS AGNs or inactive galaxies. We also see enhanced far-infrared emission in BAT AGN suggestive of higher levels of star formation compared to the comparison samples. BAT AGNs are preferentially found in the most massive host galaxies with high concentration indexes indicative of large bulge-to-disk ratios and large supermassive black holes. The narrow-line (NL) BAT AGNs have similar intrinsic luminosities as the SDSS NL Seyferts based on measurements of [O III] {lambda}5007. There is also a correlation between the stellar mass and X-ray emission. The BAT AGNs in mergers have bluer colors and greater ultra hard X-ray emission compared to the BAT sample as a whole. In agreement with the unified model of AGNs, and the relatively unbiased nature of the BAT sources, the host galaxy colors and morphologies are independent of measures of obscuration such as X-ray column density or Seyfert type. The high fraction of massive spiral galaxies and galaxy mergers in BAT AGNs suggest that host galaxy morphology is related to the activation and fueling of local AGN.« less

A statistical study of H i gas in nearby narrow-line AGN-hosting galaxies

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

Zhu, Yi-Nan; Wu, Hong, E-mail: zyn@bao.ac.cn, E-mail: hwu@bao.ac.cn

As a quenching mechanism, active galactic nucleus (AGN) feedback could suppress on going star formation in host galaxies. On the basis of a sample of galaxies selected from the Arecibo Legacy Fast ALFA (ALFALFA) H i survey, the dependence of the H i mass (M{sub H} {sub i}), stellar mass (M{sub *}), and H i-to-stellar mass ratio (M{sub H} {sub i}/M{sub *}) on various tracers of AGN activity are presented and analyzed in this paper. Almost all the AGN hostings in this sample are gas-rich galaxies, and there is not any evidence to indicate that the AGN activity could increasemore » or decrease either M{sub H} {sub i} or M{sub H} {sub i}/M{sub *}. The position of the cold neutral gas cannot be fixed accurately based only on available H i data, due to the large beam size of ALFALFA survey. In addition, even though AGN hostings are more easily detected by an H i survey compared with absorption line galaxies, these two types of galaxies show similar star formation history. If an AGN hosting would ultimately evolve into an old red galaxy with low cold gas, then when and how the gas has been exhausted must be solved by future hypotheses and observations.« less

An evolutionary missing link? A modest-mass early-type galaxy hosting an oversized nuclear black hole

NASA Astrophysics Data System (ADS)

van Loon, Jacco Th.; Sansom, Anne E.

2015-11-01

SAGE1C J053634.78-722658.5 is a galaxy at redshift z = 0.14, discovered behind the Large Magellanic Cloud in the Spitzer Space Telescope`Surveying the Agents of Galaxy Evolution' Spectroscopy survey. It has very strong silicate emission at 10 μm but negligible far-IR and UV emission. This makes it a candidate for a bare active galactic nuclei (AGN) source in the IR, perhaps seen pole-on, without significant IR emission from the host galaxy. In this paper we present optical spectra taken with the Southern African Large Telescope to investigate the nature of the underlying host galaxy and its AGN. We find broad H α emission characteristic of an AGN, plus absorption lines associated with a mature stellar population (>9 Gyr), and refine its redshift determination to z = 0.1428 ± 0.0001. There is no evidence for any emission lines associated with star formation. This remarkable object exemplifies the need for separating the emission from any AGN from that of the host galaxy when employing IR diagnostic diagrams. We estimate the black hole mass, MBH = 3.5 ± 0.8 × 108 M⊙, host galaxy mass, M_stars=2.5^{2.5}_{1.2}× 10^{10} M⊙, and accretion luminosity, Lbol(AGN) = 5.3 ± 0.4 × 1045 erg s-1 (≈12 per cent of the Eddington luminosity), and find the AGN to be more prominent than expected for a host galaxy of this modest size. The old age is in tension with the downsizing paradigm in which this galaxy would recently have transformed from a star-forming disc galaxy into an early-type, passively evolving galaxy.

Einstein X-ray observations of QSO's with absorption-line systems

NASA Technical Reports Server (NTRS)

Junkkarinen, V. T.; Marscher, A. P.; Burbidge, E. M.

1982-01-01

The detection of X-ray emission from eight QSO's is reported, plus an upper limit to the X-ray flux from one QSO, using the Einstein X-ray Observatory (HEAO-2). Each object in the sample contains at least one absorption-line system that has been identified in its optical spectrum. The present results are combined with those of other investigators to form a sample of 44 absorption-line QSO's (with 2 sub e greater than 1.2) which have been observed in the X-ray. This sample cannot be distinguished, in terms of X-ray properties, from one which consists of QSO's in which no absorption systems have been identified. These results are consistent with extrinsic models for absorption-line clouds, as well as with current versions of intrinsic models.

Hα Imaging of Nearby Seyfert Host Galaxies

NASA Astrophysics Data System (ADS)

Theios, Rachel L.; Malkan, Matthew A.; Ross, Nathaniel R.

2016-05-01

We used narrowband (Δλ = 70 Å) interference filters with the CCD imaging camera on the Nickel 1.0 m telescope at Lick Observatory to observe 31 nearby (z < 0.03) Seyfert galaxies in the 12 μm active galaxy sample. We obtained pure emission-line images of each galaxy, which reach down to a flux limit of 7.3 × 10-15 erg cm-2 s-1 arcsec-2, and corrected these images for [N II] emission and extinction. We separated the Hα emission line of the “nucleus” (central 100-1000 pc) from that of the host galaxy. The extended Hα emission is expected to be powered by newly formed hot stars, and indeed correlates well with other indicators of current star formation rates (SFRs) in these galaxies: extended 7.7 μm polycyclic aromatic hydrocarbon, total far-infrared, and radio luminosity. Relative to what would be expected from recent star formation, there is a 0.8 dex excess of radio emission in our Seyfert galaxies. The Hα luminosity we measured in the centers of our galaxies is dominated by the active galactic nucleus (AGN), and is linearly correlated with the hard X-ray luminosity. There is, however, an upward offset of 1 dex in this correlation for the Seyfert 1s, because their nuclear Hα emission includes a strong additional contribution from the broad-line region. We found a correlation between SFR and AGN luminosity. In spite of selection effects, we concluded that the absence of bright Seyfert nuclei in galaxies with low SFRs is real, albeit only weakly significant. Finally, we used our measured spatial distributions of Hα emission to determine what these Seyfert galaxies would look like when observed through fixed apertures (e.g., a spectroscopic fiber) at high redshifts. We found that although all of these Seyfert galaxies would be detectable emission-line galaxies at any redshift, most of them would appear to be dominated by (>67%) their H II region emission. Only the most luminous AGNs (log(L Hα /erg s-1) > 41.5) would still be identified as such at z �

Census of the Local Universe (CLU) Hα Galaxy Survey: Characterization of Galaxy Catalogs from Preliminary Fields

NASA Astrophysics Data System (ADS)

Cook, David O.; Kasliwal, Mansi; Van Sistine, Anglea; Kaplan, David; iPTF

2018-01-01

In this talk I introduce the Census of the Local Universe (CLU) galaxy survey. The survey uses 4 wavelength-adjacent, narrowband filters to search for emission-line (Hα) sources across ~3π (26,470 deg2) of the sky and out to distance of 200 Mpc. I will present an analysis of galaxy candidates in 14 preliminary fields (out of 3626) to assess the limits of the survey and the potential for finding new galaxies in the local Universe. We anticipate finding tens-of-thousands of new galaxies in the full ~3π survey. In addition, I present some interesting galaxies found in these fields, which include: newly discovered blue compact dwarfs (e.g., blueberries), 1 new green pea, 1 new QSO, and a known planetary nebula. The majority of the CLU galaxies show properties similar to normal star-forming galaxies; however, the newly discovered blueberries tend to have high star formation rates for their given stellar mass.

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.

Outskirts of Distant Galaxies in Absorption

NASA Astrophysics Data System (ADS)

Chen, Hsiao-Wen

QSO absorption spectroscopy provides a sensitive probe of both the neutral medium and diffuse ionized gas in the distant Universe. It extends 21 cm maps of gaseous structures around low-redshift galaxies both to lower gas column densities and to higher redshifts. Combining galaxy surveys with absorption-line observations of gas around galaxies enables comprehensive studies of baryon cycles in galaxy outskirts over cosmic time. This chapter presents a review of the empirical understanding of the cosmic neutral gas reservoir from studies of damped Lyα absorbers (DLAs). It describes the constraints on the star formation relation and chemical enrichment history in the outskirts of distant galaxies from DLA studies. A brief discussion of available constraints on the ionized circumgalactic gas from studies of lower column density Lyα absorbers and associated ionic absorption transitions is presented at the end.

The Swift Gamma-Ray Burst Host Galaxy Legacy Survey. I. Sample Selection and Redshift Distribution

NASA Technical Reports Server (NTRS)

Perley, D. A.; Kruhler, T.; Schulze, S.; Postigo, A. De Ugarte; Hjorth, J.; Berger, E.; Cenko, S. B.; Chary, R.; Cucchiara, A.; Ellis, R.;

Revealing the Host Galaxy of a Quasar 2175 Å Dust Absorber at z =  2.12

NASA Astrophysics Data System (ADS)

Ma, Jingzhe; Brammer, Gabriel; Ge, Jian; Prochaska, J. Xavier; Lundgren, Britt

2018-04-01

We report the first detection of the host galaxy of a strong 2175 Å dust absorber at z = 2.12 toward the background quasar SDSS J121143.42+083349.7 using Hubble Space Telescope/Wide Field Camera 3 (HST/WFC3) IR F140W direct imaging and G141 grism spectroscopy. The spectroscopically confirmed host galaxy is located at a small impact parameter of ∼5.5 kpc (∼0.″65). The F140W image reveals a disk-like morphology with an effective radius of 2.24 ± 0.08 kpc. The extracted 1D spectrum is dominated by a continuum with weak emission lines ([O III] and [O II]). The [O III]-based unobscured star formation rate (SFR) is 9.4 ± 2.6 M ⊙ yr‑1, assuming an [O III]/Hα ratio of 1. The moderate 4000 Å break (Dn(4000) index ∼1.3) and Balmer absorption lines indicate that the host galaxy contains an evolved stellar population with an estimated stellar mass M * of (3–7) × 1010 M ⊙. The SFR and M * of the host galaxy are comparable to, though slightly lower than, those of typical emission-selected galaxies at z ∼ 2. As inferred from our absorption analysis in Ma et al., the host galaxy is confirmed to be a chemically enriched, evolved, massive, and star-forming disk-like galaxy that is likely in the transition from a blue star-forming galaxy to a red quiescent galaxy.

The Host Galaxy and the Extended Emission-Line Region of the Radio Galaxy 3C 79

NASA Astrophysics Data System (ADS)

Fu, Hai; Stockton, Alan

2008-04-01

We present extensive ground-based spectroscopy and HST imaging of 3C 79, an FR II radio galaxy associated with a luminous extended emission-line region (EELR). Surface brightness modeling of an emission-line-free HST R-band image reveals that the host galaxy is a massive elliptical with a compact companion 0.8'' away and 4 mag fainter. The host galaxy spectrum is best described by an intermediate-age (1.3 Gyr) stellar population (4% by mass), superimposed on a 10 Gyr old population and a power law (αλ = - 1.8); the stellar populations are consistent with supersolar metallicities, with the best fit given by the 2.5 Z⊙ models. We derive a dynamical mass of 4 × 1011 M⊙ within the effective radius from the velocity dispersion. The EELR spectra clearly indicate that the EELR is photoionized by the hidden central engine. Photoionization modeling shows evidence that the gas metallicity in both the EELR and the nuclear narrow-line region is mildly subsolar (0.3-0.7 Z⊙), significantly lower than the supersolar metallicities deduced from typical active galactic nuclei in the Sloan Digital Sky Survey. The more luminous filaments in the EELR exhibit a velocity field consistent with a common disk rotation. Fainter clouds, however, show high approaching velocities that are uncoupled from this apparent disk rotation. The striking similarities between this EELR and the EELRs around steep-spectrum radio-loud quasars provide further evidence for the orientation-dependent unification schemes. The metal-poor gas is almost certainly not native to the massive host galaxy. We suggest that the close companion galaxy could be the tidally stripped bulge of a late-type galaxy that is merging with the host galaxy. The interstellar medium of such a galaxy is probably the source for the low-metallicity gas in 3C 79. Based in part on observations obtained at the Gemini Observatory, which is operated by the Association of Universities for Research in Astronomy, Inc., under a cooperative

UV-luminous, star-forming hosts of z ~ 2 reddened quasars in the Dark Energy Survey

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

Wethers, C. F.; Banerji, M.; Hewett, P. C.

We present the first rest-frame UV population study of 17 heavily reddened, high-luminosity (E(B-V)more » $$_{\\rm{QSO}}\\gtrsim$$ 0.5; L$$_{\\rm{bol}}>$$ 10$$^{46}$$ergs$$^{-1}$$) broad-line quasars at $1.5 < z < 2.7$. We combine the first year of deep, optical, ground-based observations from the Dark Energy Survey (DES) with the near infrared VISTA Hemisphere Survey (VHS) and UKIDSS Large Area Survey (ULAS) data, from which the reddened quasars were initially identified. We demonstrate that the significant dust reddening towards the quasar in our sample allows host galaxy emission to be detected at the rest-frame UV wavelengths probed by the DES photometry. By exploiting this reddening effect, we disentangle the quasar emission from that of the host galaxy via spectral energy distribution (SED) fitting. We find evidence for a relatively unobscured, star-forming host galaxy in at least ten quasars, with a further three quasars exhibiting emission consistent with either star formation or scattered light. From the rest-frame UV emission, we derive instantaneous, dust-corrected star formation rates (SFRs) in the range 25 < SFR$$_{\\rm{UV}}$$ < 365 M$$_{\\odot}$$yr$$^{-1}$$, with an average SFR$$_{\\rm{UV}}$$ = 130 $$\\pm$$ 95 M$$_{\\odot}$$yr$$^{-1}$$. In conclusion, we find a broad correlation between SFR$$_{\\rm{UV}}$$ and the bolometric quasar luminosity. Overall, our results show evidence for coeval star formation and black hole accretion occurring in luminous, reddened quasars at the peak epoch of galaxy formation.« less

UV-luminous, star-forming hosts of z ~ 2 reddened quasars in the Dark Energy Survey

DOE PAGES

Wethers, C. F.; Banerji, M.; Hewett, P. C.; ...

2018-01-05

We present the first rest-frame UV population study of 17 heavily reddened, high-luminosity (E(B-V)more » $$_{\\rm{QSO}}\\gtrsim$$ 0.5; L$$_{\\rm{bol}}>$$ 10$$^{46}$$ergs$$^{-1}$$) broad-line quasars at $1.5 < z < 2.7$. We combine the first year of deep, optical, ground-based observations from the Dark Energy Survey (DES) with the near infrared VISTA Hemisphere Survey (VHS) and UKIDSS Large Area Survey (ULAS) data, from which the reddened quasars were initially identified. We demonstrate that the significant dust reddening towards the quasar in our sample allows host galaxy emission to be detected at the rest-frame UV wavelengths probed by the DES photometry. By exploiting this reddening effect, we disentangle the quasar emission from that of the host galaxy via spectral energy distribution (SED) fitting. We find evidence for a relatively unobscured, star-forming host galaxy in at least ten quasars, with a further three quasars exhibiting emission consistent with either star formation or scattered light. From the rest-frame UV emission, we derive instantaneous, dust-corrected star formation rates (SFRs) in the range 25 < SFR$$_{\\rm{UV}}$$ < 365 M$$_{\\odot}$$yr$$^{-1}$$, with an average SFR$$_{\\rm{UV}}$$ = 130 $$\\pm$$ 95 M$$_{\\odot}$$yr$$^{-1}$$. In conclusion, we find a broad correlation between SFR$$_{\\rm{UV}}$$ and the bolometric quasar luminosity. Overall, our results show evidence for coeval star formation and black hole accretion occurring in luminous, reddened quasars at the peak epoch of galaxy formation.« less

Host galaxy properties of mergers of stellar binary black holes and their implications for advanced LIGO gravitational wave sources

NASA Astrophysics Data System (ADS)

Cao, Liang; Lu, Youjun; Zhao, Yuetong

2018-03-01

Understanding the host galaxy properties of stellar binary black hole (SBBH) mergers is important for revealing the origin of the SBBH gravitational wave sources detected by advanced LIGO and helpful for identifying their electromagnetic counterparts. Here, we present a comprehensive analysis of the host galaxy properties of SBBHs by implementing semi-analytical recipes for SBBH formation and merger into cosmological galaxy formation model. If the time delay between SBBH formation and merger ranges from ≲ Gyr to the Hubble time, SBBH mergers at redshift z ≲ 0.3 occur preferentially in big galaxies with stellar mass M* ≳ 2 × 1010 M⊙ and metallicities Z peaking at ˜0.6 Z⊙. However, the host galaxy stellar mass distribution of heavy SBBH mergers (M•• ≳ 50 M⊙) is bimodal with one peak at ˜109 M⊙ and the other peak at ˜2 × 1010 M⊙. The contribution fraction from host galaxies with Z ≲ 0.2 Z⊙ to heavy mergers is much larger than that to less heavy mergers. If SBBHs were formed in the early Universe (e.g. z > 6), their mergers detected at z ≲ 0.3 occur preferentially in even more massive galaxies with M* > 3 × 1010 M⊙ and in galaxies with metallicities mostly ≳ 0.2 Z⊙ and peaking at Z ˜ 0.6 Z⊙, due to later cosmic assembly and enrichment of their host galaxies. SBBH mergers at z ≲ 0.3 mainly occur in spiral galaxies, but the fraction of SBBH mergers that occur in elliptical galaxies can be significant if those SBBHs were formed in the early Universe; and about two-thirds of those mergers occur in the central galaxies of dark matter haloes. We also present results on the host galaxy properties of SBBH mergers at higher redshift.

The Host Galaxy and Redshift of the Repeating Fast Radio Burst FRB 121102

NASA Astrophysics Data System (ADS)

Tendulkar, S. P.; Bassa, C. G.; Cordes, J. M.; Bower, G. C.; Law, C. J.; Chatterjee, S.; Adams, E. A. K.; Bogdanov, S.; Burke-Spolaor, S.; Butler, B. J.; Demorest, P.; Hessels, J. W. T.; Kaspi, V. M.; Lazio, T. J. W.; Maddox, N.; Marcote, B.; McLaughlin, M. A.; Paragi, Z.; Ransom, S. M.; Scholz, P.; Seymour, A.; Spitler, L. G.; van Langevelde, H. J.; Wharton, R. S.

2017-01-01

The precise localization of the repeating fast radio burst (FRB 121102) has provided the first unambiguous association (chance coincidence probability p ≲ 3 × 10-4) of an FRB with an optical and persistent radio counterpart. We report on optical imaging and spectroscopy of the counterpart and find that it is an extended (0.″6-0.″8) object displaying prominent Balmer and [O III] emission lines. Based on the spectrum and emission line ratios, we classify the counterpart as a low-metallicity, star-forming, m r‧ = 25.1 AB mag dwarf galaxy at a redshift of z = 0.19273(8), corresponding to a luminosity distance of 972 Mpc. From the angular size, the redshift, and luminosity, we estimate the host galaxy to have a diameter ≲4 kpc and a stellar mass of M * ˜ (4-7) × 107 M ⊙, assuming a mass-to-light ratio between 2 to 3 M ⊙ L ⊙ -1. Based on the Hα flux, we estimate the star formation rate of the host to be 0.4 M ⊙ yr-1 and a substantial host dispersion measure (DM) depth ≲324 pc cm-3. The net DM contribution of the host galaxy to FRB 121102 is likely to be lower than this value depending on geometrical factors. We show that the persistent radio source at FRB 121102’s location reported by Marcote et al. is offset from the galaxy’s center of light by ˜200 mas and the host galaxy does not show optical signatures for AGN activity. If FRB 121102 is typical of the wider FRB population and if future interferometric localizations preferentially find them in dwarf galaxies with low metallicities and prominent emission lines, they would share such a preference with long gamma-ray bursts and superluminous supernovae.

The Physical Constraints on a New LoBAL QSO at z = 4.82

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

Yi, Weimin; Bai, Jin-Ming; Green, Richard

Very few low-ionization broad absorption line (LoBAL) QSOs have been found at high redshifts, to date. One high-redshift LoBAL QSO, J0122+1216, was recently discovered by the Lijiang 2.4 m Telescope, with an initial redshift determination of 4.76. Aiming to investigate its physical properties, we carried out follow-up observations in the optical and near-IR spectroscopy. Near-IR spectra from UKIRT and P200 confirm that it is a LoBAL, with a new redshift determination of 4.82 ± 0.01 based on the Mg ii emission-line. The new Mg ii redshift determination reveals strong blueshifts and asymmetry of the high-ionization emission lines. We estimate amore » black hole mass of ∼2.3 × 10{sup 9} M {sub ⊙} and Eddington ratio of ∼1.0 according to the empirical Mg ii-based single-epoch relation and bolometric correction factor. It is possible that strong outflows are the result of an extreme quasar environment driven by the high Eddington ratio. A lower limit on the outflowing kinetic power (>0.9% L {sub Edd}) is derived from both emission and absorption lines, indicating that these outflows play a significant role in the feedback process that regulates the growth of its black hole, as well as host galaxy evolution.« less

DISCOVERY OF A DAMPED Lyα ABSORBER AT z = 3.3 ALONG A GALAXY SIGHT-LINE IN THE SSA22 FIELD

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

Mawatari, K.; Inoue, A. K.; Kousai, K.

2016-02-01

Using galaxies as background light sources to map the Lyα absorption lines is a novel approach to study Damped Lyα Absorbers (DLAs). We report the discovery of an intervening z = 3.335 ± 0.007 DLA along a galaxy sight-line identified among 80 Lyman Break Galaxy (LBG) spectra obtained with our Very Large Telescope/Visible Multi-Object Spectrograph survey in the SSA22 field. The measured DLA neutral hydrogen (H i) column density is log(N{sub H} {sub i}/cm{sup −2}) = 21.68 ± 0.17. The DLA covering fraction over the extended background LBG is >70% (2σ), yielding a conservative constraint on the DLA area of ≳1 kpc{sup 2}. Our search for a counterpartmore » galaxy hosting this DLA concludes that there is no counterpart galaxy with star formation rate larger than a few M{sub ⊙} yr{sup −1}, ruling out an unobscured violent star formation in the DLA gas cloud. We also rule out the possibility that the host galaxy of the DLA is a passive galaxy with M{sub *} ≳ 5 × 10{sup 10}M{sub ⊙} or a heavily dust-obscured galaxy with E(B − V) ≳ 2. The DLA may coincide with a large-scale overdensity of the spectroscopic LBGs. The occurrence rate of the DLA is compatible with that of DLAs found in QSO sight-lines.« less

VizieR Online Data Catalog: Type 2 AGN host galaxies in Chandra-COSMOS (Suh+, 2017)

NASA Astrophysics Data System (ADS)

Suh, H.; Civano, F.; Hasinger, G.; Lusso, E.; Lanzuisi, G.; Marchesi, S.; Trakhtenbrot, B.; Allevato, V.; Cappelluti, N.; Capak, P. L.; Elvis, M.; Griffiths, R. E.; Laigle, C.; Lira, P.; Riguccini, L.; Rosario, D. J.; Salvato, M.; Schawinski, K.; Vignali, C.

2018-01-01

We investigate the star formation properties of a large sample of ~2300 X-ray-selected Type 2 Active Galactic Nuclei (AGNs) host galaxies out to z~3 in the Chandra COSMOS Legacy Survey in order to understand the connection between the star formation and nuclear activity. Making use of the existing multi-wavelength photometric data available in the COSMOS field, we perform a multi-component modeling from far-infrared to near-ultraviolet using a nuclear dust torus model, a stellar population model and a starburst model of the spectral energy distributions (SEDs). Through detailed analyses of SEDs, we derive the stellar masses and the star formation rates (SFRs) of Type 2 AGN host galaxies. The stellar mass of our sample is in the range of 9host galaxies have, on average, similar SFRs compared to the normal star-forming galaxies with similar Mstellar and redshift ranges, suggesting no significant evidence for enhancement or quenching of star formation. This could be interpreted in a scenario, where the relative massive galaxies have already experienced substantial growth at higher redshift (z>3), and grow slowly through secular fueling processes hosting moderate-luminosity AGNs. (1 data file).

A Narrowband Imaging Search for [O III] Emission from Galaxies at z > 3

NASA Astrophysics Data System (ADS)

Teplitz, Harry I.; Malkan, Matthew A.; McLean, Ian S.

1999-03-01

We present the results of a narrowband survey of quasi-stellar-object (QSO) fields at redshifts that place the [O III] (5007 Å) emission line in the Δλ/λ~1% 2.16 μm filter. We have observed 3 arcmin2 and detected one emission-line candidate object in the field around PC 1109+4642. We discuss the possibilities that this object is a star-forming galaxy at the QSO redshift, zem=3.313, or a Seyfert galaxy. In the former case, we infer a star formation rate of 170 Msolar yr-1 for this K'=21.3 object. The galaxy has a compact but resolved morphology, with an FWHM=0.6" or 4.2 kpc at z=3.313 (H0=50 km s-1 Mpc-1 and q0=0.5). The comoving density of such objects in QSO environments appears to be 0.0033 Mpc-3, marginally lower (<=3 σ) than the density observed for Hα-emitters in absorption-line fields at z~2.5 but similar to the density of Lyman-break galaxies at z~3. If, on the other hand, most of the line emission is [O III] from a Seyfert 2 nucleus at z=3.31, then the high inferred volume density could imply a large evolution in the Seyfert 2 luminosity function from the current epoch. We find the field containing the object to also contain many faint extended objects in the K' image but little significant excess over the expected number-magnitude relation. We discuss the implication of the emission line being a longer wavelength line at a lower redshift.

A Population of Faint Extended Line Emitters and the Host Galaxies of Optically Thick QSO Absorption Systems

NASA Astrophysics Data System (ADS)

Rauch, Michael; Haehnelt, Martin; Bunker, Andrew; Becker, George; Marleau, Francine; Graham, James; Cristiani, Stefano; Jarvis, Matt; Lacey, Cedric; Morris, Simon; Peroux, Celine; Röttgering, Huub; Theuns, Tom

2008-07-01

We have conducted a long-slit search for low surface brightness Lyα emitters at redshift 2.67 < z < 3.75. A 92 hr long exposure with the ESO VLT FORS2 instrument down to a 1 σ surface brightness detection limit of 8 × 10-20 erg cm-2 s-1 arcsec-2 per arcsec2 aperture yielded a sample of 27 single line emitters with fluxes of a few × 10-18 erg s-1 cm-2. We present arguments that most objects are indeed Lyα. The large comoving number density, 3 × 10-2 h370 Mpc-3, the large covering factor, dN/dz ~ 0.2-1, and the often extended Lyα emission suggest that the emitters can be identified with the elusive host population of damped Lyα systems (DLAS) and high column density Lyman limit systems (LLS). A small inferred star formation rate, perhaps supplemented by cooling radiation, appears to energetically dominate the Lyα emission, and is consistent with the low metallicity, low dust content, and theoretically inferred low masses of DLAS, and with the relative lack of success of earlier searches for their optical counterparts. Some of the line profiles show evidence for radiative transfer in galactic outflows. Stacking surface brightness profiles, we find emission out to at least 4''. The centrally concentrated emission of most objects appears to light up the outskirts of the emitters (where LLS arise) down to a column density where the conversion from UV to Lyα photon becomes inefficient. DLAS, high column density LLS, and the emitter population discovered in this survey appear to be different observational manifestations of the same low-mass, protogalactic building blocks of present-day L* galaxies. Based partly on observations made with ESO Telescopes at the Paranal Observatories under Program ID LP173.A-0440, and partly on observations obtained at the Gemini Observatory, which is operated by the Association of Universities for Research in Astronomy, Inc., under a cooperative agreement with the NSF on behalf of the Gemini partnership: the National Science

A Search for Molecular Gas in the Host Galaxy of FRB 121102

NASA Astrophysics Data System (ADS)

Bower, Geoffrey C.; Rao, Ramprasad; Krips, Melanie; Maddox, Natasha; Bassa, Cees; Adams, Elizabeth A. K.; Law, C. J.; Tendulkar, Shriharsh P.; van Langevelde, Huib Jan; Paragi, Zsolt; Butler, Bryan J.; Chatterjee, Shami

2018-06-01

We present Submillimeter Array and Northern Extended Millimeter Array observations of the host galaxy of FRB 121102 in the CO 3–2 and 1–0 transitions, respectively. We do not detect emission from either transition. We set 3σ upper limits to the CO luminosity L CO < 2.5 × 107 K km s‑1 pc‑2 for CO 3–2 and L CO < 2.3 × 109 K km s‑1 pc‑2 for CO 1–0. For Milky Way–like star formation properties, we set a 3σ upper limit on the H2 mass of 2.5 × 108 M ⊙, slightly less than the predictions for the H2 mass based on the star formation rate. The true constraint on the H2 mass may be significantly higher, however, because of the reduction in CO luminosity that is common for low-metallicity dwarf galaxies like the FRB host galaxy. These results demonstrate the challenge of identifying the nature of FRB progenitors through study of the host galaxy molecular gas. We also place a limit of 42 μJy (3σ) on the continuum flux density of the persistent radio source at 97 GHz, consistent with a power-law extrapolation of the low-frequency spectrum, which may arise from an active galactic nucleus or other nonthermal source.

Host galaxy properties of calcium II and sodium I quasar absorption-line systems

NASA Astrophysics Data System (ADS)

Cherinka, Brian

Many questions remain within the areas of galaxy formation and evolution. Understanding the origin of gas in galaxy environments, whether as tidal debris, infalling High Velocity Clouds, galaxy outflows, or as gaseous material residing in galaxy disks, is an important step in answering those questions. Quasar absorption-lines can often be used to probe the environments of intervening galaxies. Traditionally, quasar absorption-lines are studied independently of the host galaxy but this method denies us the exploration of the connection between galaxy and environment. Instead, one can select pairs of known galaxies and quasars. This gives much more information regarding the host galaxy and allows us to better connect galaxy properties with associated absorbers. We use the seventh data release of the Sloan Digital Sky Survey to generate a sample of spectroscopic galaxy-quasar pairs. We cross-correlated a sample of 105,000 quasars and ˜800,000 galaxies to produce ˜98,000 galaxy-quasar pairs, with the quasar projected within 100 kpc of the galaxy. Adopting an automated line-finding algorithm and using the galaxy redshift as a prior, we search through all quasar spectra and identify Ca II and Na I absorption due to the intervening galaxy. This procedure produced 1745 Ca II absorbers and 4500 Na I absorbers detected at or above 2σ. Stacking analysis of a subset of absorbers at z > 0.01, with significances at or above 3σ, showed strong Ca II and Na I features around external galaxies. Using the same subset of absorbers at z > 0.01, we looked for correlations between absorber and galaxy properties and examined differences in galaxy properties between the absorbers and non-absorbers. We found no correlations with absorber strength or differences between many galaxy properties at the 3σ level. The lack of correlations and differences between absorbers and non-absorbers suggest a ubiquitous nature for Ca II and Na I around all types of galaxies, with the absorbers showing

Spatially Resolved Patchy Lyα Emission within the Central Kiloparsec of a Strongly Lensed Quasar Host Galaxy at z = 2.8

NASA Astrophysics Data System (ADS)

Bayliss, Matthew B.; Sharon, Keren; Acharyya, Ayan; Gladders, Michael D.; Rigby, Jane R.; Bian, Fuyan; Bordoloi, Rongmon; Runnoe, Jessie; Dahle, Hakon; Kewley, Lisa; Florian, Michael; Johnson, Traci; Paterno-Mahler, Rachel

2017-08-01

We report the detection of extended Lyα emission from the host galaxy of SDSS J2222+2745, a strongly lensed quasar at z = 2.8. Spectroscopic follow-up clearly reveals extended Lyα in emission between two images of the central active galactic nucleus (AGN). We reconstruct the lensed quasar host galaxy in the source plane by applying a strong lens model to HST imaging and resolve spatial scales as small as ˜200 pc. In the source plane, we recover the host galaxy morphology to within a few hundred parsecs of the central AGN and map the extended Lyα emission to its physical origin on one side of the host galaxy at radii ˜0.5-2 kpc from the central AGN. There are clear morphological differences between the Lyα and rest-frame ultraviolet stellar continuum emission from the quasar host galaxy. Furthermore, the relative velocity profiles of quasar Lyα, host galaxy Lyα, and metal lines in outflowing gas reveal differences in the absorbing material affecting the AGN and host galaxy. These data indicate the presence of patchy local intervening gas in front of the central quasar and its host galaxy. This interpretation is consistent with the central luminous quasar being obscured across a substantial fraction of its surrounding solid angle, resulting in strong anisotropy in the exposure of the host galaxy to ionizing radiation from the AGN. This work demonstrates the power of strong-lensing-assisted studies to probe spatial scales that are currently inaccessible by other means.

Spatially Resolved Patchy Ly α Emission within the Central Kiloparsec of a Strongly Lensed Quasar Host Galaxy at z = 2.8

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

Bayliss, Matthew B.; Bordoloi, Rongmon; Sharon, Keren

We report the detection of extended Ly α emission from the host galaxy of SDSS J2222+2745, a strongly lensed quasar at z = 2.8. Spectroscopic follow-up clearly reveals extended Ly α in emission between two images of the central active galactic nucleus (AGN). We reconstruct the lensed quasar host galaxy in the source plane by applying a strong lens model to HST imaging and resolve spatial scales as small as ∼200 pc. In the source plane, we recover the host galaxy morphology to within a few hundred parsecs of the central AGN and map the extended Ly α emission tomore » its physical origin on one side of the host galaxy at radii ∼0.5–2 kpc from the central AGN. There are clear morphological differences between the Ly α and rest-frame ultraviolet stellar continuum emission from the quasar host galaxy. Furthermore, the relative velocity profiles of quasar Ly α , host galaxy Ly α , and metal lines in outflowing gas reveal differences in the absorbing material affecting the AGN and host galaxy. These data indicate the presence of patchy local intervening gas in front of the central quasar and its host galaxy. This interpretation is consistent with the central luminous quasar being obscured across a substantial fraction of its surrounding solid angle, resulting in strong anisotropy in the exposure of the host galaxy to ionizing radiation from the AGN. This work demonstrates the power of strong-lensing-assisted studies to probe spatial scales that are currently inaccessible by other means.« less

Connections between Star Cluster Populations and Their Host Galaxy Nuclear Rings

NASA Astrophysics Data System (ADS)

Ma, Chao; de Grijs, Richard; Ho, Luis C.

2018-04-01

Nuclear rings are excellent laboratories for probing diverse phenomena such as the formation and evolution of young massive star clusters and nuclear starbursts, as well as the secular evolution and dynamics of their host galaxies. We have compiled a sample of 17 galaxies with nuclear rings, which are well resolved by high-resolution Hubble and Spitzer Space Telescope imaging. For each nuclear ring, we identified the ring star cluster population, along with their physical properties (ages, masses, and extinction values). We also determined the integrated ring properties, including the average age, total stellar mass, and current star formation rate (SFR). We find that Sb-type galaxies tend to have the highest ring stellar mass fraction with respect to the host galaxy, and this parameter is correlated with the ring’s SFR surface density. The ring SFRs are correlated with their stellar masses, which is reminiscent of the main sequence of star-forming galaxies. There are striking correlations between star-forming properties (i.e., SFR and SFR surface density) and nonaxisymmetric bar parameters, appearing to confirm previous inferences that strongly barred galaxies tend to have lower ring SFRs, although the ring star formation histories turn out to be significantly more complicated. Nuclear rings with higher stellar masses tend to be associated with lower cluster mass fractions, but there is no such relation for the ages of the rings. The two youngest nuclear rings in our sample, NGC 1512 and NGC 4314, which have the most extreme physical properties, represent the young extremity of the nuclear ring age distribution.

How Do Inflows and Outflows from Galaxies Create Their Inner Circumgalactic Medium?

NASA Astrophysics Data System (ADS)

Bowen, David

2017-08-01

We propose using COS to observe 7 QSO sightlines within half a virial radius each of two galaxies in order to probe their circumgalactic mediums (CGMs) along multiple sightlines. Results from higher redshift QSO absorption line surveys suggest that this is the region where most metal line absorbing gas clouds reside, but their origin remains controversial. The two spiral galaxies studied in this proposal are NGC 4565 (the Needle Galaxy) which is highly inclined (i=86 degrees), and NGC 3184, which has a very low inclination (i=9 degrees). Their orientation makes them ideal targets for looking for kinematic and metallicity signatures from outflows along the minor axis, or inflows into the disk along the major axis. For both galaxies, we will measure how HI and metal line column densities change globally with radius, and how the ionzation structure of the absorbers varies with position. We predict that the HI column densities we detect will be similar to the Lyman Limit, or partial-Lyman Limit systems, and that we will be able to measure the gas metallicity in these clouds. These measurements can be used to infer whether the absorbing gas is flowing into the galaxy from the IGM (where the metallicity is lower than in the galaxy) or out of the galaxy (which should be metal enriched). Given that LLS and pLLS have been shown to have a bimodal distribution in their metallicity, we will see which of the two regimes the gas in our galaxies belong to, and even whether the bimodality can be seen in a single galaxy towards different sightlines.

ARE SOME MILKY WAY GLOBULAR CLUSTERS HOSTED BY UNDISCOVERED GALAXIES?

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

Zaritsky, Dennis; Crnojević, Denija; Sand, David J., E-mail: dennis.zaritsky@gmail.com

2016-07-20

The confirmation of a globular cluster (GC) in the recently discovered ultrafaint galaxy Eridanus II (Eri II) motivated us to examine the question posed in the title. After estimating the halo mass of Eri II using a published stellar mass—halo mass relation, the one GC in this galaxy supports extending the relationship between the number of GCs hosted by a galaxy and the galaxy’s total mass about two orders of magnitude in stellar mass below the previous limit. For this empirically determined specific frequency of between 0.06 and 0.39 GCs per 10{sup 9} M {sub ⊙} of total mass, themore » surviving Milky Way (MW) subhalos with masses smaller than 10{sup 10} M {sub ⊙} could host as many as 5–31 GCs, broadly consistent with the actual population of outer halo MW GCs, although matching the radial distribution in detail remains a challenge. Using a subhalo mass function from published high-resolution numerical simulations and a Poissonian model for populating those halos with the aforementioned empirically constrained frequency, we find that about 90% of these GCs lie in lower-mass subhalos than that of Eri II. From what we know about the stellar mass–halo mass function, the subhalo mass function, and the mass-normalized GC specific frequency, we conclude that some of the MW’s outer halo GCs are likely to be hosted by undetected subhalos with extremely modest stellar populations.« less

The Cambridge-Cambridge X-ray Serendipity Survey: I X-ray luminous galaxies

NASA Technical Reports Server (NTRS)

Boyle, B. J.; Mcmahon, R. G.; Wilkes, B. J.; Elvis, M.

1994-01-01

We report on the first results obtained from a new optical identification program of 123 faint X-ray sources with S(0.5-2 keV) greater than 2 x 10(exp -14) erg/s/sq cm serendipitously detected in ROSAT PSPC pointed observations. We have spectroscopically identified the optical counterparts to more than 100 sources in this survey. Although the majority of the sample (68 objects) are QSO's, we have also identified 12 narrow emission line galaxies which have extreme X-ray luminosities (10(exp 42) less than L(sub X) less than 10(exp 43.5) erg/s). Subsequent spectroscopy reveals them to be a mixture of star-burst galaxies and Seyfert 2 galaxies in approximately equal numbers. Combined with potentially similar objects identified in the Einstein Extended Medium Sensitivity Survey, these X-ray luminous galaxies exhibit a rate of cosmological evolution, L(sub X) varies as (1 + z)(exp 2.5 +/- 1.0), consistent with that derived for X-ray QSO's. This evolution, coupled with the steep slope determined for the faint end of the X-ray luminosity function (Phi(L(sub X)) varies as L(sub X)(exp -1.9)), implies that such objects could comprise 15-35% of the soft (1-2 keV) X-ray background.

Bar Frequency & Galaxy Host Properties using the Spitzer Survey of Stellar Structure in Galaxies (S4G)

NASA Astrophysics Data System (ADS)

Sheth, Kartik; Mizusawa, T.; Kim, T.; Munoz-Mateos, J.; Regan, M. W.; de Swardt, B.; Gadotti, D.; S4G Team

2011-01-01

Using the volume limited sample of 2,331 nearby galaxies from the Spitzer Survey of Stellar Structure in Galaxies (S4G), we have classified the frequency of barred spiral galaxies. The literature abounds with frequency ranges from as low as 20% to as high as 80% but these variations are driven by the quality of the data, the sample size and the methodology of the studies. Using the 3.6 and 4.5 micron IRAC images from S4G, we are able to make a definitive measurement of the local bar fraction as a function of the galaxy host and environment. We present the results from this survey and discuss how the current bar fraction compares to the declining frequency of bars from the present day to z 1.

The Host Galaxy and Redshift of the Repeating Fast Radio Burst FRB 121102

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

Tendulkar, S. P.; Kaspi, V. M.; Bassa, C. G.

The precise localization of the repeating fast radio burst (FRB 121102) has provided the first unambiguous association (chance coincidence probability p ≲ 3 × 10{sup −4}) of an FRB with an optical and persistent radio counterpart. We report on optical imaging and spectroscopy of the counterpart and find that it is an extended (0.″6–0.″8) object displaying prominent Balmer and [O iii] emission lines. Based on the spectrum and emission line ratios, we classify the counterpart as a low-metallicity, star-forming, m{sub r′} = 25.1 AB mag dwarf galaxy at a redshift of z = 0.19273(8), corresponding to a luminosity distance ofmore » 972 Mpc. From the angular size, the redshift, and luminosity, we estimate the host galaxy to have a diameter ≲4 kpc and a stellar mass of M {sub *} ∼ (4–7) × 10{sup 7} M {sub ⊙}, assuming a mass-to-light ratio between 2 to 3 M {sub ⊙} L {sub ⊙} {sup −1}. Based on the H α flux, we estimate the star formation rate of the host to be 0.4 M {sub ⊙} yr{sup −1} and a substantial host dispersion measure (DM) depth ≲324 pc cm{sup −3}. The net DM contribution of the host galaxy to FRB 121102 is likely to be lower than this value depending on geometrical factors. We show that the persistent radio source at FRB 121102’s location reported by Marcote et al. is offset from the galaxy’s center of light by ∼200 mas and the host galaxy does not show optical signatures for AGN activity. If FRB 121102 is typical of the wider FRB population and if future interferometric localizations preferentially find them in dwarf galaxies with low metallicities and prominent emission lines, they would share such a preference with long gamma-ray bursts and superluminous supernovae.« less

H I OBSERVATIONS OF THE Ca II ABSORBING GALAXIES Mrk 1456 AND SDSS J211701.26-002633.7

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

Cherinka, B.; Schulte-Ladbeck, R. E.; Rosenberg, J. L.

2009-12-15

In an effort to study Damped Ly{alpha} (DLA) galaxies at low redshift, we have been using the Sloan Digital Sky Survey (SDSS) to identify galaxies projected onto quasi-stellar object (QSO) sight lines and to characterize their optical properties. For low-redshift galaxies, the H I 21 cm emission line can be used as an alternate tool for identifying possible DLA galaxies, since H I-emitting galaxies typically exhibit H I columns that are larger than the classical DLA limit. Here, we report on follow-up H I 21 cm emission-line observations of two DLA candidates that are both low-redshift spiral galaxies, Mrk 1456more » and SDSS J211701.26-002633.7. The observations were made using the Green Bank Telescope (GBT) and Arecibo telescope, respectively. Analysis of their H I properties reveal the galaxies to be about one and two M*{sub HI} galaxies, respectively, and to have average H I mass, gas richness, and gas-mass fraction for their morphological types. We consider Mrk 1456 and SDSS J211701.26-002633.7 to be candidate DLA systems based upon the strength of the Ca II absorption lines they cause in their QSO's spectra, and impact parameters to the QSO that are smaller than the stellar disk. Compared to the small numbers of other H I detected DLA and candidate DLA galaxies, Mrk 1456 and SDSS J211701.26-002633.7 have high H I masses. Mrk 1456 and SDSS J211701.26-002633.7 have also been found to lie in galaxy groups that are high in H I gas mass compared to the group containing SBS 1543+593, the only DLA galaxy previously known to be situated in a galaxy group. When compared with the expected properties of low-z DLAs from an H I-detected sample of galaxies, Mrk 1456 and SDSS J211701.26-002633.7 fall within the ranges for impact parameter and M{sub B} ; and the H I mass distribution for the H I-detected DLAs agrees with that of the expected H I mass distribution for low-z DLAs. Our observations support galaxy-evolution models in which high-mass galaxies make up an

The galaxy-dark matter halo connection: which galaxy properties are correlated with the host halo mass?

NASA Astrophysics Data System (ADS)

Contreras, S.; Baugh, C. M.; Norberg, P.; Padilla, N.

2015-09-01

We demonstrate how the properties of a galaxy depend on the mass of its host dark matter subhalo, using two independent models of galaxy formation. For the cases of stellar mass and black hole mass, the median property value displays a monotonic dependence on subhalo mass. The slope of the relation changes for subhalo masses for which heating by active galactic nuclei becomes important. The median property values are predicted to be remarkably similar for central and satellite galaxies. The two models predict considerable scatter around the median property value, though the size of the scatter is model dependent. There is only modest evolution with redshift in the median galaxy property at a fixed subhalo mass. Properties such as cold gas mass and star formation rate, however, are predicted to have a complex dependence on subhalo mass. In these cases, subhalo mass is not a good indicator of the value of the galaxy property. We illustrate how the predictions in the galaxy property-subhalo mass plane differ from the assumptions made in some empirical models of galaxy clustering by reconstructing the model output using a basic subhalo abundance matching scheme. In its simplest form, abundance matching generally does not reproduce the clustering predicted by the models, typically resulting in an overprediction of the clustering signal. Using the predictions of the galaxy formation model for the correlations between pairs of galaxy properties, the basic abundance matching scheme can be extended to reproduce the model predictions more faithfully for a wider range of galaxy properties. Our results have implications for the analysis of galaxy clustering, particularly for low abundance samples.

SDSS-II SUPERNOVA SURVEY: AN ANALYSIS OF THE LARGEST SAMPLE OF TYPE IA SUPERNOVAE AND CORRELATIONS WITH HOST-GALAXY SPECTRAL PROPERTIES

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

Wolf, Rachel C.; Gupta, Ravi R.; Sako, Masao

2016-04-20

Using the largest single-survey sample of Type Ia supernovae (SNe Ia) to date, we study the relationship between properties of SNe Ia and those of their host galaxies, focusing primarily on correlations with Hubble residuals (HRs). Our sample consists of 345 photometrically classified or spectroscopically confirmed SNe Ia discovered as part of the SDSS-II Supernova Survey (SDSS-SNS). This analysis utilizes host-galaxy spectroscopy obtained during the SDSS-I/II spectroscopic survey and from an ancillary program on the SDSS-III Baryon Oscillation Spectroscopic Survey that obtained spectra for nearly all host galaxies of SDSS-II SN candidates. In addition, we use photometric host-galaxy properties frommore » the SDSS-SNS data release such as host stellar mass and star formation rate. We confirm the well-known relation between HR and host-galaxy mass and find a 3.6 σ significance of a nonzero linear slope. We also recover correlations between HR and host-galaxy gas-phase metallicity and specific star formation rate as they are reported in the literature. With our large data set, we examine correlations between HR and multiple host-galaxy properties simultaneously and find no evidence of a significant correlation. We also independently analyze our spectroscopically confirmed and photometrically classified SNe Ia and comment on the significance of similar combined data sets for future surveys.« less

The Impact of Starbursts on the Gaseous Halos of Galaxies

NASA Astrophysics Data System (ADS)

Heckman, Timothy

2009-07-01

Perhaps the most important {yet uncertain} aspects of galaxy evolution are the processes by which galaxies accrete gas and by which the resulting star formation and black hole growth affects this accreting gas. It is believed that both the form of the accretion and the nature of the feedback change as a function of the galaxy mass. At low mass the gas comes in cold and the feedback is provided by massive stars. At high mass, the gas comes in hot, and the feedback is from an AGN. The changeover occurs near the mass where the galaxy population transitions from star-forming galaxies to red and dead ones. The population of red and dead galaxies is building with cosmic time, and it is believed that feedback plays an imporant role in this process: shutting down star formation by heating and/or expelling the reservoir of cold halo gas. To investigate these ideas, we propose to use COS far-UV spectra of background QSOs to measure the properties of the halo gas in a sample of galaxies near the transition mass that have undergone starbursts within the past 100 Myr to 1 Gyr. The galactic wind associated with the starburst is predicted to have affected the properties of the gaseous halo. To test this, we will compare the properties of the halos of the post-starburst galaxies to those of a control sample of galaxies matched in mass and QSO impact parameter. Do the halos of the post-starburst galaxies show a higher incidence rate of Ly-Alpha and metal absorption-lines? Are the kinematics of the halo gas more disturbed in the post-starbursts? Has the wind affected the ionization state and/or the metallicity of the halo? These data will provide fresh new insights into the role of feedback from massive stars on the evolution of galaxies, and may also offer clues about the properties of the QSO metal absorption-line systems at high-redshift.

New Ground Based facilities in QSO research; The GTC

NASA Astrophysics Data System (ADS)

Rodriguez Espinosa, J. M.

New ground based observing opportunities are becoming, or about to become, available to astronomers for QSO research. These, combined with state of the art focal plane instruments, provide unprecedented sensitivity for detecting faint surface brightness features. During the talk I will take the liberty of talking about one of these new large telescope facilities currently being built in Spain, and will discuss some of the advantages for QSO research offered by these new facilities.

The Post-starburst Evolution of Tidal Disruption Event Host Galaxies

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

French, K. Decker; Zabludoff, Ann; Arcavi, Iair

We constrain the recent star formation histories of the host galaxies of eight optical/UV-detected tidal disruption events (TDEs). Six hosts had quick starbursts of <200 Myr duration that ended 10–1000 Myr ago, indicating that TDEs arise at different times in their hosts’ post-starburst evolution. If the disrupted star formed in the burst or before, the post-burst age constrains its mass, generally excluding O, most B, and highly massive A stars. If the starburst arose from a galaxy merger, the time since the starburst began limits the coalescence timescale and thus the merger mass ratio to more equal than 12:1 inmore » most hosts. This uncommon ratio, if also that of the central supermassive black hole (SMBH) binary, disfavors the scenario in which the TDE rate is boosted by the binary but is insensitive to its mass ratio. The stellar mass fraction created in the burst is 0.5%–10% for most hosts, not enough to explain the observed 30–200× boost in TDE rates, suggesting that the host’s core stellar concentration is more important. TDE hosts have stellar masses 10{sup 9.4}–10{sup 10.3} M {sub ☉}, consistent with the Sloan Digital Sky Survey volume-corrected, quiescent Balmer-strong comparison sample and implying SMBH masses of 10{sup 5.5}–10{sup 7.5} M {sub ☉}. Subtracting the host absorption line spectrum, we uncover emission lines; at least five hosts have ionization sources inconsistent with star formation that instead may be related to circumnuclear gas, merger shocks, or post-AGB stars.« less

Host Galaxies, Obscuration, and Nuclear Structure of Three Nearby Compact Symmetric Objects

NASA Astrophysics Data System (ADS)

Perlman, Eric S.; Stocke, John T.; Conway, John; Reynolds, Chris

2001-08-01

We present three-band Hubble Space Telescope imaging of three nearby (z<=0.1) compact symmetric objects: 4C 31.04, 1946+708, and 1146+596. These objects were chosen on the basis of proximity to Earth as well as H I 21 cm line absorption. The inner H-band isophotes of these galaxies are well fitted by Nuker models, typical of nearby elliptical galaxies. Each shows a significant flattening in the isophotal profile at radii ~0.5", as well as significant variations in ellipticity and P.A. However, as previous authors have noted, neither is uncommon for elliptical galaxies. All three objects show modest departures from Nuker law models at radii of 1-5 h-160 kpc. Each galaxy shows large well-distributed dust features, which are somewhat concentrated in the nuclear regions in features that resemble disks or tori. We find that the amount of dust in these galaxies is about 10 times higher than normal for elliptical galaxies and radio galaxy hosts. The major axes of the nuclear dust disks tend to be oriented roughly perpendicular to the radio axis. One galaxy, 4C 31.04, exhibits bright nuclear regions well aligned with the radio axis, while another, 1146+596, shows a significant near-IR excess resembling a stellar bar along its dust disk. The combination of outwardly normal isophotal profiles with significant variations in P.A. and ellipticity is consistent with the host galaxies being relatively recent merger remnants and the mergers having occurred >~108 yr ago. Such a merger could have ``triggered'' the onset of the current active phase seen in these objects, but our data require a significant time delay between the merger event and the onset of nuclear activity. However, these data are also consistent with the hypothesis that the onset of nuclear activity in radio galaxies is due to relatively minor ``feeding'' events and/or the formation of ``bars within bars,'' events which would disturb the internal kinematics only slightly.

Hosts and environments of low luminosity active galaxies in the local universe: The care and feeding of weak AGN

NASA Astrophysics Data System (ADS)

Parejko, John Kenneth

The observed relationship between the mass of a galaxy's supermassive black hole and the galaxy's bulge mass suggests a relationship between the growth of the galaxy and the growth of its central black hole. When these black holes grow, they release phenomenal amounts of energy into their surroundings, possibly disrupting further growth of the galaxy. The feeding (inflowing matter) and feedback (outflowing energy) of a galaxy's central black hole may be intimately related to the properties of the host's environment, on scales many orders of magnitude beyond the black hole's gravitational influence. While feeding, a massive black hole reveals itself as an Active Galactic Nucleus (AGN), but only a few percent of all galaxies show evidence of an AGN. This thesis focuses on this question: What distinguishes galaxies that are currently hosting actively accreting black holes from those that are not? We use the vast data set provided by the Sloan Digital Sky Survey (SDSS) Data Release 7 (DR7) to study the environments of a well defined sample of AGN hosts. To reduce contamination by galaxies that do not harbor actively accreting black holes, we define a clear, unambiguous sample of local AGN. Using this sample, we search for AGN in merging galaxies and measure the 2-point cross-correlation function of AGN and all galaxies to estimate the environments of AGN hosts compared to non-AGN hosts. We also describe trends in different subsamples of AGN, including luminosity and classification sub-type. Finally, we show how these techniques may be applied to future data sets such as forthcoming SDSS III data and X-ray data from the eROSITA satellite.

PSFGAN: a generative adversarial network system for separating quasar point sources and host galaxy light

NASA Astrophysics Data System (ADS)

Stark, Dominic; Launet, Barthelemy; Schawinski, Kevin; Zhang, Ce; Koss, Michael; Turp, M. Dennis; Sartori, Lia F.; Zhang, Hantian; Chen, Yiru; Weigel, Anna K.

2018-06-01

The study of unobscured active galactic nuclei (AGN) and quasars depends on the reliable decomposition of the light from the AGN point source and the extended host galaxy light. The problem is typically approached using parametric fitting routines using separate models for the host galaxy and the point spread function (PSF). We present a new approach using a Generative Adversarial Network (GAN) trained on galaxy images. We test the method using Sloan Digital Sky Survey r-band images with artificial AGN point sources added that are then removed using the GAN and with parametric methods using GALFIT. When the AGN point source is more than twice as bright as the host galaxy, we find that our method, PSFGAN, can recover point source and host galaxy magnitudes with smaller systematic error and a lower average scatter (49 per cent). PSFGAN is more tolerant to poor knowledge of the PSF than parametric methods. Our tests show that PSFGAN is robust against a broadening in the PSF width of ± 50 per cent if it is trained on multiple PSFs. We demonstrate that while a matched training set does improve performance, we can still subtract point sources using a PSFGAN trained on non-astronomical images. While initial training is computationally expensive, evaluating PSFGAN on data is more than 40 times faster than GALFIT fitting two components. Finally, PSFGAN is more robust and easy to use than parametric methods as it requires no input parameters.

Molecular gas in the host galaxy of a quasar at redshift z = 6.42.

PubMed

Walter, Fabian; Bertoldi, Frank; Carilli, Chris; Cox, Pierre; Lo, K Y; Neri, Roberto; Fan, Xiaohui; Omont, Alain; Strauss, Michael A; Menten, Karl M

2003-07-24

Observations of molecular hydrogen in quasar host galaxies at high redshifts provide fundamental constraints on galaxy evolution, because it is out of this molecular gas that stars form. Molecular hydrogen is traced by emission from the carbon monoxide molecule, CO; cold H2 itself is generally not observable. Carbon monoxide has been detected in about ten quasar host galaxies with redshifts z > 2; the record-holder is at z = 4.69 (refs 1-3). Here we report CO emission from the quasar SDSS J114816.64 + 525150.3 (refs 5, 6) at z = 6.42. At that redshift, the Universe was only 1/16 of its present age, and the era of cosmic reionization was just ending. The presence of about 2 x 1010 M\\circ of H2 in an object at this time demonstrates that molecular gas enriched with heavy elements can be generated rapidly in the youngest galaxies.

THE FIRST OBSERVATIONS OF LOW-REDSHIFT DAMPED Ly{alpha} SYSTEMS WITH THE COSMIC ORIGINS SPECTROGRAPH

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

Meiring, J. D.; Tripp, T. M.; Prochaska, J. X.

2011-05-01

We report on the first Cosmic Origins Spectrograph observations of damped Ly{alpha} systems (DLAs) and sub-damped Ly{alpha} systems (sub-DLAs) discovered in a new survey of the gaseous halos of low-redshift galaxies. From observations of 37 sightlines, we have discovered three DLAs and four sub-DLAs. We measure the neutral gas density {Omega}{sub HI}, and redshift density d N/d z, of DLA and sub-DLA systems at z < 0.35. We find d N/dz = 0.25{sup +0.24}-{sub 0.14} and {Omega}{sub HI} = 1.4{sup +1.3}{sub -0.7} x 10{sup -3} for DLAs, and d N/d z = 0.08{sup +0.19}{sub -0.06} with {Omega}{sub HI} = 4.2{supmore » +9.6}{sub -3.5} x 10{sup -5} for sub-DLAs over a redshift path {Delta}z = 11.9. To demonstrate the scientific potential of such systems, we present a detailed analysis of the DLA at z{sub abs} = 0.1140 in the spectrum of SDSS J1009+0713. Profile fits to the absorption lines determine log N(H I) = 20.68 {+-} 0.10 with a metallicity determined from the undepleted element sulfur of [S/H] = -0.62 {+-} 0.18. The abundance pattern of this DLA is similar to that of higher z DLAs, showing mild depletion of the refractory elements Fe and Ti with [S/Fe] = +0.24 {+-} 0.22 and [S/Ti] = +0.28 {+-} 0.15. Nitrogen is underabundant in this system with [N/H] = -1.40 {+-} 0.14, placing this DLA below the plateau of the [N/{alpha}] measurements in the local universe at similar metallicities. This DLA has a simple kinematic structure with only two components required to fit the profiles and a kinematic width of {Delta}v{sub 90} = 52 km s{sup -1}. Imaging of the QSO field with the Hubble Space Telescope/Wide Field Camera 3 reveals a spiral galaxy at very small impact parameter to the QSO and several galaxies within 10'', or 20 comoving kpc at the redshift of the DLA. Follow-up spectra with the Low Resolution Imaging Spectrometer on the Keck telescope reveal that none of the nearby galaxies are at the redshift of the DLA. The spiral galaxy is identified as the host galaxy of the

Host Galaxy Properties and Black Hole Mass of Swift J164449.3+573451 from Multi-wavelength Long-term Monitoring and HST Data

NASA Astrophysics Data System (ADS)

Yoon, Yongmin; Im, Myungshin; Jeon, Yiseul; Lee, Seong-Kook; Choi, Philip; Gehrels, Neil; Pak, Soojong; Sakamoto, Takanori; Urata, Yuji

2015-07-01

We study the host galaxy properties of the tidal disruption object Swift J164449.3+573451 using long-term optical to near-infrared (NIR) data. First, we decompose the galaxy surface brightness distribution and analyze the morphology of the host galaxy using high-resolution Hubble Space Telescope WFC3 images. We conclude that the host galaxy is bulge-dominant and well described by a single Sérsic model with Sérsic index n=3.43+/- 0.05. Adding a disk component, the bulge to total host galaxy flux ratio (B/ T) is 0.83 ± 0.03, which still indicates a bulge-dominant galaxy. Second, we estimate multi-band fluxes of the host galaxy through long-term light curves. Our long-term NIR light curves reveal the pure host galaxy fluxes ˜500 days after the burst. We fit spectral energy distribution models to the multi-band fluxes from the optical to NIR of the host galaxy and determine its properties. The stellar mass, the star formation rate, and the age of the stellar population are {log}({M}\\star /{M}⊙ )={9.14}-0.10+0.13, {0.03}-0.03+0.28 {M}⊙ yr-1, and {0.63}-0.43+0.95 Gyr. Finally, we estimate the mass of the central super massive black hole which is responsible for the tidal disruption event. The black hole mass is estimated to be {10}6.7+/- 0.4 {M}⊙ from {M}{BH}-{M}\\star ,{bul} and {M}{BH}-{L}{bul} relations for the K band, although a smaller value of ˜ {10}5 {M}⊙ cannot be excluded convincingly if the host galaxy harbors a pseudobulge.

Understanding the Progenitors of Short Gamma-Ray Bursts via their Host Galaxies: A Pilot Study

NASA Astrophysics Data System (ADS)

Cenko, S. Brad

2014-08-01

While massive star core-collapse is known to power long-duration gamma-ray bursts (GRBs), the origin of short GRBs remains unconfirmed. Studies of the host galaxies of short GRBs provide critical constraints on their progenitors, particularly if (as expected) short GRBs result from the neutron star mergers. Here we request deep Keck/LRIS imaging of short GRBs lacking securely identified hosts. By constraining the fraction of events that appear to have been 'kicked' out of their host galaxy in a more unbiased manner than past efforts, we aim to infer fundamental properties about the formation and evolution of binary neutron star systems.

An optical imaging study of 0.4 ≤ z ≤ 0.8 quasar host galaxies . II. Analysis and interpretation

NASA Astrophysics Data System (ADS)

Örndahl, E.; Rönnback, J.

2005-11-01

We performed optical imaging of 102 radio-loud and radio-quiet quasars at z=0.4{-}0.8, of which 91 fields were found suitable for host galaxy analysis after the deselection of saturated and otherwise flawed images. The data sets were obtained mainly in the R band, but also in the V and I or Gunn i band, and were presented in Rönnback et al.(1996, MNRAS, 283, 282) and Örndahl et al. (2003, A&A, 404, 883). In this paper we combine the two above-mentioned samples and also separately discuss additional hosts, extracted from data taken by Wold et al. (2000, MNRAS, 316, 267; 2001, MNRAS, 323, 231). The joint sample forms a sizeable fraction of the to-date total number of observed sources at intermediate redshifts and increases the number of resolved radio-quiet hosts at z>0.4 considerably. Equal numbers of radio-loud and radio-quiet objects were observed, resulting in a detection rate of 79% for the radio-loud hosts and 66% for the radio-quiet hosts. Profile fitting could only be carried out for a minority of the sample, but it results in predominantly elliptical morphologies. This is consistent with the mean values of the axial ratios, for which we find b/a⪆0.8 for both radio-quiet and radio-loud hosts, just as in the case of normal elliptical galaxies. The mean absolute magnitudes of the radio-loud and radio-quiet hosts is M_R=-23.5 in both cases. This similarity between the mean magnitudes of the two types of host galaxy is also seen in the other imaged bands. While the radio-loud host absolute R magnitudes are correlated with redshift, only a weak trend of the same sort is seen for the radio-quiet host magnitudes. Note, however, that the sample is not fully resolved and that the detection limit, in combination with the relationship between host and nuclear luminosity, may conspire in creating the illusion of an upturn in magnitude. The average nucleus-to-host galaxy luminosity ratios of the radio-loud and radio-quiet objects do not differ significantly in any

The luminous, massive and solar metallicity galaxy hosting the Swift γ-ray burst GRB 160804A at z = 0.737

NASA Astrophysics Data System (ADS)

Heintz, K. E.; Malesani, D.; Wiersema, K.; Jakobsson, P.; Fynbo, J. P. U.; Savaglio, S.; Cano, Z.; Covino, S.; D'Elia, V.; Gomboc, A.; Hammer, F.; Kaper, L.; Milvang-Jensen, B.; Møller, P.; Piranomonte, S.; Selsing, J.; Rhodin, N. H. P.; Tanvir, N. R.; Thöne, C. C.; de Ugarte Postigo, A.; Vergani, S. D.; Watson, D.

2018-02-01

We here present the spectroscopic follow-up observations with VLT/X-shooter of the Swift long-duration gamma-ray burst GRB 160804A at z = 0.737. Typically, GRBs are found in low-mass, metal-poor galaxies that constitute the sub-luminous population of star-forming galaxies. For the host galaxy of the GRB presented here, we derive a stellar mass of log (M*/ M⊙) = 9.80 ± 0.07, a roughly solar metallicity (12 + log (O/H) = 8.74 ± 0.12) based on emission line diagnostics, and an infrared luminosity of M3.6/(1 + z) = -21.94 mag, but find it to be dust-poor (E(B - V) < 0.05 mag). This establishes the galaxy hosting GRB 160804A as one of the most luminous, massive and metal-rich GRB hosts at z < 1.5. Furthermore, the gas-phase metallicity is found to be representative of the physical conditions of the gas close to the explosion site of the burst. The high metallicity of the host galaxy is also observed in absorption, where we detect several strong Fe II transitions as well as Mg II and Mg I. Although host galaxy absorption features are common in GRB afterglow spectra, we detect absorption from strong metal lines directly in the host continuum (at a time when the afterglow was contributing to < 15 per cent). Finally, we discuss the possibility that the geometry and state of the absorbing and emitting gas are indicative of a galactic scale outflow expelled at the final stage of two merging galaxies.

Stellar Photometric Structures of the Host Galaxies of Nearby Type 1 Active Galactic Nuclei

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

Kim, Minjin; Ho, Luis C.; Peng, Chien Y.

2017-10-01

We present detailed image analysis of rest-frame optical images of 235 low-redshift ( z ≲ 0.35) Type 1 active galactic nuclei (AGNs) observed with the Hubble Space Telescope . The high-resolution images enable us to perform rigorous two-dimensional image modeling to decouple the luminous central point source from the host galaxy, which, when warranted, is further decomposed into its principal structural components (bulge, bar, and disk). In many cases, care must be taken to account for structural complexities such as spiral arms, tidal features, and overlapping or interacting companion galaxies. We employ Fourier modes to characterize the degree of asymmetrymore » of the light distribution of the stars as a quantitative measure of morphological distortion due to interactions or mergers. We examine the dependence of the physical parameters of the host galaxies on the properties of the AGNs, namely, radio-loudness and the width of the broad emission lines. In accordance with previous studies, narrow-line (H β FWHM ≤ 2000 km s{sup −1}) Type 1 AGNs, in contrast to their broad-line (H β FWHM > 2000 km s{sup −1}) counterparts, are preferentially hosted in later-type, lower-luminosity galaxies, which have a higher incidence of pseudo-bulges, are more frequently barred, and are less morphologically disturbed. This suggests that narrow-line Type 1 AGNs experienced a more quiescent evolutionary history driven primarily by internal secular evolution instead of external dynamical perturbations. The fraction of AGN hosts showing merger signatures is larger for more luminous sources. Radio-loud AGNs generally preferentially live in earlier-type (bulge-dominated), more massive hosts, although a minority of them appear to contain a significant disk component. We do not find convincing evidence for enhanced merger signatures in the radio-loud population.« less

Energy input from quasars regulates the growth and activity of black holes and their host galaxies.

PubMed

Di Matteo, Tiziana; Springel, Volker; Hernquist, Lars

2005-02-10

In the early Universe, while galaxies were still forming, black holes as massive as a billion solar masses powered quasars. Supermassive black holes are found at the centres of most galaxies today, where their masses are related to the velocity dispersions of stars in their host galaxies and hence to the mass of the central bulge of the galaxy. This suggests a link between the growth of the black holes and their host galaxies, which has indeed been assumed for a number of years. But the origin of the observed relation between black hole mass and stellar velocity dispersion, and its connection with the evolution of galaxies, have remained unclear. Here we report simulations that simultaneously follow star formation and the growth of black holes during galaxy-galaxy collisions. We find that, in addition to generating a burst of star formation, a merger leads to strong inflows that feed gas to the supermassive black hole and thereby power the quasar. The energy released by the quasar expels enough gas to quench both star formation and further black hole growth. This determines the lifetime of the quasar phase (approaching 100 million years) and explains the relationship between the black hole mass and the stellar velocity dispersion.

Radio Galaxy Zoo: Machine learning for radio source host galaxy cross-identification

NASA Astrophysics Data System (ADS)

Alger, M. J.; Banfield, J. K.; Ong, C. S.; Rudnick, L.; Wong, O. I.; Wolf, C.; Andernach, H.; Norris, R. P.; Shabala, S. S.

2018-05-01

We consider the problem of determining the host galaxies of radio sources by cross-identification. This has traditionally been done manually, which will be intractable for wide-area radio surveys like the Evolutionary Map of the Universe (EMU). Automated cross-identification will be critical for these future surveys, and machine learning may provide the tools to develop such methods. We apply a standard approach from computer vision to cross-identification, introducing one possible way of automating this problem, and explore the pros and cons of this approach. We apply our method to the 1.4 GHz Australian Telescope Large Area Survey (ATLAS) observations of the Chandra Deep Field South (CDFS) and the ESO Large Area ISO Survey South 1 (ELAIS-S1) fields by cross-identifying them with the Spitzer Wide-area Infrared Extragalactic (SWIRE) survey. We train our method with two sets of data: expert cross-identifications of CDFS from the initial ATLAS data release and crowdsourced cross-identifications of CDFS from Radio Galaxy Zoo. We found that a simple strategy of cross-identifying a radio component with the nearest galaxy performs comparably to our more complex methods, though our estimated best-case performance is near 100 per cent. ATLAS contains 87 complex radio sources that have been cross-identified by experts, so there are not enough complex examples to learn how to cross-identify them accurately. Much larger datasets are therefore required for training methods like ours. We also show that training our method on Radio Galaxy Zoo cross-identifications gives comparable results to training on expert cross-identifications, demonstrating the value of crowdsourced training data.

Supermassive black holes and central star clusters: Connection with the host galaxy kinematics and color

NASA Astrophysics Data System (ADS)

Zasov, A. V.; Cherepashchuk, A. M.

2013-11-01

The relationship between the masses of the central, supermassive black holes ( M bh) and of the nuclear star clusters ( M nc) of disk galaxies with various parameters galaxies are considered: the rotational velocity at R = 2 kpc V (2), the maximum rotational velocity V max, the indicative dynamical mass M 25, the integrated mass of the stellar population M *, and the integrated color index B-V. The rotational velocities andmasses of the central objects were taken from the literature. Themass M nc correlatesmore closely with the kinematic parameters and the disk mass than M bh, including with the velocity V max, which is closely related to the virial mass of the dark halo. On average, lenticular galaxies are characterized by higher masses M bh compared to other types of galaxies with similar characteristics. The dependence of the blackhole mass on the color index is bimodal: galaxies of the red group (red-sequence) with B-V >0.6-0.7 which are mostly early-type galaxies with weak star formation, differ appreciably from blue galaxies, which have higher values of M nc and M bh. At the dependences we consider between the masses of the central objects and the parameters of the host galaxies (except for the dependence of M bh on the central velocity dispersion), the red-group galaxies have systematically higher M bh values, even when the host-galaxy parameters are similar. In contrast, in the case of nuclear star clusters, the blue and red galaxies form unified sequences. The results agree with scenarios in which most red-group galaxies form as a result of the partial or complete loss of interstellar gas in a stage of high nuclear activity in galaxies whose central black-hole masses exceed 106-107 M ⊙ (depending on the mass of the galaxy itself). The bulk of disk galaxies with M bh > 107 M ⊙ are lenticular galaxies (types S0, E/S0) whose disks are practically devoid of gas.

A Glimpse at Quasar Host Galaxy Far-UV Emission, Using Damped Lyα's as Natural Coronagraphs

DOE PAGES

Cai, Zheng; Fan, Xiaohui; Noterdaeme, Pasquier; ...

2014-09-16

In merger-driven models of massive galaxy evolution, the luminous quasar phase is expected to be accompanied by vigorous star formation in quasar host galaxies. In this paper, we use high column density damped Lyα (DLA) systems along quasar sight lines as natural coronagraphs to directly study the far-UV (FUV) radiation from the host galaxies of luminous background quasars. Here, we have stacked the spectra of ~2000 DLA systems (N HI > 10 20.6cm –2) with a median absorption redshiftmore » $$\\langle$$z$$\\rangle$$ = 2.6 selected from quasars observed in the SDSS-III Baryon Oscillation Spectroscopic Survey. We detect residual flux in the dark troughs of the composite DLA spectra. The level of this residual flux significantly exceeds systematic errors in the Sloan Digital Sky Survey fiber sky subtraction; furthermore, the residual flux is strongly correlated with the continuum luminosity of the background quasar, while uncorrelated with DLA column density or metallicity. We conclude that the flux could be associated with the average FUV radiation from the background quasar host galaxies (with medium redshift $$\\langle$$z$$\\rangle$$ = 3.1) that is not blocked by the intervening DLA. Finally, assuming that all of the detected flux originates from quasar hosts, for the highest quasar luminosity bin ($$\\langle$$L$$\\rangle$$ = 2.5 × 10 13 L ⊙), the host galaxy has an FUV intensity of 1.5 ± 0.2 × 10 40 erg s –1 Å –1; this corresponds to an unobscured UV star formation rate of 9 M ⊙ yr –1.« less

Missing GRB host galaxies in deep mid-infrared observations: implications on the use of GRBs as star formation tracers

NASA Astrophysics Data System (ADS)

Le Floc'h, Emeric; Charmandaris, Vassilis; Forrest, Bill; Mirabel, Félix; Armus, Lee; Devost, Daniel

2006-05-01

We report on the first mid-infrared observations of 16 GRB host galaxies performed with the Spitzer Space Telescope, and investigate the presence of evolved stellar populations and dust-enshrouded star-forming activity associated with GRBs. Only a very small fraction of our sample is detected by Spitzer, which is not consistent with recent works suggesting the presence of a GRB host population dominated by massive and strongly-starbursting galaxies (SFR >~ 100Msolaryr-1). Should the GRB hosts be representative of star-forming galaxies at high redshift, models of galaxy evolution indicate that >~ 50% of GRB hosts would be easily detected at the depth of our mid-infrared observations. Unless our sample suffers from a strong observational bias which remains to be understood, we infer in this context that the GRBs identified with the current techniques can not be directly used as unbiased probes of the global and integrated star formation history of the Universe.

A CCD Color Comparison of Seyfert 1 and 2 Host Galaxies

NASA Astrophysics Data System (ADS)

Virani, S. N.; De Robertis, M. M.

2001-05-01

Wide-field, R-band CCD data of 15 Seyfert 1 and 15 Seyfert 2 galaxies taken from the CfA survey were analysed in order to compare the properties of their host galaxies. Also, B-band images for a subset of 12 Seyfert 1s and 7 Seyfert 2s were acquired and analysed in the same way. The nuclear contribution of the Seyfert host galaxies was modeled and removed empirically by using a robust technique for decomposing the nucleus, bulge and disk components (see Virani et al. 2000, De Robertis and Virani, 2001). Profile fits to the remaining bulge+disk light were then performed. Of the many B-R color comparisons that were performed (i.e., component colors, color gradient, etc.) between Seyfert 1s and 2s, only two distributions differed at greater than the 95% confidence level for the K-S test: the magnitude of the nuclear component, and the radial color gradient outside the nucleus. The former is expected. The latter could be consistent with some proposed evolutionary models. There is some suggestion that other parameters may differ, but at a lower confidence level. Color contour maps and results from all tests performed (K-S test and Wilcoxon-Rank Sum Test) are presented.

R-band host galaxy contamination of TeV γ-ray blazar Mrk 501: effects of aperture size and seeing

NASA Astrophysics Data System (ADS)

Feng, Hai-Cheng; Liu, Hong-Tao; Zhao, Ying-He; Bai, Jin-Ming; Wang, Fang; Fan, Xu-Liang

2018-02-01

We simulated the R-band contribution of the host galaxy of TeV γ-ray BL Lac object Mrk 501 in different aperture sizes and seeing conditions. An intensive set of observations was acquired with the 1.02 m optical telescope, managed by Yunnan Observatories, from 2010 May 15 to 18. Based on the host subtraction data usually used in the literature, the subtraction of host galaxy contamination results in significant seeing-brightness correlations. These correlations would lead to illusive large amplitude variations at short timescales, which will mask the intrinsic microvariability, thus giving rise to difficulty in detecting the intrinsic microvariability. Both aperture size and seeing condition influence the flux measurements, but the aperture size impacts the result more significantly. Based on the parameters of an elliptical galaxy provided in the literature, we simulated the host contributions of Mrk 501 in different aperture sizes and seeing conditions. Our simulation data of the host galaxy obviously weaken these significant seeing-brightness correlations for the host-subtracted brightness of Mrk 501, and can help us discover the intrinsic short timescale microvariability. The pure nuclear flux is ∼8.0mJy in the R band, i.e., the AGN has a magnitude of R ∼ 13.96 mag.

The effect of host cluster gravitational tidal forces on the internal dynamics of spiral galaxies

NASA Astrophysics Data System (ADS)

Mayer, Alexander

2013-04-01

New empirical observation by Bidin, Carraro, Mendez & Smith finds ``a lack of dark matter in the Solar neighborhood" (2012 ApJ 751, 30). This, and the discovery of a vast polar structure of Milky Way satellites by Pawlowski, Pflamm-Altenburg & Kroupa (2012 MNRAS 423, 1109), conflict with the prevailing interpretation of the measured Galactic rotation curve. Simulating the dynamical effects of host cluster tidal forces on galaxy disks reveals radial migration in a spiral structure and an orbital velocity that accelerates with increasing galactocentric radial coordinate. A virtual ``toy model,'' which is based on an Earth-orbiting system of particles and is physically realizable in principle, is available at GravitySim.net. Given the perturbing gravitational effect of the host cluster on a spiral galaxy disk and that a similar effect does not exist for the Solar System, the two systems represent distinct classes of gravitational dynamical systems. The observed `flat' and accelerating rotation curves of spiral galaxies can be attributed to gravitational interaction with the host cluster; no `dark matter halo' is required to explain the observable.

A glimpse at quasar host galaxy far-UV emission using damped Lyα's as natural coronagraphs

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

Cai, Zheng; Fan, Xiaohui; Wang, Ran

2014-10-01

In merger-driven models of massive galaxy evolution, the luminous quasar phase is expected to be accompanied by vigorous star formation in quasar host galaxies. In this paper, we use high column density damped Lyα (DLA) systems along quasar sight lines as natural coronagraphs to directly study the far-UV (FUV) radiation from the host galaxies of luminous background quasars. We have stacked the spectra of ∼2000 DLA systems (N {sub H} {sub I} > 10{sup 20.6} cm{sup –2}) with a median absorption redshift (z) = 2.6 selected from quasars observed in the SDSS-III Baryon Oscillation Spectroscopic Survey. We detect residual fluxmore » in the dark troughs of the composite DLA spectra. The level of this residual flux significantly exceeds systematic errors in the Sloan Digital Sky Survey fiber sky subtraction; furthermore, the residual flux is strongly correlated with the continuum luminosity of the background quasar, while uncorrelated with DLA column density or metallicity. We conclude that the flux could be associated with the average FUV radiation from the background quasar host galaxies (with medium redshift (z) = 3.1) that is not blocked by the intervening DLA. Assuming that all of the detected flux originates from quasar hosts, for the highest quasar luminosity bin ((L) = 2.5 × 10{sup 13} L {sub ☉}), the host galaxy has an FUV intensity of 1.5 ± 0.2 × 10{sup 40} erg s{sup –1} Å{sup –1}; this corresponds to an unobscured UV star formation rate of 9 M {sub ☉} yr{sup –1}.« less

Supermassive Black Holes and Their Host Spheroids. I. Disassembling Galaxies

NASA Astrophysics Data System (ADS)

Savorgnan, G. A. D.; Graham, A. W.

2016-01-01

Several recent studies have performed galaxy decompositions to investigate correlations between the black hole mass and various properties of the host spheroid, but they have not converged on the same conclusions. This is because their models for the same galaxy were often significantly different and not consistent with each other in terms of fitted components. Using 3.6 μm Spitzer imagery, which is a superb tracer of the stellar mass (superior to the K band), we have performed state-of-the-art multicomponent decompositions for 66 galaxies with directly measured black hole masses. Our sample is the largest to date and, unlike previous studies, contains a large number (17) of spiral galaxies with low black hole masses. We paid careful attention to the image mosaicking, sky subtraction, and masking of contaminating sources. After a scrupulous inspection of the galaxy photometry (through isophotal analysis and unsharp masking) and—for the first time—2D kinematics, we were able to account for spheroids large-scale, intermediate-scale, and nuclear disks bars rings spiral arms halos extended or unresolved nuclear sources; and partially depleted cores. For each individual galaxy, we compared our best-fit model with previous studies, explained the discrepancies, and identified the optimal decomposition. Moreover, we have independently performed one-dimensional (1D) and two-dimensional (2D) decompositions and concluded that, at least when modeling large, nearby galaxies, 1D techniques have more advantages than 2D techniques. Finally, we developed a prescription to estimate the uncertainties on the 1D best-fit parameters for the 66 spheroids that takes into account systematic errors, unlike popular 2D codes that only consider statistical errors.

Bulgeless Galaxies Hosting 107 M⊙ AGN in Galaxy Zoo: The Growth of Black Holes via Secular Processes

NASA Astrophysics Data System (ADS)

Simmons, Brooke; Lintott, C. J.; Schawinski, K.; Moran, E. C.; Han, A.; Kaviraj, S.; Masters, K. L.; Urry, C. M.; Willett, K.; Bamford, S. P.; Nichol, R.

2013-01-01

The growth of supermassive black holes (SMBHs) appears to proceed via multiple pathways including mergers and secular processes, but these are difficult to disentangle for most galaxies given their complex evolutionary histories. In order to understand the effects of secular galaxy evolution on black hole growth, we require a sample of active galactic nuclei (AGN) in galaxies with a calm formation history free of significant mergers, a population that heretofore has been difficult to locate. Here we present a sample of 13 AGN in massive galaxies lacking the classical bulges believed inevitably to result from mergers; they also either lack or have extremely small pseudobulges, meaning they have had very calm accretion histories. This is the largest sample to date of massive, bulgeless AGN host galaxies selected without any direct restriction on the SMBH mass. The broad-line objects in the sample have black hole masses of 106-7 M⊙ Eddington arguments imply similar masses for the rest of the sample, meaning these black holes have grown substantially in the absence of mergers or other bulge-building processes such as violent disk instabilities. The black hole masses are systematically higher than expected from established bulge-black hole relations. However, these systems may be consistent with the correlation between black hole mass and total stellar mass. We discuss these results in the context of other studies and consider the implication that the details of stellar galaxy evolution and dynamics may not be fundamental to the co-evolution of galaxies and black holes.

Stellar Photometric Structures of the Host Galaxies of Nearby Type 1 Active Galactic Nuclei

NASA Astrophysics Data System (ADS)

Kim, Minjin; Ho, Luis C.; Peng, Chien Y.; Barth, Aaron J.; Im, Myungshin

2017-10-01

We present detailed image analysis of rest-frame optical images of 235 low-redshift (z ≲ 0.35) Type 1 active galactic nuclei (AGNs) observed with the Hubble Space Telescope. The high-resolution images enable us to perform rigorous two-dimensional image modeling to decouple the luminous central point source from the host galaxy, which, when warranted, is further decomposed into its principal structural components (bulge, bar, and disk). In many cases, care must be taken to account for structural complexities such as spiral arms, tidal features, and overlapping or interacting companion galaxies. We employ Fourier modes to characterize the degree of asymmetry of the light distribution of the stars as a quantitative measure of morphological distortion due to interactions or mergers. We examine the dependence of the physical parameters of the host galaxies on the properties of the AGNs, namely, radio-loudness and the width of the broad emission lines. In accordance with previous studies, narrow-line (Hβ FWHM ≤ 2000 km s-1) Type 1 AGNs, in contrast to their broad-line (Hβ FWHM > 2000 km s-1) counterparts, are preferentially hosted in later-type, lower-luminosity galaxies, which have a higher incidence of pseudo-bulges, are more frequently barred, and are less morphologically disturbed. This suggests that narrow-line Type 1 AGNs experienced a more quiescent evolutionary history driven primarily by internal secular evolution instead of external dynamical perturbations. The fraction of AGN hosts showing merger signatures is larger for more luminous sources. Radio-loud AGNs generally preferentially live in earlier-type (bulge-dominated), more massive hosts, although a minority of them appear to contain a significant disk component. We do not find convincing evidence for enhanced merger signatures in the radio-loud population. Based on observations made with the NASA/ESA Hubble Space Telescope, obtained from the Data Archive at the Space Telescope Science Institute

Elemental gas-phase abundances of intermediate redshift type Ia supernova star-forming host galaxies

NASA Astrophysics Data System (ADS)

Moreno-Raya, M. E.; Galbany, L.; López-Sánchez, Á. R.; Mollá, M.; González-Gaitán, S.; Vílchez, J. M.; Carnero, A.

2018-05-01

The maximum luminosity of type Ia supernovae (SNe Ia) depends on the oxygen abundance of the regions of the host galaxies, where they explode. This metallicity dependence reduces the dispersion in the Hubble diagram (HD) when included with the traditional two-parameter calibration of SN Ia light-curve parameters and absolute magnitude. In this work, we use empirical calibrations to carefully estimate the oxygen abundance of galaxies hosting SNe Ia from the SDSS-II/SN (Sloan Digital Sky Survey-II Supernova) survey at intermediate redshift by measuring their emission-line intensities. We also derive electronic temperature with the direct method for a small fraction of objects for consistency. We find a trend of decreasing oxygen abundance with increasing redshift for the most massive galaxies. Moreover, we study the dependence of the HD residuals (HR) with galaxy oxygen abundance obtaining a correlation in line with those found in other works. In particular, the HR versus oxygen abundance shows a slope of -0.186 ± 0.123 mag dex-1 (1.52σ) in good agreement with theoretical expectations. This implies smaller distance modulii after corrections for SNe Ia in metal-rich galaxies. Based on our previous results on local SNe Ia, we propose this dependence to be due to the lower luminosity of the SNe Ia produced in more metal-rich environments.

Distant Galaxy Clusters Hosting Extreme Central Galaxies

NASA Astrophysics Data System (ADS)

McDonald, Michael

2014-09-01

The recently-discovered Phoenix cluster harbors the most star-forming central cluster galaxy of any cluster in the known Universe, by nearly a factor of 10. This extreme system appears to be fulfilling early cooling flow predictions, although the lack of similar systems makes any interpretation difficult. In an attempt to find other "Phoenix-like" clusters, we have cross-correlated archival all-sky surveys (in which Phoenix was detected) and isolated 4 similarly-extreme systems which are also coincident in position and redshift with an overdensity of red galaxies. We propose here to obtain Chandra observations of these extreme, Phoenix-like systems, in order to confirm them as relaxed, rapidly-cooling galaxy clusters.

A Comparison of Seyfert 1 and 2 Host Galaxies

NASA Astrophysics Data System (ADS)

De Robertis, M.; Virani, S.

2000-12-01

Wide-field, R-band CCD data of 15 Seyfert 1 and 15 Seyfert 2 galaxies taken from the CfA survey were analysed in order to compare the properties of their host galaxies. As well, B-band images for a subset of 12 Seyfert 1s and 7 Seyfert 2s were acquired and analysed in the same way. A robust technique for decomposing the three components---nucleus, bulge and disk---was developed in order determine the structural parameters for each galaxy. In effect, the nuclear contribution was removed empirically by using a spatially nearby, high signal-to-noise ratio point source as a template. Profile fits to the bulge+disk ignored data within three seeing disks of the nucleus. Of the many parameters that were compared between Seyfert 1s and 2s, only two distributions differed at greater than the 95% confidence level for the K-S test: the magnitude of the nuclear component, and the radial color gradient outside the nucleus. The former is expected. The latter could be consistent with some proposed evolutionary models. There is some suggestion that other parameters may differ, but at a lower confidence level.

First measurement of H I 21 cm emission from a GRB host galaxy indicates a post-merger system

NASA Astrophysics Data System (ADS)

Arabsalmani, Maryam; Roychowdhury, Sambit; Zwaan, Martin A.; Kanekar, Nissim; Michałowski, Michał J.

2015-11-01

We report the detection and mapping of atomic hydrogen in H I 21 cm emission from ESO 184-G82, the host galaxy of the gamma-ray burst 980425. This is the first instance where H I in emission has been detected from a galaxy hosting a gamma-ray burst (GRB). ESO 184-G82 is an isolated galaxy and contains a Wolf-Rayet region close to the location of the GRB and the associated supernova, SN 1998bw. This is one of the most luminous H II regions identified in the local Universe, with a very high inferred density of star formation. The H I 21 cm observations reveal a high H I mass for the galaxy, twice as large as the stellar mass. The spatial and velocity distribution of the H I 21 cm emission reveals a disturbed rotating gas disc, which suggests that the galaxy has undergone a recent minor merger that disrupted its rotation. We find that the Wolf-Rayet region and the GRB are both located in the highest H I column density region of the galaxy. We speculate that the merger event has resulted in shock compression of the gas, triggering extreme star formation activity, and resulting in the formation of both the Wolf-Rayet region and the GRB. The high H I column density environment of the GRB is consistent with the high H I column densities seen in absorption in the host galaxies of high-redshift GRBs.

Copious Amounts of Dust and Gas in a z = 7.5 Quasar Host Galaxy

NASA Astrophysics Data System (ADS)

Venemans, Bram P.; Walter, Fabian; Decarli, Roberto; Bañados, Eduardo; Carilli, Chris; Winters, Jan Martin; Schuster, Karl; da Cunha, Elisabete; Fan, Xiaohui; Farina, Emanuele Paolo; Mazzucchelli, Chiara; Rix, Hans-Walter; Weiss, Axel

2017-12-01

We present IRAM/NOEMA and JVLA observations of the quasar J1342+0928 at z = 7.54 and report detections of copious amounts of dust and [C II] emission in the interstellar medium (ISM) of its host galaxy. At this redshift, the age of the universe is 690 Myr, about 10% younger than the redshift of the previous quasar record holder. Yet, the ISM of this new quasar host galaxy is significantly enriched by metals, as evidenced by the detection of the [C II] 158 μm cooling line and the underlying far-infrared (FIR) dust continuum emission. To the first order, the FIR properties of this quasar host are similar to those found at a slightly lower redshift (z˜ 6), making this source by far the FIR-brightest galaxy known at z≳ 7.5. The [C II] emission is spatially unresolved, with an upper limit on the diameter of 7 kpc. Together with the measured FWHM of the [C II] line, this yields a dynamical mass of the host of < 1.5× {10}11 {M}⊙ . Using standard assumptions about the dust temperature and emissivity, the NOEMA measurements give a dust mass of (0.6{--}4.3)× {10}8 {M}⊙ . The brightness of the [C II] luminosity, together with the high dust mass, imply active ongoing star formation in the quasar host. Using [C II]-SFR scaling relations, we derive star formation rates of 85-545 {M}⊙ yr-1 in the host, consistent with the values derived from the dust continuum. Indeed, an episode of such past high star formation is needed to explain the presence of ˜108 M ⊙ of dust implied by the observations.

SUPERMASSIVE BLACK HOLES AND THEIR HOST SPHEROIDS. I. DISASSEMBLING GALAXIES

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

Savorgnan, G. A. D.; Graham, A. W., E-mail: gsavorgn@astro.swin.edu.au

Several recent studies have performed galaxy decompositions to investigate correlations between the black hole mass and various properties of the host spheroid, but they have not converged on the same conclusions. This is because their models for the same galaxy were often significantly different and not consistent with each other in terms of fitted components. Using 3.6 μm Spitzer imagery, which is a superb tracer of the stellar mass (superior to the K band), we have performed state-of-the-art multicomponent decompositions for 66 galaxies with directly measured black hole masses. Our sample is the largest to date and, unlike previous studies, containsmore » a large number (17) of spiral galaxies with low black hole masses. We paid careful attention to the image mosaicking, sky subtraction, and masking of contaminating sources. After a scrupulous inspection of the galaxy photometry (through isophotal analysis and unsharp masking) and—for the first time—2D kinematics, we were able to account for spheroids; large-scale, intermediate-scale, and nuclear disks; bars; rings; spiral arms; halos; extended or unresolved nuclear sources; and partially depleted cores. For each individual galaxy, we compared our best-fit model with previous studies, explained the discrepancies, and identified the optimal decomposition. Moreover, we have independently performed one-dimensional (1D) and two-dimensional (2D) decompositions and concluded that, at least when modeling large, nearby galaxies, 1D techniques have more advantages than 2D techniques. Finally, we developed a prescription to estimate the uncertainties on the 1D best-fit parameters for the 66 spheroids that takes into account systematic errors, unlike popular 2D codes that only consider statistical errors.« less

SDSS-II Supernova survey. An analysis of the largest sample of type IA supernovae and correlations with host-galaxy spectral properties

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

Wolf, Rachel C.; D’Andrea, Chris B.; Gupta, Ravi R.

2016-04-20

Using the largest single-survey sample of Type Ia supernovae (SNe Ia) to date, we study the relationship between properties of SNe Ia and those of their host galaxies, focusing primarily on correlations with Hubble residuals (HR). Our sample consists of 345 photometrically-classified or spectroscopicallyconfirmed SNe Ia discovered as part of the SDSS-II Supernova Survey (SDSS-SNS). This analysis utilizes host-galaxy spectroscopy obtained during the SDSS-I/II spectroscopic survey and from an ancillary program on the SDSS-III Baryon Oscillation Spectroscopic Survey (BOSS) that obtained spectra for nearly all host galaxies of SDSS-II SN candidates. In addition, we use photometric hostgalaxy properties from themore » SDSS-SNS data release (Sako et al. 2014) such as host stellar mass and star-formation rate. We confirm the well-known relation between HR and host-galaxy mass and find a 3.6σ significance of a non-zero linear slope. We also recover correlations between HR and hostgalaxy gas-phase metallicity and specific star-formation rate as they are reported in the literature. With our large dataset, we examine correlations between HR and multiple host-galaxy properties simultaneously and find no evidence of a significant correlation. We also independently analyze our spectroscopically-confirmed and photometrically-classified SNe Ia and comment on the significance of similar combined datasets for future surveys.« less

Image decomposition of barred galaxies and AGN hosts

NASA Astrophysics Data System (ADS)

Gadotti, Dimitri Alexei

2008-02-01

I present the results of multicomponent decomposition of V and R broad-band images of a sample of 17 nearby galaxies, most of them hosting bars and active galactic nuclei (AGN). I use BUDDA v2.1 to produce the fits, allowing the inclusion of bars and AGN in the models. A comparison with previous results from the literature shows a fairly good agreement. It is found that the axial ratio of bars, as measured from ellipse fits, can be severely underestimated if the galaxy axisymmetric component is relatively luminous. Thus, reliable bar axial ratios can only be determined by taking into account the contributions of bulge and disc to the light distribution in the galaxy image. Through a number of tests, I show that neglecting bars when modelling barred galaxies can result in an overestimation of the bulge-to-total luminosity ratio of a factor of 2. Similar effects result when bright, type 1 AGN are not considered in the models. By artificially redshifting the images, I show that the structural parameters of more distant galaxies can in general be reliably retrieved through image fitting, at least up to the point where the physical spatial resolution is ~1.5kpc. This corresponds, for instance, to images of galaxies at z = 0.05 with a seeing full width at half-maximum (FWHM) of 1.5arcsec, typical of the Sloan Digital Sky Survey (SDSS). In addition, such a resolution is also similar to what can be achieved with the Hubble Space Telescope (HST), and ground-based telescopes with adaptive optics, at z ~ 1-2. Thus, these results also concern deeper studies such as COSMOS and SINS. This exercise shows that disc parameters are particularly robust, but bulge parameters are prone to errors if its effective radius is small compared to the seeing radius, and might suffer from systematic effects. For instance, the bulge-to-total luminosity ratio is systematically overestimated, on average, by 0.05 (i.e. 5 per cent of the galaxy total luminosity). In this low-resolution regime, the

THE SWIFT GRB HOST GALAXY LEGACY SURVEY. II. REST-FRAME NEAR-IR LUMINOSITY DISTRIBUTION AND EVIDENCE FOR A NEAR-SOLAR METALLICITY THRESHOLD

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

Perley, D. A.; Tanvir, N. R.; Hjorth, J.

2016-01-20

We present rest-frame near-IR (NIR) luminosities and stellar masses for a large and uniformly selected population of gamma-ray burst (GRB) host galaxies using deep Spitzer Space Telescope imaging of 119 targets from the Swift GRB Host Galaxy Legacy Survey spanning 0.03 < z < 6.3, and we determine the effects of galaxy evolution and chemical enrichment on the mass distribution of the GRB host population across cosmic history. We find a rapid increase in the characteristic NIR host luminosity between z ∼ 0.5 and z ∼ 1.5, but little variation between z ∼ 1.5 and z ∼ 5. Dust-obscured GRBs dominate the massive host population but are only rarely seen associated withmore » low-mass hosts, indicating that massive star-forming galaxies are universally and (to some extent) homogeneously dusty at high redshift while low-mass star-forming galaxies retain little dust in their interstellar medium. Comparing our luminosity distributions with field surveys and measurements of the high-z mass–metallicity relation, our results have good consistency with a model in which the GRB rate per unit star formation is constant in galaxies with gas-phase metallicity below approximately the solar value but heavily suppressed in more metal-rich environments. This model also naturally explains the previously reported “excess” in the GRB rate beyond z ≳ 2; metals stifle GRB production in most galaxies at z < 1.5 but have only minor impact at higher redshifts. The metallicity threshold we infer is much higher than predicted by single-star models and favors a binary progenitor. Our observations also constrain the fraction of cosmic star formation in low-mass galaxies undetectable to Spitzer to be small at z < 4.« less

The Influence of Host Galaxies in Type Ia Supernova Cosmology

NASA Astrophysics Data System (ADS)

Uddin, Syed A.; Mould, Jeremy; Lidman, Chris; Ruhlmann-Kleider, Vanina; Zhang, Bonnie R.

2017-10-01

We use a sample of 1338 spectroscopically confirmed and photometrically classified Type Ia supernovae (SNe Ia) sourced from Carnegie Supernova Project, Center for Astrophysics Supernova Survey, Sloan Digital Sky Survey-II, and SuperNova Legacy Survey SN samples to examine the relationships between SNe Ia and the galaxies that host them. Our results provide confirmation with improved statistical significance that SNe Ia, after standardization, are on average more luminous in massive hosts (significance >5σ), and decline more rapidly in massive hosts (significance >9σ) and in hosts with low specific star formation rates (significance >8σ). We study the variation of these relationships with redshift and detect no evolution. We split SNe Ia into pairs of subsets that are based on the properties of the hosts and fit cosmological models to each subset. Including both systematic and statistical uncertainties, we do not find any significant shift in the best-fit cosmological parameters between the subsets. Among different SN Ia subsets, we find that SNe Ia in hosts with high specific star formation rates have the least intrinsic scatter (σ int = 0.08 ± 0.01) in luminosity after standardization.

The Influence of Host Galaxies in Type Ia Supernova Cosmology

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

Uddin, Syed A.; Mould, Jeremy; Lidman, Chris

We use a sample of 1338 spectroscopically confirmed and photometrically classified Type Ia supernovae (SNe Ia) sourced from Carnegie Supernova Project, Center for Astrophysics Supernova Survey, Sloan Digital Sky Survey-II, and SuperNova Legacy Survey SN samples to examine the relationships between SNe Ia and the galaxies that host them. Our results provide confirmation with improved statistical significance that SNe Ia, after standardization, are on average more luminous in massive hosts (significance >5 σ ), and decline more rapidly in massive hosts (significance >9 σ ) and in hosts with low specific star formation rates (significance >8 σ ). We studymore » the variation of these relationships with redshift and detect no evolution. We split SNe Ia into pairs of subsets that are based on the properties of the hosts and fit cosmological models to each subset. Including both systematic and statistical uncertainties, we do not find any significant shift in the best-fit cosmological parameters between the subsets. Among different SN Ia subsets, we find that SNe Ia in hosts with high specific star formation rates have the least intrinsic scatter ( σ {sub int} = 0.08 ± 0.01) in luminosity after standardization.« less

[C ii] 158-μm emission from the host galaxies of damped Lyman-alpha systems.

PubMed

Neeleman, Marcel; Kanekar, Nissim; Prochaska, J Xavier; Rafelski, Marc; Carilli, Chris L; Wolfe, Arthur M

2017-03-24

Gas surrounding high-redshift galaxies has been studied through observations of absorption line systems toward background quasars for decades. However, it has proven difficult to identify and characterize the galaxies associated with these absorbers due to the intrinsic faintness of the galaxies compared with the quasars at optical wavelengths. Using the Atacama Large Millimeter/Submillimeter Array, we report on detections of [C ii] 158-μm line and dust-continuum emission from two galaxies associated with two such absorbers at a redshift of z ~ 4. Our results indicate that the hosts of these high-metallicity absorbers have physical properties similar to massive star-forming galaxies and are embedded in enriched neutral hydrogen gas reservoirs that extend well beyond the star-forming interstellar medium of these galaxies. Copyright © 2017, American Association for the Advancement of Science.

Do the Most Massive Black Holes at z = 2 Grow via Major Mergers?

NASA Astrophysics Data System (ADS)

Mechtley, M.; Jahnke, K.; Windhorst, R. A.; Andrae, R.; Cisternas, M.; Cohen, S. H.; Hewlett, T.; Koekemoer, A. M.; Schramm, M.; Schulze, A.; Silverman, J. D.; Villforth, C.; van der Wel, A.; Wisotzki, L.

2016-10-01

The most frequently proposed model for the origin of quasars holds that the high accretion rates seen in luminous active galactic nuclei (AGN) are primarily triggered during major mergers between gas-rich galaxies. While plausible for decades, this model has only begun to be tested with statistical rigor in the past few years. Here, we report on a Hubble Space Telescope study to test this hypothesis for z = 2 quasars with high supermassive black hole masses ({M}{BH}={10}9{--}{10}10 {M}⊙ ), which dominate cosmic black hole growth at this redshift. We compare Wide Field Camera 3 F160W (rest-frame V-band) imaging of 19 point source-subtracted quasar hosts to a matched sample of 84 inactive galaxies, testing whether the quasar hosts have greater evidence for strong gravitational interactions. Using an expert ranking procedure, we find that the quasar hosts are uniformly distributed within the merger sequence of inactive galaxies, with no preference for quasars in high-distortion hosts. Using a merger/non-merger cutoff approach, we recover distortion fractions of {f}{{m},{qso}}=0.39+/- 0.11 for quasar hosts and {f}{{m},{gal}}=0.30+/- 0.05 for inactive galaxies (distribution modes, 68% confidence intervals), with both measurements subjected to the same observational conditions and limitations. The slight enhancement in distorted fraction for quasar hosts over inactive galaxies is not significant, with a probability that the quasar fraction is higher P({f}{{m},{qso}}\\gt {f}{{m},{gal}})=0.78 (0.78σ ), in line with results for lower mass and lower z AGN. We find no evidence that major mergers are the primary triggering mechanism for the massive quasars that dominate accretion at the peak of cosmic quasar activity.

The early phase of the SMBH-galaxy coevolution in low-z "young" galaxies

NASA Astrophysics Data System (ADS)

Nagao, Tohru

2014-01-01

It is now widely recognized that most galaxies have a supermassive black hole (SMBH) in their nucleus, and the evolution of SMBHs is closely related with that of their host galaxies (the SMBH-galaxy coevolution). This is suggested by the correlation in the mass of SMBHs and their host galaxies, that has been observed in low redshifts. However, the physics of the coevolution is totally unclear, that prevents us from complete understandings of the galaxy evolution. One possible strategy to tackle this issue is measuring the mass ratio between SMBHs and their host galaxies (M_BH/M_host) at high redshifs, since different scenarios predict different evolution of the ratio ofMBH/Mhost. However it is extremely challenging to measure the mass of the host of high-z quasars, given the faint surface brightness of the host at close to the glaring quasar nucleus. Here we propose a brand-new approach to assess the early phase of the SMBH-galaxy coevolution, by focusing on low-z AGN-hosting "young" galaxies. Specifically, we focus on some very metal-poor galaxies with broadline Balmer lines at z ~ 0.1 - 0.3. By examining the SMBH scaling relations in some low-z metal-poor AGNs through high-resolution IRCS imaging observations, we will discriminate various scenarios for the SMBH-galaxy coevolution.

The host galaxies of ultra hard X-ray selected AGN

NASA Astrophysics Data System (ADS)

Koss, Michael J.

One of the great mysteries surrounding active galactic nuclei (AGN) is their triggering mechanism. Since the discovery that almost all massive galaxies host nuclear supermassive black holes, it has become clear that a trigger mechanism is required to 'turn on' and continue to fuel the central black hole. While it is established that accretion processes are responsible for the energy emitted, the source of the accreting material is still controversial. Furthermore, the energy input from phases of black hole growth is thought to be a key regulator in the formation of galaxies and the establishment of various scaling relations. Theorists often invoke galaxy mergers as the violent mechanism to drive gas into the central regions and ignite luminous quasars, but among more common moderate luminosity AGN, there has been great controversy whether secular processes or mergers dominate AGN fueling. A survey in the ultra hard X-ray band (14--195 keV) is an important new way to answer the fundamental question of AGN fueling. This method is independent of selection effects such as dust extinction and obscuration that plague surveys at other wavelengths because of the ability of the primary continuum to easily pass through large columns of obscuring gas and dust (<10 24 cm-2). In this PhD, we have assembled the largest sample of ultra hard X-ray selected AGN with host galaxy optical data to date, with 185 nearby (z<0.05), moderate luminosity AGN from the Swift BAT sample. We find that these AGN show much higher rates of both mergers and massive spirals suggesting both mergers and accretion of cold gas in late type systems are important in AGN fueling. We also find that the most common AGN survey technique, optical line diagnostics, is heavily biased against finding AGN in mergers or spirals. Finally, in agreement with the merger driven AGN link, we find that dual AGN systems may be more common than current observation suggest since some of them are only detected using high

Host Galaxies Of Luminous Z ˜ 0.6 Quasars: Major Mergers Are Not Prevalent At The Highest Agn Luminosities

NASA Astrophysics Data System (ADS)

Villforth, Carolin; Hamilton, T.; Pawlik, M. M.; Hewlett, T.; Rowlands, K.; Herbst, H.; Shankar, F.; Fontana, A.; Hamann, F.; Koekemoer, A.; Pforr, J.; Trump, J.; Wuyts, S.

2017-06-01

Galaxy interactions are thought to be one of the main triggers of active galactic nuclei (AGN), especially at high luminosities, where the accreted gas mass during the AGN lifetime is substantial. Evidence for a connection between mergers and AGN, however, remains mixed. Possible triggering mechanisms remain particularly poorly understood for luminous AGN, which are thought to require triggering by major mergers, rather than secular processes. We analyse the host galaxies of a sample of 20 optically and X-ray selected luminous AGN (log(Lbol [erg s-1]) > 45) at z ˜ 0.6 using Hubble Space Telescope Wide Field Camera 3 data in the F160W/H band. 15/20 sources have resolved host galaxies. We create a control sample of mock AGN by matching the AGN host galaxies to a control sample of non-AGN galaxies. Visual signs of disturbances are found in about 25 per cent of sources in both the AGN hosts and control galaxies. Using both visual classification and quantitative morphology measures, we show that the levels of disturbance are not enhanced when compared to a matched control sample. We find no signs that major mergers play a dominant role in triggering AGN at high luminosities, suggesting that minor mergers and secular processes dominate AGN triggering up to the highest AGN luminosities. The upper limit on the enhanced fraction of major mergers is ≤20 per cent. While major mergers might increase the incidence of luminous AGN, they are not the prevalent triggering mechanism in the population of unobscured AGN.

Host galaxies of luminous z ˜ 0.6 quasars: major mergers are not prevalent at the highest AGN luminosities

NASA Astrophysics Data System (ADS)

Villforth, C.; Hamilton, T.; Pawlik, M. M.; Hewlett, T.; Rowlands, K.; Herbst, H.; Shankar, F.; Fontana, A.; Hamann, F.; Koekemoer, A.; Pforr, J.; Trump, J.; Wuyts, S.

2017-04-01

Galaxy interactions are thought to be one of the main triggers of active galactic nuclei (AGN), especially at high luminosities, where the accreted gas mass during the AGN lifetime is substantial. Evidence for a connection between mergers and AGN, however, remains mixed. Possible triggering mechanisms remain particularly poorly understood for luminous AGN, which are thought to require triggering by major mergers, rather than secular processes. We analyse the host galaxies of a sample of 20 optically and X-ray selected luminous AGN (log(Lbol [erg s-1]) > 45) at z ˜ 0.6 using Hubble Space Telescope Wide Field Camera 3 data in the F160W/H band. 15/20 sources have resolved host galaxies. We create a control sample of mock AGN by matching the AGN host galaxies to a control sample of non-AGN galaxies. Visual signs of disturbances are found in about 25 per cent of sources in both the AGN hosts and control galaxies. Using both visual classification and quantitative morphology measures, we show that the levels of disturbance are not enhanced when compared to a matched control sample. We find no signs that major mergers play a dominant role in triggering AGN at high luminosities, suggesting that minor mergers and secular processes dominate AGN triggering up to the highest AGN luminosities. The upper limit on the enhanced fraction of major mergers is ≤20 per cent. While major mergers might increase the incidence of luminous AGN, they are not the prevalent triggering mechanism in the population of unobscured AGN.

First Results from the ISO-IRAS Faint Galaxy Survey

NASA Astrophysics Data System (ADS)

Levine, Deborah A.; Lonsdale, Carol J.; Hurt, Robert L.; Smith, Harding E.; Helou, George; Beichman, Charles; Cesarsky, Catherine; Elbaz, David; Klaas, Ulrich; Laureijs, Rene; Lemke, Detrich; Lord, Steven; McMahon, Richard; Moshir, Mehrdad; Neugebauer, Gerry; Soifer, B. T.; Van Buren, Dave; Wehrle, Ann; Wolstencroft, Ray

1998-09-01

We present the first results from the ISO-IRAS Faint Galaxy Survey (IIFGS), a program designed to obtain ISO observations of the most distant and luminous galaxies in the IRAS Faint Source Survey by filling short gaps in the ISO observing schedule with pairs of 12 μm ISOCAM and 90 μm ISOPHOT observations. As of 1997 October, over 500 sources have been observed, with an ISOCAM detection rate over 80%, covering over 1.25 deg2 of sky to an 11.5 μm point-source completeness limit of approximately 1.0 mJy (corresponding to a ~10 σ detection sensitivity). Observations are presented for nine sources detected by ISOPHOT and ISOCAM early in the survey for which we have ground-based G- and I-band images and optical spectroscopy. The ground-based data confirm that the IIFGS strategy efficiently detects moderate-redshift (z = 0.11-0.38 for this small sample) strong emission line galaxies with L60 μm >~ 1011 L⊙ one of our sample has L60 μm > 1012 L⊙ (H0 = 75 km s-1 Mpc-1, Ω = 1). The infrared-optical spectral energy distributions are comparable to those of nearby luminous infrared galaxies, which span the range from pure starburst (e.g., Arp 220) to infrared QSO (Mrk 231). Two of the systems show signs of strong interaction, and four show active galactic nucleus (AGN)-like excitation; one of the AGNs, F15390+6038, which shows a high excitation Seyfert 2 spectrum, has an unusually warm far- to mid-infrared color and may be an obscured QSO. The IIFGS sample is one of the largest and deepest samples of infrared-luminous galaxies available, promising to be a rich sample for studying infrared-luminous galaxies up to z ~ 1 and for understanding the evolution of infrared galaxies and the star formation rate in the universe. 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 the participation of ISAS and NASA.

Discovery of a Dwarf Poststarburst Galaxy near a High Column Density Local Lyα Absorber

NASA Astrophysics Data System (ADS)

Stocke, John T.; Keeney, Brian A.; McLin, Kevin M.; Rosenberg, Jessica L.; Weymann, R. J.; Giroux, Mark L.

2004-07-01

We report the discovery of a dwarf (MB=-13.9) poststarburst galaxy coincident in recession velocity (within uncertainties) with the highest column density absorber (NHI=1015.85 cm-2 at cz=1586 km s- 1) in the 3C 273 sight line. This galaxy is by far the closest galaxy to this absorber, projected just 71h-170 kpc on the sky from the sight line. The mean properties of the stellar populations in this galaxy are consistent with a massive starburst ~3.5 Gyr ago, whose attendant supernovae, we argue, could have driven sufficient gas from this galaxy to explain the nearby absorber. Beyond its proximity on the sky and in recession velocity, the further evidence in favor of this conclusion includes both a match in the metallicities of absorber and galaxy and the fact that the absorber has an overabundance of Si/C, suggesting recent Type II supernova enrichment. Thus, this galaxy and its ejecta are in the expected intermediate stage in the fading dwarf evolutionary sequence envisioned by Babul & Rees to explain the abundance of faint blue galaxies at intermediate redshifts. While this one instance of a QSO metal-line absorber and a nearby dwarf galaxy is not proof of a trend, a similar dwarf galaxy would be too faint to be observed by galaxy surveys around more distant metal-line absorbers. Thus, we cannot exclude the possibility that dwarf galaxies are primarily responsible for weak (NHI=1014-1017 cm-2) metal-line absorption systems in general. If a large fraction of the dwarf galaxies expected to exist at high redshift had a similar history (i.e., they had a massive starburst that removed all or most of their gas), these galaxies could account for at least several hundred high-z metal-line absorbers along the line of sight to a high-z QSO. The volume-filling factor for this gas, however, would be less than 1%. ID="FN1"> 1Based on observations made with the Apache Point 3.5 m telescope, operated by the Astronomical Research Consortium, and the 2.6 m du Pont telescope of the

The z = 1.6748 C I Absorber Toward the QSO PKS 1756+237

NASA Astrophysics Data System (ADS)

Roth, Katherine C.; Bauer, James M.; Jim, Kevin T. C.

We have detected C I ground-state absorption at zabs = 1.6748 toward the QSO PKS 1756+237 (zem = 1.725), making this only the fourth known C I QSO absorber. The absence of excited-state fine-structure C I lines is compatible with the redshifted Cosmic Microwave Background Radiation at an expected temperature of TCMBR (1+z) = 7.291 K (Mather et al. 1994, ApJ, 354, L37). We find a 2 σ upper-limit on the C I excitation temperature of Tex <= 7.73(+0.53, -0.46) K (Roth & Bauer 1999, ApJ, submitted). Our Keck HIRES spectra (8.3 km s-1 FWHM) obtained in May 1997 also reveal the existence of Ni II and Fe II lines with a sub-solar Ni/Fe abundance ratio, presumably indicative of dust. We have obtained deep, high resolution (0.3'' FWHM) images in H+K' with the UH 2.2m Tip-Tilt system of the QSO field in order to identify the system responsible for the zabs = 1.6748 absorption. We detect two faint candidate systems within 1.5'' and 3'' (≅ 15 and 30 kpc, Hcirc = 65) of the QSO.

The host galaxy of a fast radio burst.

PubMed

Keane, E F; Johnston, S; Bhandari, S; Barr, E; Bhat, N D R; Burgay, M; Caleb, M; Flynn, C; Jameson, A; Kramer, M; Petroff, E; Possenti, A; van Straten, W; Bailes, M; Burke-Spolaor, S; Eatough, R P; Stappers, B W; Totani, T; Honma, M; Furusawa, H; Hattori, T; Morokuma, T; Niino, Y; Sugai, H; Terai, T; Tominaga, N; Yamasaki, S; Yasuda, N; Allen, R; Cooke, J; Jencson, J; Kasliwal, M M; Kaplan, D L; Tingay, S J; Williams, A; Wayth, R; Chandra, P; Perrodin, D; Berezina, M; Mickaliger, M; Bassa, C

2016-02-25

In recent years, millisecond-duration radio signals originating in distant galaxies appear to have been discovered in the so-called fast radio bursts. These signals are dispersed according to a precise physical law and this dispersion is a key observable quantity, which, in tandem with a redshift measurement, can be used for fundamental physical investigations. Every fast radio burst has a dispersion measurement, but none before now have had a redshift measurement, because of the difficulty in pinpointing their celestial coordinates. Here we report the discovery of a fast radio burst and the identification of a fading radio transient lasting ~6 days after the event, which we use to identify the host galaxy; we measure the galaxy's redshift to be z = 0.492 ± 0.008. The dispersion measure and redshift, in combination, provide a direct measurement of the cosmic density of ionized baryons in the intergalactic medium of ΩIGM = 4.9 ± 1.3 per cent, in agreement with the expectation from the Wilkinson Microwave Anisotropy Probe, and including all of the so-called 'missing baryons'. The ~6-day radio transient is largely consistent with the radio afterglow of a short γ-ray burst, and its existence and timescale do not support progenitor models such as giant pulses from pulsars, and supernovae. This contrasts with the interpretation of another recently discovered fast radio burst, suggesting that there are at least two classes of bursts.

Multi-Wavelength Analysis of Active Galactic Nuclei and Host Galaxies Physical Properties

NASA Astrophysics Data System (ADS)

Azadi, Mojegan

In this dissertation we study the properties of active galactic nuclei (AGN), which are powered by the accretion activity of supermassive black holes residing at the centers of galaxies. While observations propose that growth of AGN and galaxies are globally tied, we investigate whether this connection exists in individual galaxies. We also investigate various AGN selection techniques and star formation rate (SFR) estimates using multi-wavelength data from Chandra, Spitzer and rest-frame optical spectra from the Keck telescope. We find that combining multi-wavelength identification techniques provides a more complete AGN sample, as each selection method suffers from selection biases. In particular, all selection techniques are biased against identifying AGN in lower mass galaxies. Once stellar mass selection biases are taken into account, we find that AGN reside in galaxies with similar physical properties (i.e., SFR) as inactive galaxies. We find that while AGN are prevalent in both star-forming and quiescent galaxies, AGN of a given accretion rate are more likely to reside in star-forming galaxies. The probability of fueling an AGN does not strongly depend on SFR for a star-forming galaxy, though it decreases when star formation is shut down in quiescent galaxies. We also find no evidence for a strong correlation between SFR or stellar mass of the host galaxy and AGN luminosity. These results indicate that while both AGN and galaxy growth are reliant on the same fuel, enhanced star formation activity does not necessarily go hand-in-hand with increased AGN activity. While the star formation activity of galaxies can be traced with various indicators, our investigations indicate that extrapolations from mid-infrared data using calibrations based on local galaxies overestimates SFRs at higher redshift. We show that a combina- tion of mid-infrared and far-infrared data provide a more reliable SFR estimation than the mid-infrared data alone. We also find that the

A catalogue of faint local radio AGN and the properties of their host galaxies

NASA Astrophysics Data System (ADS)

Lofthouse, E. K.; Kaviraj, S.; Smith, D. JB; Hardcastle, M. J.

2018-05-01

We present a catalogue of local (z < 0.1) galaxies that contain faint AGN. We select these objects by identifying galaxies that exhibit a significant excess in their radio luminosities, compared to what is expected from the observed levels of star-formation activity in these systems. This is achieved by comparing the optical (spectroscopic) star formation rate (SFR) to the 1.4 GHz luminosity measured from the FIRST survey. The majority of the AGN identified in this study are fainter than those in previous work, such as in the Best and Heckman (2012) catalogue. We show that these faint AGN make a non-negligible contribution to the radio luminosity function at low luminosities (below 1022.5 W Hz-1), and host ˜13 per cent of the local radio luminosity budget. Their host galaxies are predominantly high stellar-mass systems (with a median stellar mass of 1011M⊙), are found across a range of environments (but typically in denser environments than star-forming galaxies) and have early-type morphologies. This study demonstrates a general technique to identify AGN in galaxy populations where reliable optical SFRs can be extracted using spectro-photometry and where radio data are also available so that a radio excess can be measured. Our results also demonstrate that it is unsafe to infer SFRs from radio emission alone, even if bright AGN have been excluded from a sample, since there is a significant population of faint radio AGN which may contaminate the radio-derived SFRs.

The Quasar Pairs Environment At z ∼ 0.5

NASA Astrophysics Data System (ADS)

Sandrinelli, Angela; Falomo, R.; Treves, A.; Scarpa, R.; Uslenghi, M.

2016-10-01

We analyze the environment of a sample of 20 quasar physical pairs at 0.4QSO activity and their environments. In particular we aim to explore if QSO that are embedded the same galaxy environment (projected distance < 0.5 Mpc) inhabit different environments than isolated QSO of similar luminosity. The galaxy environments of QSO pairs as derived from SDSS imaging data is compared with a larger sample of isolated QSO matched in terms of redshift and luminosityFrom the comparison of the two samples we find the the galaxy density at 250 kpc from the QSO that are in pairs is about a factor 2 larger than that of isolated QSO. In addition we also complement these imaging study with high quality optical spectroscopy gathered at GTC in La Palma to get info on the dynamic of the systemsImplications of these results based on a small (but "complete") sample are briefly discussed.

The host of the Type I SLSN 2017egm. A young, sub-solar metallicity environment in a massive spiral galaxy

NASA Astrophysics Data System (ADS)

Izzo, L.; Thöne, C. C.; García-Benito, R.; de Ugarte Postigo, A.; Cano, Z.; Kann, D. A.; Bensch, K.; Della Valle, M.; Galadí-Enríquez, D.; Hedrosa, R. P.

2018-02-01

Context. Type I superluminous supernova (SLSN) host galaxies are predominantly low-metallicity, highly star-forming (SF) dwarfs. One of the current key questions is whether Type I SLSNe can only occur in such environments and hosts. Aims: Here we present an integral-field study of the massive, high-metallicity spiral NGC 3191, the host of SN 2017egm, the closest Type I SLSN known to date. We use data from PMAS/CAHA and the public MaNGA survey to shed light on the properties of the SLSN site and the origin of star formation in this non-starburst spiral galaxy. Methods: We map the physical properties of different H II regions throughout the galaxy and characterise their stellar populations using the STARLIGHT fitting code. Kinematical information allows us to study a possible interaction with its neighbouring galaxy as the origin of recent star formation activity which could have caused the SLSN. Results: NGC 3191 shows intense star formation in the western part with three large SF regions of low metallicity. Taking only the properties of emitting gas, the central regions of the host have a higher metallicity, a lower specific star formation rate, and lower ionisation. Modelling the stellar populations gives a different picture: the SLSN region has two dominant stellar populations with different ages, the younger one with an age of 2-10 Myr and lower metallicity, likely the population from which the SN progenitor originated. Emission line kinematics of NGC 3191 show indications of interaction with its neighbour MCG+08-19-017 at 45 kpc, which might be responsible for the recent starburst. In fact, this galaxy pair has hosted a total of four SNe, 1988B (Type Ia), SN 2003ds (Type Ic in MCG+08-19-017), PTF10bgl (Type II), and 2017egm, underlying the enhanced SF in both galaxies due to interaction. Conclusions: Our study shows that care should be taken when interpreting global host and even gas properties without looking at the stellar population history of the region

The middle infrared properties of OH megamaser host galaxies

NASA Astrophysics Data System (ADS)

Zhang, J. S.; Wang, J. Z.; Di, G. X.; Zhu, Q. F.; Guo, Q.; Wang, J.

2014-10-01

We compiled all 119 OH maser galaxies (110 out of them are megamasers, i.e., LOH> 10 L⊙) published so far and cross-identified these OH masers with the Wide-Field Infrared Survey Explorer (WISE) catalog, to investigate the middle infrared (MIR) properties of OH maser galaxies. The WISE magnitude data at the 3.4, 4.6, 12 and 22 μm (W1 to W4) are collected for the OH maser sample and one control sample, which are non-detection sources. The color-color diagrams show that both OH megamaser (OHM) and non-OHM (ultra)luminous infrared galaxies ((U)LIRGs) are far away from the single blackbody model line and many of them can follow the path described by the power-law model. The active galaxy nuclei (AGN) fraction is about ~40% for both OHM and non-OHM (U)LIRGs, according to the AGN criteria W1 - W2 ≥ 0.8. Among the Arecibo survey sample, OHM sources tend to have a lower luminosity at short MIR wavelengths (e.g., 3.4 μm and 4.6 μm) than that of non-OHM sources, which should come from the low OHM fraction among the survey sample with large 3.4 μm and 4.6 μm luminosity. The OHM fraction tends to increase with cooler MIR colors (larger F22 μm/F3.4 μm). These may be good for sample selection when searching OH megamasers, such as excluding extreme luminous sources at short MIR wavelengths, choosing sources with cooler MIR colors. In the case of the power-law model, we derived the spectral indices for our samples. For the Arecibo survey sample, OHM (U)LIRGs tend to have larger spectral index α22-12 than non-OHM sources, which agrees with previous results. One significant correlation exists between the WISE infrared luminosity at 22μm and the color [W1]-[W4] for the Arecibo OHM hosts. These clues should provide suitable constraints on the sample selection for OH megamaser surveys by future advanced telescopes (e.g., FAST). In addition, the correlation of maser luminosity and the MIR luminosity of maser hosts tends to be non-significant, which may indirectly support

The Large Area Radio Galaxy Evolution Spectroscopic Survey (LARGESS): survey design, data catalogue and GAMA/WiggleZ spectroscopy

NASA Astrophysics Data System (ADS)

Ching, John H. Y.; Sadler, Elaine M.; Croom, Scott M.; Johnston, Helen M.; Pracy, Michael B.; Couch, Warrick J.; Hopkins, A. M.; Jurek, Russell J.; Pimbblet, K. A.

2017-01-01

We present the Large Area Radio Galaxy Evolution Spectroscopic Survey (LARGESS), a spectroscopic catalogue of radio sources designed to include the full range of radio AGN populations out to redshift z ˜ 0.8. The catalogue covers ˜800 deg2 of sky, and provides optical identifications for 19 179 radio sources from the 1.4 GHz Faint Images of the Radio Sky at Twenty-cm (FIRST) survey down to an optical magnitude limit of Imod < 20.5 in Sloan Digital Sky Survey (SDSS) images. Both galaxies and point-like objects are included, and no colour cuts are applied. In collaboration with the WiggleZ and Galaxy And Mass Assembly (GAMA) spectroscopic survey teams, we have obtained new spectra for over 5000 objects in the LARGESS sample. Combining these new spectra with data from earlier surveys provides spectroscopic data for 12 329 radio sources in the survey area, of which 10 856 have reliable redshifts. 85 per cent of the LARGESS spectroscopic sample are radio AGN (median redshift z = 0.44), and 15 per cent are nearby star-forming galaxies (median z = 0.08). Low-excitation radio galaxies (LERGs) comprise the majority (83 per cent) of LARGESS radio AGN at z < 0.8, with 12 per cent being high-excitation radio galaxies (HERGs) and 5 per cent radio-loud QSOs. Unlike the more homogeneous LERG and QSO sub-populations, HERGs are a heterogeneous class of objects with relatively blue optical colours and a wide dispersion in mid-infrared colours. This is consistent with a picture in which most HERGs are hosted by galaxies with recent or ongoing star formation as well as a classical accretion disc.

The connection between globular cluster systems and their host galaxy and environment: a case study of the isolated elliptical NGC 821

NASA Astrophysics Data System (ADS)

Spitler, Lee R.; Forbes, Duncan A.; Strader, Jay; Brodie, Jean P.; Gallagher, Jay S.

2008-03-01

In an effort to probe the globular cluster (GC) system of an isolated elliptical galaxy, a comprehensive analysis of the NGC 821 GC system was performed. New imaging from the WIYN Mini-Mosaic imager, supplemented with Hubble Space Telescope (HST) WFPC2 images reveals a GC system similar to those found in counterpart ellipticals located in high-density environments. To put these results into the context of galaxy formation, a robustly determined census of GC systems is presented and analysed for galaxies spanning a wide range of masses (> M*), morphologies and environments. Results from this meta-study: (1) confirm previous findings that the number of GCs normalized by host galaxy stellar mass increases with host stellar mass. Spiral galaxies in the sample show smaller relative GC numbers than those of massive ellipticals, suggesting the GC systems of massive ellipticals were not formed from major spiral-spiral mergers; (2) indicate that GC system numbers per unit galaxy baryon mass increases with host baryon mass and that GC formation efficiency may not be universal as previously thought; (3) suggest previously reported trends with environment may be incorrect due to sample bias or the use of galaxy stellar masses to normalize GC numbers. Thus claims for environmentally dependent GC formation efficiencies should be revisited; (4) in combination with weak-lensing halo mass estimates, suggest that GCs formed in direct proportion to the halo mass; (5) are consistent with theoretical predictions whereby the local epoch of reionization did not vary significantly with environment or host galaxy type. Based upon data from the WIYN Observatory, which is a joint facility of the University of Wisconsin-Madison, Indiana University, Yale University and the National Optical Astronomy Observatories. Also includes analysis of observations made with the Hubble Space Telescope obtained from the ESO/ST-ECF Science Archive Facility. E-mail: lspitler@astro.swin.edu.au

Is Black Hole Growth a Universal Process? Exploring Selection Effects in Measurements of AGN Accretion Rates and Host Galaxies.

NASA Astrophysics Data System (ADS)

Jones, Mackenzie

2018-01-01

At the center of essentially every massive galaxy is a monstrous black hole producing luminous radiation driven by the accretion of gas. By observing these active galactic nuclei (AGN) we may trace the growth of black holes across cosmic time. However, our knowledge of the full underlying AGN population is hindered by complex observational biases. My research aims to untangle these biases by using a novel approach to simulate the impact of selection effects on multiwavelength observations.The most statistically powerful studies of AGN to date come from optical spectroscopic surveys, with some reporting a complex relationship between AGN accretion rates and host galaxy characteristics. However, the optical waveband can be strongly influenced by selection effects and dilution from host galaxy star formation. I have shown that accounting for selection effects, the Eddington ratio distribution for optically-selected AGN is consistent with a broad power-law, as seen in the X-rays (Jones et al. 2016). This suggests that a universal Eddington ratio distribution may be enough to describe the full multiwavelength AGN population.Building on these results, I have expanded a semi-numerical galaxy formation simulation to include this straightforward prescription for AGN accretion and explicitly model selection effects. I have found that a simple model for AGN accretion can broadly reproduce the host galaxies and halos of X-ray AGN, and that different AGN selection techniques yield samples with very different host galaxy properties (Jones et al. 2017). Finally, I will discuss the capabilities of this simulation to build synthetic multiwavelength SEDs in order to explore what AGN populations would be detected with the next generation of observatories. This research is supported by a NASA Jenkins Graduate Fellowship under grant no. NNX15AU32H.

Black Hole Growth Is Mainly Linked to Host-galaxy Stellar Mass Rather Than Star Formation Rate

NASA Astrophysics Data System (ADS)

Yang, G.; Chen, C.-T. J.; Vito, F.; Brandt, W. N.; Alexander, D. M.; Luo, B.; Sun, M. Y.; Xue, Y. Q.; Bauer, F. E.; Koekemoer, A. M.; Lehmer, B. D.; Liu, T.; Schneider, D. P.; Shemmer, O.; Trump, J. R.; Vignali, C.; Wang, J.-X.

2017-06-01

We investigate the dependence of black hole accretion rate (BHAR) on host-galaxy star formation rate (SFR) and stellar mass (M *) in the CANDELS/GOODS-South field in the redshift range of 0.5≤slant z< 2.0. Our sample consists of ≈ {{18,000}} galaxies, allowing us to probe galaxies with 0.1{M}⊙ {{yr}}-1≲ {SFR}≲ 100 {M}⊙ {{yr}}-1 and/or {10}8{M}⊙ ≲ {M}* ≲ {10}11 {M}⊙ . We use sample-mean BHAR to approximate long-term average BHAR. Our sample-mean BHARs are derived from the Chandra Deep Field-South 7 Ms observations, while the SFRs and M * have been estimated by the CANDELS team through spectral energy distribution fitting. The average BHAR is correlated positively with both SFR and M *, and the BHAR-SFR and BHAR-M * relations can both be described acceptably by linear models with a slope of unity. However, BHAR appears to be correlated more strongly with M * than SFR. This result indicates that M * is the primary host-galaxy property related to supermassive black hole (SMBH) growth, and the apparent BHAR-SFR relation is largely a secondary effect due to the star-forming main sequence. Among our sources, massive galaxies ({M}* ≳ {10}10{M}⊙ ) have significantly higher BHAR/SFR ratios than less massive galaxies, indicating that the former have higher SMBH fueling efficiency and/or higher SMBH occupation fraction than the latter. Our results can naturally explain the observed proportionality between {M}{BH} and M * for local giant ellipticals and suggest that their {M}{BH}/{M}* is higher than that of local star-forming galaxies. Among local star-forming galaxies, massive systems might have higher {M}{BH}/{M}* compared to dwarfs.

Quasar outflows at z ≥ 6: the impact on the host galaxies

NASA Astrophysics Data System (ADS)

Barai, Paramita; Gallerani, Simona; Pallottini, Andrea; Ferrara, Andrea; Marconi, Alessandro; Cicone, Claudia; Maiolino, Roberto; Carniani, Stefano

2018-01-01

We investigate quasar outflows at z ≥ 6 by performing zoom-in cosmological hydrodynamical simulations. By employing the smoothed particle hydrodynamics code GADGET-3, we zoom in the 2R200 region around a 2 × 1012 M⊙ halo at z = 6, inside a (500 Mpc)3 comoving volume. We compare the results of our active galactic nuclei (AGN) runs with a control simulation in which only stellar/SN feedback is considered. Seeding 105 M⊙ black holes (BHs) at the centres of 109 M⊙ haloes, we find the following results. BHs accrete gas at the Eddington rate over z = 9-6. At z = 6, our most-massive BH has grown to MBH = 4 × 109 M⊙. Fast (vr > 1000 km s-1), powerful (\\dot{M}_out ˜ 2000 M_{⊙} yr-1) outflows of shock-heated low-density gas form at z ∼ 7, and propagate up to hundreds kpc. Star formation is quenched over z = 8-6, and the total star formation rate (SFR surface density near the galaxy centre) is reduced by a factor of 5 (1000). We analyse the relative contribution of multiple physical process: (i) disrupting cosmic filamentary cold gas inflows, (ii) reducing central gas density, (iii) ejecting gas outside the galaxy; and find that AGN feedback has the following effects at z = 6. The inflowing gas mass fraction is reduced by ∼ 12 per cent, the high-density gas fraction is lowered by ∼ 13 per cent, and ∼ 20 per cent of the gas outflows at a speed larger than the escape velocity (500 km s-1). We conclude that quasar-host galaxies at z ≥ 6 are accreting non-negligible amount of cosmic gas, nevertheless AGN feedback quenches their star formation dominantly by powerful outflows ejecting gas out of the host galaxy halo.

Host galaxy and environment of the BL Lacertae object PKS 0548-322: Observations with subarcsecond resolution

NASA Technical Reports Server (NTRS)

Falomo, Renato; Pesce, Joseph E.; Treves, Aldo

1995-01-01

We report on direct, subarcsecond resolution imaging of the nebulosity and spectroscopy of galaxies in the field of the BL Lacertae object PKS 0548-322. Surface photometry of the nebulosity is used to derive the properties of the host galaxy (M(sub V) = -23.4), which exhibits signs of interaction with a close companion galaxy at approximately 25 kpc. The radial brightness profile of the nebulosity is well fitted by the contribution of a bulge (r(exp 1/4)) plus a point source and a small internal disk. An analysis of the galaxies in the field shows that the source is located in a rich cluster of galaxies. Spectra of five galaxies in the field indicate that they are at the same redshift as the BL Lac object, thus supporting the imaging result of a surrounding cluster associated with the BL Lac. This cluster is most likely Abell S0549.

Empirical Constraints on the Origin of Fast Radio Bursts: Volumetric Rates and Host Galaxy Demographics as a Test of Millisecond Magnetar Connection

NASA Astrophysics Data System (ADS)

Nicholl, M.; Williams, P. K. G.; Berger, E.; Villar, V. A.; Alexander, K. D.; Eftekhari, T.; Metzger, B. D.

2017-07-01

The localization of the repeating fast radio burst (FRB) 121102 to a low-metallicity dwarf galaxy at z = 0.193, and its association with a luminous quiescent radio source, suggests the possibility that FRBs originate from magnetars, formed by the unusual supernovae that occur in such galaxies. We investigate this possibility via a comparison of magnetar birth rates, the FRB volumetric rate, and host galaxy demographics. We calculate average volumetric rates of possible millisecond magnetar production channels, such as superluminous supernovae (SLSNe), long and short gamma-ray bursts (GRBs), and general magnetar production via core-collapse supernovae (CCSNe). For each channel, we also explore the expected host galaxy demographics using their known properties. We determine for the first time the number density of FRB emitters (the product of their volumetric birth rate and lifetime), {R}{FRB}τ ≈ {10}4 Gpc-3, assuming that FRBs are predominantly emitted from repetitive sources similar to FRB 121102 and adopting a beaming factor of 0.1. By comparing rates, we find that production via rare channels (SLSNe, GRBs) implies a typical FRB lifetime of ˜30-300 years, in good agreement with other lines of argument. The total energy emitted over this time is consistent with the available energy stored in the magnetic field. On the other hand, any relation to magnetars produced via normal CCSNe leads to a very short lifetime of ˜0.5 years, in conflict with both theory and observation. We demonstrate that due to the diverse host galaxy distributions of the different progenitor channels, many possible sources of FRB birth can be ruled out with ≲ 10 host galaxy identifications. Conversely, targeted searches of galaxies that have previously hosted decades-old SLSNe and GRBs may be a fruitful strategy for discovering new FRBs and related quiescent radio sources, and determining the nature of their progenitors.

Matching Supernovae to Galaxies

NASA Astrophysics Data System (ADS)

Kohler, Susanna

2016-12-01

One of the major challenges for modern supernova surveys is identifying the galaxy that hosted each explosion. Is there an accurate and efficient way to do this that avoids investing significant human resources?Why Identify Hosts?One problem in host galaxy identification. Here, the supernova lies between two galaxies but though the centroid of the galaxy on the right is closer in angular separation, this may be a distant background galaxy that is not actually near the supernova. [Gupta et al. 2016]Supernovae are a critical tool for making cosmological predictions that help us to understand our universe. But supernova cosmology relies on accurately identifying the properties of the supernovae including their redshifts. Since spectroscopic followup of supernova detections often isnt possible, we rely on observations of the supernova host galaxies to obtain redshifts.But how do we identify which galaxy hosted a supernova? This seems like a simple problem, but there are many complicating factors a seemingly nearby galaxy could be a distant background galaxy, for instance, or a supernovas host could be too faint to spot.The authors algorithm takes into account confusion, a measure of how likely the supernova is to be mismatched. In these illustrations of low (left) and high (right) confusion, the supernova is represented by a blue star, and the green circles represent possible host galaxies. [Gupta et al. 2016]Turning to AutomationBefore the era of large supernovae surveys, searching for host galaxies was done primarily by visual inspection. But current projects like the Dark Energy Surveys Supernova Program is finding supernovae by the thousands, and the upcoming Large Synoptic Survey Telescope will likely discover hundreds of thousands. Visual inspection will not be possible in the face of this volume of data so an accurate and efficient automated method is clearly needed!To this end, a team of scientists led by Ravi Gupta (Argonne National Laboratory) has recently

Black Hole Caught Zapping Galaxy into Existence?

NASA Astrophysics Data System (ADS)

2009-11-01

across the whole electromagnetic spectrum; particularly spectacular is the case of quasars, where the active core is so overwhelmingly bright that it outshines the luminosity of the host galaxy. [2] This part of the study is based on observations performed at mid-infrared wavelengths, with the powerful VLT spectrometer and imager for the mid-infrared (VISIR) instrument at the VLT, combined with additional data including: spectra acquired using VLT-FORS, optical and infrared images from the NASA/ESA Hubble Space Telescope, and radio observations from the Australia Telescope National Facility. [3] Most galaxies in the local Universe contain a supermassive black hole with a mass about 1/700th the mass of the stellar bulge. The origin of this black hole mass versus stellar mass relation is one of the most debated subjects in modern astrophysics. More information This research was presented in papers published in the journal Astronomy & Astrophysics: "Quasar induced galaxy formation: a new paradigm?" by Elbaz et al., and in the Astrophysical Journal "The QSO HE0450-2958: Scantily dressed or heavily robed? A normal quasar as part of an unusual ULIRG" by Jahnke et al. The team is composed of David Elbaz (Service d'Astrophysique, CEA Saclay, France), Knud Jahnke (Max Planck Institute for Astronomy, Heidelberg, Germany), Eric Pantin (Service d'Astrophysique, CEA Saclay, France), Damien Le Borgne (Paris University 6 and CNRS, Institut d'Astrophysique de Paris, France) and Géraldine Letawe (Institut d'Astrophysique et de Géophysique, Université de Liège, Belgium). 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

Why are classical bulges more common in S0 galaxies than in spiral galaxies?

NASA Astrophysics Data System (ADS)

Mishra, Preetish K.; Wadadekar, Yogesh; Barway, Sudhanshu

2018-05-01

In this paper, we try to understand why the classical bulge fraction observed in S0 galaxies is significantly higher than that in spiral galaxies. We carry out a comparative study of the bulge and global properties of a sample of spiral and S0 galaxies in a fixed environment. Our sample is flux limited and contains 262 spiral and 155 S0 galaxies drawn from the Sloan Digital Sky Survey. We have classified bulges into classical and pseudobulge categories based on their position on the Kormendy diagram. Dividing our sample into bins of galaxy stellar mass, we find that the fraction of S0 galaxies hosting a classical bulge is significantly higher than the classical bulge fraction seen in spirals even at fixed stellar mass. We have compared the bulge and the global properties of spirals and S0 galaxies in our sample and find indications that spiral galaxies which host a classical bulge, preferentially get converted into S0 population as compared to pseudobulge hosting spirals. By studying the star formation properties of our galaxies in the NUV - r color-mass diagram, we find that the pseudobulge hosting spirals are mostly star forming while the majority of classical bulge host spirals are in the green valley or in the passive sequence. We suggest that some internal process, such as AGN feedback or morphological quenching due to the massive bulge, quenches these classical bulge hosting spirals and transforms them into S0 galaxies, thus resulting in the observed predominance of the classical bulge in S0 galaxies.

Why are classical bulges more common in S0 galaxies than in spiral galaxies?

NASA Astrophysics Data System (ADS)

Mishra, Preetish K.; Wadadekar, Yogesh; Barway, Sudhanshu

2018-07-01

In this paper, we try to understand why the classical bulge fraction observed in S0 galaxies is significantly higher than that in spiral galaxies. We carry out a comparative study of the bulge and global properties of a sample of spiral and S0 galaxies in a fixed environment. Our sample is flux limited and contains 262 spiral and 155 S0 galaxies drawn from the Sloan Digital Sky Survey. We have classified bulges into classical and pseudo-bulge categories based on their position on the Kormendy diagram. Dividing our sample into bins of galaxy stellar mass, we find that the fraction of S0 galaxies hosting a classical bulge is significantly higher than the classical bulge fraction seen in spirals even at fixed stellar mass. We have compared the bulge and the global properties of spirals and S0 galaxies in our sample and find indications that spiral galaxies which host a classical bulge, preferentially get converted into S0 population as compared to pseudo-bulge hosting spirals. By studying the star formation properties of our galaxies in the NUV-r colour-mass diagram, we find that the pseudo-bulge hosting spirals are mostly star forming while the majority of classical bulge host spirals are in the green valley or in the passive sequence. We suggest that some internal process, such as AGN feedback or morphological quenching due to the massive bulge, quenches these classical bulge hosting spirals and transforms them into S0 galaxies, thus resulting in the observed predominance of the classical bulge in S0 galaxies.

The most luminous heavily obscured quasars have a high merger fraction: morphological study of wise -selected hot dust-obscured galaxies

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

Fan, Lulu; Gao, Ying; Zhang, Dandan

Previous studies have shown that Wide-field Infrared Survey Explorer -selected hyperluminous, hot dust-obscured galaxies (Hot DOGs) are powered by highly dust-obscured, possibly Compton-thick active galactic nuclei (AGNs). High obscuration provides us a good chance to study the host morphology of the most luminous AGNs directly. We analyze the host morphology of 18 Hot DOGs at z ∼ 3 using Hubble Space Telescope /WFC3 imaging. We find that Hot DOGs have a high merger fraction (62 ± 14%). By fitting the surface brightness profiles, we find that the distribution of Sérsic indices in our Hot DOG sample peaks around 2, whichmore » suggests that most Hot DOGs have transforming morphologies. We also derive the AGN bolometric luminosity (∼10{sup 14} L {sub ⊙}) of our Hot DOG sample by using IR spectral energy distributions decomposition. The derived merger fraction and AGN bolometric luminosity relation is well consistent with the variability-based model prediction. Both the high merger fraction in an IR-luminous AGN sample and relatively low merger fraction in a UV/optical-selected, unobscured AGN sample can be expected in the merger-driven evolutionary model. Finally, we conclude that Hot DOGs are merger-driven and may represent a transit phase during the evolution of massive galaxies, transforming from the dusty starburst-dominated phase to the unobscured QSO phase.« less

GAMMA-RAY BURST HOST GALAXY SURVEYS AT REDSHIFT z {approx}> 4: PROBES OF STAR FORMATION RATE AND COSMIC REIONIZATION

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

Trenti, Michele; Perna, Rosalba; Levesque, Emily M.

2012-04-20

Measuring the star formation rate (SFR) at high redshift is crucial for understanding cosmic reionization and galaxy formation. Two common complementary approaches are Lyman break galaxy (LBG) surveys for large samples and gamma-ray burst (GRB) observations for sensitivity to SFR in small galaxies. The z {approx}> 4 GRB-inferred SFR is higher than the LBG rate, but this difference is difficult to understand, as both methods rely on several modeling assumptions. Using a physically motivated galaxy luminosity function model, with star formation in dark matter halos with virial temperature T{sub vir} {approx}> 2 Multiplication-Sign 10{sup 4} K (M{sub DM} {approx}> 2more » Multiplication-Sign 10{sup 8} M{sub Sun }), we show that GRB- and LBG-derived SFRs are consistent if GRBs extend to faint galaxies (M{sub AB} {approx}< -11). To test star formation below the detection limit L{sub lim} {approx} 0.05L*{sub z=3} of LBG surveys, we propose to measure the fraction f{sub det}(L > L{sub lim}, z) of GRB hosts with L > L{sub lim}. This fraction quantifies the missing star formation fraction in LBG surveys, constraining the mass-suppression scale for galaxy formation, with weak dependence on modeling assumptions. Because f{sub det}(L > L{sub lim}, z) corresponds to the ratio of SFRs derived from LBG and GRB surveys, if these estimators are unbiased, measuring f{sub det}(L > L{sub lim}, z) also constrains the redshift evolution of the GRB production rate per unit mass of star formation. Our analysis predicts significant success for GRB host detections at z {approx} 5 with f{sub det}(L > L{sub lim}, z) {approx} 0.4, but rarer detections at z > 6. By analyzing the upper limits on host galaxy luminosities of six z > 5 GRBs from literature data, we infer that galaxies with M{sub AB} > -15 were present at z > 5 at 95% confidence, demonstrating the key role played by very faint galaxies during reionization.« less

Host Galaxy Morphologies Of Hard X-ray Selected AGN From The Swift BAT Survey

NASA Astrophysics Data System (ADS)

Koss, Michael; Mushotzky, R.; Veilleux, S.

2009-01-01

Surveys of AGN taken in the optical, UV, and soft X-rays miss an important population of obscured AGN only visible in the hard X-rays and mid-IR wavelengths. The SWIFT BAT survey in the hard X-ray range (14-195 keV) has provided a uniquely unbiased sample of 258 AGN unaffected by galactic or circumnuclear absorption. Optical imaging of this unbiased sample provides a new opportunity to understand how the environments of the host galaxies are linked to AGN. For these host galaxies, only a fraction, 29%, have high quality optical images, predominately from the SDSS. In addition, about 33% show peculiar morphologies and interaction. In 2008, we observed 110 of these targets at Kitt Peak with the 2.1m in the SDSS bands over 17 nights. Using these observations and SDSS data we review the relationships between color, morphology, merger activity, star formation, and AGN luminosity.

Dark Galaxies and Lost Baryons (IAU S244)

NASA Astrophysics Data System (ADS)

Davies, Jonathan I.; Disney, Michael J.

2008-05-01

Preface; Conference prelims; The HI that barked in the night M. J. Disney; The detection of dark galaxies in blind HI surveys J. I. Davies; Red haloes of galaxies - reservoirs of baryonic dark matter? E. Zackrisson, N. Bergvall, C. Flynn, G. Ostlin, G. Micheva and B. Baldwell; Constraints on dark and visible mass in galaxies from strong gravitational lensing S. Dye and S. Warren; Lost baryons at low redshift S. Mathur, F. Nicastro and R. Williams; Observed properties of dark matter on small spatial scales R. Wyse and G. Gilmore; The mass distribution in spiral galaxies P. Salucci; Connecting lost baryons and dark galaxies via QSO absorption lines T. Tripp; ALFALFA: HI cosmology in the local universe R. Giovanelli; The ALFALFA search for (almost) dark galaxies across the HI mass function M. Haynes; HI clouds detected towards Virgo with the Arecibo Legacy Fast ALFA Survey B. Kent; Cosmic variance in the HI mass function S. Schneider; The Arecibo Galaxy Environments Survey - potential for finding dark galaxies and results so far R. Minchin et al.; Free-floating HI clouds in the M81 group E. Brinks, F. Walter and E. Skillman; Where are the stars in dark galaxies J. Rosenberg, J. Salzer and J. Cannon; The halo by halo missing baryon problem S. McGaugh; The local void is really empty R. Tully; Voids in the local volume: a limit on appearance of a galaxy in a dark matter halo A. Tikhonov and A. Klypin; Dim baryons in the cosmic web C. Impey; A census of baryons in galaxy clusters and groups A. Gonzalez, D. Zaritsky and A. Zabludo; Statistical properties of the intercluster light from SDSS image stacking S. Zibetti; QSO strong gravitational lensing and the detection of dark halos A. Maccio; Strong gravitational lensing: bright galaxies and lost dark-matter L. Koopmans; Mapping the distribution of luminous and dark matter in strong lensing galaxies I. Ferreras, P. Saha, L. Williams and S. Burles; Tidal debris posing as dark galaxies P. Duc, F. Bournaud and E. Brinks

THE HOST GALAXY OF THE SUPER-LUMINOUS SN 2010gx AND LIMITS ON EXPLOSIVE {sup 56}Ni PRODUCTION

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

Chen, Ting-Wan; Smartt, Stephen J.; Kotak, Rubina

2013-02-01

Super-luminous supernovae have a tendency to occur in faint host galaxies which are likely to have low mass and low metallicity. While these extremely luminous explosions have been observed from z = 0.1 to 1.55, the closest explosions allow more detailed investigations of their host galaxies. We present a detailed analysis of the host galaxy of SN 2010gx (z = 0.23), one of the best studied super-luminous type Ic supernovae. The host is a dwarf galaxy (M{sub g} = -17.42 {+-} 0.17) with a high specific star formation rate. It has a remarkably low metallicity of 12 + log (O/H)more » = 7.5 {+-} 0.1 dex as determined from the detection of the [O III] {lambda}4363 line. This is the first reliable metallicity determination of a super-luminous stripped-envelope supernova host. We collected deep multi-epoch imaging with Gemini + GMOS between 240 and 560 days after explosion to search for any sign of radioactive {sup 56}Ni, which might provide further insights on the explosion mechanism and the progenitor's nature. We reach griz magnitudes of m{sub AB} {approx} 26, but do not detect SN 2010gx at these epochs. The limit implies that any {sup 56}Ni production was similar to or below that of SN 1998bw (a luminous type Ic SN that produced around 0.4 M{sub Sun} of {sup 56}Ni). The low volumetric rates of these supernovae ({approx}10{sup -4} of the core-collapse population) could be qualitatively matched if the explosion mechanism requires a combination of low-metallicity (below 0.2 Z{sub Sun }), high progenitor mass (>60 M{sub Sun }) and high rotation rate (fastest 10% of rotators).« less

The X-rays of a bright QSO well within the epoch of reionization at z=7.54

NASA Astrophysics Data System (ADS)

Banados, Eduardo

2016-09-01

After almost a decade of intense search, our team has finally discovered a bright QSO well within the epoch of reionization, at z=7.54. This is by far the most distant QSO known (previous record: 7.08), at a cosmic age of 690 Myr, i.e., only 5% of our universe's current age. This is the first QSO whose spectrum shows clear evidence of an intergalactic medium that is >20% neutral and that reionization is underway. We propose Chandra observations of this unique object to (i) probe evolution of the X-ray-to-optical luminosity ratio (alpha-ox) to the highest accessible redshift; (ii) provide a more reliable estimate of the QSO's bolometric luminosity, and (iii) assess the feasibility of deeper Chandra and XMM observations for the upcoming cycles, which would allow us to test whether the first black holes are accreting at super-Eddington rates.

Understanding the Host Galaxies of Tidal Disruption Flares

NASA Astrophysics Data System (ADS)

Stone, Nicholas; Generozov, Aleksey; Vasiliev, Eugene; Metzger, Brian

2018-01-01

Recent observations suggest that stellar tidal disruption events (TDE) are strongly overrepresented in rare, post-starburst galaxies. Several dynamical mechanisms have been proposed to elevate their TDE rates, ranging from central stellar overdensities to the presence of supermassive black hole (SMBH) binaries. These, and other, dynamical hypotheses can be disentangled by comparing observations to theoretical predictions for the TDE delay time distribution (DTD). We show that SMBH binaries are a less plausible solution for the post-starburst preference, as they can only reproduce the observed DTD with extensive fine-tuning. The overdensity hypothesis produces a reasonable match to the observed DTD (based on the limited data currently available), provided that the initial stellar density profile created during the starburst, ρ(r), is exceptional in both steepness and normalization. In particular, explaining the post-starburst preference requires ρ∝r‑γ with γ>2.5, i.e. much steeper than the classic Bahcall-Wolf equilibrium profile of γ=7/4. Radial velocity anisotropies also represent a promising explanation, provided that initial anisotropy parameters of β0≈0.5 are sustainable against the radial orbit instability. As the sample of TDEs with well-studied host galaxies grows, the DTD will become a powerful tool for constraining the exceptional dynamical properties of post-starburst galactic nuclei.

The connection between the host halo and the satellite galaxies of the Milky Way

DOE PAGES

Lu, Yu; Benson, Andrew; Mao, Yao -Yuan; ...

2016-10-11

Many properties of the Milky Way's (MW) dark matter halo, including its mass-assembly history, concentration, and subhalo population, remain poorly constrained. We explore the connection between these properties of the MW and its satellite galaxy population, especially the implication of the presence of the Magellanic Clouds for the properties of the MW halo. Using a suite of high-resolution N-body simulations of MW-mass halos with a fixed finalmore » $${M}_{\\mathrm{vir}}\\sim {10}^{12.1}\\,{M}_{\\odot }$$, we find that the presence of Magellanic Cloud-like satellites strongly correlates with the assembly history, concentration, and subhalo population of the host halo, such that MW-mass systems with Magellanic Clouds have lower concentration, more rapid recent accretion, and more massive subhalos than typical halos of the same mass. Using a flexible semi-analytic galaxy formation model that is tuned to reproduce the stellar mass function of the classical dwarf galaxies of the MW with Markov-Chain Monte-Carlo, we show that adopting host halos with different mass-assembly histories and concentrations can lead to different best-fit models for galaxy-formation physics, especially for the strength of feedback. These biases arise because the presence of the Magellanic Clouds boosts the overall population of high-mass subhalos, thus requiring a different stellar-mass-to-halo-mass ratio to match the data. These biases also lead to significant differences in the mass–metallicity relation, the kinematics of low-mass satellites, the number counts of small satellites associated with the Magellanic Clouds, and the stellar mass of MW itself. Finally, observations of these galaxy properties can thus provide useful constraints on the properties of the MW halo.« less

The ULIRG Monster Mash: The Evolution of Massive Mergers Since z~1

NASA Astrophysics Data System (ADS)

Rothberg, Barry; Fischer, Jacqueline; Pirzkal, Nor; Rodrigues, Myriam

2018-01-01

Theoretical models and observations in the local Universe indicate there is a clear progression from merger-induced star-formation (SF) to QSO activity via Ultraluminous Infrared Galaxies (ULIRGs), systems with L8-1000 µm ≥ 1012 LSun. Not all mergers are ULIRGs, but all local ULIRGs are mergers, and likely the progenitors of QSO host galaxies. At earlier epochs, this relationship is less well accepted. Here, we first present an overview of how the dynamical properties of local (z < 0.4) ULIRGs are statistically indistinguishable from Radio Loud and Radio Quiet QSOs. Then, transition to the critical redshift range 0.4 < z < 1.0, where the star-formation rates, gas fractions, and masses of galaxies are believed to be significantly higher than in the local universe. ULIRGs at these redshifts begin to dominate the SF activity and are responsible for up to 70% of the co-moving IR density. We use rest-frame UV & optical imaging and spectra to apply the same techniques used for local ULIRGs to a sample of "classically" selected (i.e via integrated 12, 25, 60 and 100μm fluxes) systems at 0.4 < z < 1.0. Although, in general, galaxies at z > 0.4 are not the same as those in the local Universe, these intermediate redshift ULIRGs are dynamically similar, but more powerful, than their local counterparts. Furthermore, they show evidence of merging, while containing a powerful AGN hosted within a massive galaxy.

Galaxy and Mass Assembly (GAMA): the red fraction and radial distribution of satellite galaxies

NASA Astrophysics Data System (ADS)

Prescott, Matthew; Baldry, I. K.; James, P. A.; Bamford, S. P.; Bland-Hawthorn, J.; Brough, S.; Brown, M. J. I.; Cameron, E.; Conselice, C. J.; Croom, S. M.; Driver, S. P.; Frenk, C. S.; Gunawardhana, M.; Hill, D. T.; Hopkins, A. M.; Jones, D. H.; Kelvin, L. S.; Kuijken, K.; Liske, J.; Loveday, J.; Nichol, R. C.; Norberg, P.; Parkinson, H. R.; Peacock, J. A.; Phillipps, S.; Pimbblet, K. A.; Popescu, C. C.; Robotham, A. S. G.; Sharp, R. G.; Sutherland, W. J.; Taylor, E. N.; Tuffs, R. J.; van Kampen, E.; Wijesinghe, D.

2011-10-01

We investigate the properties of satellite galaxies that surround isolated hosts within the redshift range 0.01 < z < 0.15, using data taken as part of the Galaxy And Mass Assembly survey. Making use of isolation and satellite criteria that take into account stellar mass estimates, we find 3514 isolated galaxies of which 1426 host a total of 2998 satellites. Separating the red and blue populations of satellites and hosts, using colour-mass diagrams, we investigate the radial distribution of satellite galaxies and determine how the red fraction of satellites varies as a function of satellite mass, host mass and the projected distance from their host. Comparing the red fraction of satellites to a control sample of small neighbours at greater projected radii, we show that the increase in red fraction is primarily a function of host mass. The satellite red fraction is about 0.2 higher than the control sample for hosts with ?, while the red fractions show no difference for hosts with ?. For the satellites of more massive hosts, the red fraction also increases as a function of decreasing projected distance. Our results suggest that the likely main mechanism for the quenching of star formation in satellites hosted by isolated galaxies is strangulation.

Fitting and Phenomenology in Type IA Supernova Cosmology: Generalized Likelihood Analyses for Multiple Evolving Populations and Observations of Near-Infrared Lightcurves Including Host Galaxy Properties

NASA Astrophysics Data System (ADS)

Ponder, Kara A.

In the late 1990s, Type Ia supernovae (SNeIa) led to the discovery that the Universe is expanding at an accelerating rate due to dark energy. Since then, many different tracers of acceleration have been used to characterize dark energy, but the source of cosmic acceleration has remained a mystery. To better understand dark energy, future surveys such as the ground-based Large Synoptic Survey Telescope and the space-based Wide-Field Infrared Survey Telescope will collect thousands of SNeIa to use as a primary dark energy probe. These large surveys will be systematics limited, which makes it imperative for our insight regarding systematics to dramatically increase over the next decade for SNeIa to continue to contribute to precision cosmology. I approach this problem by improving statistical methods in the likelihood analysis and collecting near infrared (NIR) SNeIa with their host galaxies to improve the nearby data set and search for additional systematics. Using more statistically robust methods to account for systematics within the likelihood function can increase accuracy in cosmological parameters with a minimal precision loss. Though a sample of at least 10,000 SNeIa is necessary to confirm multiple populations of SNeIa, the bias in cosmology is ˜ 2 sigma with only 2,500 SNeIa. This work focused on an example systematic (host galaxy correlations), but it can be generalized for any systematic that can be represented by a distribution of multiple Gaussians. The SweetSpot survey gathered 114 low-redshift, NIR SNeIa that will act as a crucial anchor sample for the future high redshift surveys. NIR observations are not as affected by dust contamination, which may lead to increased understanding of systematics seen in optical wavelengths. We obtained spatially resolved spectra for 32 SweetSpot host galaxies to test for local host galaxy correlations. For the first time, we probe global host galaxy correlations with NIR brightnesses from the current literature

Cosmological test with the QSO Hubble diagram

NASA Astrophysics Data System (ADS)

López-Corredoira, M.; Melia, F.; Lusso, E.; Risaliti, G.

2016-03-01

A Hubble diagram (HD) has recently been constructed in the redshift range 0 ≲ z ≲ 6.5 using a nonlinear relation between the ultraviolet (UV) and X-ray luminosities of quasi stellar objects (QSOs). The Type Ia Supernovae (SN) HD has already provided a high-precision test of cosmological models, but the fact that the QSO distribution extends well beyond the supernova range (z ≲ 1.8), in principle provides us with an important complementary diagnostic whose significantly greater leverage in z can impose tighter constraints on the distance versus redshift relationship. In this paper, we therefore perform an independent test of nine different cosmological models, among which six are expanding, while three are static. Many of these are disfavored by other kinds of observations (including the aforementioned Type Ia SNe). We wish to examine whether the QSO HD confirms or rejects these earlier conclusions. We find that four of these models (Einstein-de Sitter, the Milne universe, the static universe with simple tired light and the static universe with plasma tired light) are excluded at the > 99% C.L. The quasi-steady state model is excluded at > 95% C.L. The remaining four models (ΛCDM/wCDM, the Rh = ct universe, the Friedmann open universe and a static universe with a linear Hubble law) all pass the test. However, only ΛCDM/wCDM and Rh = ct also pass the Alcock-Paczyński (AP) test. The optimized parameters in ΛCDM/wCDM are Ωm = 0.20-0.20+0.24 and wde = -1.2-∞+1.6 (the dark energy equation-of-state). Combined with the AP test, these values become Ωm = 0.38-0.19+0.20 and wde = -0.28-0.40+0.52. But whereas this optimization of parameters in ΛCDM/wCDM creates some tension with their concordance values, the Rh = ct universe has the advantage of fitting the QSO and AP data without any free parameters.

The Sightline to Q2343-BX415: Clues to Galaxy Formation in a Quasar Environment

NASA Astrophysics Data System (ADS)

Rix, Samantha A.; Pettini, Max; Steidel, Charles C.; Reddy, Naveen A.; Adelberger, Kurt L.; Erb, Dawn K.; Shapley, Alice E.

2007-11-01

We have discovered a strong DLA coincident in redshift with the faint QSO Q2343-BX415 (R=20.2, zem=2.57393). Follow-up observations at intermediate spectral resolution reveal that the metal lines associated with this proximate DLA (PDLA) consist of two sets of absorption components. One set is moving toward the quasar with velocities of ~150-600 km s-1 this gas is highly ionized and does not fully cover the continuum source, suggesting that it is physically close to the active nucleus. The other, which accounts for most of the neutral gas, is blueshifted relative to the QSO, with the strongest component at ~-160 km s-1. We consider the possibility that the PDLA arises in the outflowing interstellar medium of the host galaxy of Q2343-BX415, an interpretation supported by strong C IV and N V absorption at nearby velocities, and by the intense radiation field longward of the Lyman limit implied by the high C II*/H I ratio. If Q2343-BX415 is the main source of these UV photons, then the PDLA is located at either ~8 or ~37 kpc from the active nucleus. Alternatively, the absorber may be a foreground star-forming galaxy unrelated to the quasar and coincidentally at the same redshift, but our deep imaging and follow-up spectroscopy of the field of Q2343-BX415 has not yet produced a likely candidate. We measure the abundances of 14 elements in the PDLA, finding an overall metallicity of ~1/5 solar and a normal pattern of relative element abundances for this metallicity. Thus, in this PDLA there is no evidence for the supersolar metallicities that have been claimed for some proximate, high-ionization, systems. Based on data obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among 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.

THE CLUSTERING OF ALFALFA GALAXIES: DEPENDENCE ON H I MASS, RELATIONSHIP WITH OPTICAL SAMPLES, AND CLUES OF HOST HALO PROPERTIES

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

Papastergis, Emmanouil; Giovanelli, Riccardo; Haynes, Martha P.

We use a sample of ≈6000 galaxies detected by the Arecibo Legacy Fast ALFA (ALFALFA) 21 cm survey to measure the clustering properties of H I-selected galaxies. We find no convincing evidence for a dependence of clustering on galactic atomic hydrogen (H I) mass, over the range M{sub H{sub I}} ≈ 10{sup 8.5}-10{sup 10.5} M{sub ☉}. We show that previously reported results of weaker clustering for low H I mass galaxies are probably due to finite-volume effects. In addition, we compare the clustering of ALFALFA galaxies with optically selected samples drawn from the Sloan Digital Sky Survey (SDSS). We findmore » that H I-selected galaxies cluster more weakly than even relatively optically faint galaxies, when no color selection is applied. Conversely, when SDSS galaxies are split based on their color, we find that the correlation function of blue optical galaxies is practically indistinguishable from that of H I-selected galaxies. At the same time, SDSS galaxies with red colors are found to cluster significantly more than H I-selected galaxies, a fact that is evident in both the projected as well as the full two-dimensional correlation function. A cross-correlation analysis further reveals that gas-rich galaxies 'avoid' being located within ≈3 Mpc of optical galaxies with red colors. Next, we consider the clustering properties of halo samples selected from the Bolshoi ΛCDM simulation. A comparison with the clustering of ALFALFA galaxies suggests that galactic H I mass is not tightly related to host halo mass and that a sizable fraction of subhalos do not host H I galaxies. Lastly, we find that we can recover fairly well the correlation function of H I galaxies by just excluding halos with low spin parameter. This finding lends support to the hypothesis that halo spin plays a key role in determining the gas content of galaxies.« less

Molecular outflow and feedback in the obscured quasar XID2028 revealed by ALMA

NASA Astrophysics Data System (ADS)

Brusa, M.; Cresci, G.; Daddi, E.; Paladino, R.; Perna, M.; Bongiorno, A.; Lusso, E.; Sargent, M. T.; Casasola, V.; Feruglio, C.; Fraternali, F.; Georgiev, I.; Mainieri, V.; Carniani, S.; Comastri, A.; Duras, F.; Fiore, F.; Mannucci, F.; Marconi, A.; Piconcelli, E.; Zamorani, G.; Gilli, R.; La Franca, F.; Lanzuisi, G.; Lutz, D.; Santini, P.; Scoville, N. Z.; Vignali, C.; Vito, F.; Rabien, S.; Busoni, L.; Bonaglia, M.

2018-04-01

We imaged, with ALMA and ARGOS/LUCI, the molecular gas and dust and stellar continuum in XID2028, which is an obscured quasi-stellar object (QSO) at z = 1.593, where the presence of a massive outflow in the ionised gas component traced by the [OIII]5007 emission has been resolved up to 10 kpc. This target represents a unique test case to study QSO feedback in action at the peak epoch of AGN-galaxy co-evolution. The QSO was detected in the CO(5 - 4) transition and in the 1.3 mm continuum at 30 and 20σ significance, respectively; both emissions are confined in the central (<2 kpc) radius area. Our analysis suggests the presence of a fast rotating molecular disc (v 400 km s-1) on very compact scales well inside the galaxy extent seen in the rest-frame optical light ( 10 kpc, as inferred from the LUCI data). Adding available measurements in additional two CO transitions, CO(2 - 1) and CO(3 - 2), we could derive a total gas mass of 1010 M⊙, thanks to a critical assessment of CO excitation and the comparison with the Rayleigh-Jeans continuum estimate. This translates into a very low gas fraction (<5%) and depletion timescales of 40-75 Myr, reinforcing the result of atypical gas consumption conditions in XID2028, possibly because of feedback effects on the host galaxy. Finally, we also detect the presence of high velocity CO gas at 5σ, which we interpret as a signature of galaxy-scale molecular outflow that is spatially coincident with the ionised gas outflow. XID2028 therefore represents a unique case in which the measurement of total outflowing mass, of 500-800 M⊙ yr-1 including the molecular and atomic components in both the ionised and neutral phases, was attempted for a high-z QSO.

Host Galaxy Spectra of Stripped SN from the Palomar Transient Factory: SN Progenitor Diagnostics and the SN-GRB Connection

NASA Astrophysics Data System (ADS)

Modjaz, Maryam; Gal-Yam, Avishay; Arcavi, Iair

2012-02-01

Stripped core-collapse supernovae (Stripped SNe) are powerful cosmic engines that energize and enrich the ISM and that sometimes accompany GRBs, but the exact mass and metallicity range of their massive progenitors is not known, nor the detailed physics of the explosion. We propose to continue conducting the first uniform and statistically significant study of host galaxies of 60 stripped SNe from the same innovative, homogeneous and galaxy-unbiased survey Palomar Transient Factory in order to determine the environmental conditions that influence the various kinds of massive stellar deaths. By obtaining spectra of the immediate host environments of our sample of stripped SN, we will (1) measure local abundances in order to differentiate between the two progenitor scenarios for stripped SN and (2) derive stellar population ages, masses and star formation histories via detailed stellar population synthesis models. Moreover, we will test if natal chemical abundance has effects on basic SN characteristics, such as peak luminosity. Any observed trends will have ramifications on SN and GRB explosion models and imply important demographic SN considerations. Our dataset will provide a crucial complimentary set to host galaxy studies of long-duration GRBs and pave the way for host studies of transients and SN found via upcoming surveys such as LSST.

The Faint Optical Afterglow and Host Galaxy of GRB 020124: Implications for the Nature of Dark Gamma-Ray Bursts

NASA Astrophysics Data System (ADS)

Berger, E.; Kulkarni, S. R.; Bloom, J. S.; Price, P. A.; Fox, D. W.; Frail, D. A.; Axelrod, T. S.; Chevalier, R. A.; Colbert, E.; Costa, E.; Djorgovski, S. G.; Frontera, F.; Galama, T. J.; Halpern, J. P.; Harrison, F. A.; Holtzman, J.; Hurley, K.; Kimble, R. A.; McCarthy, P. J.; Piro, L.; Reichart, D.; Ricker, G. R.; Sari, R.; Schmidt, B. P.; Wheeler, J. C.; Vanderppek, R.; Yost, S. A.

2002-12-01

We present ground-based optical observations of GRB 020124 starting 1.6 hr after the burst, as well as subsequent Very Large Array and Hubble Space Telescope (HST) observations. The optical afterglow of GRB 020124 is one of the faintest afterglows detected to date, and it exhibits a relatively rapid decay, Fν~t-1.60+/-0.04, followed by further steepening. In addition, a weak radio source was found coincident with the optical afterglow. The HST observations reveal that a positionally coincident host galaxy must be the faintest host to date, R>~29.5 mag. The afterglow observations can be explained by several models requiring little or no extinction within the host galaxy, AhostV~0-0.9 mag. These observations have significant implications for the interpretation of the so-called dark bursts (bursts for which no optical afterglow is detected), which are usually attributed to dust extinction within the host galaxy. The faintness and relatively rapid decay of the afterglow of GRB 020124, combined with the low inferred extinction, indicate that some dark bursts are intrinsically dim and not dust obscured. Thus, the diversity in the underlying properties of optical afterglows must be observationally determined before substantive inferences can be drawn from the statistics of dark bursts.

EmpiriciSN: Re-sampling Observed Supernova/Host Galaxy Populations Using an XD Gaussian Mixture Model

NASA Astrophysics Data System (ADS)

Holoien, Thomas W.-S.; Marshall, Philip J.; Wechsler, Risa H.

2017-06-01

We describe two new open-source tools written in Python for performing extreme deconvolution Gaussian mixture modeling (XDGMM) and using a conditioned model to re-sample observed supernova and host galaxy populations. XDGMM is new program that uses Gaussian mixtures to perform density estimation of noisy data using extreme deconvolution (XD) algorithms. Additionally, it has functionality not available in other XD tools. It allows the user to select between the AstroML and Bovy et al. fitting methods and is compatible with scikit-learn machine learning algorithms. Most crucially, it allows the user to condition a model based on the known values of a subset of parameters. This gives the user the ability to produce a tool that can predict unknown parameters based on a model that is conditioned on known values of other parameters. EmpiriciSN is an exemplary application of this functionality, which can be used to fit an XDGMM model to observed supernova/host data sets and predict likely supernova parameters using a model conditioned on observed host properties. It is primarily intended to simulate realistic supernovae for LSST data simulations based on empirical galaxy properties.

EmpiriciSN: Re-sampling Observed Supernova/Host Galaxy Populations Using an XD Gaussian Mixture Model

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

Holoien, Thomas W. -S.; Marshall, Philip J.; Wechsler, Risa H.

We describe two new open-source tools written in Python for performing extreme deconvolution Gaussian mixture modeling (XDGMM) and using a conditioned model to re-sample observed supernova and host galaxy populations. XDGMM is new program that uses Gaussian mixtures to perform density estimation of noisy data using extreme deconvolution (XD) algorithms. Additionally, it has functionality not available in other XD tools. It allows the user to select between the AstroML and Bovy et al. fitting methods and is compatible with scikit-learn machine learning algorithms. Most crucially, it allows the user to condition a model based on the known values of amore » subset of parameters. This gives the user the ability to produce a tool that can predict unknown parameters based on a model that is conditioned on known values of other parameters. EmpiriciSN is an exemplary application of this functionality, which can be used to fit an XDGMM model to observed supernova/host data sets and predict likely supernova parameters using a model conditioned on observed host properties. It is primarily intended to simulate realistic supernovae for LSST data simulations based on empirical galaxy properties.« less

The x ray properties of a large, uniform QSO sample: Einstein observations of the LBQS

NASA Technical Reports Server (NTRS)

Margon, B.; Anderson, S. F.; Xu, X.; Green, P. J.; Foltz, C. B.

1992-01-01

Although there are large numbers of Quasi Stellar Objects (QSO's) now observed in X rays, extensive X-ray observations of uniformly selected, 'complete' QSO samples are more rare. The Large Bright QSO Survey (LBQS) consists of about 1000 objects with well understood properties, most brighter than B = 18.8 and thus amenable to X-ray detections in relatively brief exposures. The sample is thought to be highly complete in the range 0.2 less than z less than 3.3, a significantly broader interval than many other surveys. The Einstein IPC observed 150 of these objects, mostly serendipitously, during its lifetime. We report the results of an analysis of these IPC data, considering not only the 20 percent of the objects we find to have positive X-ray detections, but also the ensemble X-ray properties derived by 'image stacking'.

ON THE DEPENDENCE OF TYPE Ia SNe LUMINOSITIES ON THE METALLICITY OF THEIR HOST GALAXIES

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

Moreno-Raya, Manuel E.; Mollá, Mercedes; López-Sánchez, Ángel R.

The metallicity of the progenitor system producing a type Ia supernova (SN Ia) could play a role in its maximum luminosity, as suggested by theoretical predictions. We present an observational study to investigate if such a relationship exists. Using the 4.2 m William Herschel Telescope (WHT) we have obtained intermediate-resolution spectroscopy data of a sample of 28 local galaxies hosting SNe Ia, for which distances have been derived using methods independent of those based on SN Ia parameters. From the emission lines observed in their optical spectra, we derived the gas-phase oxygen abundance in the region where each SN Ia exploded. Our datamore » show a trend, with an 80% of chance not being due to random fluctuation, between SNe Ia absolute magnitudes and the oxygen abundances of the host galaxies, in the sense that luminosities tend to be higher for galaxies with lower metallicities. This result seems likely to be in agreement with both the theoretically expected behavior and with other observational results. This dependence M{sub B}–Z might induce systematic errors when it is not considered when deriving SNe Ia luminosities and then using them to derive cosmological distances.« less

Galaxies of all Shapes Host Black Holes

NASA Technical Reports Server (NTRS)

2008-01-01

This artist's concept illustrates the two types of spiral galaxies that populate our universe: those with plump middles, or central bulges (upper left), and those lacking the bulge (foreground).

New observations from NASA's Spitzer Space Telescope provide strong evidence that the slender, bulgeless galaxies can, like their chubbier counterparts, harbor supermassive black holes at their cores. Previously, astronomers thought that a galaxy without a bulge could not have a supermassive black hole. In this illustration, jets shooting away from the black holes are depicted as thin streams.

The findings are reshaping theories of galaxy formation, suggesting that a galaxy's 'waistline' does not determine whether it will be home to a big black hole.

GALAXY EVOLUTION. An over-massive black hole in a typical star-forming galaxy, 2 billion years after the Big Bang.

PubMed

Trakhtenbrot, Benny; Urry, C Megan; Civano, Francesca; Rosario, David J; Elvis, Martin; Schawinski, Kevin; Suh, Hyewon; Bongiorno, Angela; Simmons, Brooke D

2015-07-10

Supermassive black holes (SMBHs) and their host galaxies are generally thought to coevolve, so that the SMBH achieves up to about 0.2 to 0.5% of the host galaxy mass in the present day. The radiation emitted from the growing SMBH is expected to affect star formation throughout the host galaxy. The relevance of this scenario at early cosmic epochs is not yet established. We present spectroscopic observations of a galaxy at redshift z = 3.328, which hosts an actively accreting, extremely massive BH, in its final stages of growth. The SMBH mass is roughly one-tenth the mass of the entire host galaxy, suggesting that it has grown much more efficiently than the host, contrary to models of synchronized coevolution. The host galaxy is forming stars at an intense rate, despite the presence of a SMBH-driven gas outflow. Copyright © 2015, American Association for the Advancement of Science.

VizieR Online Data Catalog: Host galaxies of Superluminous Supernovae (Angus+, 2016)

NASA Astrophysics Data System (ADS)

Angus, C. R.; Levan, A. J.; Perley, D. A.; Tanvir, N. R.; Lyman, J. D.; Stanway, E. R.; Fruchter, A. S.

2016-11-01

Here we use nIR and rest-frame UV observations of a sample of 21 SLSN host galaxies, within a redshift range of 0.019 SCP 06F6). This HST sample (programme GO-13025; PI: Levan) comprised 21 targets, based on the sample of Neill et al. (2011ApJ...727...15N), supplemented with luminous SNe from the literature (up to 2012 Jan). (6 data files).

Strong bimodality in the host halo mass of central galaxies from galaxy-galaxy lensing

NASA Astrophysics Data System (ADS)

Mandelbaum, Rachel; Wang, Wenting; Zu, Ying; White, Simon; Henriques, Bruno; More, Surhud

2016-04-01

We use galaxy-galaxy lensing to study the dark matter haloes surrounding a sample of locally brightest galaxies (LBGs) selected from the Sloan Digital Sky Survey. We measure mean halo mass as a function of the stellar mass and colour of the central galaxy. Mock catalogues constructed from semi-analytic galaxy formation simulations demonstrate that most LBGs are the central objects of their haloes, greatly reducing interpretation uncertainties due to satellite contributions to the lensing signal. Over the full stellar mass range, 10.3 < log [M*/M⊙] < 11.6, we find that passive central galaxies have haloes that are at least twice as massive as those of star-forming objects of the same stellar mass. The significance of this effect exceeds 3σ for log [M*/M⊙] > 10.7. Tests using the mock catalogues and on the data themselves clarify the effects of LBG selection and show that it cannot artificially induce a systematic dependence of halo mass on LBG colour. The bimodality in halo mass at fixed stellar mass is reproduced by the astrophysical model underlying our mock catalogue, but the sign of the effect is inconsistent with recent, nearly parameter-free age-matching models. The sign and magnitude of the effect can, however, be reproduced by halo occupation distribution models with a simple (few-parameter) prescription for type dependence.

Resolving Fe-rich Neutral ISM in a Massive Quiescent Galaxy at z 0.4

NASA Astrophysics Data System (ADS)

Zahedy, Fakhri

2016-10-01

Roughly 40% of elliptical galaxies are found to contain cool gas but exhibit no on-going star formation, indicating that some feedback mechanisms are at work. While AGN feedback is commonly thought to be responsible for quenching star formation in massive halos, recent work has reiterated the importance of feedback from old stellar populations, including Type Ia supernovae (SNe Ia). In Zahedy et al. (2016), we reported detections of ultra-strong MgII absorption (>3.6 Ang) at 1-2 effective radii of a massive quiescent lensing galaxy at z=0.408. Strong MgII, FeII, MgI, and CaII absorption are found at the lens redshift along two lensed QSO sightlines separated by 8 kpc. The absorbers are resolved into 15 components with line-of-sight velocity spread of 600 km/s. The large observed ionic column densities, N>1e14 cm^-2 suggest large neutral hydrogen column densities N(HI)>1e18 cm^-2 and a significant neutral gas fraction. The most striking feature is the uniformly large Fe/Mg ratio across the full 600 km/s velocity range, suggesting a large contribution in chemical enrichment from SNe Ia (>20%). Here we propose QSO absorption-line spectroscopy of this unique system using STIS and the G140L grating with the slit oriented along the two lensed QSOs. The goal is to determine N(HI) from observations of the full Lyman absorption series and gas-phase metallicity of the interstellar medium at two locations separated by 8 kpc in an elliptical galaxy beyond the local universe. With a modest investment of HST time, we will be able to examine the extent SNe Ia-driven feedback in a distant quiescent galaxy using this unique double-lens system.

The Type Ia Supernova Color-Magnitude Relation and Host Galaxy Dust: A Simple Hierarchical Bayesian Model

NASA Astrophysics Data System (ADS)

Mandel, Kaisey S.; Scolnic, Daniel M.; Shariff, Hikmatali; Foley, Ryan J.; Kirshner, Robert P.

2017-06-01

Conventional Type Ia supernova (SN Ia) cosmology analyses currently use a simplistic linear regression of magnitude versus color and light curve shape, which does not model intrinsic SN Ia variations and host galaxy dust as physically distinct effects, resulting in low color-magnitude slopes. We construct a probabilistic generative model for the dusty distribution of extinguished absolute magnitudes and apparent colors as the convolution of an intrinsic SN Ia color-magnitude distribution and a host galaxy dust reddening-extinction distribution. If the intrinsic color-magnitude (M B versus B - V) slope {β }{int} differs from the host galaxy dust law R B , this convolution results in a specific curve of mean extinguished absolute magnitude versus apparent color. The derivative of this curve smoothly transitions from {β }{int} in the blue tail to R B in the red tail of the apparent color distribution. The conventional linear fit approximates this effective curve near the average apparent color, resulting in an apparent slope {β }{app} between {β }{int} and R B . We incorporate these effects into a hierarchical Bayesian statistical model for SN Ia light curve measurements, and analyze a data set of SALT2 optical light curve fits of 248 nearby SNe Ia at z< 0.10. The conventional linear fit gives {β }{app}≈ 3. Our model finds {β }{int}=2.3+/- 0.3 and a distinct dust law of {R}B=3.8+/- 0.3, consistent with the average for Milky Way dust, while correcting a systematic distance bias of ˜0.10 mag in the tails of the apparent color distribution. Finally, we extend our model to examine the SN Ia luminosity-host mass dependence in terms of intrinsic and dust components.

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

Aravena, M.; Wagg, J.; Papadopoulos, P. P.

We report the detection of the {sup 12}CO J = 1-0 emission line in [H89]1821+643, one of the most optically luminous quasi-stellar objects (QSOs) in the local universe, and a template ULIRG-to-QSO transition object, located in a rich, cool-core cluster at z = 0.297. The CO emission is likely to be extended, highly asymmetric with respect to the center of the host elliptical where the QSO resides, and correspond with a molecular gas mass of {approx}8.0 x 10{sup 9} M{sub sun}. The dynamical mass enclosed by the CO emission-line region could amount to {approx}1.7 x 10{sup 12} M{sub sun} (80%more » of the total mass of the elliptical host). The bulk of the CO emission is located at {approx}9 kpc southeast from the nuclei position, close to a faint optical structure, suggesting that the CO emission could either represent a gas-rich companion galaxy merging with the elliptical host or a tail-like structure reminiscent of a previous interaction. We argue that the first scenario is more likely given the large masses implied by the CO source, which would imply a highly asymmetric elliptical host. The close alignment between the CO emission's major axis and the radio plume suggests a possible role in the excitation of the ambient gas reservoir by the latter. The stacking technique was used to search for CO emission and 3-mm continuum emission from galaxies in the surrounding cluster. However, no detection was found toward individual galaxies or the stacked ensemble of galaxies, with a 3{sigma} limit of <1.1 x 10{sup 9} M{sub sun} for the molecular gas.« less

The Type Ia Supernova Color-Magnitude Relation and Host Galaxy Dust: A Simple Hierarchical Bayesian Model

NASA Astrophysics Data System (ADS)

Mandel, Kaisey; Scolnic, Daniel; Shariff, Hikmatali; Foley, Ryan; Kirshner, Robert

2017-01-01

Inferring peak optical absolute magnitudes of Type Ia supernovae (SN Ia) from distance-independent measures such as their light curve shapes and colors underpins the evidence for cosmic acceleration. SN Ia with broader, slower declining optical light curves are more luminous (“broader-brighter”) and those with redder colors are dimmer. But the “redder-dimmer” color-luminosity relation widely used in cosmological SN Ia analyses confounds its two separate physical origins. An intrinsic correlation arises from the physics of exploding white dwarfs, while interstellar dust in the host galaxy also makes SN Ia appear dimmer and redder. Conventional SN Ia cosmology analyses currently use a simplistic linear regression of magnitude versus color and light curve shape, which does not model intrinsic SN Ia variations and host galaxy dust as physically distinct effects, resulting in low color-magnitude slopes. We construct a probabilistic generative model for the dusty distribution of extinguished absolute magnitudes and apparent colors as the convolution of an intrinsic SN Ia color-magnitude distribution and a host galaxy dust reddening-extinction distribution. If the intrinsic color-magnitude (MB vs. B-V) slope βint differs from the host galaxy dust law RB, this convolution results in a specific curve of mean extinguished absolute magnitude vs. apparent color. The derivative of this curve smoothly transitions from βint in the blue tail to RB in the red tail of the apparent color distribution. The conventional linear fit approximates this effective curve near the average apparent color, resulting in an apparent slope βapp between βint and RB. We incorporate these effects into a hierarchical Bayesian statistical model for SN Ia light curve measurements, and analyze a dataset of SALT2 optical light curve fits of 277 nearby SN Ia at z < 0.10. The conventional linear fit obtains βapp ≈ 3. Our model finds a βint = 2.2 ± 0.3 and a distinct dust law of RB = 3.7 ± 0

Galaxy And Mass Assembly (GAMA): gas fuelling of spiral galaxies in the local Universe II. - direct measurement of the dependencies on redshift and host halo mass of stellar mass growth in central disc galaxies

NASA Astrophysics Data System (ADS)

Grootes, M. W.; Dvornik, A.; Laureijs, R. J.; Tuffs, R. J.; Popescu, C. C.; Robotham, A. S. G.; Liske, J.; Brown, M. J. I.; Holwerda, B. W.; Wang, L.

2018-06-01

We present a detailed analysis of the specific star formation rate-stellar mass (sSFR-M*) of z ≤ 0.13 disc central galaxies using a morphologically selected mass-complete sample (M* ≥ 109.5 M⊙). Considering samples of grouped and ungrouped galaxies, we find the sSFR-M* relations of disc-dominated central galaxies to have no detectable dependence on host dark-matter halo (DMH) mass, even where weak-lensing measurements indicate a difference in halo mass of a factor ≳ 5. We further detect a gradual evolution of the sSFR-M* relation of non-grouped (field) central disc galaxies with redshift, even over a Δz ≈ 0.04 (≈5 × 108 yr) interval, while the scatter remains constant. This evolution is consistent with extrapolation of the `main sequence of star-forming-galaxies' from previous literature that uses larger redshift baselines and coarser sampling. Taken together, our results present new constraints on the paradigm under which the SFR of galaxies is determined by a self-regulated balance between gas inflows and outflows, and consumption of gas by star formation in discs, with the inflow being determined by the product of the cosmological accretion rate and a fuelling efficiency - \\dot{M}_{b,halo}ζ. In particular, maintaining the paradigm requires \\dot{M}_{b,halo}ζ to be independent of the mass Mhalo of the host DMH. Furthermore, it requires the fuelling efficiency ζ to have a strong redshift dependence (∝(1 + z)2.7 for M* = 1010.3 M⊙ over z = 0-0.13), even though no morphological transformation to spheroids can be invoked to explain this in our disc-dominated sample. The physical mechanisms capable of giving rise to such dependencies of ζ on Mhalo and z for discs are unclear.

The Jet-driven Outflow in the Radio Galaxy SDSS J1517+3353: Implications for Double-peaked Narrow-line Active Galactic Nucleus

NASA Astrophysics Data System (ADS)

Rosario, D. J.; Shields, G. A.; Taylor, G. B.; Salviander, S.; Smith, K. L.

2010-06-01

We report on the study of an intriguing active galaxy that was selected as a potential multiple supermassive black hole merger in the early-type host SDSS J151709.20+335324.7 (z = 0.135) from a complete search for double-peaked [O III] lines from the SDSS spectroscopic quasi-stellar object (QSO) database. Ground-based SDSS imaging reveals two blue structures on either side of the photometric center of the host galaxy, separated from each other by about 5.7 kpc. From a combination of SDSS fiber and Keck/HIRES long-slit spectroscopy, it is demonstrated that, in addition to these two features, a third distinct structure surrounds the nucleus of the host galaxy. All three structures exhibit highly ionized line emission with line ratios characteristic of Seyfert II active galactic nuclei. The analysis of spatially resolved emission-line profiles from the HIRES spectrum reveal three distinct kinematic subcomponents, one at rest and the other two moving at -350 km s-1 and 500 km s-1 with respect to the systemic velocity of the host galaxy. A comparison of imaging and spectral data confirm a strong association between the kinematic components and the spatial knots, which implies a highly disturbed and complex active region in this object. A comparative analysis of the broadband positions, colors, kinematics, and spectral properties of the knots in this system lead to two plausible explanations: (1) a multiple active galactic nucleus (AGN) produced due to a massive dry merger, or (2) a very powerful radio jet-driven outflow. Subsequent VLA radio imaging reveals a clear jet aligned with the emission-line gas, confirming the latter explanation. We use the broadband radio measurements to examine the impact of the jet on the interstellar medium of the host galaxy, and find that the energy in the radio lobes can heat a significant fraction of the gas to the virial temperature. Finally, we discuss tests that may help future surveys distinguish between jet-driven kinematics and

Spectroscopic observations of a major flare in QSO TXS0917+624.

NASA Astrophysics Data System (ADS)

Wyrzykowski, L.; Gromadzki, M.; Kozlowski, Sz.; Mroz, P.; Shahbandeh, M.; Hsiao, E.; Berton, M.; Ciroi, S.; Pastorello, A.; Chen, S.; Reguitti, A.

2018-01-01

We report on optical and near-IR spectroscopy of QSO TXS0917+624 (radio and gamma source) which showed a major 2 magnitude flare on 9th of December 2017 (Spiridonova, Moskvitin and Vlasyuk 2017, ATEL #11048).

Near-infrared imaging of CfA Seyfert galaxies

NASA Astrophysics Data System (ADS)

McLeod, K. K.; Rieke, G. H.

1995-03-01

We present near-IR images of 43 Seyfert galaxies from the CfA Seyfert sample. The near-IR luminosity is a good tracer of luminous mass in these galaxies. Most of the Seyfert nuclei are found in hosts of mass similar to that of L* galaxies and ranging in type from S0 to Sc. In addition, there is a population of low-mass host galaxies with very low luminosity Seyfert nuclei. We have examined our images for signs of perturbations that could drive fuel toward the galaxy nucleus, but there are none we can identify at a significant level. The critical element for fueling is evidently not reflected clearly in the large-scale distribution of luminous mass in the galaxy. The Seyfert hosts are compared with a sample of 50 low-redshift quasar host galaxies we have also imaged. The radio-quiet quasars and the Seyfert nuclei lie in similar kinds of galaxies spanning the same range of mass centered around L*. However, for the most luminous quasars, there is a correlation between the minimum host-galaxy mass and the luminosity of the active nucleus. Radio-loud quasars are generally found in hosts more massive than an L* galaxy. The low-luminosity quasars and the Seyfert nuclei both tend to lie in host galaxies seen preferentially face-on, which suggests that there is a substantial amount of obscuration coplanar with the galaxian disk. The obscuration must be geometrically thick (thickness-to-radius ratio approximately 1) and must cover a significant fraction of the narrow-line region (r greater than 100 pc).

Variability of the broad absorption lines in the QSO UM 232

NASA Technical Reports Server (NTRS)

Barlow, Thomas A.; Junkkarinen, Vesa T.; Burbidge, E. Margaret

1989-01-01

Low-resolution spectra of UM 232 taken in 1978, 1979, and 1988 at Lick Observatory are presented. Large changes in the Si IV lambda 1397, CIV lambda 1549, and Al III lambda 1857 broad absorption lines are apparent. The decrease in column density in all three ions and an observed brightening of the QSO suggests that these changes are due to an increase in the ionization level driven by an increase in the central source luminosity. This mechanism has been proposed by Smith and Penston to explain small changes in the absorption spectrum of the QSO 1246-057. The spectra of UM 232 show that the fractional decrease in optical depth is smaller at higher outflow velocies. The structure of the broad absorption-line region (BALR) is investigted by estimating an ionization parameter for each ion species as a function of velocity.

Novel Relationship among Spiral Arm Pitch Angles (p) and momentum parameter of the host spiral galaxies

NASA Astrophysics Data System (ADS)

Al-Baidhany, Ismaeel; Rashid, Hayfa G.; Chiad, Sami S.; Habubi, Nadir F.; Jandow, Nidhal N.; Jabbar, Wasmaa A.; Abass, khalid H.

2018-05-01

In this study, we have found a novel relationship among spiral arm pitch angles (p) and momentum parameter of the host spiral galaxies. In this study, we measured the momentum parameter for specimen of Spitzer/IRAC 3.6 μm images of 41 spiral galaxies evaluated employing a relation(Mbulge σ*/c)where Mbulge is mass of the bulge and σ* is the stellar velocity dispersion. We have taken velocity dispersions (σ*) from the literature. In order to determine the spiral arm pitch angles. The selection of specimen of nearly face-on spiral galaxies and employ IRAF ellipse to indicate the ellipticity and major-axis position angle so as to deproject the images to face-on, employing 2D Fast Fourier Transform decomposition mehtod. The specified bulge mass (Mbulge) using the virial theorem was include.

Possible correlations between gamma-ray burst and its host galaxy offset

NASA Astrophysics Data System (ADS)

Wang, Fei-Fei; Zou, Yuan-Chuan; Liu, Yu; Liao, Bin; Moharana, Reetanjali

2018-06-01

We collected the information of 304 gamma-ray bursts (GRBs) from the literature, and analyzed the correlations among the host galaxy offsets (the distance from the site of the GRB to the center of its host galaxy), T90,i (the duration T90 in rest-frame), TR45,i (the duration TR45 in rest-frame), Eγ,iso (the isotropic equivalent energy), Lγ,iso (=Eγ,iso /T90,i, the isotropic equivalent luminosity) and Lpk (peak luminosity). We found that T90,i, TR45,i, Eγ,iso, Lpk have negative correlation with offset, which is consistent with origin of short GRBs (SGRBs) and long GRBs (LGRBs). On separate analysis, we found similar results for log ⁡Eγ,iso - log ⁡ (offset) and log ⁡Lpk - log ⁡ (offset) relations in case of SGRBs only, while no obvious relation for LGRBs. There is no correlations between offset and Lγ,iso. We also put the special GRB 170817A and GRB 060218A on the plots. The two GRBs both have low luminosity and small offset. In the log ⁡ (offset) - log ⁡T90,i plot, we found GRB 170817A locates in between the two regions of SGRBs and LGRBs and it is the outlier in the offset -Eγ,iso, offset -Lγ,iso and offset -Lpk plots. Together with GRB 060218A being an outlier in all plots, it indicates the speciality of GRBs 170817A and 060218A, and might imply more subgroups of the GRB samples.

Spatially Resolved MaNGA Observations of the Host Galaxy of Superluminous Supernova 2017egm

NASA Astrophysics Data System (ADS)

Chen, Ting-Wan; Schady, Patricia; Xiao, Lin; Eldridge, J. J.; Schweyer, Tassilo; Lee, Chien-Hsiu; Yu, Po-Chieh; Smartt, Stephen J.; Inserra, Cosimo

2017-11-01

Superluminous supernovae (SLSNe) are found predominantly in dwarf galaxies, indicating that their progenitors have a low metallicity. However, the most nearby SLSN to date, SN 2017egm, occurred in the spiral galaxy NGC 3191, which has a relatively high stellar mass and correspondingly high metallicity. In this Letter, we present detailed analysis of the nearby environment of SN 2017egm using MaNGA IFU data, which provides spectral data on kiloparsec scales. From the velocity map we find no evidence that SN 2017egm occurred within some intervening satellite galaxy, and at the SN position most metallicity diagnostics yield a solar and above solar metallicity (12+{log}({{O}}/{{H}})∼ 8.8{--}9.1). Additionally, we measure a small Hα equivalent width (EW) at the SN position of just 34 Å, which is one of the lowest EWs measured at any SLSN or gamma-ray burst position, and indicative of the progenitor star being comparatively old. We also compare the observed properties of NGC 3191 with other SLSN host galaxies. The solar-metallicity environment at the position of SN 2017egm presents a challenge to our theoretical understanding, and our spatially resolved spectral analysis provides further constraints on the progenitors of SLSNe.

Characterizing the Circumgalactic Medium of Nearby Galaxies with HST/COS and HST/STIS Absorption-line Spectroscopy. II. Methods and Models

NASA Astrophysics Data System (ADS)

Keeney, Brian A.; Stocke, John T.; Danforth, Charles W.; Shull, J. Michael; Pratt, Cameron T.; Froning, Cynthia S.; Green, James C.; Penton, Steven V.; Savage, Blair D.

2017-05-01

We present basic data and modeling for a survey of the cool, photoionized circumgalactic medium (CGM) of low-redshift galaxies using far-UV QSO absorption-line probes. This survey consists of “targeted” and “serendipitous” CGM subsamples, originally described in Stocke et al. (Paper I). The targeted subsample probes low-luminosity, late-type galaxies at z< 0.02 with small impact parameters (< ρ > =71 kpc), and the serendipitous subsample probes higher luminosity galaxies at z≲ 0.2 with larger impact parameters (< ρ > =222 kpc). Hubble Space Telescope and FUSE UV spectroscopy of the absorbers and basic data for the associated galaxies, derived from ground-based imaging and spectroscopy, are presented. We find broad agreement with the COS-Halos results, but our sample shows no evidence for changing ionization parameter or hydrogen density with distance from the CGM host galaxy, probably because the COS-Halos survey probes the CGM at smaller impact parameters. We find at least two passive galaxies with H I and metal-line absorption, confirming the intriguing COS-Halos result that galaxies sometimes have cool gas halos despite no on-going star formation. Using a new methodology for fitting H I absorption complexes, we confirm the CGM cool gas mass of Paper I, but this value is significantly smaller than that found by the COS-Halos survey. We trace much of this difference to the specific values of the low-z metagalactic ionization rate assumed. After accounting for this difference, a best-value for the CGM cool gas mass is found by combining the results of both surveys to obtain {log}(M/{M}⊙ )=10.5+/- 0.3, or ˜30% of the total baryon reservoir of an L≥slant {L}* , star-forming galaxy. Based on observations with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by AURA, Inc., under NASA contract NAS 5-26555.

CONNECTING GRBs AND ULIRGs: A SENSITIVE, UNBIASED SURVEY FOR RADIO EMISSION FROM GAMMA-RAY BURST HOST GALAXIES AT 0 < z < 2.5

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

Perley, D. A.; Perley, R. A.; Hjorth, J.

2015-03-10

Luminous infrared galaxies and submillimeter galaxies contribute significantly to stellar mass assembly and provide an important test of the connection between the gamma-ray burst (GRB) rate and that of overall cosmic star formation. We present sensitive 3 GHz radio observations using the Karl G. Jansky Very Large Array of 32 uniformly selected GRB host galaxies spanning a redshift range from 0 < z < 2.5, providing the first fully dust- and sample-unbiased measurement of the fraction of GRBs originating from the universe's most bolometrically luminous galaxies. Four galaxies are detected, with inferred radio star formation rates (SFRs) ranging between 50 and 300 Mmore » {sub ☉} yr{sup –1}. Three of the four detections correspond to events consistent with being optically obscured 'dark' bursts. Our overall detection fraction implies that between 9% and 23% of GRBs between 0.5 < z < 2.5 occur in galaxies with S {sub 3GHz} > 10 μJy, corresponding to SFR > 50 M {sub ☉} yr{sup –1} at z ∼ 1 or >250 M {sub ☉} yr{sup –1} at z ∼ 2. Similar galaxies contribute approximately 10%-30% of all cosmic star formation, so our results are consistent with a GRB rate that is not strongly biased with respect to the total SFR of a galaxy. However, all four radio-detected hosts have stellar masses significantly lower than IR/submillimeter-selected field galaxies of similar luminosities. We suggest that the GRB rate may be suppressed in metal-rich environments but independently enhanced in intense starbursts, producing a strong efficiency dependence on mass but little net dependence on bulk galaxy SFR.« less

NE VIII lambda 774 and time variable associated absorption in the QSO UM 675

NASA Astrophysics Data System (ADS)

Hamann, Fred; Barlow, Thomas A.; Beaver, E. A.; Burbidge, E. M.; Cohen, Ross D.; Junkkarinen, Vesa; Lyons, R.

1995-04-01

We discuss measurements of Ne VIII lambda 774 absorption and the time variability of other lines in the za approximately equal ze absorption system of the ze = 2.15 QSO UM 675 (0150-203). The C IV lambda 1549 and N V 1240 doublets at za = 2.1340 (shifted approximately 1500 km/s from ze strengthened by a factor of approximately 3 between observations by Sargent, Boksenberg and Steidel (1981 November) and our earliest measurements (1990 November and December). We have no information on changes in other za approximately equal ze absorption lines. Continued monitoring since 1990 November shows no clear changes in any of the absorptions between approximately 1100 and 1640 A rest. The short timescale of the variability (less than or approximately equal to 2.9 yr rest) strongly suggests that the clouds are dense, compact, close to the QSO, and photoionized by the QSO continuum. If the line variability is caused by changes in the ionization, the timescale requires densities greater than approximately 4000/cu cm. Photoionization calculations place the absorbing clouds within approximately 200 pc of the continuum source. The full range of line ionizations (from Ne VIII lambda 774 to C III lambda 977) in optically thin gas (no Lyman limit) implies that the absorbing regions span a factor of more than approximately 10 in distance or approximately 100 in density. Across these regions, the total hydrogen (H I + H II) column ranges from a few times 1018/sq cm in the low-ionization gas to approximately 1020/sq cm where the Ne VIII doublet forms. The metallicity is roughly solar or higher, with nitrogen possibly more enhanced by factors of a few. The clouds might contribute significant line emission if they nearly envelop the QSO. The presence of highly ionized Ne VIII lambda 774 absorption near the QSO supports recent studies that link za approximately equal to ze systems with X-ray 'wamr absorbers. We show that the Ne VIII absorbing gas would itself produce measurable warm

Ultraviolet Broad Absorption Features and the Spectral Energy Distribution of the QSO PG 1351+64. 3.1

NASA Technical Reports Server (NTRS)

Zheng, W.; Kriss, G. A.; Wang, J. X.; Brotherton, M.; Oegerle, W. R.; Blair, W. P.; Davidsen, A. F.; Green, R. F.; Hutchings, J. B.; Kaiser, M. E.;

Ultraviolet Broad Absorption Features and the Spectral Energy Distribution of the QSO PG 1351+641. 2.5

NASA Technical Reports Server (NTRS)

Zheng, W.; Kriss, G. A.; Wang, J. X.; Brotherton, M.; Oegerle, W. R.; Blair, W. P.; Davidsen, A. F.; Green, R. F.; Hutchings, J. B.; Kaiser, M. E.;

Galaxy evolution. Isolated compact elliptical galaxies: stellar systems that ran away.

PubMed

Chilingarian, Igor; Zolotukhin, Ivan

2015-04-24

Compact elliptical galaxies form a rare class of stellar system (~30 presently known) characterized by high stellar densities and small sizes and often harboring metal-rich stars. They were thought to form through tidal stripping of massive progenitors, until two isolated objects were discovered where massive galaxies performing the stripping could not be identified. By mining astronomical survey data, we have now found 195 compact elliptical galaxies in all types of environment. They all share similar dynamical and stellar population properties. Dynamical analysis for nonisolated galaxies demonstrates the feasibility of their ejection from host clusters and groups by three-body encounters, which is in agreement with numerical simulations. Hence, isolated compact elliptical and isolated quiescent dwarf galaxies are tidally stripped systems that ran away from their hosts. Copyright © 2015, American Association for the Advancement of Science.

Deep imaging of high redshift QSO fields below the Lyman limit. II - Number counts and colors of field galaxies

NASA Technical Reports Server (NTRS)

Steidel, Charles C.; Hamilton, Donald

1993-01-01

We present an analysis of the number counts and colors of faint galaxies to about 26.5 mag in the fields of two high Galactic latitude, very-high-redshift QSOs. We concentrate on the general properties of the field galaxies at faint magnitudes. In particular, we readdress the faint galaxy number counts and colors as a function of apparent magnitude and we reexamine the possible contribution of very-high-redshift galaxies to the faint samples. We find that the number counts to R = 26 are well fitted by the relation log N(m) = 0.31R + C. The G-band counts for the same galaxies are consistent with the same slope fainter than G about 23.5, but exhibit a much steeper slope at brighter magnitudes. At R = 25.5, the differential number counts have reached about 1.2 x 10 exp 5/sq deg; the same surface density of galaxies is reached at G = 26.5. We confirm the existence of a gradual 'blueing' trend of the field galaxies toward fainter apparent magnitude; however, the blueing trend appears to extend only as faint as G about 24, fainter than which both the (G-R) and (U sub n-G) colors appear to level off. The mean colors of faint galaxies are considerably redder than flat spectrum. There are essentially no objects to R = 26 which have spectral energy distributions which are bluer than flat spectrum. The potential contribution of very-high-redshift galaxies may have been underestimated in previous analyses; the current data are consistent with the same population of relatively luminous galaxies at z about 3 as exist at z about 0.7.

New Members in the Galaxy Group Around Giant Radio Galaxy DA 240

NASA Astrophysics Data System (ADS)

Chen, Ru-Rong; Peng, Bo; Strom, Richard

2018-05-01

With new spectroscopic observations of group candidates around the giant radio galaxy DA 240, we have identified five new group members, increasing the number to twenty-five. While all the new members are located some distance from the host galaxy, two of them lie in one of the radio lobes, and the rest are found at a distance from the radio components. The new group members reinforce our earlier conclusion that the distribution of the DA 240 group with respect to the radio lobes is unusual among giant radio galaxy host environments.

ALMA observations of the host galaxy of GRB 090423 at z = 8.23: deep limits on obscured star formation 630 million years after the big bang

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

Berger, E.; Zauderer, B. A.; Chary, R.-R.

2014-12-01

We present rest-frame far-infrared (FIR) and optical observations of the host galaxy of GRB 090423 at z = 8.23 from the Atacama Large Millimeter Array (ALMA) and the Spitzer Space Telescope, respectively. The host remains undetected to 3σ limits of F {sub ν}(222 GHz) ≲ 33 μJy and F {sub ν}(3.6 μm) ≲ 81 nJy. The FIR limit is about 20 times fainter than the luminosity of the local ULIRG Arp 220 and comparable to the local starburst M 82. Comparing this with model spectral energy distributions, we place a limit on the infrared (IR) luminosity of L {sub IR}(8-1000more » μm) ≲ 3 × 10{sup 10} L {sub ☉}, corresponding to a limit on the obscured star formation rate of SFR{sub IR}≲5 M {sub ☉} yr{sup –1}. For comparison, the limit on the unobscured star formation rate from Hubble Space Telescope rest-frame ultraviolet (UV) observations is SFR{sub UV} ≲ 1 M {sub ☉} yr{sup –1}. We also place a limit on the host galaxy stellar mass of M {sub *} ≲ 5 × 10{sup 7} M {sub ☉} (for a stellar population age of 100 Myr and constant star formation rate). Finally, we compare our millimeter observations to those of field galaxies at z ≳ 4 (Lyman break galaxies, Lyα emitters, and submillimeter galaxies) and find that our limit on the FIR luminosity is the most constraining to date, although the field galaxies have much larger rest-frame UV/optical luminosities than the host of GRB 090423 by virtue of their selection techniques. We conclude that GRB host galaxies at z ≳ 4, especially those with measured interstellar medium metallicities from afterglow spectroscopy, are an attractive sample for future ALMA studies of high redshift obscured star formation.« less

The distant red galaxy neighbour population of 1

NASA Astrophysics Data System (ADS)

Bornancini, C.; García Lambas, D.

We study the Distant Red Galaxy (DRG, J-Ks > 2.3) neighbour population of Quasi Stellar Objects (QSOs) selected from the Sloan Digital Sky Survey (SDSS) in the redshift range 1 < z < 2. We perform a similar analysis for optically obscured AGNs (i.e. with a limiting magnitude I > 24) detected in the mid-infrared (24 microns) with the Spitzer Space Telescope and a mean redshift z~2.2 in the Flamingos Extragalactic Survey (FLAMEX). We present results on the cross-correlation function of DRGs around QSOs and optically faint mid-infrared sources. The corresponding correlation length obtained for the QSO sample targets is r_0=5.4+/-1.6 Mpc. For the optically obscured galaxy sample we find r_0=8.9+/-1.4 Mpc. These results indicate that optically faint obscured sources are located in denser environment of evolved red galaxies compare to QSOs.

The Host Galaxy and Central Engine of the Dwarf Active Galactic Nucleus POX 52

NASA Astrophysics Data System (ADS)

Thornton, Carol E.; Barth, Aaron J.; Ho, Luis C.; Rutledge, Robert E.; Greene, Jenny E.

2008-10-01

We present new multiwavelength observations of the dwarf Seyfert 1 galaxy POX 52 in order to investigate the properties of the host galaxy and the active nucleus and to examine the mass of its black hole, previously estimated to be ~105 M⊙. HST ACS HRC images show that the host galaxy has a dwarf elliptical morphology (MI = - 18.4 mag, Sérsic index n = 4.3) with no detected disk component or spiral structure, confirming previous results from ground-based imaging. X-ray observations from both Chandra and XMM-Newton show strong (factor of 2) variability over timescales as short as 500 s, as well as a dramatic decrease in the absorbing column density over a 9 month period. We attribute this change to a partial covering absorber, with a 94% covering fraction and NH = 58+ 8.4-9.2 × 1021 cm -2, that moved out of the line of sight in between the XMM-Newton and Chandra observations. Combining these data with observations from the VLA, Spitzer, and archival data from 2MASS and GALEX, we examine the SED of the active nucleus. Its shape is broadly similar to typical radio-quiet quasar SEDs, despite the very low bolometric luminosity of Lbol = 1.3 × 1043 ergs s-1. Finally, we compare black hole mass estimators, including methods based on X-ray variability, and optical scaling relations using the broad Hβ line width and AGN continuum luminosity, finding a range of black hole mass from all methods to be MBH = (2.2-4.2) × 105 M⊙, with an Eddington ratio of Lbol/LEdd ≈ 0.2-0.5.

Detection of very high energy gamma-ray emission from the gravitationally lensed blazar QSO B0218+357 with the MAGIC telescopes

NASA Astrophysics Data System (ADS)

Ahnen, M. L.; Ansoldi, S.; Antonelli, L. A.; Antoranz, P.; Arcaro, C.; Babic, A.; Banerjee, B.; Bangale, P.; Barres de Almeida, U.; Barrio, J. A.; Becerra González, J.; Bednarek, W.; Bernardini, E.; Berti, A.; Biasuzzi, B.; Biland, A.; Blanch, O.; Bonnefoy, S.; Bonnoli, G.; Borracci, F.; Bretz, T.; Buson, S.; Carosi, A.; Chatterjee, A.; Clavero, R.; Colin, P.; Colombo, E.; Contreras, J. L.; Cortina, J.; Covino, S.; Da Vela, P.; Dazzi, F.; De Angelis, A.; De Lotto, B.; de Oña Wilhelmi, E.; Di Pierro, F.; Doert, M.; Domínguez, A.; Dominis Prester, D.; Dorner, D.; Doro, M.; Einecke, S.; Eisenacher Glawion, D.; Elsaesser, D.; Engelkemeier, M.; Fallah Ramazani, V.; Fernández-Barral, A.; Fidalgo, D.; Fonseca, M. V.; Font, L.; Frantzen, K.; Fruck, C.; Galindo, D.; García López, R. J.; Garczarczyk, M.; Garrido Terrats, D.; Gaug, M.; Giammaria, P.; Godinović, N.; Gora, D.; Guberman, D.; Hadasch, D.; Hahn, A.; Hayashida, M.; Herrera, J.; Hose, J.; Hrupec, D.; Hughes, G.; Idec, W.; Kodani, K.; Konno, Y.; Kubo, H.; Kushida, J.; La Barbera, A.; Lelas, D.; Lindfors, E.; Lombardi, S.; Longo, F.; López, M.; López-Coto, R.; Majumdar, P.; Makariev, M.; Mallot, K.; Maneva, G.; Manganaro, M.; Mannheim, K.; Maraschi, L.; Marcote, B.; Mariotti, M.; Martínez, M.; Mazin, D.; Menzel, U.; Miranda, J. M.; Mirzoyan, R.; Moralejo, A.; Moretti, E.; Nakajima, D.; Neustroev, V.; Niedzwiecki, A.; Nievas Rosillo, M.; Nilsson, K.; Nishijima, K.; Noda, K.; Nogués, L.; Paiano, S.; Palacio, J.; Palatiello, M.; Paneque, D.; Paoletti, R.; Paredes, J. M.; Paredes-Fortuny, X.; Pedaletti, G.; Peresano, M.; Perri, L.; Persic, M.; Poutanen, J.; Prada Moroni, P. G.; Prandini, E.; Puljak, I.; Garcia, J. R.; Reichardt, I.; Rhode, W.; Ribó, M.; Rico, J.; Saito, T.; Satalecka, K.; Schroeder, S.; Schweizer, T.; Shore, S. N.; Sillanpää, A.; Sitarek, J.; Snidaric, I.; Sobczynska, D.; Stamerra, A.; Strzys, M.; Surić, T.; Takalo, L.; Tavecchio, F.; Temnikov, P.; Terzić, T.; Tescaro, D.; Teshima, M.; Torres, D. F.; Toyama, T.; Treves, A.; Vanzo, G.; Verguilov, V.; Vovk, I.; Ward, J. E.; Will, M.; Wu, M. H.; Zanin, R.; Desiante, R.

2016-11-01

Context. QSO B0218+357 is a gravitationally lensed blazar located at a redshift of 0.944. The gravitational lensing splits the emitted radiation into two components that are spatially indistinguishable by gamma-ray instruments, but separated by a 10-12 day delay. In July 2014, QSO B0218+357 experienced a violent flare observed by the Fermi-LAT and followed by the MAGIC telescopes. Aims: The spectral energy distribution of QSO B0218+357 can give information on the energetics of z 1 very high energy gamma-ray sources. Moreover the gamma-ray emission can also be used as a probe of the extragalactic background light at z 1. Methods: MAGIC performed observations of QSO B0218+357 during the expected arrival time of the delayed component of the emission. The MAGIC and Fermi-LAT observations were accompanied by quasi-simultaneous optical data from the KVA telescope and X-ray observations by Swift-XRT. We construct a multiwavelength spectral energy distribution of QSO B0218+357 and use it to model the source. The GeV and sub-TeV data obtained by Fermi-LAT and MAGIC are used to set constraints on the extragalactic background light. Results: Very high energy gamma-ray emission was detected from the direction of QSO B0218+357 by the MAGIC telescopes during the expected time of arrival of the trailing component of the flare, making it the farthest very high energy gamma-ray source detected to date. The observed emission spans the energy range from 65 to 175 GeV. The combined MAGIC and Fermi-LAT spectral energy distribution of QSO B0218+357 is consistent with current extragalactic background light models. The broadband emission can be modeled in the framework of a two-zone external Compton scenario, where the GeV emission comes from an emission region in the jet, located outside the broad line region.

Detection of very high energy gamma-ray emission from the gravitationally lensed blazar QSO B0218+357 with the MAGIC telescopes

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

Ahnen, M. L.; Ansoldi, S.; Antonelli, L. A.

QSO B0218+357 is a gravitationally lensed blazar located at a redshift of 0.944. The gravitational lensing splits the emitted radiation into two components that are spatially indistinguishable by gamma-ray instruments, but separated by a 10–12 day delay. In July 2014, QSO B0218+357 experienced a violent flare observed by the Fermi-LAT and followed by the MAGIC telescopes. The spectral energy distribution of QSO B0218+357 can give information on the energetics of z ~ 1 very high energy gamma-ray sources. Furthermore, the gamma-ray emission can also be used as a probe of the extragalactic background light at z ~ 1. MAGIC performedmore » observations of QSO B0218+357 during the expected arrival time of the delayed component of the emission. The MAGIC and Fermi-LAT observations were accompanied by quasi-simultaneous optical data from the KVA telescope and X-ray observations by Swift-XRT. We construct a multiwavelength spectral energy distribution of QSO B0218+357 and use it to model the source. The GeV and sub-TeV data obtained by Fermi-LAT and MAGIC are used to set constraints on the extragalactic background light. We detected very high energy gamma-ray emission from the direction of QSO B0218+357 by the MAGIC telescopes during the expected time of arrival of the trailing component of the flare, making it the farthest very high energy gamma-ray source detected to date. We also observed emission spans the energy range from 65 to 175 GeV. The combined MAGIC and Fermi-LAT spectral energy distribution of QSO B0218+357 is consistent with current extragalactic background light models. The broadband emission can be modeled in the framework of a two-zone external Compton scenario, where the GeV emission comes from an emission region in the jet, located outside the broad line region.« less

Detection of very high energy gamma-ray emission from the gravitationally lensed blazar QSO B0218+357 with the MAGIC telescopes

DOE PAGES

Ahnen, M. L.; Ansoldi, S.; Antonelli, L. A.; ...

2016-11-04

QSO B0218+357 is a gravitationally lensed blazar located at a redshift of 0.944. The gravitational lensing splits the emitted radiation into two components that are spatially indistinguishable by gamma-ray instruments, but separated by a 10–12 day delay. In July 2014, QSO B0218+357 experienced a violent flare observed by the Fermi-LAT and followed by the MAGIC telescopes. The spectral energy distribution of QSO B0218+357 can give information on the energetics of z ~ 1 very high energy gamma-ray sources. Furthermore, the gamma-ray emission can also be used as a probe of the extragalactic background light at z ~ 1. MAGIC performedmore » observations of QSO B0218+357 during the expected arrival time of the delayed component of the emission. The MAGIC and Fermi-LAT observations were accompanied by quasi-simultaneous optical data from the KVA telescope and X-ray observations by Swift-XRT. We construct a multiwavelength spectral energy distribution of QSO B0218+357 and use it to model the source. The GeV and sub-TeV data obtained by Fermi-LAT and MAGIC are used to set constraints on the extragalactic background light. We detected very high energy gamma-ray emission from the direction of QSO B0218+357 by the MAGIC telescopes during the expected time of arrival of the trailing component of the flare, making it the farthest very high energy gamma-ray source detected to date. We also observed emission spans the energy range from 65 to 175 GeV. The combined MAGIC and Fermi-LAT spectral energy distribution of QSO B0218+357 is consistent with current extragalactic background light models. The broadband emission can be modeled in the framework of a two-zone external Compton scenario, where the GeV emission comes from an emission region in the jet, located outside the broad line region.« less

Gas inflow and outflow in an interacting high-redshift galaxy. The remarkable host environment of GRB 080810 at z = 3.35

NASA Astrophysics Data System (ADS)

Wiseman, P.; Perley, D. A.; Schady, P.; Prochaska, J. X.; de Ugarte Postigo, A.; Krühler, T.; Yates, R. M.; Greiner, J.

2017-11-01

We reveal multiple components of an interacting galaxy system at z ≈ 3.35 through a detailed analysis of the exquisite high-resolution Keck/HIRES spectrum of the afterglow of a gamma-ray burst (GRB). Through Voigt-profile fitting of absorption lines from the Lyman series, we constrain the neutral hydrogen column density to NH I ≤ 1018.35 cm-2 for the densest of four distinct systems at the host redshift of GRB 080810, which is among the lowest NH I ever observed in a GRB host, even though the line of sight passes within a projected 5 kpc of the galaxy centres. By detailed analysis of the corresponding metal absorption lines, we derive chemical, ionic, and kinematic properties of the individual absorbing systems, and thus build a picture of the host as a whole. Striking differences between the systems imply that the line of sight passes through several phases of gas: the star-forming regions of the GRB host; enriched material in the form of a galactic outflow; the hot and ionised halo of a second interacting galaxy falling towards the host at a line-of-sight velocity of 700 km s-1; and a cool metal-poor cloud that may represent one of the best candidates yet for the inflow of metal-poor gas from the intergalactic medium. The reduced spectrum is only 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/607/A107

The Role of Radiation Pressure in the Narrow Line Regions of Seyfert Host Galaxies

NASA Astrophysics Data System (ADS)

Davies, Rebecca L.; Dopita, Michael A.; Kewley, Lisa; Groves, Brent; Sutherland, Ralph; Hampton, Elise J.; Shastri, Prajval; Kharb, Preeti; Bhatt, Harish; Scharwächter, Julia; Jin, Chichuan; Banfield, Julie; Zaw, Ingyin; James, Bethan; Juneau, Stéphanie; Srivastava, Shweta

2016-06-01

We investigate the relative significance of radiation pressure and gas pressure in the extended narrow line regions (ENLRs) of four Seyfert galaxies from the integral field Siding Spring Southern Seyfert Spectroscopic Snapshot Survey (S7). We demonstrate that there exist two distinct types of starburst-active galactic nucleus (AGN) mixing curves on standard emission line diagnostic diagrams, which reflect the balance between gas pressure and radiation pressure in the ENLR. In two of the galaxies the ENLR is radiation pressure dominated throughout and the ionization parameter remains constant (log U ˜ 0). In the other two galaxies radiation pressure is initially important, but gas pressure becomes dominant as the ionization parameter in the ENLR decreases from log U ˜ 0 to -3.2 ≲ log U ≲ -3.4. Where radiation pressure is dominant, the AGN regulates the density of the interstellar medium on kiloparsec scales and may therefore have a direct impact on star formation activity and/or the incidence of outflows in the host galaxy to scales far beyond the zone of influence of the black hole. We find that both radiation pressure dominated and gas pressure dominated ENLRs are dynamically active with evidence for outflows, indicating that radiation pressure may be an important source of AGN feedback even when it is not dominant over the entire ENLR.

Host Galaxy Properties of SWIFT Hard X-ray Selected AGN

NASA Astrophysics Data System (ADS)

Koss, Michael; Mushotzky, R.; Veilleux, S.; Winter, L.

2010-01-01

Surveys of AGN taken in the optical, UV, and soft X-rays miss an important population of obscured AGN only visible in the hard X-rays and mid-IR wavelengths. The SWIFT BAT survey in the hard X-ray range (14-195 keV) has provided a uniquely unbiased sample of 258 AGN unaffected by galactic or circumnuclear absorption. Optical imaging of this unbiased sample provides a new opportunity to understand how the environments of the host galaxies are linked to AGN. In 2008, we observed 110 of these targets at Kitt Peak with the 2.1m in the SDSS ugriz bands over 17 nights. Using these observations and SDSS data we review the relationships between color, morphology, merger activity, star formation, and AGN luminosity.

Polar ring galaxies in the Galaxy Zoo

NASA Astrophysics Data System (ADS)

Finkelman, Ido; Funes, José G.; Brosch, Noah

2012-05-01

We report observations of 16 candidate polar-ring galaxies (PRGs) identified by the Galaxy Zoo project in the Sloan Digital Sky Survey (SDSS) data base. Deep images of five galaxies are available in the SDSS Stripe82 data base, while to reach similar depth we observed the remaining galaxies with the 1.8-m Vatican Advanced Technology Telescope. We derive integrated magnitudes and u-r colours for the host and ring components and show continuum-subtracted Hα+[N II] images for seven objects. We present a basic morphological and environmental analysis of the galaxies and discuss their properties in comparison with other types of early-type galaxies. Follow-up photometric and spectroscopic observations will allow a kinematic confirmation of the nature of these systems and a more detailed analysis of their stellar populations.

Black hole growth and starburst activity at z = 0.6-4 in the Chandra Deep Field South. Host galaxies properties of obscured AGN

NASA Astrophysics Data System (ADS)

Brusa, M.; Fiore, F.; Santini, P.; Grazian, A.; Comastri, A.; Zamorani, G.; Hasinger, G.; Merloni, A.; Civano, F.; Fontana, A.; Mainieri, V.

2009-12-01

Aims: The co-evolution of host galaxies and the active black holes which reside in their centre is one of the most important topics in modern observational cosmology. Here we present a study of the properties of obscured active galactic nuclei (AGN) detected in the CDFS 1 Ms observation and their host galaxies. Methods: We limited the analysis to the MUSIC area, for which deep K-band observations obtained with ISAAC@VLT are available, ensuring accurate identifications of the counterparts of the X-ray sources as well as reliable determination of photometric redshifts and galaxy parameters, such as stellar masses and star formation rates. In particular, we: 1) refined the X-ray/infrared/optical association of 179 sources in the MUSIC area detected in the Chandra observation; 2) studied the host galaxies observed and rest frame colors and properties. Results: We found that X-ray selected (LX ⪆ 1042 erg s-1) AGN show Spitzer colors consistent with both AGN and starburst dominated infrared continuum; the latter would not have been selected as AGN from infrared diagnostics. The host galaxies of X-ray selected obscured AGN are all massive (Mast > 1010 M_⊙) and, in 50% of the cases, are also actively forming stars (1/SSFR < tHubble) in dusty environments. The median L/LEdd value of the active nucleus is between 2% and 10% depending on the assumed MBH/Mast ratio. Finally, we found that the X-ray selected AGN fraction increases with the stellar mass up to a value of 30% at z > 1 and Mast > 3 × 1011 M_⊙, a fraction significantly higher than in the local Universe for AGN of similar luminosities. Tables [see full textsee full textsee full text] and [see full textsee full textsee full text] are only available in electronic form at http://www.aanda.org

A dichotomy in satellite quenching around L* galaxies

NASA Astrophysics Data System (ADS)

Phillips, John I.; Wheeler, Coral; Boylan-Kolchin, Michael; Bullock, James S.; Cooper, Michael C.; Tollerud, Erik J.

2014-01-01

We examine the star formation properties of bright (˜0.1 L*) satellites around isolated ˜L* hosts in the local Universe using spectroscopically confirmed systems in the Sloan Digital Sky Survey Data Release 7. Our selection method is carefully designed with the aid of N-body simulations to avoid groups and clusters. We find that satellites are significantly more likely to be quenched than a stellar mass-matched sample of isolated galaxies. Remarkably, this quenching occurs only for satellites of hosts that are themselves quenched: while star formation is unaffected in the satellites of star-forming hosts, satellites around quiescent hosts are more than twice as likely to be quenched than stellar-mass-matched field samples. One implication of this is that whatever shuts down star formation in isolated, passive L* galaxies also play at least an indirect role in quenching star formation in their bright satellites. The previously reported tendency for `galactic conformity' in colour/morphology may be a by-product of this host-specific quenching dichotomy. The Sérsic indices of quenched satellites are statistically identical to those of field galaxies with the same specific star formation rates, suggesting that environmental and secular quenching give rise to the same morphological structure. By studying the distribution of pairwise velocities between the hosts and satellites, we find dynamical evidence that passive host galaxies reside in dark matter haloes that are ˜45 per cent more massive than those of star-forming host galaxies of the same stellar mass. We emphasize that even around passive hosts, the mere fact that galaxies become satellites does not typically result in star formation quenching: we find that only ˜30 per cent of ˜0.1L* galaxies that fall in from the field are quenched around passive hosts, compared with ˜0 per cent around star-forming hosts.

Investigating the host galaxies of luminous AGN in the local universe with integral field spectroscopy

NASA Astrophysics Data System (ADS)

McElroy, Rebecca; Croom, Scott; Husemann, Bernd; Close AGN Reference Survey; SAMI Galaxy Survey

2017-01-01

This thesis investigates how galaxies and their super massive black holes coevolve. We use integral field spectroscopy to search for evidence of AGN feedback and triggering. We demonstrate that outflows are ubiquitous among luminous local type 2 AGN using observations from the AAT's SPIRAL instrument. Using multiple component Gaussian emission line decomposition we are able to disentangle the kinematic and ionisation properties of these winds. This allows us to argue that the outflows from these AGN are directly impacting the surrounding ISM within the galaxies. We search for evidence of AGN triggering using data from The Close AGN Reference Survey (CARS). CARS aims to provide a detailed multi-wavelength view of 40 nearby (0.01 < z < 0.06) unobscured AGN to study the link between AGN and their host galaxies. The primary CARS observations come from the MUSE integral field unit on the VLT, and complementary multi-wavelength observations have been approved from SOFIA, Chandra, VLA, HST, and others. We compare the stellar kinematics of active galaxies from CARS to similar inactive galaxies. We then use kinemetry to estimate the degree of dynamical disturbance, to determine whether active nuclei are preferentially hosted in dynamically disturbed or merging systems. Finally, we highlight the discovery of an AGN that has changed spectral type not once, but twice. So called ‘changing look’ AGN are an uncommon phenomenon, but twice changed AGN are much rarer. This AGN first transitioned from a narrow line AGN (type 2) to a broad line AGN (type 1) in the 1980s. It was recently observed as part of CARS. Examination of the MUSE data for this particular source showed that it no longer had the spectral features typical of a type 1 AGN. The continuum emission from the accretion disk was no longer visible and the broad lines were dramatically diminished. In this talk we describe the possible reasons for this change, supported by analysis of multi-epoch optical photometry and

Identification and properties of host galaxies of RCR radio sources

NASA Astrophysics Data System (ADS)

Zhelenkova, O. P.; Soboleva, N. S.; Majorova, E. K.; Temirova, A. V.

2013-01-01

FIRST and NVSS radio maps are used to cross identify the radio sources of the RCR catalog, which is based on observational data obtained in several runs of the "Cold" survey, with the SDSS and DPOSS digital optical sky surveys and the 2MASS, LAS UKIDSS, and WISE infrared surveys. Digital images in various filters and the coadded gri-band SDSS images, red and infrared DPOSS images, JHK-band UKIDSS images, and JHK-band 2MASS images are analyzed for the sources with no optical candidates found in the above catalogs. Our choice of optical candidates was based on the data on the structure of the radio source, its photometry, and spectroscopy (where available). We found reliable identifications for 86% of the radio sources; possible counterparts for 8% of the sources, and failed to find any optical counterparts for 6% of the sources because their host objects proved to be fainter than the limiting magnitude of the corresponding surveys. A little over half of all the identifications proved to be galaxies; about one quarter were quasars, and the types of the remaining objects were difficult to determine because of their faintness. A relation between the luminosity and the radioloudness index was derived and used to estimate the 1.4 and 3.94 GHz luminosities for the sources with unknown redshifts. We found 3% and 60% of all the RCR radio sources to be FRI-type objects ( L ≲ 1024 W/Hz at 1.4 GHz) and powerful FRII-type galaxies ( L ≳ 1026.5 W/Hz), respectively, whereas the rest are sources including objects of the FRI, FRII, and mixed FRI-FRII types. Unlike quasars, galaxies show a trend of decreasing luminosity with decreasing flux density. Note that identification would be quite problematic without the software and resources of the virtual observatory.

A Compact Group of Galaxies at z = 2.48 Hosting an AGN-driven Outflow

NASA Astrophysics Data System (ADS)

Shih, Hsin-Yi; Stockton, Alan

2015-12-01

We present observations of a remarkable compact group of galaxies at z = 2.48. Four galaxies, all within 40 kpc of each other, surround a powerful high-redshift radio source. This group comprises two compact red passive galaxies and a pair of merging galaxies. One of the red galaxies, with an apparent stellar mass of 3.6 × 1011M⊙ and an effective radius of 470 pc, is one of the most extreme examples of a massive quiescent compact galaxy found so far. One of the pair of merging galaxies hosts the active galactic nucleus (AGN) producing the large powerful radio structure. The merger is massive and enriched, consistent with the mass-metallicity relation expected at this redshift. Close to the merging nuclei, the emission lines exhibit broad and asymmetric profiles that suggest outflows powered either by a very young expanding radio jet or by AGN radiation. At ≳50 kpc from the system, we found a fainter extended-emission region that may be a part of a radio-jet-driven outflow. Some of the data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation. The work is also based, in part, on data collected at the Subaru Telescope, which is operated by the National Astronomical Observatory of Japan, and on observations obtained at the Gemini Observatory, which is operated by the Association of Universities for Research in Astronomy, Inc., under a cooperative agreement with the NSF on behalf of the Gemini partnership: the National Science Foundation (United States), the National Research Council (Canada), CONICYT (Chile), the Australian Research Council (Australia), Ministério da Ciência, Tecnologia e Inovação (Brazil), and Ministerio de Ciencia, Tecnología e Innovación Productiva (Argentina).

Low-redshift Lyman-alpha absorption lines and the dark matter halos of disk galaxies

NASA Technical Reports Server (NTRS)

Maloney, Philip

1992-01-01

Ultraviolet observations of the low-redshift quasar 3C 273 using the Hubble Space Telescope have revealed many more Lyman-alpha absorption lines than would be expected from extrapolation of the absorption systems seen toward QSOs at z about 2. It is shown here that these absorption lines can plausibly be produced by gas at large radii in the disks of spiral and irregular galaxies; the gas is confined by the dark matter halos and ionized and heated by the extragalactic radiation field. This scenario does not require the extragalactic ionizing radiation field to decline as rapidly with decreasing z as the QSO emissivity. Observations of Ly-alpha absorption through the halos of known galaxies at low redshift will constrain both the extragalactic background and the properties of galactic halos.

NE VIII lambda 774 and time variable associated absorption in the QSO UM 675

NASA Technical Reports Server (NTRS)

Hamann, Fred; Barlow, Thomas A.; Beaver, E. A.; Burbidge, E. M.; Cohen, Ross D.; Junkkarinen, Vesa; Lyons, R.

1995-01-01

We discuss measurements of Ne VIII lambda 774 absorption and the time variability of other lines in the z(sub a) approximately equal z(sub e) absorption system of the z(sub e) = 2.15 QSO UM 675 (0150-203). The C IV lambda 1549 and N V 1240 doublets at z(sub a) = 2.1340 (shifted approximately 1500 km/s from z(sub e) strengthened by a factor of approximately 3 between observations by Sargent, Boksenberg and Steidel (1981 November) and our earliest measurements (1990 November and December). We have no information on changes in other z(sub a) approximately equal z(sub e) absorption lines. Continued monitoring since 1990 November shows no clear changes in any of the absorptions between approximately 1100 and 1640 A rest. The short timescale of the variability (less than or approximately equal to 2.9 yr rest) strongly suggests that the clouds are dense, compact, close to the QSO, and photoionized by the QSO continuum. If the line variability is caused by changes in the ionization, the timescale requires densities greater than approximately 4000/cu cm. Photoionization calculations place the absorbing clouds within approximately 200 pc of the continuum source. The full range of line ionizations (from Ne VIII lambda 774 to C III lambda 977) in optically thin gas (no Lyman limit) implies that the absorbing regions span a factor of more than approximately 10 in distance or approximately 100 in density. Across these regions, the total hydrogen (H I + H II) column ranges from a few times 10(exp 18)/sq cm in the low-ionization gas to approximately 10(exp 20)/sq cm where the Ne VIII doublet forms. The metallicity is roughly solar or higher, with nitrogen possibly more enhanced by factors of a few. The clouds might contribute significant line emission if they nearly envelop the QSO. The presence of highly ionized Ne VIII lambda 774 absorption near the QSO supports recent studies that link z(sub a) approximately equal to z(sub e) systems with X-ray 'wamr absorbers. We show that the

The afterglow and elliptical host galaxy of the short gamma-ray burst GRB 050724.

PubMed

Berger, E; Price, P A; Cenko, S B; Gal-Yam, A; Soderberg, A M; Kasliwal, M; Leonard, D C; Cameron, P B; Frail, D A; Kulkarni, S R; Murphy, D C; Krzeminski, W; Piran, T; Lee, B L; Roth, K C; Moon, D-S; Fox, D B; Harrison, F A; Persson, S E; Schmidt, B P; Penprase, B E; Rich, J; Peterson, B A; Cowie, L L

2005-12-15

Despite a rich phenomenology, gamma-ray bursts (GRBs) are divided into two classes based on their duration and spectral hardness--the long-soft and the short-hard bursts. The discovery of afterglow emission from long GRBs was a watershed event, pinpointing their origin to star-forming galaxies, and hence the death of massive stars, and indicating an energy release of about 10(51) erg. While theoretical arguments suggest that short GRBs are produced in the coalescence of binary compact objects (neutron stars or black holes), the progenitors, energetics and environments of these events remain elusive despite recent localizations. Here we report the discovery of the first radio afterglow from the short burst GRB 050724, which unambiguously associates it with an elliptical galaxy at a redshift z = 0.257. We show that the burst is powered by the same relativistic fireball mechanism as long GRBs, with the ejecta possibly collimated in jets, but that the total energy release is 10-1,000 times smaller. More importantly, the nature of the host galaxy demonstrates that short GRBs arise from an old (> 1 Gyr) stellar population, strengthening earlier suggestions and providing support for coalescing compact object binaries as the progenitors.

Demise of faint satellites around isolated early-type galaxies

NASA Astrophysics Data System (ADS)

Park, Changbom; Hwang, Ho Seong; Park, Hyunbae; Lee, Jong Chul

2018-02-01

The hierarchical galaxy formation scenario in the Cold Dark Matter cosmology with a non-vanishing cosmological constant Λ and geometrically flat space (ΛCDM) has been very successful in explaining the large-scale distribution of galaxies. However, there have been claims that ΛCDM over-predicts the number of satellite galaxies associated with massive galaxies compared with observations—the missing satellite galaxy problem1-3. Isolated groups of galaxies hosted by passively evolving massive early-type galaxies are ideal laboratories for identifying the missing physics in the current theory4-11. Here, we report—based on a deep spectroscopic survey—that isolated massive and passive early-type galaxies without any signs of recent wet mergers or accretion episodes have almost no satellite galaxies fainter than the r-band absolute magnitude of about Mr = -14. If only early-type satellites are used, the cutoff is at the somewhat brighter magnitude of about Mr = -15. Such a cutoff has not been found in other nearby satellite galaxy systems hosted by late-type galaxies or those with merger features. Various physical properties of satellites depend strongly on the host-centric distance. Our observations indicate that the satellite galaxy luminosity function is largely determined by the interaction of satellites with the environment provided by their host.

An Archival COS Study of Multi-phase Galactic Outflows and Their Dependence on Host Galaxy Properties

NASA Astrophysics Data System (ADS)

Chisholm, John

2013-10-01

Galactic outflows have become vital for understanding galaxy evolution. Outflows have been used to explain the mass-metallicity relation, the star formation history of the universe, and the shape of the baryonic mass function. However, few studies have focused on the basic question of how outflow velocities depend upon the physical properties of their host galaxies. Here we propose an archival project utilizing 52 COS spectra of local star-forming galaxies spanning four decades of star formation rate, and stellar mass. We will preform a self-consistent analysis of trends between galactic properties {star formation rate, stellar mass, specific star formation rate and star formation rate surface density} and outflow velocities measured from interstellar metal absorption lines {e.g., CII 1335}. We will extend this analysis to different gas phases - cold, warm, and hot - to gain a more comprehensive understanding of the physics of multi-phase outflows. The trends we observe will provide insights into the feedback process and will be crucial new benchmarks for simulations.

Type Ia supernova Hubble residuals and host-galaxy properties

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

Kim, A. G.; Aldering, G.; Aragon, C.

2014-03-20

Kim et al. introduced a new methodology for determining peak-brightness absolute magnitudes of type Ia supernovae from multi-band light curves. We examine the relation between their parameterization of light curves and Hubble residuals, based on photometry synthesized from the Nearby Supernova Factory spectrophotometric time series, with global host-galaxy properties. The K13 Hubble residual step with host mass is 0.013 ± 0.031 mag for a supernova subsample with data coverage corresponding to the K13 training; at <<1σ, the step is not significant and lower than previous measurements. Relaxing the data coverage requirement of the Hubble residual step with the host massmore » is 0.045 ± 0.026 mag for the larger sample; a calculation using the modes of the distributions, less sensitive to outliers, yields a step of 0.019 mag. The analysis of this article uses K13 inferred luminosities, as distinguished from previous works that use magnitude corrections as a function of SALT2 color and stretch parameters: steps at >2σ significance are found in SALT2 Hubble residuals in samples split by the values of their K13 x(1) and x(2) light-curve parameters. x(1) affects the light-curve width and color around peak (similar to the Δm {sub 15} and stretch parameters), and x(2) affects colors, the near-UV light-curve width, and the light-curve decline 20-30 days after peak brightness. The novel light-curve analysis, increased parameter set, and magnitude corrections of K13 may be capturing features of SN Ia diversity arising from progenitor stellar evolution.« less

Morphology of Dwarf Galaxies in Isolated Satellite Systems

NASA Astrophysics Data System (ADS)

Ann, Hong Bae

2017-08-01

The environmental dependence of the morphology of dwarf galaxies in isolated satellite systems is analyzed to understand the origin of the dwarf galaxy morphology using the visually classified morphological types of 5836 local galaxies with z ≲ 0.01. We consider six sub-types of dwarf galaxies, dS0, dE, dE_{bc}, dSph, dE_{blue}, and dI, of which the first four sub-types are considered as early-type and the last two as late-type. The environmental parameters we consider are the projected distance from the host galaxy (r_{p}), local and global background densities, and the host morphology. The spatial distributions of dwarf satellites of early-type galaxies are much different from those of dwarf satellites of late-type galaxies, suggesting the host morphology combined with r_{p} plays a decisive role on the morphology of the dwarf satellite galaxies. The local and global background densities play no significant role on the morphology of dwarfs in the satellite systems hosted by early-type galaxies. However, in the satellite system hosted by late-type galaxies, the global background densities of dE and dSph satellites are significantly different from those of dE_{bc}, dE_{blue}, and dI satellites. The blue-cored dwarf satellites (dE_{bc}) of early-type galaxies are likely to be located at r_{p} > 0.3 Mpc to keep their cold gas from the ram pressure stripping by the hot corona of early-type galaxies. The spatial distribution of dE_{bc} satellites of early-type galaxies and their global background densities suggest that their cold gas is intergalactic material accreted before they fall into the satellite systems.

Sweating the small stuff: simulating dwarf galaxies, ultra-faint dwarf galaxies, and their own tiny satellites

NASA Astrophysics Data System (ADS)

Wheeler, Coral; Oñorbe, Jose; Bullock, James S.; Boylan-Kolchin, Michael; Elbert, Oliver D.; Garrison-Kimmel, Shea; Hopkins, Philip F.; Kereš, Dušan

2015-10-01

We present Feedback in Realistic Environment (FIRE)/GIZMO hydrodynamic zoom-in simulations of isolated dark matter haloes, two each at the mass of classical dwarf galaxies (Mvir ≃ 1010 M⊙) and ultra-faint galaxies (Mvir ≃ 109 M⊙), and with two feedback implementations. The resulting central galaxies lie on an extrapolated abundance matching relation from M⋆ ≃ 106 to 104 M⊙ without a break. Every host is filled with subhaloes, many of which form stars. Each of our dwarfs with M⋆ ≃ 106 M⊙ has 1-2 well-resolved satellites with M⋆ = 3-200 × 103 M⊙. Even our isolated ultra-faint galaxies have star-forming subhaloes. If this is representative, dwarf galaxies throughout the Universe should commonly host tiny satellite galaxies of their own. We combine our results with the Exploring the Local Volume in Simulations (ELVIS) simulations to show that targeting ˜ 50 kpc regions around nearby isolated dwarfs could increase the chances of discovering ultra-faint galaxies by ˜35 per cent compared to random pointings, and specifically identify the region around the Phoenix dwarf galaxy as a good potential target. The well-resolved ultra-faint galaxies in our simulations (M⋆ ≃ 3-30 × 103 M⊙) form within Mpeak ≃ 0.5-3 × 109 M⊙ haloes. Each has a uniformly ancient stellar population ( > 10 Gyr) owing to reionization-related quenching. More massive systems, in contrast, all have late-time star formation. Our results suggest that Mhalo ≃ 5 × 109 M⊙ is a probable dividing line between haloes hosting reionization `fossils' and those hosting dwarfs that can continue to form stars in isolation after reionization.

Radio Galaxy Zoo: A Search for Hybrid Morphology Radio Galaxies

NASA Astrophysics Data System (ADS)

Kapińska, A. D.; Terentev, I.; Wong, O. I.; Shabala, S. S.; Andernach, H.; Rudnick, L.; Storer, L.; Banfield, J. K.; Willett, K. W.; de Gasperin, F.; Lintott, C. J.; López-Sánchez, Á. R.; Middelberg, E.; Norris, R. P.; Schawinski, K.; Seymour, N.; Simmons, B.

2017-12-01

Hybrid morphology radio sources (HyMoRS) are a rare type of radio galaxy that display different Fanaroff-Riley classes on opposite sides of their nuclei. To enhance the statistical analysis of HyMoRS, we embarked on a large-scale search of these sources within the international citizen science project, Radio Galaxy Zoo (RGZ). Here, we present 25 new candidate hybrid morphology radio galaxies. Our selected candidates are moderate power radio galaxies ({L}{median}=4.7× {10}24 W Hz-1 sr-1) at redshifts 0.14< z< 1.0. Hosts of nine candidates have spectroscopic observations, of which six are classified as quasars, one as high- and two as low-excitation galaxies. Two candidate HyMoRS are giant (> 1 Mpc) radio galaxies, one resides at the center of a galaxy cluster, and one is hosted by a rare green bean galaxy. Although the origin of the hybrid morphology radio galaxies is still unclear, this type of radio source starts depicting itself as a rather diverse class. We discuss hybrid radio morphology formation in terms of the radio source environment (nurture) and intrinsically occurring phenomena (nature; activity cessation and amplification), showing that these peculiar radio galaxies can be formed by both mechanisms. While high angular resolution follow-up observations are still necessary to confirm our candidates, we demonstrate the efficacy of the RGZ in the pre-selection of these sources from all-sky radio surveys, and report the reliability of citizen scientists in identifying and classifying complex radio sources.

DISCOVERY OF A PSEUDOBULGE GALAXY LAUNCHING POWERFUL RELATIVISTIC JETS

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

Kotilainen, Jari K.; Olguín-Iglesias, Alejandro; León-Tavares, Jonathan

Supermassive black holes launching plasma jets at close to the speed of light, producing gamma-rays, have ubiquitously been found to be hosted by massive elliptical galaxies. Since elliptical galaxies are generally believed to be built through galaxy mergers, active galactic nuclei (AGN) launching relativistic jets are associated with the latest stages of galaxy evolution. We have discovered a pseudobulge morphology in the host galaxy of the gamma-ray AGN PKS 2004-447. This is the first gamma-ray emitter radio-loud AGN found to have been launched from a system where both the black hole and host galaxy have been actively growing via secularmore » processes. This is evidence of an alternative black hole–galaxy co-evolutionary path to develop powerful relativistic jets, which is not merger driven.« less

SED Constraints on the Highest- z Blazar Jet: QSO J0906+6930

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

An, Hongjun; Romani, Roger W.

Here, we report on Gemini, NuSTAR, and eight years of Fermi observations of the most distant blazar QSO J0906+6930 (z = 5.48). We construct a broadband spectral energy distribution (SED) and model the SED using a synchro-Compton model. The measurements yield a mass of ~4 × 10 9 M ⊙ for the black hole and a spectral break at ~4 keV in the combined fit of the new NuSTAR and archival Chandra data. The SED fitting constrains the bulk Doppler factor δ of the jet to 9 +2.5 –3 for QSO J0906+6930. Similar, but weaker, constraints on δ are derivedmore » from SED modeling of the three other claimed z > 5 blazars. Together, these extrapolate to ~620 similar sources, fully 20% of the optically bright, high-mass active galactic nuclei expected at 5 < z < 5.5. This has interesting implications for the early growth of massive black holes.« less

SED Constraints on the Highest-z Blazar Jet: QSO J0906+6930

NASA Astrophysics Data System (ADS)

An, Hongjun; Romani, Roger W.

2018-04-01

We report on Gemini, NuSTAR, and eight years of Fermi observations of the most distant blazar QSO J0906+6930 (z = 5.48). We construct a broadband spectral energy distribution (SED) and model the SED using a synchro-Compton model. The measurements yield a mass of ∼4 × 109 M ⊙ for the black hole and a spectral break at ∼4 keV in the combined fit of the new NuSTAR and archival Chandra data. The SED fitting constrains the bulk Doppler factor δ of the jet to 9+2.5 ‑3 for QSO J0906+6930. Similar, but weaker, constraints on δ are derived from SED modeling of the three other claimed z > 5 blazars. Together, these extrapolate to ∼620 similar sources, fully 20% of the optically bright, high-mass active galactic nuclei expected at 5 < z < 5.5. This has interesting implications for the early growth of massive black holes.

SED Constraints on the Highest- z Blazar Jet: QSO J0906+6930

DOE PAGES

An, Hongjun; Romani, Roger W.

2018-03-29

Here, we report on Gemini, NuSTAR, and eight years of Fermi observations of the most distant blazar QSO J0906+6930 (z = 5.48). We construct a broadband spectral energy distribution (SED) and model the SED using a synchro-Compton model. The measurements yield a mass of ~4 × 10 9 M ⊙ for the black hole and a spectral break at ~4 keV in the combined fit of the new NuSTAR and archival Chandra data. The SED fitting constrains the bulk Doppler factor δ of the jet to 9 +2.5 –3 for QSO J0906+6930. Similar, but weaker, constraints on δ are derivedmore » from SED modeling of the three other claimed z > 5 blazars. Together, these extrapolate to ~620 similar sources, fully 20% of the optically bright, high-mass active galactic nuclei expected at 5 < z < 5.5. This has interesting implications for the early growth of massive black holes.« less

Low Ionization Absorbing Gas Kinematics Around Z ~ 1 Galaxies

NASA Astrophysics Data System (ADS)

Churchill, C. W.; Steidel, C. C.; Vogt, S. S.

1996-12-01

Absorption profiles of the Mg II lambda lambda 2796,2803 doublet arising from gas associated with 48 ``normal'' intermediate redshift (0.4 < z < 1.7) galaxies have been resolved in QSO spectra at 6 km s(-1) resolution using HIRES on Keck I. We have found evidence for pronounced redshift evolution in the subcomponent velocity two--point correlation function, suggestive that the gas surrounding galaxies has settled over a 5--10 Gyr look--back time. Based upon a sub--sample of 15 galaxies at z<1, we found no evidence for correlations between the absorbing gas kinematics and the projected galactocentric distance of the gas, galaxy luminosities, or galaxy rest--frame colors (though trends between galaxy properties and absorption properties are apparent from a larger low resolution absorption line sample). The implication is that low ionization gas surrounding early epoch galaxies was not smoothly distributed either spatially or kinematically out to a galactocentric distance ~ 40 kpc. Directly from the profiles, we have measured the number of separate absorbing ``kinematic subsystems'' associated with each galaxy, and each subsystem's profile velocity width, asymmetry (skew), and integrated column density. The distribution in these subsystem properties with velocity is highly peaked at zero, and does not exhibit a bimodality. The lack of a bimodality is suggestive that the gas kinematics is not dominated by quasi--symmetric infall into galactic potential wells. In view of absorption line studies of local galaxies, it appears that extended regions of low ionization gas surrounding galaxies represent a dynamical and active epoch of ``normal'' galaxy evolution. The reservoirs of gas for these extended ``halos'' were probably residual infalling fragments (from earlier formation processes and on--going dynamical events) whose evolution first included a settling in velocity dispersion and then more recently a decline in number. The build up of thick and/or extended gaseous

Secular Black Hole Growth and Feedback in Merger-Free Galaxies

NASA Astrophysics Data System (ADS)

Simmons, Brooke

2016-10-01

We will measure the merger-free galaxy-black hole mass relation for the first time, using a unique, newly-discovered sample of luminous active galactic nuclei (AGN) hosted in galaxies that have not grown via mergers. Our preliminary study has shown that supermassive black holes (SMBHs) in bulgeless galaxies - i.e., galaxies that have never undergone a significant merger - can have substantial growth: bulges are not required for the formation and growth of SMBHs. The proposed targets are broad-line AGN with black hole masses spanning a wide mass range (1e6 to >1e9 M_Sun) and hosted in strongly disk dominated galaxies (>80% light from a disk). This sample is an ideal laboratory for understanding merger-free black hole growth and its feedback on the host galaxy. HST imaging will allow us to disentangle bright nuclear emission from host galaxy, measure bulge type and strength, and identify bulgeless galaxies that have evolved under purely secular conditions. In addition, we will determine whether merger-free galaxies lie on the same SMBH-galaxy relation as galaxies with substantial past mergers, or whether merger-free growth results in a separate relation. The answer to this question has profound consequences for the role of baryon dynamics in driving black hole-galaxy co-evolution.

AM 2217-490: A polar ring galaxy under construction

NASA Astrophysics Data System (ADS)

Freitas-Lemes, P.; Rodrigues, I.; Faúndez-Abans, M.; Dors, O.

2014-10-01

This work is part of a series of case studies of Polar Ring Galaxies (PRGs) (see also Posters GAL-1: 163, GAL-2: 178). A PRG is formed by an early type host galaxy (e.g. lenticular or elliptical), surrounded by a ring of gas and stars orbiting approximately at the polar plane of the host galaxy. AM2217-490 is an interesting case of PRG in formation, with a still asymmetrical ring that surrounds the host galaxy. Apparently, this bluish structure (characteristic of the rings of PRGs), is not yet in equilibrium with the host galaxy. This study is based on spectra on the range 6250-7250 Å obtained with the CTIO 1.5 m telescope - Chile. From them, we measure a heliocentric radial velocity of 9152± 18 km/s. The value of the ionization parameter (log U = -3.5) is similar to that in interacting galaxies (Freitas-Lemes et al. 2013, submitted to MNRAS; and Krabbe et al. 2013, MNRAS Accepted), and lower than that of isolated ones. The electron density shows little variation along the major axis of the host galaxy, and a mean value typical of interacting galaxies. Diagnostic diagrams show that the nuclear region harbors an AGN, following a trend among polar ring galaxies. The low-resolution images of the SDSS show no tails or bridges connecting the galaxy to other objects, however, in a radius of 5 arcmin there are three other galaxies with similar speeds, featuring a group. A plausible hypothesis is that one of these galaxies may have interacted with AM2217-490, donating material to form the ring.

Gravitational microlensing - The effect of random motion of individual stars in the lensing galaxy

NASA Technical Reports Server (NTRS)

Kundic, Tomislav; Wambsganss, Joachim

1993-01-01

We investigate the influence of random motion of individual stars in the lensing galaxy on the light curve of a gravitationally lensed background quasar. We compare this with the effects of the transverse motion of the galaxy. We find that three-dimensional random motion of stars with a velocity dispersion sigma in each dimension is more effective in producing 'peaks' in a microlensed light curve by a factor a about 1.3 than motion of the galaxy with a transverse velocity v(t) = sigma. This effectiveness parameter a seems to depend only weakly on the surface mass density. With an assumed transverse velocity of v(t) = 600 km/s of the galaxy lensing the QSO 2237+0305 and a measured velocity dispersion of sigma = 215 km/s, the expected rate of maxima in the light curves calculated for bulk motion alone has to be increased by about 10 percent due to the random motion of stars. As a consequence, the average time interval Delta t between two high-magnification events is smaller than the time interval Delta(t) bulk, calculated for bulk motion alone, Delta t about 0.9 Delta(t) bulk.

PEARS Emission Line Galaxies

NASA Technical Reports Server (NTRS)

Pirzkal, Nor; Rothberg, Barry; Ly, Chun; Rhoads, James E.; Malhotra, Sangeeta; Grogin, Norman A.; Dahlen, Tomas; Meurer, Gerhardt R.; Walsh, Jeremy; Hathi, Nimish P.;

Revisiting the Abundance Gradient in the Maser Host Galaxy NGC 4258

NASA Astrophysics Data System (ADS)

Bresolin, Fabio

2011-03-01

New spectroscopic observations of 36 H II regions in NGC 4258 obtained with the Gemini telescope are combined with existing data from the literature to measure the radial oxygen abundance gradient in this galaxy. The [O III]λ4363 auroral line was detected in four of the outermost targets (17-22 kpc from the galaxy center), allowing a determination of the electron temperature Te of the ionized gas. From the use of different calibrations of the R 23 abundance indicator, an oxygen abundance gradient of approximately -0.012 ± 0.002 dex kpc-1 is derived. Such a shallow gradient, combined with the difference in the distance moduli measured from the Cepheid period-luminosity relation by Macri et al. between two distinct fields in NGC 4258, would yield an unrealistically strong effect of metallicity on the Cepheid distances. This strengthens the suggestion that systematic biases might affect the Cepheid distance of the outer field. Evidence for a similar effect in the differential study of M33 by Scowcroft et al. is presented. A revision of the transformation between strong-line and Te -based abundances in Cepheid-host galaxies is discussed. In the Te abundance scale, the oxygen abundance of the inner field of NGC 4258 is found to be comparable with the LMC value. Based on observations obtained at the Gemini Observatory, which is operated by the Association of Universities for Research in Astronomy, Inc., under a cooperative agreement with the NSF on behalf of the Gemini partnership: the National Science Foundation (United States), the Science and Technology Facilities Council (United Kingdom), the National Research Council (Canada), CONICYT (Chile), the Australian Research Council (Australia), Ministério da Ciência e Tecnologia (Brazil) and Ministerio de Ciencia, Tecnología e Innovación Productiva (Argentina).

QSO absorption spectroscopy and baryonic dark matter

NASA Astrophysics Data System (ADS)

Cirković, Milan M.

2005-04-01

The present book should serve a double purpose: first, as an introduction into the host of tightly related topics in astrophysics and cosmology all dealing with the history and evolution of the baryonic matter in the universe. Secondly, it gives argument for still somewhat controversial view that large baryonic reservoirs are present (at least in the low-redshift regime) in form of huge gaseous galactic haloes surrounding normal luminous galaxies, and manifesting through the Lyman-α absorption lines in spectra of background sources. If accepted, this view would profoundly impact our understanding of the galactic structure and evolution, and will deeply influence our views of the future evolution of galactic systems. After an introduction into cosmological jargon and symbols used throughout, and other important introductory material given in Chapter 1, the bulk of the argumentation is given in Chapter 2, which exposes phenomenology of Lyα absorption systems and various theories advanced to account for their physical origin. Chapter 3 deals with models of absorbing gas in the extended haloes of normal galaxies, and Chapter 4 gives a global discussion of main candidates for the reservoirs of the still elusive baryonic dark matter. A set of closely related technical issues which are used at several places in the main narrative are given in the appendices.

Galactic satellite systems: radial distribution and environment dependence of galaxy morphology

NASA Astrophysics Data System (ADS)

Ann, H. B.; Park, Changbom; Choi, Yun-Young

2008-09-01

We have studied the radial distribution of the early (E/S0) and late (S/Irr) types of satellites around bright host galaxies. We made a volume-limited sample of 4986 satellites brighter than Mr = -18.0 associated with 2254 hosts brighter than Mr = -19.0 from the Sloan Digital Sky Survey Data Release 5 sample. The morphology of satellites is determined by an automated morphology classifier, but the host galaxies are visually classified. We found segregation of satellite morphology as a function of the projected distance from the host galaxy. The amplitude and shape of the early-type satellite fraction profile are found to depend on the host luminosity. This is the morphology-radius/density relation at the galactic scale. There is a strong tendency for morphology conformity between the host galaxy and its satellites. The early-type fraction of satellites hosted by early-type galaxies is systematically larger than that of late-type hosts, and is a strong function of the distance from the host galaxies. Fainter satellites are more vulnerable to the morphology transformation effects of hosts. Dependence of satellite morphology on the large-scale background density was detected. The fraction of early-type satellites increases in high-density regions for both early- and late-type hosts. It is argued that the conformity in morphology of galactic satellite system is mainly originated by the hydrodynamical and radiative effects of hosts on satellites.

C IV broad absorption line variability in QSO spectra from SDSS surveys

NASA Astrophysics Data System (ADS)

De Cicco, Demetra; Brandt, William N.; Grier, Catherine J.; Paolillo, Maurizio

2017-12-01

Broad absorption lines (BALs) in the spectra of quasi-stellar objects (QSOs) are thought to arise from outflowing winds along our line of sight; winds, in turn, are thought to originate from the accretion disk, in the very surroundings of the central supermassive black hole (SMBH), and they likely affect the accretion process onto the SMBH, as well as galaxy evolution. BALs can exhibit variability on timescales typically ranging from months to years. We analyze such variability and, in particular, BAL disappearance, with the aim of investigating QSO physics and structure. We search for disappearing C IV BALs in the spectra of 1319 QSOs from different programs from the Sloan Digital Sky Survey (SDSS); the analyzed time span covers 0.28-4.9 yr (rest frame), and the source redshifts are in the range 1.68-4.27. This is to date the largest sample ever used for such a study. We find 67 sources (5.1_{-0.6}^{+0.7}% of the sample) with 73 disappearing BALs in total (3.9_{-0.5}^{+0.5}% of the total number of C IV BALs detected; some sources have more than one BAL that disappears). We compare the sample of disappearing BALs to the whole sample of BALs, and investigate the correlation in the variability of multiple troughs in the same spectrum. We also derive estimates of the average lifetime of a BAL trough and of the BAL phase along our line of sight.

SUPPRESSION OF STAR FORMATION IN THE HOSTS OF LOW-EXCITATION RADIO GALAXIES

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

Pace, Cameron; Salim, Samir, E-mail: cameronpace@suu.edu, E-mail: salims@indiana.edu

The feedback from radio-loud active galactic nuclei (R-AGNs) may help maintain low star-formation (SF) rates in their early-type hosts, but the observational evidence for this mechanism has been inconclusive. We study systematic differences of aggregate spectral energy distributions (SEDs) of various subsets of ∼4000 low-redshift R-AGNs from Best and Heckman with respect to (currently) inactive control samples selected to have matching redshift, stellar mass, population age, axis ratio, and environment. Aggregate SEDs, ranging from the ultraviolet (UV) through mid-infrared (mid-IR, 22 μm), were constructed using a Bayesian method that eliminates biases from non-detections in Galaxy Evolution Explorer and Wide-field Infraredmore » Survey Explorer. We study rare high-excitation sources separately from low-excitation ones, which we split by environment and host properties. We find that both the UV and mid-IR emission of non-cluster R-AGNs (80% of sample) are suppressed by ∼0.2 dex relative to that of the control group, especially for moderately massive galaxies (log M{sub *} ≲ 11). The difference disappears for high-mass R-AGNs and for R-AGNs in clusters, where other, non-AGN quenching/maintenance mechanisms may dominate, or where the suppression of SF due to AGNs may persist between active phases of the central engine, perhaps because of the presence of a hot gaseous halo storing AGN energy. High-excitation (high accretion rate) sources, which make up 2% of the R-AGN sample, do not show any evidence of SF suppression (their UV is the same as in controls), but they exhibit a strong mid-IR excess due to AGN dust heating.« less

Star Formation in the Central Regions of Galaxies

NASA Astrophysics Data System (ADS)

Tsai, Mengchun

2015-08-01

The galactic central region connects the galactic nucleus to the host galaxy. If the central black hole co-evolved with the host galaxies, there should be some evidence left in the central region. We use the environmental properties in the central regions such as star-forming activity, stellar population and molecular abundance to figure out a possible scenario of the evolution of galaxies. In this thesis at first we investigated the properties of the central regions in the host galaxies of active and normal galaxies. We used radio emission around the nuclei of the host galaxies to represent activity of active galactic nuclei (AGNs), and used infrared ray (IR) emission to represent the star-forming activity and stellar population of the host galaxies. We determined that active galaxies have higher stellar masses (SMs) within the central kiloparsec radius than normal galaxies do independent of the Hubble types of the host galaxies; but both active and normal galaxies exhibit similar specific star formation rates (SSFRs). We also discovered that certain AGNs exhibit substantial inner stellar structures in the IR images; most of the AGNs with inner structures are Seyferts, whereas only a few LINERs exhibit inner structures. We note that the AGNs with inner structures show a positive correlation between the radio activity of the AGNs and the SFRs of the host galaxies, but the sources without inner structures show a negative correlation between the radio power and the SFRs. These results might be explained with a scenario of starburst-AGN evolution. In this scenario, AGN activities are triggered following a nuclear starburst; during the evolution, AGN activities are accompanied by SF activity in the inner regions of the host galaxies; at the final stage of the evolution, the AGNs might transform into LINERs, exhibiting weak SF activity in the central regions of the host galaxies. For further investigation about the inner structure, we choose the most nearby and luminous

On the Supermassive Black Hole-Galaxy Coevolution

NASA Astrophysics Data System (ADS)

Hegde, Sahil; Zhang, Shawn; Rodriguez, Aldo; Primack, Joel R.

2017-01-01

In recent years, a major focus of astronomy has been the study of the effects of supermassive black holes (SMBH) on their host galaxies. Recent results have found strong correlations between SMBH mass and host galaxy properties, most notably in the bulge velocity dispersion and galaxy stellar mass. We utilize these relations along with a novel convolution method to construct number density models of different galaxy properties. Using these models, we compare two fundamental methods for constructing a black hole mass function (BHMF) with the M⊙-σ and M⊙-M* relations. With these methods, we estimate the redshift evolution of the BHMF and, based on that, compare mass growth histories of central black holes and their host galaxies. Additionally, we utilize a data compilation of over 500 galaxies with individual measurements of galaxy properties (BH mass, stellar velocity dispersion, stellar mass, etc.) and classify galaxies by their morphologies in order to shed light on the controversial Shankar et al. (2016) argument that observations are biased in favor of massive SMBHs. We find that such a bias has little impact on the SMBH-galaxy relations.We conclude that the galaxy sample is a fair representation of the local universe and argue that our BH number density and scaling relations can be employed in the future to constrain relevant mechanisms for galaxy formation. We emphasize that this is the most comprehensive and accurate study of SMBH-galaxy coevolution as of now. Most of this work was carried out by high school students working under the auspices of the Science Internship Program at UC Santa Cruz.

Impact of seeing and host galaxy into the analysis of photo-polarimetric microvariability in blazars. Case study of the nearby blazars 1ES 1959+650 and HB89 2201+044

NASA Astrophysics Data System (ADS)

Sosa, M. S.; von Essen, C.; Andruchow, I.; Cellone, S. A.

2017-11-01

Blazars, a type of Active Galactic Nuclei, present a particular orientation of their jets close to the line of sight. Their radiation is thus relativistically beamed, giving rise to extreme behaviors, specially strong variability on very short timescales (I.e., microvariability). Here we present simultaneous photometric and polarimetric observations of two relatively nearby blazars, 1ES 1959+650 and HB89 2201+044, that were obtained using the Calar Alto Faint Object Spectrograph mounted at the 2.2 m telescope in Calar Alto, Spain. An outstanding characteristic of these two blazars is the presence of well resolved host galaxies. This particular feature allows us to produce a study of their intrinsic polarization, a measurement of the polarization state of the galactic nucleus unaffected by the host galaxy. To carry out this work, we computed photometric fluxes from which we calculated the degree and orientation of the blazars polarization. Then, we analyzed the depolarizing effect introduced by the host galaxy with the main goal to recover the intrinsic polarization of the galactic nucleus, carefully taking into consideration the spurious polarimetric variability introduced by changes in seeing along the observing nights. We find that the two blazars do not present intra-night photo-polarimetric variability, although we do detect a significant inter-night variability. Comparing polarimetric values before and after accounting for the host galaxies, we observe a significant difference in the polarization degree of about 1% in the case of 1ES 1959+650, and 0.3% in the case of HB89 2201+044, thus evidencing the non-negligible impact introduced by the host galaxies. We note that this host galaxy effect depends on the waveband, and varies with changing seeing conditions, so it should be particularly considered when studying frequency-dependent polarization in blazars. Based on observations collected at the Centro Astronómico Hispano Alemán (CAHA) at Calar Alto, operated

The Carnegie Supernova Project I. Methods to estimate host-galaxy reddening of stripped-envelope supernovae

NASA Astrophysics Data System (ADS)

Stritzinger, M. D.; Taddia, F.; Burns, C. R.; Phillips, M. M.; Bersten, M.; Contreras, C.; Folatelli, G.; Holmbo, S.; Hsiao, E. Y.; Hoeflich, P.; Leloudas, G.; Morrell, N.; Sollerman, J.; Suntzeff, N. B.

2018-02-01

We aim to improve upon contemporary methods to estimate host-galaxy reddening of stripped-envelope (SE) supernovae (SNe). To this end the Carnegie Supernova Project (CSP-I) SE SN photometry data release, consisting of nearly three dozen objects, is used to identify a minimally reddened sub-sample for each traditionally defined spectroscopic sub-type (i.e., SNe IIb, SNe Ib, SNe Ic). Inspection of the optical and near-infrared (NIR) colors and color evolution of the minimally reddened sub-samples reveals a high degree of homogeneity, particularly between 0 d to +20 d relative to B-band maximum. This motivated the construction of intrinsic color-curve templates, which when compared to the colors of reddened SE SNe, yields an entire suite of optical and NIR color excess measurements. Comparison of optical/optical vs. optical/NIR color excess measurements indicates the majority of the CSP-I SE SNe suffer relatively low amounts of reddening (i.e., E(B-V)host< 0.20 mag) and we find evidence for different RVhost values among different SE SN. Fitting the color excess measurements of the seven most reddened (i.e., E(B-V)host> 0.20 mag) objects with the Fitzpatrick (1999, PASP, 111, 63) reddening law model provides robust estimates of the host visual-extinction AVhost and RVhost. In the case of the SE SNe with relatively low amounts of reddening, a preferred value of RVhost is adopted for each sub-type, resulting in estimates of AVhost through Fitzpatrick (1999) reddening law model fits to the observed color excess measurements. Our analysis suggests SE SNe reside in galaxies characterized by a range of dust properties. We also find evidence that SNe Ic are more likely to occur in regions characterized by larger RVhost values compared to SNe IIb/Ib and they also tend to suffer more extinction. The later finding is consistent with work in the literature suggesting SNe Ic tend to occur in regions of on-going star formation. Based on observations collected at Las Campanas

Host Galaxy Spectra of Stripped SN from the Palomar Transient Factory: SN Progenitor Diagnostics and the SN-GRB Connection

NASA Astrophysics Data System (ADS)

Modjaz, Maryam; Gal-Yam, Avishay; Arcavi, Iair

2011-02-01

Stripped core-collapse supernovae (Stripped SN) are powerful cosmic engines that energize and enrich the ISM and that sometimes accompany GRBs, but the exact mass and metallicity range of their massive progenitors is not known, nor the detailed physics of the explosion. With the harvest of 50 stripped SN from the innovative survey Palomar Transient Factory, we propose to conduct the first uniform and statistically significant study with SN from the same homogeneous and galaxy-unbiased survey in order to determine the environmental conditions that influence the various kinds of massive stellar deaths. By obtaining spectra of the immediate host environments of our sample of stripped SN, we will (1) measure local abundances in order to differentiate between the two progenitor scenarios for stripped SN and (2) derive stellar population ages, masses and star formation histories via detailed stellar population synthesis models. Moreover, we will test if natal chemical abundance has effects on basic SN characteristics, such as peak luminosity. Any observed trends will have ramifications on SN and GRB explosion models and imply important demographic SN considerations. Our dataset will provide a crucial complimentary set to host galaxy studies of long-duration GRBs and pave the way for host studies of transients and SN found via upcoming surveys such as LSST.

Quenching and ram pressure stripping of simulated Milky Way satellite galaxies

NASA Astrophysics Data System (ADS)

Simpson, Christine; Grand, Robert; Gomez, Facundo; Marinacci, Federico; Pakmor, Rüdiger; Springel, Volker; Campbell, David; Frenk, Carlos; Auriga Project, Virgo Consortium

2018-01-01

We present predictions for the quenching of star formation in satellite galaxies of the Local Group from a suite of 30 cosmological zoom simulations of Milky Way-like host galaxies. The Auriga simulations resolve satellites down to the luminosity of the classical dwarf spheroidal galaxies of the Milky Way. We find strong mass-dependent and distance-dependent quenching signals, where dwarf systems beyond 600 kpc are only strongly quenched below a stellar mass of 107 M⊙. Ram pressure stripping appears to be the dominant quenching mechanism and 50% of quenched systems cease star formation within 1 Gyr of first infall. We demonstrate that systems within a host galaxy's R200 radius are comprised of two populations: (i) a first infall population that has entered the host halo within the past few Gyrs and (ii) a population of returning `backsplash' systems that have had a much more extended interaction with the host. Backsplash galaxies that do not return to the host galaxy by redshift zero exhibit quenching properties similar to galaxies within R200 and are distinct from other external systems. The simulated quenching trend with stellar mass has some tension with observations, but our simulations are able reproduce the range of quenching times measured from resolved stellar populations of Local Group dwarf galaxies.

Quenching and ram pressure stripping of simulated Milky Way satellite galaxies

NASA Astrophysics Data System (ADS)

Simpson, Christine M.; Grand, Robert J. J.; Gómez, Facundo A.; Marinacci, Federico; Pakmor, Rüdiger; Springel, Volker; Campbell, David J. R.; Frenk, Carlos S.

2018-07-01

We present predictions for the quenching of star formation in satellite galaxies of the Local Group from a suite of 30 cosmological zoom simulations of Milky Way-like host galaxies. The Auriga simulations resolve satellites down to the luminosity of the classical dwarf spheroidal galaxies of the Milky Way. We find strong mass-dependent and distance-dependent quenching signals, where dwarf systems beyond 600 kpc are only strongly quenched below a stellar mass of 107 M⊙. Ram pressure stripping appears to be the dominant quenching mechanism and 50 per cent of quenched systems cease star formation within 1 Gyr of first infall. We demonstrate that systems within a host galaxy's R200 radius are comprised of two populations: (i) a first infall population that has entered the host halo within the past few Gyrs and (ii) a population of returning `backsplash' systems that have had a much more extended interaction with the host. Backsplash galaxies that do not return to the host galaxy by redshift zero exhibit quenching properties similar to galaxies within R200 and are distinct from other external systems. The simulated quenching trend with stellar mass has some tension with observations, but our simulations are able reproduce the range of quenching times measured from resolved stellar populations of Local Group dwarf galaxies.

Quenching and ram pressure stripping of simulated Milky Way satellite galaxies

NASA Astrophysics Data System (ADS)

Simpson, Christine M.; Grand, Robert J. J.; Gómez, Facundo A.; Marinacci, Federico; Pakmor, Rüdiger; Springel, Volker; Campbell, David J. R.; Frenk, Carlos S.

2018-03-01

We present predictions for the quenching of star formation in satellite galaxies of the Local Group from a suite of 30 cosmological zoom simulations of Milky Way-like host galaxies. The Auriga simulations resolve satellites down to the luminosity of the classical dwarf spheroidal galaxies of the Milky Way. We find strong mass-dependent and distance-dependent quenching signals, where dwarf systems beyond 600 kpc are only strongly quenched below a stellar mass of 107 M⊙. Ram pressure stripping appears to be the dominant quenching mechanism and 50% of quenched systems cease star formation within 1 Gyr of first infall. We demonstrate that systems within a host galaxy's R200 radius are comprised of two populations: (i) a first infall population that has entered the host halo within the past few Gyrs and (ii) a population of returning `backsplash' systems that have had a much more extended interaction with the host. Backsplash galaxies that do not return to the host galaxy by redshift zero exhibit quenching properties similar to galaxies within R200 and are distinct from other external systems. The simulated quenching trend with stellar mass has some tension with observations, but our simulations are able reproduce the range of quenching times measured from resolved stellar populations of Local Group dwarf galaxies.

Galaxy gas as obscurer - II. Separating the galaxy-scale and nuclear obscurers of active galactic nuclei

NASA Astrophysics Data System (ADS)

Buchner, Johannes; Bauer, Franz E.

2017-03-01

The 'torus' obscurer of active galactic nuclei (AGN) is poorly understood in terms of its density, sub-structure and physical mechanisms. Large X-ray surveys provide model boundary constraints, for both Compton-thin and Compton-thick levels of obscuration, as obscured fractions are mean covering factors fcov. However, a major remaining uncertainty is host-galaxy obscuration. In Paper I, we discovered a relation of {NH} ∝ M_{star }^{1/3} for the obscuration of galaxy-scale gas. Here, we apply this observational relation to the AGN population, and find that galaxy-scale gas is responsible for a luminosity-independent fraction of Compton-thin AGN, but does not produce Compton-thick columns. With the host-galaxy obscuration understood, we present a model of the remaining nuclear obscurer, which is consistent with a range of observations. Our radiation-lifted torus model consists of a Compton-thick component (fcov ∼ 35 per cent) and a Compton-thin component (fcov ∼ 40 per cent), which depends on both black hole mass and luminosity. This provides a useful summary of observational constraints for torus modellers who attempt to reproduce this behaviour. It can also be employed as a sub-grid recipe in cosmological simulations that do not resolve the torus. We also investigate host-galaxy X-ray obscuration inside cosmological, hydrodynamic simulations (Evolution and Assembly of Galaxies and their Environment; Illustris). The obscuration from ray-traced galaxy gas can agree with observations, but is highly sensitive to the chosen feedback assumptions.

Hubble Space Telescope Observations of the Afterglow, Supernova and Host Galaxy Associated with the Extremely Bright GRB 130427A

NASA Technical Reports Server (NTRS)

Levan, A.J.; Tanvir, N. R.; Fruchter, A. S.; Hjorth, J.; Pian, E.; Mazzali, P.; Hounsell, R. A.; Perley, D. A.; Cano, Z.; Graham, J.;

THE STELLAR AGES AND MASSES OF SHORT GAMMA-RAY BURST HOST GALAXIES: INVESTIGATING THE PROGENITOR DELAY TIME DISTRIBUTION AND THE ROLE OF MASS AND STAR FORMATION IN THE SHORT GAMMA-RAY BURST RATE

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

Leibler, C. N.; Berger, E.

2010-12-10

We present multi-band optical and near-infrared observations of 19 short {gamma}-ray burst (GRB) host galaxies, aimed at measuring their stellar masses and population ages. The goals of this study are to evaluate whether short GRBs track the stellar mass distribution of galaxies, to investigate the progenitor delay time distribution, and to explore any connection between long and short GRB progenitors. Using single stellar population models we infer masses of log(M{sub *}/M{sub sun}) {approx} 8.8-11.6, with a median of (log(M{sub *}/M{sub sun})) {approx} 10.1, and population ages of {tau}{sub *} {approx} 0.03-4.4 Gyr with a median of ({tau}{sub *}) {approx} 0.3more » Gyr. We further infer maximal masses of log(M{sub *}/M{sub sun}) {approx} 9.7-11.9 by assuming stellar population ages equal to the age of the universe at each host's redshift. Comparing the distribution of stellar masses to the general galaxy mass function, we find that short GRBs track the cosmic stellar mass distribution only if the late-type hosts generally have maximal masses. However, there is an apparent dearth of early-type hosts compared to the equal contribution of early- and late-type galaxies to the cosmic stellar mass budget. Similarly, the short GRB rate per unit old stellar mass appears to be elevated in the late-type hosts. These results suggest that stellar mass may not be the sole parameter controlling the short GRB rate, and raise the possibility of a two-component model with both mass and star formation playing a role (reminiscent of the case for Type Ia supernovae). If short GRBs in late-type galaxies indeed track the star formation activity, the resulting typical delay time is {approx}0.2 Gyr, while those in early-type hosts have a typical delay of {approx}3 Gyr. Using the same stellar population models, we fit the broadband photometry for 22 long GRB host galaxies in a similar redshift range and find that they have significantly lower masses and younger population ages, with

ALMA Observations Show Major Mergers Among the Host Galaxies of Fast-growing, High-redshift​ Supermassive​ Black Holes

NASA Astrophysics Data System (ADS)

Trakhtenbrot, Benny; Lira, Paulina; Netzer, Hagai; Cicone, Claudia; Maiolino, Roberto; Shemmer, Ohad

2017-02-01

We present new ALMA band-7 data for a sample of six luminous quasars at z≃ 4.8, powered by fast-growing supermassive black holes (SMBHs) with rather uniform properties: the typical accretion rates and black hole masses are L/{L}{Edd}≃ 0.7 and {M}{BH}≃ {10}9 {M}⊙ . Our sample consists of three “FIR-bright” sources, which were individually detected in previous Herschel/SPIRE observations, with star formation rates of {SFR}> 1000 {M}⊙ {{yr}}-1, and three “FIR-faint” sources for which Herschel stacking analysis implies a typical SFR of ˜400 {M}⊙ {{yr}}-1. The dusty interstellar medium in the hosts of all six quasars is clearly detected in the ALMA data and resolved on scales of ˜2 kpc, in both continuum ({λ }{rest}˜ 150 μ {{m}}) and [{{C}} {{II}}] λ 157.74 μ {{m}} line emission. The continuum emission is in good agreement with the expectations from the Herschel data, confirming the intense SF activity in the quasar hosts. Importantly, we detect companion sub-millimeter galaxies (SMGs) for three sources—one FIR-bright and two FIR-faint, separated by ˜ 14{--}45 {kpc} and < 450 {km} {{{s}}}-1 from the quasar hosts. The [{{C}} {{II}}]-based dynamical mass estimates for the interacting SMGs are within a factor of ˜3 of the quasar hosts’ masses, while the continuum emission implies {{SFR}}{quasar}˜ (2{--}11)× {{SFR}}{SMG}. Our ALMA data therefore clearly support the idea that major mergers are important drivers for rapid early SMBH growth. However, the fact that not all high-SFR quasar hosts are accompanied by interacting SMGs and the gas kinematics as observed by ALMA suggest that other processes may be fueling these systems. Our analysis thus demonstrates the diversity of host galaxy properties and gas accretion mechanisms associated with early and rapid SMBH growth.

Optical/Near-infrared Selection of Red Quasi-stellar Objects: Evidence for Steep Extinction Curves toward Galactic Centers?

NASA Astrophysics Data System (ADS)

Fynbo, J. P. U.; Krogager, J.-K.; Venemans, B.; Noterdaeme, P.; Vestergaard, M.; Møller, P.; Ledoux, C.; Geier, S.

2013-01-01

We present the results of a search for red QSOs using a selection based on optical imaging from the Sloan Digital Sky Survey (SDSS) and near-infrared imaging from UKIDSS. Our main goal with the selection is to search for QSOs reddened by foreground dusty absorber galaxies. For a sample of 58 candidates (including 20 objects fulfilling our selection criteria that already have spectra in the SDSS), 46 (79%) are confirmed to be QSOs. The QSOs are predominantly dust-reddened except for a handful at redshifts z >~ 3.5. However, the dust is most likely located in the QSO host galaxies (and for two, the reddening is primarily caused by Galactic dust) rather than in the intervening absorbers. More than half of the QSOs show evidence of associated absorption (BAL absorption). Four (7%) of the candidates turned out to be late-type stars, and another four (7%) are compact galaxies. We could not identify the remaining four objects. In terms of their optical spectra, these QSOs are similar to the QSOs selected in the FIRST-2MASS Red Quasar Survey except they are on average fainter, more distant, and only two are detected in the FIRST survey. As per the usual procedure, we estimate the amount of extinction using the SDSS QSO template reddened by Small-Magellanic-Cloud-(SMC) like dust. It is possible to get a good match to the observed (rest-frame ultraviolet) spectra, but it is not possible to match the observed near-IR photometry from UKIDSS for nearly all the reddened QSOs. The most likely reasons are that the SDSS QSO template is too red at optical wavelengths due to contaminating host galaxy light and because the assumed SMC extinction curve is too shallow. Three of the compact galaxies display old stellar populations with ages of several Gyr and masses of about 1010 M ⊙ (based on spectral energy distribution modeling). The inferred stellar densities in these galaxies exceed 1010 M ⊙ kpc-2, which is among the highest measured for early-type galaxies. Our survey has

Neutral Hydrogen Radio Propperties of ASAS-SN Supernovae Hosts

NASA Astrophysics Data System (ADS)

Ross, Timothy W.; Salter, Chris; Ghosh, Tapasi; Minchin, Robert; Jones, Kristen; All-Sky Automated Survey for Supernovae (ASAS-SN)

2018-01-01

We compiled properties of the galaxies containing recent supernovae. The galaxies were observed in the Hydrogen 21-cm region using the Arecibo 305-m Radio Telescope, and the supernovae were found by the All-Sky Automated Survey for Supernovae (ASAS-SN) project. We were able to detect the neutral hydrogen hyperfine transition in 50 new galaxies to date, and retrieved information on 52 host galaxies with previous detections. Including archival detections, the detection rates of Type CC SNe was 96.9%, that of Type Ia was 76.3%, while no Tidal Disruption Events (TDEs) had detections. In all we calculated the integrated HI flux of 102 host galaxies in the Arecibo sky. With the integrated HI flux we calculated mass values. The median HI mass, log [MHI/(h‑2C M⊙)], with h =.73, for all SN host galaxies was 9.47±0.02, with the median for Type Ia hosts being 9.55±0.02 and the median for Type CC being 9.30±0.02.

The Nature of Optical Features in the Inner Region of the 3C 48 Host Galaxy

NASA Astrophysics Data System (ADS)

Stockton, Alan; Canalizo, Gabriela; Fu, Hai; Keel, William

2007-04-01

The well-known quasar 3C 48 is the most powerful compact steep-spectrum radio-loud QSO at low redshifts. It also has two unusual optical features within the radius of the radio jet (~1"): (1) an anomalous, high-velocity narrow-line component, and (2) a bright continuum peak (3C 48A) ~1" northeast of the quasar. Both of these optical features have been conjectured to be related to the radio jet. We have obtained Gemini North GMOS integral field unit (IFU) spectroscopy of the central region around 3C 48. We use the unique features of the IFU data to remove unresolved emission at the position of the quasar. The resolved emission at the wavelength of the high-velocity component is peaked <~0.25" north of the quasar, at the same position angle as the base of the radio jet. These observations appear to confirm that this high-velocity gas is connected with the radio jet. However, most of the emission comes from a region where the jet is still well collimated, rather than from the regions where the radio maps indicate strong disruption. We also present the results of HST STIS spectroscopy of 3C 48A. We show that 3C 48A is dominated by stars with a luminosity-weighted age of ~1.4×108 yr, substantially older than any reasonable estimate for the age of the radio source. Thus, 3C 48A almost certainly cannot be attributed to jet-induced star formation. The host galaxy of 3C 48 is clearly the result of a merger, and 3C 48A seems much more likely to be the distorted nucleus of the merging partner in which star formation was induced during the previous close passage. 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 GO-09365. Also based in part on observations obtained at the Gemini Observatory, which is operated by the Association of

The extraordinarily bright optical afterglow of GRB 991208 and its host galaxy

NASA Astrophysics Data System (ADS)

Castro-Tirado, A. J.; Sokolov, V. V.; Gorosabel, J.; Castro Cerón, J. M.; Greiner, J.; Wijers, R. A. M. J.; Jensen, B. L.; Hjorth, J.; Toft, S.; Pedersen, H.; Palazzi, E.; Pian, E.; Masetti, N.; Sagar, R.; Mohan, V.; Pandey, A. K.; Pandey, S. B.; Dodonov, S. N.; Fatkhullin, T. A.; Afanasiev, V. L.; Komarova, V. N.; Moiseev, A. V.; Hudec, R.; Simon, V.; Vreeswijk, P.; Rol, E.; Klose, S.; Stecklum, B.; Zapatero-Osorio, M. R.; Caon, N.; Blake, C.; Wall, J.; Heinlein, D.; Henden, A.; Benetti, S.; Magazzù, A.; Ghinassi, F.; Tommasi, L.; Bremer, M.; Kouveliotou, C.; Guziy, S.; Shlyapnikov, A.; Hopp, U.; Feulner, G.; Dreizler, S.; Hartmann, D.; Boehnhardt, H.; Paredes, J. M.; Martí, J.; Xanthopoulos, E.; Kristen, H. E.; Smoker, J.; Hurley, K.

2001-05-01

Broad-band optical observations of the extraordinarily bright optical afterglow of the intense gamma-ray burst GRB 991208 started ~2.1 days after the event and continued until 4 Apr. 2000. The flux decay constant of the optical afterglow in the R-band is -2.30 +/- 0.07 up to ~5 days, which is very likely due to the jet effect, and it is followed by a much steeper decay with constant -3.2 +/- 0.2, the fastest one ever seen in a GRB optical afterglow. A negative detection in several all-sky films taken simultaneously with the event, that otherwise would have reached naked eye brightness, implies either a previous additional break prior to ~2 days after the occurrence of the GRB (as expected from the jet effect) or a maximum, as observed in GRB 970508. The existence of a second break might indicate a steepening in the electron spectrum or the superposition of two events, resembling GRB 000301C. Once the afterglow emission vanished, contribution of a bright underlying supernova was found on the basis of the late-time R-band measurements, but the light curve is not sufficiently well sampled to rule out a dust echo explanation. Our redshift determination of z = 0.706 indicates that GRB 991208 is at 3.7 Gpc (for Ho = 60 km s-1 Mpc-1, OMEGAo = 1 and LAMDAo = 0), implying an isotropic energy release of 1.15 x 1053 erg which may be relaxed by beaming by a factor >102. Precise astrometry indicates that the GRB coincides within 0.2" with the host galaxy, thus supporting a massive star origin. The absolute magnitude of the galaxy is MB = -18.2, well below the knee of the galaxy luminosity function and we derive a star-forming rate of (11.5 +/- 7.1) Msun yr-1, which is much larger than the present-day rate in our Galaxy. The quasi-simultaneous broad-band photometric spectral energy distribution of the afterglow was determined ~3.5 day after the burst (Dec. 12.0) implying a cooling frequency nuc below the optical band, i.e. supporting a jet model with p = -2.30 as the index of

The Extreme Hosts of Extreme Supernovae

NASA Astrophysics Data System (ADS)

Neill, James D.

2012-01-01

We present the results from a deeper survey of Luminous Supernova (LSN) hosts with the Galaxy Evolution Explorer (GALEX). We have added new, multiple kilo-second observations to our original observations of seventeen LSN hosts providing better constraints on their physical properties. We place the LSNe hosts on the galaxy NUV-r versus M(r) color magnitude diagram (CMD) with a larger comparison sample ( 26,000) to illustrate the extreme nature of these galaxies. The LSN hosts favor low-density regions of the galaxy CMD falling on the blue edge of the blue cloud toward the low luminosity end. The new observations provide tighter constraints on the star formation rates (SFRs) and stellar masses, M(*), and show that the LSNe result from regions of high specific star formation and yet low total SFR. This regime is of particular interest for exploring the upper end of the stellar IMF and its variation. If our understanding of the progenitors of the LSNe leans toward very massive (> 200 M_sun) progenitors, the potential for a conflict with IMF theory exists because the conditions found in the hosts producing the LSNe should not create such massive stars. If it also required that LSNe can only be produced in primordial or very low metallicity environments, then they will also provide evidence for strong variation in metallicity within a dwarf galaxy, since their masses are consistent with low, but not extreme metallicity.

Intrinsic alignments of galaxies in the EAGLE and cosmo-OWLS simulations

NASA Astrophysics Data System (ADS)

Velliscig, Marco; Cacciato, Marcello; Schaye, Joop; Hoekstra, Henk; Bower, Richard G.; Crain, Robert A.; van Daalen, Marcel P.; Furlong, Michelle; McCarthy, I. G.; Schaller, Matthieu; Theuns, Tom

2015-12-01

We report results for the alignments of galaxies in the EAGLE and cosmo-OWLS hydrodynamical cosmological simulations as a function of galaxy separation (-1 ≤ log10(r/[ h-1 Mpc]) ≤ 2) and halo mass (10.7 ≤ log10(M200/[h-1 M⊙]) ≤ 15). We focus on two classes of alignments: the orientations of galaxies with respect to either the directions to, or the orientations of, surrounding galaxies. We find that the strength of the alignment is a strongly decreasing function of the distance between galaxies. For galaxies hosted by the most massive haloes in our simulations the alignment can remain significant up to ˜100 Mpc. Galaxies hosted by more massive haloes show stronger alignment. At a fixed halo mass, more aspherical or prolate galaxies exhibit stronger alignments. The spatial distribution of satellites is anisotropic and significantly aligned with the major axis of the main host halo. The major axes of satellite galaxies, when all stars are considered, are preferentially aligned towards the centre of the main host halo. The predicted projected direction-orientation alignment, ɛg+(rp), is in broad agreement with recent observations. We find that the orientation-orientation alignment is weaker than the orientation-direction alignment on all scales. Overall, the strength of galaxy alignments depends strongly on the subset of stars that are used to measure the orientations of galaxies and it is always weaker than the alignment of dark matter haloes. Thus, alignment models that use halo orientation as a direct proxy for galaxy orientation overestimate the impact of intrinsic galaxy alignments.

Gravitational wave sources from Pop III stars are preferentially located within the cores of their host Galaxies

NASA Astrophysics Data System (ADS)

Pacucci, Fabio; Loeb, Abraham; Salvadori, Stefania

2017-10-01

The detection of gravitational waves (GWs) generated by merging black holes has recently opened up a new observational window into the Universe. The mass of the black holes in the first and third Laser Interferometer Gravitational Wave Observatory (LIGO) detections (36-29 M⊙ and 32-19 M⊙) suggests low-metallicity stars as their most likely progenitors. Based on high-resolution N-body simulations, coupled with state-of-the-art metal enrichment models, we find that the remnants of Pop III stars are preferentially located within the cores of galaxies. The probability of a GW signal to be generated by Pop III stars reaches ∼90 per cent at ∼0.5 kpc from the galaxy centre, compared to a benchmark value of ∼5 per cent outside the core. The predicted merger rates inside bulges is ∼60 × βIII Gpc-3 yr-1 (βIII is the Pop III binarity fraction). To match the 90 per cent credible range of LIGO merger rates, we obtain: 0.03 < βIII < 0.88. Future advances in GW observatories and the discovery of possible electromagnetic counterparts could allow the localization of such sources within their host galaxies. The preferential concentration of GW events within the bulge of galaxies would then provide an indirect proof for the existence of Pop III stars.

Dual Active Galactic Nuclei in Nearby Galaxies

NASA Astrophysics Data System (ADS)

Das, Mousumi; Rubinur, Khatun; Karb, Preeti; Varghese, Ashlin; Novakkuni, Navyasree; James, Atul

2018-04-01

Galaxy mergers play a crucial role in the formation of massive galaxies and the buildup of their bulges. An important aspect of the merging process is the in-spiral of the supermassive black-holes (SMBHs) to the centre of the merger remnant and the eventual formation of a SMBH binary. If both the SMBHs are accreting they will form a dual or binary active galactic nucleus (DAGN). The final merger remnant is usually very bright and shows enhanced star formation. In this paper we summarise the current sample of DAGN from previous studies and describe methods that can be used to identify strong DAGN candidates from optical and spectroscopic surveys. These methods depend on the Doppler separation of the double peaked AGN emission lines, the nuclear velocity dispersion of the galaxies and their optical/UV colours. We describe two high resolution, radio observations of DAGN candidates that have been selected based on their double peaked optical emission lines (DPAGN). We also examine whether DAGN host galaxies have higher star formation rates (SFRs) compared to merging galaxies that do not appear to have DAGN. We find that the SFR is not higher for DAGN host galaxies. This suggests that the SFRs in DAGN host galaxies is due to the merging process itself and not related to the presence of two AGN in the system.

Morphological Differences Between Seyfert Hosts and Normal Galaxies

NASA Astrophysics Data System (ADS)

Shlosman, Isaac

Using new sub-arcsecond resolution imaging we compare large-scale stellar bar fraction in CfA sample of Seyferts and a closely matched control sample of normal galaxies. We find a difference between the samples on the 2.5σ level. We further compare the axial ratios of bars in all available samples quoted in the literature and find a deficiency of small axial ratio bars in Seyferts compared to normal galaxies.

Spectacular mergers at the cosmic dawn: a HST, ALMA, and JWST synergy

NASA Astrophysics Data System (ADS)

Banados, Eduardo

2016-10-01

How did the first massive galaxies in the universe form? Theoretical models predict that these form through mergers of gas-rich galaxies at very high-redshifts. These models are often invoked to explain the existence of massive 'red and dead' galaxies by z 2. We have unexpectedly identified a sample of six z>6 QSOs with close, gas-rich companions at the same redshifts through our on-going ALMA survey of [CII] and dust emission in QSO host galaxies. This is the first unambiguous direct observational evidence of gravitational interactions within the first Gyr of the universe, supporting the aforementioned theoretical models. These newly discovered QSO-galaxy pairs are a unique sample to demonstrate key capabilities of JWST in early science, such as the multi-object and IFU modes of NIRSpec. Remarkably, three of these systems are separated by less than 10 kpc (<2 arcsec), which makes them prime targets to exploit the unparalleled IFU capabilities of JWST/NIRSpec in early science. Such observations will allow us to map the morphology and kinematics of these gravitational interactions as function of separation from the QSOs, which will enlighten our understanding of early black hole and galaxy growth. Thus, it is of critical importance to characterize the rest-frame UV/optical properties of these companions before the JWST launch. Here we propose deep WFC3/IR F140W observations to set the first firm constraints on their rest-frame UV properties, which can only be achieved by the sensitivity and resolution of HST. These timely HST observations will be essential to enable a plethora of JWST early science programs.

THE NATURE OF A GALAXY ALONG THE SIGHT LINE TO PKS 0454+039

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

Takamiya, Marianne; Chun, Mark; Kulkarni, Varsha P.

2012-10-01

We report on the properties of a faint blue galaxy (G1) along the line of sight to the QSO PKS 0454+039 from spectroscopic and imaging data. We measured emission lines of H{alpha}, [S II] {lambda}{lambda}6716, 6732, and [N II] {lambda}6584 in the spectrum of G1 obtained with the Gemini/GMOS instrument. The spectroscopic redshift of G1 is z = 0.0715 {+-} 0.0002. From the extinction-corrected H{alpha} flux, we determine a modest star formation rate of SFR = 0.07 M{sub Sun} yr{sup -1} and a specific SFR of log (sSFR) -8.4. Using three different abundance indicators, we determine a nebular abundance 12more » + log (O/H) ranging from 7.6 to 8.2. Based on the velocity dispersion inferred from the emission line widths and the observed surface brightness profile, we estimate the virial mass of G1 to be M{sub vir} {approx} 6.7 Multiplication-Sign 10{sup 9} M{sub Sun} with an effective radius of 2.0 kpc. We estimate the stellar mass of G1 using spectral energy distribution fitting to be M{sub *} Almost-Equal-To 1.2 Multiplication-Sign 10{sup 7} M{sub Sun} and an r'-luminosity of L{sub r'} = 1.5x10{sup 8} L{sub Sun }. Overall, G1 is a faint, low-mass, low-metallicity Im/H II galaxy. We also report on the line flux limits of another source (G3) which is the most likely candidate for the absorber system at z = 0.8596. From the spectrum of the QSO itself, we report a previously undetected Mg II {lambda}{lambda}2796, 2803 absorption line system at z = 1.245.« less

Infrared Spectral Energy Distribution Decomposition of WISE-selected, Hyperluminous Hot Dust-obscured Galaxies

NASA Astrophysics Data System (ADS)

Fan, Lulu; Han, Yunkun; Nikutta, Robert; Drouart, Guillaume; Knudsen, Kirsten K.

2016-06-01

We utilize a Bayesian approach to fit the observed mid-IR-to-submillimeter/millimeter spectral energy distributions (SEDs) of 22 WISE-selected and submillimeter-detected, hyperluminous hot dust-obscured galaxies (Hot DOGs), with spectroscopic redshift ranging from 1.7 to 4.6. We compare the Bayesian evidence of a torus plusgraybody (Torus+GB) model with that of a torus-only (Torus) model and find that the Torus+GB model has higher Bayesian evidence for all 22 Hot DOGs than the torus-only model, which presents strong evidence in favor of the Torus+GB model. By adopting the Torus+GB model, we decompose the observed IR SEDs of Hot DOGs into torus and cold dust components. The main results are as follows. (1) Hot DOGs in our submillimeter-detected sample are hyperluminous ({L}{IR}≥slant {10}13{L}⊙ ), with torus emission dominating the IR energy output. However, cold dust emission is non-negligible, contributing on average ˜ 24% of total IR luminosity. (2) Compared to QSO and starburst SED templates, the median SED of Hot DOGs shows the highest luminosity ratio between mid-IR and submillimeter at rest frame, while it is very similar to that of QSOs at ˜ 10{--}50 μ {{m}}, suggesting that the heating sources of Hot DOGs should be buried AGNs. (3) Hot DOGs have high dust temperatures ({T}{dust}˜ 72 K) and high IR luminosity of cold dust. The {T}{dust}{--}{L}{IR} relation of Hot DOGs suggests that the increase in IR luminosity for Hot DOGs is mostly due to the increase of the dust temperature, rather than dust mass. Hot DOGs have lower dust masses than submillimeter galaxies (SMGs) and QSOs within a similar redshift range. Both high IR luminosity of cold dust and relatively low dust mass in Hot DOGs can be expected by their relatively high dust temperatures. (4) Hot DOGs have high dust-covering factors (CFs), which deviate from the previously proposed trend of the dust CF decreasing with increasing bolometric luminosity. Finally, we can reproduce the observed

Spitzer Observations of GRB Hosts: A Legacy Approach

NASA Astrophysics Data System (ADS)

Perley, Daniel; Tanvir, Nial; Hjorth, Jens; Berger, Edo; Laskar, Tanmoy; Michalowski, Michal; Chary, Ranga-Ram; Fynbo, Johan; Levan, Andrew

2012-09-01

The host galaxies of long-duration GRBs are drawn from uniquely broad range of luminosities and redshifts. Thus they offer the possibility of studying the evolution of star-forming galaxies without the limitations of other luminosity-selected samples, which typically are increasingly biased towards the most massive systems at higher redshift. However, reaping the full benefits of this potential requires careful attention to the selection biases affecting host identification. To this end, we propose observations of a Legacy sample of 70 GRB host galaxies (an additional 70 have already been observed by Spitzer), in order to constrain the mass and luminosity function in GRB-selected galaxies at high redshift, including its dependence on redshift and on properties of the afterglow. Crucially, and unlike previous Spitzer surveys, this sample is carefully designed to be uniform and free of optical selection biases that have caused previous surveys to systematically under-represent the role of luminous, massive hosts. We also propose to extend to larger, more powerfully constraining samples the study of two science areas where Spitzer observations have recently shown spectacular success: the hosts of dust-obscured GRBs (which promise to further our understanding of the connection between GRBs and star-formation in the most luminous galaxies), and the evolution of the mass-metallicity relation at z>2 (for which GRB host observations provide particularly powerful constraints on high-z chemical evolution).

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.;

The dust masses of powerful radio galaxies: clues to the triggering of their activity

NASA Astrophysics Data System (ADS)

Tadhunter, C.; Dicken, D.; Morganti, R.; Konyves, V.; Ysard, N.; Nesvadba, N.; Ramos Almeida, C.

2014-11-01

We use deep Herschel Space Observatory observations of a 90 per cent complete sample of 32 intermediate-redshift 2Jy radio galaxies (0.05 < z < 0.7) with strong emission lines to estimate the dust masses of their host galaxies and thereby investigate the triggering mechanisms for their quasar-like AGN. The dust masses derived for the radio galaxies (7.2 × 105 < Md < 2.6 × 108 M⊙) are intermediate between those of quiescent elliptical galaxies on the one hand, and ultraluminous infrared galaxies (ULIRGs) on the other. Consistent with simple models for the co-evolution of supermassive black holes and their host galaxies, these results suggest that most radio galaxies represent the late time re-triggering of AGN activity via mergers between the host giant elliptical galaxies and companion galaxies with relatively low gas masses. However, a minority of the radio galaxies in our sample (˜20 per cent) have high, ULIRG-like dust masses, along with evidence for prodigious star formation activity. The latter objects are more likely to have been triggered in major, gas-rich mergers that represent a rapid growth phase for both their host galaxies and their supermassive black holes.

The role of black holes in galaxy formation and evolution.

PubMed

Cattaneo, A; Faber, S M; Binney, J; Dekel, A; Kormendy, J; Mushotzky, R; Babul, A; Best, P N; Brüggen, M; Fabian, A C; Frenk, C S; Khalatyan, A; Netzer, H; Mahdavi, A; Silk, J; Steinmetz, M; Wisotzki, L

2009-07-09

Virtually all massive galaxies, including our own, host central black holes ranging in mass from millions to billions of solar masses. The growth of these black holes releases vast amounts of energy that powers quasars and other weaker active galactic nuclei. A tiny fraction of this energy, if absorbed by the host galaxy, could halt star formation by heating and ejecting ambient gas. A central question in galaxy evolution is the degree to which this process has caused the decline of star formation in large elliptical galaxies, which typically have little cold gas and few young stars, unlike spiral galaxies.

A New Survey for Low-Redshift Damped Lyman-Alpha Lines in QSO MgII Systems

NASA Astrophysics Data System (ADS)

Rao, Sandhya

2000-07-01

Studies have shown that most of the observable neutral gas mass in the Universe resides in QSO damped LyAlpha {DLA} systems. However, at low redshift {z<1.65}, DLA can only be found by searching in the UV with HST. Such searches are crucial since z<1.65 corresponds to 3/4 of the age of the Universe. The identification of significant numbers of low- redshift DLA systems is imperative if we ever hope to effectively study this cosmologically massive component of neutral gas. To this end, we recently reported on the results of our initial HST survey to study low-redshift DLA absorbers in QSO MgII systems. We discovered 14 DLA systems and had a success rate of 14%. Now, based on these results and our improved understanding of the selection criteria for successful DLA searches, we propose a new survey for low-redshift DLA lines in QSO MgII systems. With our new revised selection criteria, we can empirically show that our success rate would be 35%. Specifically, we propose to observe the LyAlpha line of 55 MgII systems. We estimate that we will discover 19 new DLA systems with redshift z<1.65. Finding these systems will facilitate the type of research that can be done with DLA systems. By boot-strapping from the MgII statistics, we will be able to further improve the determination of the low- redshift statistical properties of DLA {their incidence and cosmological mass density} and open up new opportunities for studies at low redshift.

Do Typical Galaxies in Adolescence Already Host Growing Black Holes?

NASA Astrophysics Data System (ADS)

Trump, Jonathan

2012-10-01

This archival grism proposal achieves a 100-fold gain in high-quality {5+sigma} information for discovering which properties of adolescent {0.7galaxies of typical mass and SFR are linked to AGN activity. We propose to analyze 147 WFC3 G141 and 111 ACS 800L pointings of 2-orbit grism data in the CANDELS fields, for a sample of 3000 galaxies reaching SFR 5 Msun/yr and stellar masses of log{M*/Msun} 9 at z 1.5. We will leverage spatially-resolved line ratios to uniquely distinguish a nuclear AGN from extended low-metallicity or shocked gas. Compared to our 30-galaxy published sample that hints at AGNs in low-mass z 2 galaxies {Trump et al. 2011}, this 3000 galaxy sample enables a 100-fold gain in divisions by galaxy morphology, SFR, and stellar mass to discover which galaxy properties correlate most with rapid SMBH growth. We will stack the deep {0.8-4 Ms} Chandra data available in these fields as an independent check of the grism AGN/SF diagnostics. The unique ancillary data in these fields also include ACS+WFC3 imaging for morphologies, deep multiwavelength data for well-sampled SEDs and stellar masses, and previous optical {and future near-IR} spectroscopy to supplement the G141 coverage. Based on discussions with the GOODS-N and 3D-HST teams, our proposed AGN science does not overlap with their proposed or funded science goals. As a value-added product for the community we will release, via the public Rainbow-CANDELS database server, an atlas of spatial maps of emission lines and line ratios {and associated errors} for the entire sample of 3000 galaxies.

Detection of an unprecedented outburst in IDV QSO TXS0917+624

NASA Astrophysics Data System (ADS)

Spiridonova, O. I.; Moskvitin, A. S.; Vlasyuk, V. V.

2017-12-01

We report on an unprecedented optical flare of TXS0917+624 -- popular QSO (z=1.446) with effects of intraday variability in radio range. Our measurements, made with 1-meter telescope of SAO of RAS, equipped by UBVRI CCD photometer, showed that apparent magnitude of object in R-band increased up to 15.34 +/- 0.02 on December 8th, 2017 (MJD = 58096.5) and 15.31 +/- 0.03 on December 9th, 2017 (MJD = 58097.5).

Galaxy interactions and strength of nuclear activity

NASA Technical Reports Server (NTRS)

Simkin, S. M.

1990-01-01

Analysis of data in the literature for differential velocities and projected separations of nearby Seyfert galaxies with possible companions shows a clear difference in projected separations between type 1's and type 2's. This kinematic difference between the two activity classes reinforces other independent evidence that their different nuclear characteristics are related to a non-nuclear physical distinction between the two classes. The differential velocities and projected separations of the galaxy pairs in this sample yield mean galaxy masses, sizes, and mass to light ratios which are consistent with those found by the statistical methods of Karachentsev. Although the galaxy sample discussed here is too small and too poorly defined to provide robust support for these conclusions, the results strongly suggest that nuclear activity in Seyfert galaxies is associated with gravitational perturbations from companion galaxies, and that there are physical distinctions between the host companions of Seyfert 1 and Seyfert 2 nuclei which may depend both on the environment and the structure of the host galaxy itself.

Scaling Relations Between Warm Galactic Outflows and Their Host Galaxies

NASA Astrophysics Data System (ADS)

Chisholm, John; Tremonti, Christy A.; Leitherer, Claus; Chen, Yanmei; Wofford, Aida; Lundgren, Britt

2015-10-01

We report on a sample of 48 nearby, star-forming galaxies observed with the Cosmic Origin Spectrograph on the Hubble Space Telescope. We measure the kinematics of warm gas in galactic outflows using a combination of four Si ii absorption lines. We use multi-wavelength ancillary data to estimate stellar masses (M*), star formation rates (SFR), circular velocities (vcirc), and morphologies. The galaxies cover four orders of magnitude in M* and SFR, and sample a wide range of morphologies from starbursting mergers to normal star-forming galaxies. We derive 3.0-3.5σ relations between outflow velocity and SFR, M*, and vcirc. The outflow velocities scale as SFR0.08-0.22, {M}*0.12-0.20 and {v}{circ}0.44-0.87, with the range depending on whether we use a maximum or a central velocity to quantify the outflow velocity. After accounting for their increased SFR, mergers drive 32% faster outflows than non-merging galaxies, with all of the highest velocity outflows arising from mergers. Low-mass galaxies (log(M*/ M⊙) < 10.5) lose some low-ionization gas through galactic outflows, while more massive galaxies retain all of their low-ionization gas, unless they undergo a merger.

Subaru High-z Exploration of Low-Luminosity Quasars (SHELLQs). III. Star formation properties of the host galaxies at z ≳ 6 studied with ALMA

NASA Astrophysics Data System (ADS)

Izumi, Takuma; Onoue, Masafusa; Shirakata, Hikari; Nagao, Tohru; Kohno, Kotaro; Matsuoka, Yoshiki; Imanishi, Masatoshi; Strauss, Michael A.; Kashikawa, Nobunari; Schulze, Andreas; Silverman, John D.; Fujimoto, Seiji; Harikane, Yuichi; Toba, Yoshiki; Umehata, Hideki; Nakanishi, Kouichiro; Greene, Jenny E.; Tamura, Yoichi; Taniguchi, Akio; Yamaguchi, Yuki; Goto, Tomotsugu; Hashimoto, Yasuhiro; Ikarashi, Soh; Iono, Daisuke; Iwasawa, Kazushi; Lee, Chien-Hsiu; Makiya, Ryu; Minezaki, Takeo; Tang, Ji-Jia

2018-04-01

We present our ALMA Cycle 4 measurements of the [C II] emission line and the underlying far-infrared (FIR) continuum emission from four optically low-luminosity (M1450 > -25) quasars at z ≳ 6 discovered by the Subaru Hyper Suprime Cam (HSC) survey. The [C II] line and FIR continuum luminosities lie in the ranges L_[C II] = (3.8-10.2)× 108 L_{⊙} and LFIR = (1.2-2.0) × 1011 L_{⊙}, which are at least one order of magnitude smaller than those of optically-luminous quasars at z ≳ 6. We estimate the star formation rates (SFRs) of our targets as ≃ 23-40 M_{⊙} yr-1. Their line and continuum-emitting regions are marginally resolved, and found to be comparable in size to those of optically-luminous quasars, indicating that their SFR or likely gas mass surface densities (key controlling parameter of mass accretion) are accordingly different. The L_[C II]/L_FIR ratios of the hosts, ≃ (2.2-8.7) × 10-3, are fully consistent with local star-forming galaxies. Using the [C II] dynamics, we derived their dynamical masses within a radius of 1.5-2.5 kpc as ≃ (1.4-8.2) × 1010 M_{⊙}. By interpreting these masses as stellar ones, we suggest that these faint quasar hosts are on or even below the star-forming main sequence at z ˜ 6, i.e., they appear to be transforming into quiescent galaxies. This is in contrast to the optically-luminous quasars at those redshifts, which show starburst-like properties. Finally, we find that the ratios of black hole mass to host galaxy dynamical mass of most of the low-luminosity quasars, including the HSC ones, are consistent with the local value. The mass ratios of the HSC quasars can be reproduced by a semi-analytical model that assumes merger-induced black hole host galaxy evolution.

Subaru High-z Exploration of Low-Luminosity Quasars (SHELLQs). III. Star formation properties of the host galaxies at z ≳ 6 studied with ALMA

NASA Astrophysics Data System (ADS)

Izumi, Takuma; Onoue, Masafusa; Shirakata, Hikari; Nagao, Tohru; Kohno, Kotaro; Matsuoka, Yoshiki; Imanishi, Masatoshi; Strauss, Michael A.; Kashikawa, Nobunari; Schulze, Andreas; Silverman, John D.; Fujimoto, Seiji; Harikane, Yuichi; Toba, Yoshiki; Umehata, Hideki; Nakanishi, Kouichiro; Greene, Jenny E.; Tamura, Yoichi; Taniguchi, Akio; Yamaguchi, Yuki; Goto, Tomotsugu; Hashimoto, Yasuhiro; Ikarashi, Soh; Iono, Daisuke; Iwasawa, Kazushi; Lee, Chien-Hsiu; Makiya, Ryu; Minezaki, Takeo; Tang, Ji-Jia

2018-06-01

We present our ALMA Cycle 4 measurements of the [C II] emission line and the underlying far-infrared (FIR) continuum emission from four optically low-luminosity (M1450 > -25) quasars at z ≳ 6 discovered by the Subaru Hyper Suprime Cam (HSC) survey. The [C II] line and FIR continuum luminosities lie in the ranges L_[C II] = (3.8-10.2)× 108 L_{⊙} and LFIR = (1.2-2.0) × 1011 L_{⊙}, which are at least one order of magnitude smaller than those of optically-luminous quasars at z ≳ 6. We estimate the star formation rates (SFRs) of our targets as ≃ 23-40 M_{⊙} yr-1. Their line and continuum-emitting regions are marginally resolved, and found to be comparable in size to those of optically-luminous quasars, indicating that their SFR or likely gas mass surface densities (key controlling parameter of mass accretion) are accordingly different. The L_[C II}]}/L_FIR ratios of the hosts, ≃ (2.2-8.7) × 10-3, are fully consistent with local star-forming galaxies. Using the [C II] dynamics, we derived their dynamical masses within a radius of 1.5-2.5 kpc as ≃ (1.4-8.2) × 1010 M_{⊙}. By interpreting these masses as stellar ones, we suggest that these faint quasar hosts are on or even below the star-forming main sequence at z ˜ 6, i.e., they appear to be transforming into quiescent galaxies. This is in contrast to the optically-luminous quasars at those redshifts, which show starburst-like properties. Finally, we find that the ratios of black hole mass to host galaxy dynamical mass of most of the low-luminosity quasars, including the HSC ones, are consistent with the local value. The mass ratios of the HSC quasars can be reproduced by a semi-analytical model that assumes merger-induced black hole host galaxy evolution.

Co-evolution of Massive Black Holes and Their Host Galaxies

NASA Astrophysics Data System (ADS)

Chen, Y. M.

2010-07-01

A scenario of co-evolution of supermassive black holes (SMBHs) and galaxies has been clearly conducted by the important evidence from observational results of quasar host galaxies and the relation between spheroid and SMBH mass. There are a plenty of unresolved problems and questions, some being basic, to be addressed in this scenario. The main goal of the present thesis is focusing on the mysterious scenario including growth of primordial black holes, cosmological evolution of spins and duty cycle of SMBHs, and interaction between the SMBH activity and star formation in galaxies from low to high redshifts. We review the main progress of this field over the past decade since the discovery of Magorrian relation and present comments on some questions in light of our view of points. The key questions to be addressed in this thesis work are: (1) how does the fast growth of primordial black holes influence their evolution? (2) what is the equation to describe the co-evolution of SMBHs and galaxies? (3) what is the mechanism to control the co-evolution? (4) how to transport the fueling gas from kpc scale to the center? It has been suggested that fast growth of primordial black holes via super-Eddington accretion is a promising way to form SMBHs in high redshift universe. Neutrino cooling has been employed and expedites the growth. We consider the Compton heating of the surroundings of the primordial black holes. We find that the realistic accretion rate is only a few percent of the Eddington rate, and the accretion is episodic. It implies that the fast growth via super-Eddington is not feasible. These conclusions have been confirmed by the detailed numerical simulations of Milosavljevic et al. (2008). The difficulties of the fast growth via accretion of baryon particles make the formation of SMBHs elusive in high redshift universe. We developed a new formulation to calculate the duty cycle of SMBHs based on the Soltan argument. We show it can be expressed by the mass

Isolated Galaxies and Isolated Satellite Systems

NASA Astrophysics Data System (ADS)

Ann, H. B.; Park, C.; Choi, Y. Y.

2010-10-01

We search for isolated galaxies using a volume-limited sample of galaxies with 0.02 < z < 0.04742 from SDSS DR7 supplemented by bright galaxies. We devise a diagnostic tool to select isolated galaxies in different environments using the projected separation (rp) normalized by the virial radius of the nearest neighbor (rvir,nei) and the local background density. We find that the isolation condition of rp > rvir,nei and ρ < ρbar well segregates the CIG galaxies. We confirm the morphology conformity between the host and their satellites, which suggests the importance to galaxy evolution of hydrodynamic interactions among galaxies within their virial radii.

Ionised outflows in z ~ 2.4 quasar host galaxies

NASA Astrophysics Data System (ADS)

Carniani, S.; Marconi, A.; Maiolino, R.; Balmaverde, B.; Brusa, M.; Cano-Díaz, M.; Cicone, C.; Comastri, A.; Cresci, G.; Fiore, F.; Feruglio, C.; La Franca, F.; Mainieri, V.; Mannucci, F.; Nagao, T.; Netzer, H.; Piconcelli, E.; Risaliti, G.; Schneider, R.; Shemmer, O.

2015-08-01

Aims: Outflows driven by active galactic nuclei (AGN) are invoked by galaxy evolutionary models to quench star formation and to explain the origin of the relations observed locally between super-massive black holes and their host galaxies. We here aim to detect extended ionised outflows in luminous quasars, where we expect the highest activity both in star formation and in black-hole accretion. Currently, there are only a few studies based on spatially resolved observations of outflows at high redshift, z > 2. Methods: We analysed a sample of six luminous (L > 1047 erg/s) quasars at z ~ 2.4, observed in H-band using the near-IR integral field spectrometer SINFONI at the VLT. We performed a kinematic analysis of the [Oiii] emission line at λ = 5007 Å. Results: We detect fast, spatially extended outflows in five out of six targets. [Oiii]λ5007 has a complex gas kinematic, with blue-shifted velocities of a few hundreds of km s-1 and line widths up to 1500 km s-1. Using the spectroastrometric method, we infer a size of the ionised outflows of up to ~2 kpc. The properties of the ionised outflows, mass outflow rate, momentum rate, and kinetic power, are correlated with the AGN luminosity. The increase in outflow rate with increasing AGN luminosity is consistent with the idea that a luminous AGN pushes away the surrounding gas through fast outflows that are driven by radiation pressure, which depends on the emitted luminosity. Conclusions: We derive mass outflow rates of about 6-700 M⊙ yr-1 for our sample, which are lower than those observed in molecular outflows. The physical properties of ionised outflows show dependences on AGN luminosity that are similar to those of molecular outflows, but indicate that the mass of ionised gas is lower than that of molecular outflows. Alternatively, this discrepancy between ionised and molecular outflows could be explained with different acceleration mechanisms. Based on Observations collected at the European Organisation for

ALMA Examines a Distant Quasar Host

NASA Astrophysics Data System (ADS)

Kohler, Susanna

2017-04-01

The dust continuum (top) and the [CII] emission (bottom) maps for the region around J1120+0641. [Adapted from Venemans et al. 2017]A team of scientists has used the Atacama Large Millimeter/submillimeter Array (ALMA) to explore the host galaxy of the most distant quasar known. Their observations may help us to build a picture of how the first supermassive black holes in the universe formed and evolved.Faraway Monsters and Their GalaxiesWe know that quasars the incredibly luminous and active centers of some distant galaxies are powered by accreting, supermassive black holes. These monstrous powerhouses have been detected out to redshifts of z 7, when the universe was younger than a billion years old.Though weve observed over a hundred quasars at high redshift, we still dont understand how these early supermassive black holes formed, or whether the black holes and the galaxies that host them co-evolved. In order to answer questions like these, however, we first need to gather information about the properties and behavior of various supermassive black holes and their host galaxies.A team of scientists led by Bram Venemans (Max-Planck Institute for Astronomy, Germany) recently used the unprecedented sensitivity and angular resolution of ALMA as well as the Very Large Array and the IRAM Plateau de Bure Interferometer to examine the most distant quasar currently known, J1120+0641, located at a redshift of z = 7.1.A High-Resolution LookThe teams observations of the dust and gas emission from the quasars host galaxy revealed a number of intriguing things:The red and blue sides of the [CII] emission line are shown here as contours, demonstrating that theres no ordered rotational motion of the gas on kpc scales. [Adapted from Venemans et al. 2017]The majority of the galaxys emission is very compact. Around 80% of the observed flux came from a region of only 11.5 kpc in diameter.Despite the fact that the 2.4-billion-solar-mass black hole at the galaxys center is accreting at

The Redshift Completeness of Local Galaxy Catalogs

NASA Astrophysics Data System (ADS)

Kulkarni, S. R.; Perley, D. A.; Miller, A. A.

2018-06-01

There is considerable interest in understanding the demographics of galaxies within the local universe (defined, for our purposes, as the volume within a radius of 200 Mpc or z ≤ 0.05). In this pilot paper, using supernovae (SNe) as signposts to galaxies, we investigate the redshift completeness of catalogs of nearby galaxies. In particular, type Ia SNe are bright and are good tracers of the bulk of the galaxy population, as they arise in both old and young stellar populations. Our input sample consists of SNe with redshift ≤0.05, discovered by the flux-limited ASAS-SN survey. We define the redshift completeness fraction (RCF) as the number of SN host galaxies with known redshift prior to SN discovery, determined, in this case, via the NASA Extragalactic Database, divided by the total number of newly discovered SNe. Using SNe Ia, we find {RCF}=78{+/- }76% (90% confidence interval) for z < 0.03. We examine the distribution of host galaxies with and without cataloged redshifts as a function of absolute magnitude and redshift, and, unsurprisingly, find that higher-z and fainter hosts are less likely to have a known redshift prior to the detection of the SN. However, surprisingly, some {L}* galaxies are also missing. We conclude with thoughts on the future improvement of RCF measurements that will be made possible from large SN samples resulting from ongoing and especially upcoming time-domain surveys.

GRB 090417B and its Host Galaxy: A Step Towards an Understanding of Optically-Dark Gamma-Ray Bursts

NASA Technical Reports Server (NTRS)

Holland, Stephen T.; Sbarufatti, Boris; Shen, Rongfeng; Schady, Patricia; Cummings, Jay R.; Fonseca, Emmanuel; Fynbo, Johan P. U.; Jakobsson, Pall; Leitet, Elisabet; Linne, Staffan;

PISCO: The PMAS/PPak Integral-field Supernova Hosts Compilation

NASA Astrophysics Data System (ADS)

Galbany, L.; Anderson, J. P.; Sánchez, S. F.; Kuncarayakti, H.; Pedraz, S.; González-Gaitán, S.; Stanishev, V.; Domínguez, I.; Moreno-Raya, M. E.; Wood-Vasey, W. M.; Mourão, A. M.; Ponder, K. A.; Badenes, C.; Mollá, M.; López-Sánchez, A. R.; Rosales-Ortega, F. F.; Vílchez, J. M.; García-Benito, R.; Marino, R. A.

2018-03-01

We present the PMAS/PPak Integral-field Supernova hosts COmpilation (PISCO), which comprises integral field spectroscopy (IFS) of 232 supernova (SN) host galaxies that hosted 272 SNe, observed over several semesters with the 3.5 m telescope at the Calar Alto Observatory (CAHA). PISCO is the largest collection of SN host galaxies observed with wide-field IFS, totaling 466,347 individual spectra covering a typical spatial resolution of ∼380 pc. Focused studies regarding specific SN Ia-related topics will be published elsewhere; this paper aims to present the properties of the SN environments, using stellar population (SP) synthesis, and the gas-phase interstellar medium, providing additional results separating stripped-envelope SNe into their subtypes. With 11,270 H II regions detected in all galaxies, we present for the first time a statistical analysis of H II regions, which puts H II regions that have hosted SNe in context with all other star-forming clumps within their galaxies. SNe Ic are associated with environments that are more metal-rich and have higher EW(Hα) and higher star formation rate within their host galaxies than the mean of all H II regions detected within each host. This in contrast to SNe IIb, which occur in environments that are very different compared to other core-collapse SNe types. We find two clear components of young and old SPs at SNe IIn locations. We find that SNe II fast decliners tend to explode at locations where the ΣSFR is more intense. Finally, we outline how a future dedicated IFS survey of galaxies in parallel to an untargeted SN search would overcome the biases in current environmental studies.

Structural properties of faint low surface brightness galaxies

NASA Astrophysics Data System (ADS)

Pahwa, Isha; Saha, Kanak

2018-05-01

We study the structural properties of Low Surface Brightness galaxies (LSB) using a sample of 263 galaxies observed by the Green Bank Telescope (Schneider et al. 1992). We perform 2D decompositions of these galaxies in the SDSS g, r and i bands using the GALFIT software. Our decomposition reveals that about 60% of these galaxies are bulgeless i.e., their light distributions are well modelled by pure exponential disks. The rest of the galaxies were fitted with two components: a Sersic bulge and an exponential disk. Most of these galaxies have bulge-to-total (B/T) ratio less than 0.1. However, of these 104 galaxies, 20% have B/T > 0.1 i.e., hosting significant bulge component and they are more prominent amongst the fainter LSBs. According to g - r colour criteria, most of the LSB galaxies in our sample are blue, with only 7 classified as red LSBs. About 15% of the LSB galaxies (including both blue and red) in our sample host stellar bars. The incidence of bars is more prominent in relatively massive blue LSB galaxies with very high gas fraction. These findings may provide important clues to the formation and evolution of LSB galaxies - in particular on the bar/bulge formation in faint LSB disks.

Supermassive black holes and their host galaxies. I. Bulge luminosities from dedicated near-infrared data

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

Läsker, Ronald; Van de Ven, Glenn; Ferrarese, Laura, E-mail: laesker@mpia.de

2014-01-01

In an effort to secure, refine, and supplement the relation between central supermassive black hole masses, M {sub •}, and the bulge luminosities of their host galaxies, L {sub bul}, we obtained deep, high spatial resolution K-band images of 35 nearby galaxies with securely measured M {sub •}, using the wide-field WIRCam imager at the Canada-France-Hawaii-Telescope. A dedicated data reduction and sky subtraction strategy was adopted to estimate the brightness and structure of the sky, a critical step when tracing the light distribution of extended objects in the near-infrared. From the final image product, bulge and total magnitudes were extractedmore » via two-dimensional profile fitting. As a first order approximation, all galaxies were modeled using a simple Sérsic-bulge+exponential-disk decomposition. However, we found that such models did not adequately describe the structure that we observed in a large fraction of our sample galaxies which often include cores, bars, nuclei, inner disks, spiral arms, rings, and envelopes. In such cases, we adopted profile modifications and/or more complex models with additional components. The derived bulge magnitudes are very sensitive to the details and number of components used in the models, although total magnitudes remain almost unaffected. Usually, but not always, the luminosities and sizes of the bulges are overestimated when a simple bulge+disk decomposition is adopted in lieu of a more complex model. Furthermore, we found that some spheroids are not well fit when the ellipticity of the Sérsic model is held fixed. This paper presents the details of the image processing and analysis, while we discuss how model-induced biases and systematics in bulge magnitudes impact the M {sub •}-L {sub bul} relation in a companion paper.« less

Supermassive Black Holes and Their Host Galaxies. I. Bulge Luminosities from Dedicated Near-infrared Data

NASA Astrophysics Data System (ADS)

Läsker, Ronald; Ferrarese, Laura; van de Ven, Glenn

2014-01-01

In an effort to secure, refine, and supplement the relation between central supermassive black hole masses, M •, and the bulge luminosities of their host galaxies, L bul, we obtained deep, high spatial resolution K-band images of 35 nearby galaxies with securely measured M •, using the wide-field WIRCam imager at the Canada-France-Hawaii-Telescope. A dedicated data reduction and sky subtraction strategy was adopted to estimate the brightness and structure of the sky, a critical step when tracing the light distribution of extended objects in the near-infrared. From the final image product, bulge and total magnitudes were extracted via two-dimensional profile fitting. As a first order approximation, all galaxies were modeled using a simple Sérsic-bulge+exponential-disk decomposition. However, we found that such models did not adequately describe the structure that we observed in a large fraction of our sample galaxies which often include cores, bars, nuclei, inner disks, spiral arms, rings, and envelopes. In such cases, we adopted profile modifications and/or more complex models with additional components. The derived bulge magnitudes are very sensitive to the details and number of components used in the models, although total magnitudes remain almost unaffected. Usually, but not always, the luminosities and sizes of the bulges are overestimated when a simple bulge+disk decomposition is adopted in lieu of a more complex model. Furthermore, we found that some spheroids are not well fit when the ellipticity of the Sérsic model is held fixed. This paper presents the details of the image processing and analysis, while we discuss how model-induced biases and systematics in bulge magnitudes impact the M •-L bul relation in a companion paper.

CHANDRA X-RAY AND HUBBLE SPACE TELESCOPE IMAGING OF OPTICALLY SELECTED KILOPARSEC-SCALE BINARY ACTIVE GALACTIC NUCLEI. II. HOST GALAXY MORPHOLOGY AND AGN ACTIVITY

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

Shangguan, Jinyi; Ho, Luis C.; Liu, Xin

Binary active galactic nuclei (AGNs) provide clues to how gas-rich mergers trigger and fuel AGNs and how supermassive black hole (SMBH) pairs evolve in a gas-rich environment. While significant effort has been invested in their identification, the detailed properties of binary AGNs and their host galaxies are still poorly constrained. In a companion paper, we examined the nature of ionizing sources in the double nuclei of four kiloparsec-scale binary AGNs with redshifts between 0.1 and 0.2. Here, we present their host galaxy morphology based on F336W ( U -band) and F105W ( Y -band) images taken by the Wide Fieldmore » Camera 3 on board the Hubble Space Telescope . Our targets have double-peaked narrow emission lines and were confirmed to host binary AGNs with follow-up observations. We find that kiloparsec-scale binary AGNs occur in galaxy mergers with diverse morphological types. There are three major mergers with intermediate morphologies and a minor merger with a dominant disk component. We estimate the masses of the SMBHs from their host bulge stellar masses and obtain Eddington ratios for each AGN. Compared with a representative control sample drawn at the same redshift and stellar mass, the AGN luminosities and Eddington ratios of our binary AGNs are similar to those of single AGNs. The U − Y color maps indicate that clumpy star-forming regions could significantly affect the X-ray detection of binary AGNs, e.g., the hardness ratio. Considering the weak X-ray emission in AGNs triggered in merger systems, we suggest that samples of X-ray-selected AGNs may be biased against gas-rich mergers.« less

The theory of QSO absorption line systems and their relationship to the galaxies

NASA Technical Reports Server (NTRS)

Charlton, Jane

1993-01-01

The fundamental goal of this effort is to paint a picture of what the Ly-alpha forest clouds are and how they are distributed in space. Progress during the first phase of this program involved development of the 'Cheshire Cat Model' of Ly-alpha clouds in which systems over a large range of column densities are produced by disks with somewhat smaller column densities than those of normal galaxies. A prediction of the slab model of Ly-alpha clouds was confirmed by a new observational result, and the comparison of models to the new data allowed an estimate of the pressure of the intergalactic medium. This result should be forthcoming in pre-print form within the next month. The various results will now be described in more detail.

The host galaxy and Fermi-LAT counterpart of HESS J1943+213

NASA Astrophysics Data System (ADS)

Peter, D.; Domainko, W.; Sanchez, D. A.; van der Wel, A.; Gässler, W.

2014-11-01

Context. The very-high energy (VHE, E> 100 GeV) gamma-ray sky shows diverse Galactic and extragalactic source populations. For some sources the astrophysical object class could not be identified so far. Aims: The nature (Galactic or extragalactic) of the VHE gamma-ray source HESS J1943+213 is explored. We specifically investigate the proposed near-infrared counterpart 2MASS J19435624+2118233 of HESS J1943+213 and investigate the implications of a physical association. Methods: We present K-band imaging from the 3.5 m CAHA telescope of 2MASS J19435624+2118233. Furthermore, 5 years of Fermi-LAT data were analyzed to search for a high-energy (HE, 100 MeV galaxy, and thus point toward an extragalactic scenario for the VHE gamma-ray source, assuming that the near-infrared source is the counterpart of HESS J1943+213. A high-Sérsic index profile provides a better fit than an exponential profile, indicating that the surface brightness profile of 2MASS J19435624+2118233 follows that of a typical, massive elliptical galaxy more closely than that of a disk galaxy. With Fermi-LAT a HE counterpart is found with a power-law spectrum above 1 GeV, with a normalization of (3.0 ± 0.8stat ± 0.6sys) × 10-15 cm-2 s-1 MeV-1 at the decorrelation energy Edec = 15.1 GeV and a spectral index of Γ = 1.59 ± 0.19stat ± 0.13sys. This gamma-ray spectrum shows a rather sharp break between the HE and VHE regimes of ΔΓ = 1.47 ± 0.36. Conclusions: The infrared and HE data strongly favor an extragalactic origin of HESS J1943+213, where the infrared counterpart traces the host galaxy of an extreme blazar and where the rather sharp spectral break between the HE and VHE regime indicates attenuation on extragalactic background light. The

The properties of the extended warm ionised gas around low-redshift QSOs and the lack of extended high-velocity outflows

NASA Astrophysics Data System (ADS)

Husemann, B.; Wisotzki, L.; Sánchez, S. F.; Jahnke, K.

2013-01-01

We present a detailed analysis of a large sample of 31 low-redshift, mostly radio-quiet type 1 quasi-stellar objects (QSOs) observed with integral field spectroscopy to study their extended emission-line regions (EELRs). We focus on the ionisation state of the gas, size and luminosity of extended narrow line regions (ENLRs), which corresponds to those parts of the EELR dominated by ionisation from the QSO, as well as the kinematics of the ionised gas. We detect EELRs around 19 of our 31 QSOs (61%) after deblending the unresolved QSO emission and the extended host galaxy light in the integral field data with a new dedicated algorithm. Based on standard emission-line diagnostics we identify 13 EELRs to be entirely ionised by the QSO radiation, 3 EELRs are composed of H ii regions and 3 EELRs display signatures of both ionisation mechanisms at different locations. The typical size of the ENLR is ~10 kpc at a median nuclear [O iii] luminosity of log (L([O iii])/ [ergs-1]) = 42.7 ± 0.15. We show that the ENLR sizes are least a factor of ~2 larger than determined with the Hubble Space Telescope, but are consistent with those of recently reported type 2 QSOs at matching [O iii] luminosities. The ENLR of type 1 and type 2 QSOs therefore appear to follow the same size-luminosity relation. Furthermore, we show for the first time that the ENLR size is much better correlated with the QSO continuum luminosity than with the total/nuclear [O iii] luminosity. We show that ENLR luminosity and radio luminosity are correlated, and argue that radio jets even in radio-quiet QSOs are important for shaping the properties of the ENLR. Strikingly, the kinematics of the ionised gas is quiescent and likely gravitationally driven in the majority of cases and we find only 3 objects with radial gas velocities exceeding >400 km s-1 in specific regions of the EELR that can be associate with radio jets. In general, these are significantly lower outflow velocities and detection rates compared to

DETERMINING TYPE Ia SUPERNOVA HOST GALAXY EXTINCTION PROBABILITIES AND A STATISTICAL APPROACH TO ESTIMATING THE ABSORPTION-TO-REDDENING RATIO R{sub V}

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

Cikota, Aleksandar; Deustua, Susana; Marleau, Francine, E-mail: acikota@eso.org

We investigate limits on the extinction values of Type Ia supernovae (SNe Ia) to statistically determine the most probable color excess, E(B – V), with galactocentric distance, and use these statistics to determine the absorption-to-reddening ratio, R{sub V}, for dust in the host galaxies. We determined pixel-based dust mass surface density maps for 59 galaxies from the Key Insight on Nearby Galaxies: a Far-infrared Survey with Herschel (KINGFISH). We use SN Ia spectral templates to develop a Monte Carlo simulation of color excess E(B – V) with R{sub V} = 3.1 and investigate the color excess probabilities E(B – V) with projected radial galaxymore » center distance. Additionally, we tested our model using observed spectra of SN 1989B, SN 2002bo, and SN 2006X, which occurred in three KINGFISH galaxies. Finally, we determined the most probable reddening for Sa–Sap, Sab–Sbp, Sbc–Scp, Scd–Sdm, S0, and irregular galaxy classes as a function of R/R{sub 25}. We find that the largest expected reddening probabilities are in Sab–Sb and Sbc–Sc galaxies, while S0 and irregular galaxies are very dust poor. We present a new approach for determining the absorption-to-reddening ratio R{sub V} using color excess probability functions and find values of R{sub V} = 2.71 ± 1.58 for 21 SNe Ia observed in Sab–Sbp galaxies, and R{sub V} = 1.70 ± 0.38, for 34 SNe Ia observed in Sbc–Scp galaxies.« less

Multimessenger Signatures of Massive Black Holes in Dwarf Galaxies

NASA Astrophysics Data System (ADS)

Bellovary, Jillian; Cleary, Colleen; Tremmel, Michael; Munshi, Ferah

2018-01-01

Inspired by the recent discovery of several nearby dwarf galaxies hosting active galactic nuclei, we present results from a series of cosmological hydrodynamic simulations focusing on dwarf galaxies which host supermassive black holes (SMBHs). Cosmological simulations are a vital tool for predicting SMBH populations and merger events which will eventually be observed by LISA. Dwarf galaxies are the most numerous in the universe, so even though the occupation fraction of SMBHs in dwarfs is less than unity, their contribution to the gravitational wave background could be non-negligible. We find that electromagnetic signatures from SMBH accretion are not common among most SMBH-hosting dwarfs, but the gravitational wave signatures can be substantial. The most common mass ratio for SMBH mergers in low-mass galaxy environments is ~1:20, which is an unexplored region of gravitational waveform parameter space. We discuss the occupation fraction of SMBHs in low-mass galaxies as well as differences in field and satellite populations, providing clues to search for and characterize these elusive giants lurking in the dwarfs.

A Hot Gaseous Galaxy Halo Candidate with Mg X Absorption

NASA Astrophysics Data System (ADS)

Qu, Zhijie; Bregman, Joel N.

2016-12-01

The hot gas in galaxy halos may account for a significant fraction of missing baryons in galaxies, and some of these gases can be traced by high ionization absorption systems in QSO UV spectra. Using high S/N Hubble Space Telescope/Cosmic Origins Spectrograph spectra, we discovered a high ionization state system at z = 1.1912 in the sightline toward LBQS 1435-0134, and two-component absorption lines are matched for Mg x, Ne viii, Ne VI, O VI, Ne v, O v, Ne IV, O IV, N IV, O III, and H I. Mg x, detected for the first time (5.8σ), is a particularly direct tracer of hot galactic halos, as its peak ion fraction occurs near 106.1 K, about the temperature of a virialized hot galaxy halo of mass ˜ 0.5{M}* . With Mg x and Ne viii, a photoionization model cannot reproduce the observed column densities with path lengths of galaxy halos. For collisional ionization models, one or two-temperature models do not produce acceptable fits, but a three-temperature model or a power-law model can produce the observed results. In the power-law model, {dN}/{dT}={10}4.4+/- 2.2-[Z/X]{T}1.55+/- 0.41 with temperatures in the range of {10}4.39+/- 0.13 {{K}}\\lt T\\lt {10}6.04+/- 0.05 {{K}}, the total hydrogen column density is 8.2× {10}19(0.3 {Z}⊙ /Z) {{cm}}-2 and the positive power-law index indicates most of the mass is at the high temperature end. We suggest that this absorption system is a hot volume-filled galaxy halo rather than interaction layers between the hot halo and cool clouds. The temperature dependence of the column density is likely due to the local mixture of multiple phase gases.

Galaxy And Mass Assembly (GAMA): the signatures of galaxy interactions as viewed from small scale galaxy clustering

NASA Astrophysics Data System (ADS)

Gunawardhana, M. L. P.; Norberg, P.; Zehavi, I.; Farrow, D. J.; Loveday, J.; Hopkins, A. M.; Davies, L. J. M.; Wang, L.; Alpaslan, M.; Bland-Hawthorn, J.; Brough, S.; Holwerda, B. W.; Owers, M. S.; Wright, A. H.

2018-06-01

Statistical studies of galaxy-galaxy interactions often utilise net change in physical properties of progenitors as a function of the separation between their nuclei to trace both the strength and the observable timescale of their interaction. In this study, we use two-point auto, cross and mark correlation functions to investigate the extent to which small-scale clustering properties of star forming galaxies can be used to gain physical insight into galaxy-galaxy interactions between galaxies of similar optical brightness and stellar mass. The Hα star formers, drawn from the highly spatially complete Galaxy And Mass Assembly (GAMA) survey, show an increase in clustering on small separations. Moreover, the clustering strength shows a strong dependence on optical brightness and stellar mass, where (1) the clustering amplitude of optically brighter galaxies at a given separation is larger than that of optically fainter systems, (2) the small scale clustering properties (e.g. the strength, the scale at which the signal relative to the fiducial power law plateaus) of star forming galaxies appear to differ as a function of increasing optical brightness of galaxies. According to cross and mark correlation analyses, the former result is largely driven by the increased dust content in optically bright star forming galaxies. The latter could be interpreted as evidence of a correlation between interaction-scale and optical brightness of galaxies, where physical evidence of interactions between optically bright star formers, likely hosted within relatively massive halos, persist over larger separations than those between optically faint star formers.

Satellite dwarf galaxies in a hierarchical universe: the prevalence of dwarf-dwarf major mergers

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

Deason, Alis; Wetzel, Andrew; Garrison-Kimmel, Shea, E-mail: alis@ucolick.org

Mergers are a common phenomenon in hierarchical structure formation, especially for massive galaxies and clusters, but their importance for dwarf galaxies in the Local Group remains poorly understood. We investigate the frequency of major mergers between dwarf galaxies in the Local Group using the ELVIS suite of cosmological zoom-in dissipationless simulations of Milky Way- and M31-like host halos. We find that ∼10% of satellite dwarf galaxies with M {sub star} > 10{sup 6} M {sub ☉} that are within the host virial radius experienced a major merger of stellar mass ratio closer than 0.1 since z = 1, with amore » lower fraction for lower mass dwarf galaxies. Recent merger remnants are biased toward larger radial distance and more recent virial infall times, because most recent mergers occurred shortly before crossing within the virial radius of the host halo. Satellite-satellite mergers also occur within the host halo after virial infall, catalyzed by the large fraction of dwarf galaxies that fell in as part of a group. The merger fraction doubles for dwarf galaxies outside of the host virial radius, so the most distant dwarf galaxies in the Local Group are the most likely to have experienced a recent major merger. We discuss the implications of these results on observable dwarf merger remnants, their star formation histories, the gas content of mergers, and massive black holes in dwarf galaxies.« less

Blowin' in the wind: both `negative' and `positive' feedback in an outflowing quasar at z~1.6

NASA Astrophysics Data System (ADS)

Cresci, Giovanni

2015-02-01

Quasar feedback in the form of powerful outflows is invoked as a key mechanism to quench star formation, preventing massive galaxies to over-grow and producing the red colors of ellipticals. On the other hand, some models are also requiring `positive' AGN feedback, inducing star formation in the host galaxy through enhanced gas pressure in the interstellar medium. However, finding observational evidence of the effects of both types of feedback is still one of the main challenges of extragalactic astronomy, as few observations of energetic and extended radiatively-driven winds are available. We present SINFONI near infrared integral field spectroscopy of XID2028, an obscured, radio-quiet z=1.59 QSO, in which we clearly resolve a fast (1500 km/s) and extended (up to 13 kpc from the black hole) outflow in the [OIII] lines emitting gas, whose large velocity and outflow rate are not sustainable by star formation only. The narrow component of Hα emission and the rest frame U band flux show that the outflow position lies in the center of an empty cavity surrounded by star forming regions on its edge. The outflow is therefore removing the gas from the host galaxy (`negative feedback'), but also triggering star formation by outflow induced pressure at the edges (`positive feedback'). XID2028 represents the first example of a host galaxy showing both types of feedback simultaneously at work.

Redshift determination of the BL Lac object 3C 66A by the detection of its host galaxy cluster at z = 0.340

NASA Astrophysics Data System (ADS)

Torres-Zafra, Juanita; Cellone, Sergio A.; Buzzoni, Alberto; Andruchow, Ileana; Portilla, José G.

2018-03-01

The BL Lac object 3C 66A is one of the most luminous extragalactic sources at TeV γ-rays (very high energy, i.e. E > 100 GeV). Since TeV γ-ray radiation is absorbed by the extragalactic background light (EBL), it is crucial to know the redshift of the source in order to reconstruct its original spectral energy distribution, as well as to constrain EBL models. However, the optical spectrum of this BL Lac is almost featureless, so a direct measurement of z is very difficult; in fact, the published redshift value for this source (z = 0.444) has been strongly questioned. Based on EBL absorption arguments, several constraints to its redshift, in the range 0.096 < z < 0.5, were proposed. Since these active galactic nuclei (AGNs) are hosted, typically, in early-type galaxies that are members of groups or clusters, we have analysed spectro-photometrically the environment of 3C 66A, with the goal of finding the galaxy group hosting this blazar. This study was made using optical images of a 5.5 × 5.5 arcmin2 field centred on the blazar, and spectra of 24 sources obtained with Gemini/GMOS-N multi-object spectroscopy. We found spectroscopic evidence of two galaxy groups along the blazar's line of sight: one at z ≃ 0.020 and the second one at z ≃ 0.340. The first one is consistent with a known foreground structure, while the second group presented here has six spectroscopically confirmed members. Their location along a red sequence in the colour-magnitude diagram allows us to identify 34 additional candidate members of the more distant group. The blazar's spectrum shows broad absorption features that we identify as arising in the intergalactic medium, thus allowing us to tentatively set a redshift lower limit at z_3C66A ≳ 0.33. As a consequence, we propose that 3C 66A is hosted in a galaxy that belongs to a cluster at z = 0.340.