First direct comparison of high and low ionization line kinematics in active galactic nuclei

NASA Technical Reports Server (NTRS)

Sulentic, J. W.; Marziani, P.; Dultzin-Hacyan, D.; Calvani, M.; Moles, M.

1995-01-01

We present first results of a comparison of emission line shift properties for the high (HILs) and low (LILs) ionization lines in 43 low-reshift quasars. We identify a core sample of C IV lambda 1549 and hydrogen beta profiles with a wide distribution of red- and blueshifts (less than or equal to +/- 1000 km/sec). We also identify two tails in this distribution: one with large hydrogen beta redshifts (greater than or equal to 2000 km/sec) and another with large C IV blueshifts (greater than or equal to 1500 km/sec). The tails are mutually exclusive. All objects with extreme hydrogen beta redshift are radio loud, and all objects with extreme C IV blueshift are radio quiet. The core samples of smaller shifts can be most simply divided into: (1) hydrogen beta - a redshifted radio-loud population (related to the tail) and a radio-quiet population with mean shift near zero, and (2) C IV - a blueshifted radio-quiet population (related to the tail) and a radio-loud population with mean shift near zero. The results suggest fundamentally different kinematics for the HILs and LILs. They also suggest very different kinematics for radio-loud and radio-quiet active galactic nuclei. They also favor a predominance of radial motion in a large fraction of the sample.

Tracing Large-Scale Structure with Radio Sources

NASA Astrophysics Data System (ADS)

Lindsay, S. N.

2015-02-01

In this thesis, I investigate the spatial distribution of radio sources, and quantify their clustering strength over a range of redshifts, up to z _ 2:2, using various forms of the correlation function measured with data from several multi-wavelength surveys. I present the optical spectra of 30 radio AGN (S1:4 > 100 mJy) in the GAMA/H-ATLAS fields, for which emission line redshifts could be deduced, from observations of 79 target sources with the EFOSC2 spectrograph on the NTT. The mean redshift of these sources is z = 1:2; 12 were identified as quasars (40 per cent), and 6 redshifts (out of 24 targets) were found for AGN hosts to multiple radio components. While obtaining spectra for hosts of these multi-component sources is possible, their lower success rate highlights the difficulty in acheiving a redshift-complete radio sample. Taking an existing spectroscopic redshift survey (GAMA) and radio sources from the FIRST survey (S1:4 > 1 mJy), I then present a cross-matched radio sample with 1,635 spectroscopic redshifts with a median value of z = 0:34. The spatial correlation function of this sample is used to find the redshiftspace (s0) and real-space correlation lengths (r0 _ 8:2 h Mpc), and a mass bias of _1.9. Insight into the redshift-dependence of these quantities is gained by using the angular correlation function and Limber inversion to measure the same spatial clustering parameters. Photometric redshifts! from SDSS/UKIDSS are incorporated to produce a larger matched radio sample at z ' 0:48 (and low- and high-redshift subsamples at z ' 0:30 and z ' 0:65), while their redshift distribution is subtracted from that taken from the SKADS radio simulations to estimate the redshift distribution of the remaining unmatched sources (z ' 1:55). The observed bias evolution over this redshift range is compared with model predictions based on the SKADS simulations, with good agreement at low redshift. The bias found at high redshift significantly exceeds these predictions, however, suggesting a more massive population of galaxies than expected, either due to the relative proportions of different radio sources, or a greater typical halo mass for the high-redshift sources. Finally, the reliance on a model redshift distribution to reach to higher redshifts is removed, as the angular cross-correlation function is used with deep VLA data (S1:4 > 90 _Jy) and optical/IR data from VIDEO/CFHTLS (Ks < 23:5) over 1 square degree. With high-quality photometric redshifts up to z _ 4, and a high signal-to-noise clustering measurement (due to the _100,000 Ks-selected galaxies), I am able to find the bias of a matched sample of only 766 radio sources (as well as of v vi the VIDEO sources), divided into 4 redshift bins reaching a median bias at z ' 2:15. Again, at high redshift, the measured bias appears to exceed the prediction made from the SKADS simulations. Applying luminosity cuts to the radio sample at L > 1023 WHz and higher (removing any non-AGN sources), I find a bias of 8-10 at z _ 1:5, considerably higher than for the full sample, and consistent with the more numerous FRI AGN having similar mass to the FRIIs (M _ 10^14 M_), contrary to the assumptions made in the SKADS simulations. Applying this adjustment to the model bias produces a better fit to the observations for the FIRST radio sources cross-matched with GAMA/SDSS/UKIDSS, as well as for the high-redshift radio sources in VIDEO. Therefore, I have shown that we require a more robust model of the evolution of AGN, and their relation to the underlying dark matter distribution. In particular, understanding these quantities for the abundant FRI population is crucial if we are to use such sources to probe the cosmological model as has been suggested by a number of authors (e.g. Raccanelli et al., 2012; Camera et al., 2012; Ferramacho et al., 2014).

Statistical tests of peaks and periodicities in the observed redshift distribution of quasi-stellar objects

NASA Astrophysics Data System (ADS)

Duari, Debiprosad; Gupta, Patrick D.; Narlikar, Jayant V.

1992-01-01

An overview of statistical tests of peaks and periodicities in the redshift distribution of quasi-stellar objects is presented. The tests include the power-spectrum analysis carried out by Burbidge and O'Dell (1972), the generalized Rayleigh test, the Kolmogorov-Smirnov test, and the 'comb-tooth' test. The tests reveal moderate to strong evidence for periodicities of 0.0565 and 0.0127-0.0129. The confidence level of the periodicity of 0.0565 in fact marginally increases when redshifts are transformed to the Galactocentric frame. The same periodicity, first noticed in 1968, persists to date with a QSO population that has since grown about 30 times its original size. The prima facie evidence for periodicities in 1n(1 + z) is found to be of no great significance.

Dark Energy Survey Year 1 Results: redshift distributions of the weak-lensing source galaxies

NASA Astrophysics Data System (ADS)

Hoyle, B.; Gruen, D.; Bernstein, G. M.; Rau, M. M.; De Vicente, J.; Hartley, W. G.; Gaztanaga, E.; DeRose, J.; Troxel, M. A.; Davis, C.; Alarcon, A.; MacCrann, N.; Prat, J.; Sánchez, C.; Sheldon, E.; Wechsler, R. H.; Asorey, J.; Becker, M. R.; Bonnett, C.; Carnero Rosell, A.; Carollo, D.; Carrasco Kind, M.; Castander, F. J.; Cawthon, R.; Chang, C.; Childress, M.; Davis, T. M.; Drlica-Wagner, A.; Gatti, M.; Glazebrook, K.; Gschwend, J.; Hinton, S. R.; Hoormann, J. K.; Kim, A. G.; King, A.; Kuehn, K.; Lewis, G.; Lidman, C.; Lin, H.; Macaulay, E.; Maia, M. A. G.; Martini, P.; Mudd, D.; Möller, A.; Nichol, R. C.; Ogando, R. L. C.; Rollins, R. P.; Roodman, A.; Ross, A. J.; Rozo, E.; Rykoff, E. S.; Samuroff, S.; Sevilla-Noarbe, I.; Sharp, R.; Sommer, N. E.; Tucker, B. E.; Uddin, S. A.; Varga, T. N.; Vielzeuf, P.; Yuan, F.; Zhang, B.; Abbott, T. M. C.; Abdalla, F. B.; Allam, S.; Annis, J.; Bechtol, K.; Benoit-Lévy, A.; Bertin, E.; Brooks, D.; Buckley-Geer, E.; Burke, D. L.; Busha, M. T.; Capozzi, D.; Carretero, J.; Crocce, M.; D'Andrea, C. B.; da Costa, L. N.; DePoy, D. L.; Desai, S.; Diehl, H. T.; Doel, P.; Eifler, T. F.; Estrada, J.; Evrard, A. E.; Fernandez, E.; Flaugher, B.; Fosalba, P.; Frieman, J.; García-Bellido, J.; Gerdes, D. W.; Giannantonio, T.; Goldstein, D. A.; Gruendl, R. A.; Gutierrez, G.; Honscheid, K.; James, D. J.; Jarvis, M.; Jeltema, T.; Johnson, M. W. G.; Johnson, M. D.; Kirk, D.; Krause, E.; Kuhlmann, S.; Kuropatkin, N.; Lahav, O.; Li, T. S.; Lima, M.; March, M.; Marshall, J. L.; Melchior, P.; Menanteau, F.; Miquel, R.; Nord, B.; O'Neill, C. R.; Plazas, A. A.; Romer, A. K.; Sako, M.; Sanchez, E.; Santiago, B.; Scarpine, V.; Schindler, R.; Schubnell, M.; Smith, M.; Smith, R. C.; Soares-Santos, M.; Sobreira, F.; Suchyta, E.; Swanson, M. E. C.; Tarle, G.; Thomas, D.; Tucker, D. L.; Vikram, V.; Walker, A. R.; Weller, J.; Wester, W.; Wolf, R. C.; Yanny, B.; Zuntz, J.

2018-07-01

We describe the derivation and validation of redshift distribution estimates and their uncertainties for the populations of galaxies used as weak-lensing sources in the Dark Energy Survey (DES) Year 1 cosmological analyses. The Bayesian Photometric Redshift (BPZ) code is used to assign galaxies to four redshift bins between z ≈ 0.2 and ≈1.3, and to produce initial estimates of the lensing-weighted redshift distributions n^i_PZ(z)∝ dn^i/dz for members of bin i. Accurate determination of cosmological parameters depends critically on knowledge of ni, but is insensitive to bin assignments or redshift errors for individual galaxies. The cosmological analyses allow for shifts n^i(z)=n^i_PZ(z-Δ z^i) to correct the mean redshift of ni(z) for biases in n^i_PZ. The Δzi are constrained by comparison of independently estimated 30-band photometric redshifts of galaxies in the Cosmic Evolution Survey (COSMOS) field to BPZ estimates made from the DES griz fluxes, for a sample matched in fluxes, pre-seeing size, and lensing weight to the DES weak-lensing sources. In companion papers, the Δzi of the three lowest redshift bins are further constrained by the angular clustering of the source galaxies around red galaxies with secure photometric redshifts at 0.15 < z < 0.9. This paper details the BPZ and COSMOS procedures, and demonstrates that the cosmological inference is insensitive to details of the ni(z) beyond the choice of Δzi. The clustering and COSMOS validation methods produce consistent estimates of Δzi in the bins where both can be applied, with combined uncertainties of σ_{Δ z^i}=0.015, 0.013, 0.011, and 0.022 in the four bins. Repeating the photo-z procedure instead using the Directional Neighbourhood Fitting algorithm, or using the ni(z) estimated from the matched sample in COSMOS, yields no discernible difference in cosmological inferences.

Dark Energy Survey Year 1 Results: Redshift distributions of the weak lensing source galaxies

NASA Astrophysics Data System (ADS)

Hoyle, B.; Gruen, D.; Bernstein, G. M.; Rau, M. M.; De Vicente, J.; Hartley, W. G.; Gaztanaga, E.; DeRose, J.; Troxel, M. A.; Davis, C.; Alarcon, A.; MacCrann, N.; Prat, J.; Sánchez, C.; Sheldon, E.; Wechsler, R. H.; Asorey, J.; Becker, M. R.; Bonnett, C.; Carnero Rosell, A.; Carollo, D.; Carrasco Kind, M.; Castander, F. J.; Cawthon, R.; Chang, C.; Childress, M.; Davis, T. M.; Drlica-Wagner, A.; Gatti, M.; Glazebrook, K.; Gschwend, J.; Hinton, S. R.; Hoormann, J. K.; Kim, A. G.; King, A.; Kuehn, K.; Lewis, G.; Lidman, C.; Lin, H.; Macaulay, E.; Maia, M. A. G.; Martini, P.; Mudd, D.; Möller, A.; Nichol, R. C.; Ogando, R. L. C.; Rollins, R. P.; Roodman, A.; Ross, A. J.; Rozo, E.; Rykoff, E. S.; Samuroff, S.; Sevilla-Noarbe, I.; Sharp, R.; Sommer, N. E.; Tucker, B. E.; Uddin, S. A.; Varga, T. N.; Vielzeuf, P.; Yuan, F.; Zhang, B.; Abbott, T. M. C.; Abdalla, F. B.; Allam, S.; Annis, J.; Bechtol, K.; Benoit-Lévy, A.; Bertin, E.; Brooks, D.; Buckley-Geer, E.; Burke, D. L.; Busha, M. T.; Capozzi, D.; Carretero, J.; Crocce, M.; D'Andrea, C. B.; da Costa, L. N.; DePoy, D. L.; Desai, S.; Diehl, H. T.; Doel, P.; Eifler, T. F.; Estrada, J.; Evrard, A. E.; Fernandez, E.; Flaugher, B.; Fosalba, P.; Frieman, J.; García-Bellido, J.; Gerdes, D. W.; Giannantonio, T.; Goldstein, D. A.; Gruendl, R. A.; Gutierrez, G.; Honscheid, K.; James, D. J.; Jarvis, M.; Jeltema, T.; Johnson, M. W. G.; Johnson, M. D.; Kirk, D.; Krause, E.; Kuhlmann, S.; Kuropatkin, N.; Lahav, O.; Li, T. S.; Lima, M.; March, M.; Marshall, J. L.; Melchior, P.; Menanteau, F.; Miquel, R.; Nord, B.; O'Neill, C. R.; Plazas, A. A.; Romer, A. K.; Sako, M.; Sanchez, E.; Santiago, B.; Scarpine, V.; Schindler, R.; Schubnell, M.; Smith, M.; Smith, R. C.; Soares-Santos, M.; Sobreira, F.; Suchyta, E.; Swanson, M. E. C.; Tarle, G.; Thomas, D.; Tucker, D. L.; Vikram, V.; Walker, A. R.; Weller, J.; Wester, W.; Wolf, R. C.; Yanny, B.; Zuntz, J.; DES Collaboration

2018-04-01

We describe the derivation and validation of redshift distribution estimates and their uncertainties for the populations of galaxies used as weak lensing sources in the Dark Energy Survey (DES) Year 1 cosmological analyses. The Bayesian Photometric Redshift (BPZ) code is used to assign galaxies to four redshift bins between z ≈ 0.2 and ≈1.3, and to produce initial estimates of the lensing-weighted redshift distributions n^i_PZ(z)∝ dn^i/dz for members of bin i. Accurate determination of cosmological parameters depends critically on knowledge of ni but is insensitive to bin assignments or redshift errors for individual galaxies. The cosmological analyses allow for shifts n^i(z)=n^i_PZ(z-Δ z^i) to correct the mean redshift of ni(z) for biases in n^i_PZ. The Δzi are constrained by comparison of independently estimated 30-band photometric redshifts of galaxies in the COSMOS field to BPZ estimates made from the DES griz fluxes, for a sample matched in fluxes, pre-seeing size, and lensing weight to the DES weak-lensing sources. In companion papers, the Δzi of the three lowest redshift bins are further constrained by the angular clustering of the source galaxies around red galaxies with secure photometric redshifts at 0.15 < z < 0.9. This paper details the BPZ and COSMOS procedures, and demonstrates that the cosmological inference is insensitive to details of the ni(z) beyond the choice of Δzi. The clustering and COSMOS validation methods produce consistent estimates of Δzi in the bins where both can be applied, with combined uncertainties of σ _{Δ z^i}=0.015, 0.013, 0.011, and 0.022 in the four bins. Repeating the photo-z proceedure instead using the Directional Neighborhood Fitting (DNF) algorithm, or using the ni(z) estimated from the matched sample in COSMOS, yields no discernible difference in cosmological inferences.

Improving Photometric Redshifts for Hyper Suprime-Cam

NASA Astrophysics Data System (ADS)

Speagle, Josh S.; Leauthaud, Alexie; Eisenstein, Daniel; Bundy, Kevin; Capak, Peter L.; Leistedt, Boris; Masters, Daniel C.; Mortlock, Daniel; Peiris, Hiranya; HSC Photo-z Team; HSC Weak Lensing Team

2017-01-01

Deriving accurate photometric redshift (photo-z) probability distribution functions (PDFs) are crucial science components for current and upcoming large-scale surveys. We outline how rigorous Bayesian inference and machine learning can be combined to quickly derive joint photo-z PDFs to individual galaxies and their parent populations. Using the first 170 deg^2 of data from the ongoing Hyper Suprime-Cam survey, we demonstrate our method is able to generate accurate predictions and reliable credible intervals over ~370k high-quality redshifts. We then use galaxy-galaxy lensing to empirically validate our predicted photo-z's over ~14M objects, finding a robust signal.

Photometric redshifts in the SWIRE Survey

NASA Astrophysics Data System (ADS)

Rowan-Robinson, Michael; Babbedge, Tom; Oliver, Seb; Trichas, Markos; Berta, Stefano; Lonsdale, Carol; Smith, Gene; Shupe, David; Surace, Jason; Arnouts, Stephane; Ilbert, Olivier; Le Févre, Olivier; Afonso-Luis, Alejandro; Perez-Fournon, Ismael; Hatziminaoglou, Evanthia; Polletta, Mari; Farrah, Duncan; Vaccari, Mattia

2008-05-01

We present the SWIRE Photometric Redshift Catalogue 1025119 redshifts of unprecedented reliability and of accuracy comparable with or better than previous work. Our methodology is based on fixed galaxy and quasi-stellar object templates applied to data at 0.36-4.5 μm, and on a set of four infrared emission templates fitted to infrared excess data at 3.6-170 μm. The galaxy templates are initially empirical, but are given greater physical validity by fitting star formation histories to them, which also allows us to estimate stellar masses. The code involves two passes through the data, to try to optimize recognition of active galactic nucleus (AGN) dust tori. A few carefully justified priors are used and are the key to supression of outliers. Extinction, AV, is allowed as a free parameter. The full reduced χ2ν (z) distribution is given for each source, so the full error distribution can be used, and aliases investigated. We use a set of 5982 spectroscopic redshifts, taken from the literature and from our own spectroscopic surveys, to analyse the performance of our method as a function of the number of photometric bands used in the solution and the reduced χ2ν. For seven photometric bands (5 optical + 3.6, 4.5 μm), the rms value of (zphot - zspec)/(1 + zspec) is 3.5 per cent, and the percentage of catastrophic outliers [defined as >15 per cent error in (1 + z)], is ~1 per cent. These rms values are comparable with the best achieved in other studies, and the outlier fraction is significantly better. The inclusion of the 3.6- and 4.5-μm IRAC bands is crucial in supression of outliers. We discuss the redshift distributions at 3.6 and 24 μm. In individual fields, structure in the redshift distribution corresponds to clusters which can be seen in the spectroscopic redshift distribution, so the photometric redshifts are a powerful tool for large-scale structure studies. 10 per cent of sources in the SWIRE photometric redshift catalogue have z > 2, and 4 per cent have z > 3, so this catalogue is a huge resource for high-redshift galaxies. A key parameter for understanding the evolutionary status of infrared galaxies is Lir/Lopt. For cirrus galaxies this is a measure of the mean extinction in the interstellar medium of the galaxy. There is a population of ultraluminous galaxies with cool dust and we have shown SEDs for some of the reliable examples. For starbursts, we estimate the specific star formation rate, φ*/M*. Although the very highest values of this ratio tend to be associated with Arp220 starbursts, by no means all ultraluminous galaxies are. We discuss an interesting population of galaxies with elliptical-like spectral energy distributions in the optical and luminous starbursts in the infrared. For dust tori around type 1 AGN, Ltor/Lopt is a measure of the torus covering factor and we deduce a mean covering factor of 40 per cent. Our infrared templates also allow us to estimate dust masses for all galaxies with an infrared excess.

Calibrating photometric redshifts of luminous red galaxies

DOE PAGES

Padmanabhan, Nikhil; Budavari, Tamas; Schlegel, David J.; ...

2005-05-01

We discuss the construction of a photometric redshift catalogue of luminous red galaxies (LRGs) from the Sloan Digital Sky Survey (SDSS), emphasizing the principal steps necessary for constructing such a catalogue: (i) photometrically selecting the sample, (ii) measuring photometric redshifts and their error distributions, and (iii) estimating the true redshift distribution. We compare two photometric redshift algorithms for these data and find that they give comparable results. Calibrating against the SDSS and SDSS–2dF (Two Degree Field) spectroscopic surveys, we find that the photometric redshift accuracy is σ~ 0.03 for redshifts less than 0.55 and worsens at higher redshift (~ 0.06more » for z < 0.7). These errors are caused by photometric scatter, as well as systematic errors in the templates, filter curves and photometric zero-points. We also parametrize the photometric redshift error distribution with a sum of Gaussians and use this model to deconvolve the errors from the measured photometric redshift distribution to estimate the true redshift distribution. We pay special attention to the stability of this deconvolution, regularizing the method with a prior on the smoothness of the true redshift distribution. The methods that we develop are applicable to general photometric redshift surveys.« less

The TexOx-1000 redshift survey of radio sources I: the TOOT00 region

NASA Astrophysics Data System (ADS)

Vardoulaki, Eleni; Rawlings, Steve; Hill, Gary J.; Mauch, Tom; Inskip, Katherine J.; Riley, Julia; Brand, Kate; Croft, Steve; Willott, Chris J.

2010-01-01

We present optical spectroscopy, near-infrared (mostly K-band) and radio (151-MHz and 1.4-GHz) imaging of the first complete region (TOOT00) of the TexOx-1000 (TOOT) redshift survey of radio sources. The 0.0015-sr (~5 deg2) TOOT00 region is selected from pointed observations of the Cambridge Low-Frequency Survey Telescope at 151 MHz at a flux density limit of ~=100 mJy, approximately five times fainter than the 7C Redshift Survey (7CRS), and contains 47 radio sources. We have obtained 40 spectroscopic redshifts (~85 per cent completeness). Adding redshifts estimated for the seven other cases yields a median redshift zmed ~ 1.25. We find a significant population of objects with Fanaroff-Riley type I (FRI) like radio structures at radio luminosities above both the low-redshift FRI/II break and the break in the radio luminosity function. The redshift distribution and subpopulations of TOOT00 are broadly consistent with extrapolations from the 7CRS/6CE/3CRR data sets underlying the SKADS Simulated Skies Semi-Empirical Extragalactic Data base, S3-SEX.

Clustering redshift distributions for the Dark Energy Survey

NASA Astrophysics Data System (ADS)

Helsby, Jennifer

Accurate determination of photometric redshifts and their errors is critical for large scale structure and weak lensing studies for constraining cosmology from deep, wide imaging surveys. Current photometric redshift methods suffer from bias and scatter due to incomplete training sets. Exploiting the clustering between a sample of galaxies for which we have spectroscopic redshifts and a sample of galaxies for which the redshifts are unknown can allow us to reconstruct the true redshift distribution of the unknown sample. Here we use this method in both simulations and early data from the Dark Energy Survey (DES) to determine the true redshift distributions of galaxies in photometric redshift bins. We find that cross-correlating with the spectroscopic samples currently used for training provides a useful test of photometric redshifts and provides reliable estimates of the true redshift distribution in a photometric redshift bin. We discuss the use of the cross-correlation method in validating template- or learning-based approaches to redshift estimation and its future use in Stage IV surveys.

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.;

Distributions of Gas and Galaxies from Galaxy Clusters to Larger Scales

NASA Astrophysics Data System (ADS)

Patej, Anna

2017-01-01

We address the distributions of gas and galaxies on three scales: the outskirts of galaxy clusters, the clustering of galaxies on large scales, and the extremes of the galaxy distribution. In the outskirts of galaxy clusters, long-standing analytical models of structure formation and recent simulations predict the existence of density jumps in the gas and dark matter profiles. We use these features to derive models for the gas density profile, obtaining a simple fiducial model that is in agreement with both observations of cluster interiors and simulations of the outskirts. We next consider the galaxy density profiles of clusters; under the assumption that the galaxies in cluster outskirts follow similar collisionless dynamics as the dark matter, their distribution should show a steep jump as well. We examine the profiles of a low-redshift sample of clusters and groups, finding evidence for the jump in some of these clusters. Moving to larger scales where massive galaxies of different types are expected to trace the same large-scale structure, we present a test of this prediction by measuring the clustering of red and blue galaxies at z 0.6, finding low stochasticity between the two populations. These results address a key source of systematic uncertainty - understanding how target populations of galaxies trace large-scale structure - in galaxy redshift surveys. Such surveys use baryon acoustic oscillations (BAO) as a cosmological probe, but are limited by the expense of obtaining sufficiently dense spectroscopy. With the intention of leveraging upcoming deep imaging data, we develop a new method of detecting the BAO in sparse spectroscopic samples via cross-correlation with a dense photometric catalog. This method will permit the extension of BAO measurements to higher redshifts than possible with the existing spectroscopy alone. Lastly, we connect galaxies near and far: the Local Group dwarfs and the high redshift galaxies observed by Hubble and Spitzer. We examine how the local dwarfs may have appeared in the past and compare their properties to the detection limits of the upcoming James Webb Space Telescope (JWST), finding that JWST should be able to detect galaxies similar to the progenitors of a few of the brightest of the local galaxies, revealing a hitherto unobserved population of galaxies at high redshifts.

The redshift distribution of cosmological samples: a forward modeling approach

NASA Astrophysics Data System (ADS)

Herbel, Jörg; Kacprzak, Tomasz; Amara, Adam; Refregier, Alexandre; Bruderer, Claudio; Nicola, Andrina

2017-08-01

Determining the redshift distribution n(z) of galaxy samples is essential for several cosmological probes including weak lensing. For imaging surveys, this is usually done using photometric redshifts estimated on an object-by-object basis. We present a new approach for directly measuring the global n(z) of cosmological galaxy samples, including uncertainties, using forward modeling. Our method relies on image simulations produced using \\textsc{UFig} (Ultra Fast Image Generator) and on ABC (Approximate Bayesian Computation) within the MCCL (Monte-Carlo Control Loops) framework. The galaxy population is modeled using parametric forms for the luminosity functions, spectral energy distributions, sizes and radial profiles of both blue and red galaxies. We apply exactly the same analysis to the real data and to the simulated images, which also include instrumental and observational effects. By adjusting the parameters of the simulations, we derive a set of acceptable models that are statistically consistent with the data. We then apply the same cuts to the simulations that were used to construct the target galaxy sample in the real data. The redshifts of the galaxies in the resulting simulated samples yield a set of n(z) distributions for the acceptable models. We demonstrate the method by determining n(z) for a cosmic shear like galaxy sample from the 4-band Subaru Suprime-Cam data in the COSMOS field. We also complement this imaging data with a spectroscopic calibration sample from the VVDS survey. We compare our resulting posterior n(z) distributions to the one derived from photometric redshifts estimated using 36 photometric bands in COSMOS and find good agreement. This offers good prospects for applying our approach to current and future large imaging surveys.

The redshift distribution of cosmological samples: a forward modeling approach

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

Herbel, Jörg; Kacprzak, Tomasz; Amara, Adam

Determining the redshift distribution n ( z ) of galaxy samples is essential for several cosmological probes including weak lensing. For imaging surveys, this is usually done using photometric redshifts estimated on an object-by-object basis. We present a new approach for directly measuring the global n ( z ) of cosmological galaxy samples, including uncertainties, using forward modeling. Our method relies on image simulations produced using \\textsc(UFig) (Ultra Fast Image Generator) and on ABC (Approximate Bayesian Computation) within the MCCL (Monte-Carlo Control Loops) framework. The galaxy population is modeled using parametric forms for the luminosity functions, spectral energy distributions, sizesmore » and radial profiles of both blue and red galaxies. We apply exactly the same analysis to the real data and to the simulated images, which also include instrumental and observational effects. By adjusting the parameters of the simulations, we derive a set of acceptable models that are statistically consistent with the data. We then apply the same cuts to the simulations that were used to construct the target galaxy sample in the real data. The redshifts of the galaxies in the resulting simulated samples yield a set of n ( z ) distributions for the acceptable models. We demonstrate the method by determining n ( z ) for a cosmic shear like galaxy sample from the 4-band Subaru Suprime-Cam data in the COSMOS field. We also complement this imaging data with a spectroscopic calibration sample from the VVDS survey. We compare our resulting posterior n ( z ) distributions to the one derived from photometric redshifts estimated using 36 photometric bands in COSMOS and find good agreement. This offers good prospects for applying our approach to current and future large imaging surveys.« less

The Halo Occupation Distribution of Active Galactic Nuclei

NASA Astrophysics Data System (ADS)

Chatterjee, Suchetana; Nagai, D.; Richardson, J.; Zheng, Z.; Degraf, C.; DiMatteo, T.

2011-05-01

We investigate the halo occupation distribution of active galactic nuclei (AGN) using a state-of-the-art cosmological hydrodynamic simulation that self-consistently incorporates the growth and feedback of supermassive black holes and the physics of galaxy formation (DiMatteo et al. 2008). We show that the mean occupation function can be modeled as a softened step function for central AGN and a power law for the satellite population. The satellite occupation is consistent with weak redshift evolution and a power law index of unity. The number of satellite black holes at a given halo mass follows a Poisson distribution. We show that at low redshifts (z=1.0) feedback from AGN is responsible for higher suppression of black hole growth in higher mass halos. This effect introduces a bias in the correlation between instantaneous AGN luminosity and the host halo mass, making AGN clustering depend weakly on luminosity at low redshifts. We show that the radial distribution of AGN follows a power law which is fundamentally different from those of galaxies and dark matter. The best-fit power law index is -2.26 ± 0.23. The power law exponent do not show any evolution with redshift, host halo mass and AGN luminosity within statistical limits. Incorporating the environmental dependence of supermassive black hole accretion and feedback, our formalism provides the most complete theoretical tool for interpreting current and future measurements of AGN clustering.

THE REDSHIFT DISTRIBUTION OF DUSTY STAR-FORMING GALAXIES FROM THE SPT SURVEY

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

Strandet, M. L.; Weiss, A.; Vieira, J. D.

2016-05-10

We use the Atacama Large Millimeter/submillimeter Array (ALMA) in Cycle 1 to determine spectroscopic redshifts of high-redshift dusty star-forming galaxies (DSFGs) selected by their 1.4 mm continuum emission in the South Pole Telescope (SPT) survey. We present ALMA 3 mm spectral scans between 84 and 114 GHz for 15 galaxies and targeted ALMA 1 mm observations for an additional eight sources. Our observations yield 30 new line detections from CO, [C i], [N ii], H{sub 2}O and NH{sub 3}. We further present Atacama Pathfinder Experiment [C ii] and CO mid- J observations for seven sources for which only a singlemore » line was detected in spectral-scan data from ALMA Cycle 0 or Cycle 1. We combine the new observations with previously published and new millimeter/submillimeter line and photometric data of the SPT-selected DSFGs to study their redshift distribution. The combined data yield 39 spectroscopic redshifts from molecular lines, a success rate of >85%. Our sample represents the largest data set of its kind today and has the highest spectroscopic completeness among all redshift surveys of high- z DSFGs. The median of the redshift distribution is z = 3.9 ± 0.4, and the highest-redshift source in our sample is at z = 5.8. We discuss how the selection of our sources affects the redshift distribution, focusing on source brightness, selection wavelength, and strong gravitational lensing. We correct for the effect of gravitational lensing and find the redshift distribution for 1.4 mm selected sources with a median redshift of z = 3.1 ± 0.3. Comparing to redshift distributions selected at shorter wavelengths from the literature, we show that selection wavelength affects the shape of the redshift distribution.« less

The Redshift Distribution of Dusty Star-forming Galaxies from the SPT Survey

NASA Astrophysics Data System (ADS)

Strandet, M. L.; Weiss, A.; Vieira, J. D.; de Breuck, C.; Aguirre, J. E.; Aravena, M.; Ashby, M. L. N.; Béthermin, M.; Bradford, C. M.; Carlstrom, J. E.; Chapman, S. C.; Crawford, T. M.; Everett, W.; Fassnacht, C. D.; Furstenau, R. M.; Gonzalez, A. H.; Greve, T. R.; Gullberg, B.; Hezaveh, Y.; Kamenetzky, J. R.; Litke, K.; Ma, J.; Malkan, M.; Marrone, D. P.; Menten, K. M.; Murphy, E. J.; Nadolski, A.; Rotermund, K. M.; Spilker, J. S.; Stark, A. A.; Welikala, N.

2016-05-01

We use the Atacama Large Millimeter/submillimeter Array (ALMA) in Cycle 1 to determine spectroscopic redshifts of high-redshift dusty star-forming galaxies (DSFGs) selected by their 1.4 mm continuum emission in the South Pole Telescope (SPT) survey. We present ALMA 3 mm spectral scans between 84 and 114 GHz for 15 galaxies and targeted ALMA 1 mm observations for an additional eight sources. Our observations yield 30 new line detections from CO, [C I], [N II], H2O and NH3. We further present Atacama Pathfinder Experiment [C II] and CO mid-J observations for seven sources for which only a single line was detected in spectral-scan data from ALMA Cycle 0 or Cycle 1. We combine the new observations with previously published and new millimeter/submillimeter line and photometric data of the SPT-selected DSFGs to study their redshift distribution. The combined data yield 39 spectroscopic redshifts from molecular lines, a success rate of >85%. Our sample represents the largest data set of its kind today and has the highest spectroscopic completeness among all redshift surveys of high-z DSFGs. The median of the redshift distribution is z = 3.9 ± 0.4, and the highest-redshift source in our sample is at z = 5.8. We discuss how the selection of our sources affects the redshift distribution, focusing on source brightness, selection wavelength, and strong gravitational lensing. We correct for the effect of gravitational lensing and find the redshift distribution for 1.4 mm selected sources with a median redshift of z = 3.1 ± 0.3. Comparing to redshift distributions selected at shorter wavelengths from the literature, we show that selection wavelength affects the shape of the redshift distribution.

THE EVOLUTION OF EARLY- AND LATE-TYPE GALAXIES IN THE COSMIC EVOLUTION SURVEY UP TO z {approx} 1.2

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

Pannella, Maurilio; Gabasch, Armin; Drory, Niv

2009-08-10

The Cosmic Evolution Survey (COSMOS) allows for the first time a highly significant census of environments and structures up to redshift 1, as well as a full morphological description of the galaxy population. In this paper we present a study aimed to constrain the evolution, in the redshift range 0.2 < z < 1.2, of the mass content of different morphological types and its dependence on the environmental density. We use a deep multicolor catalog, covering an area of {approx}0.7 deg{sup 2} inside the COSMOS field, with accurate photometric redshifts (i {approx}< 26.5 and {delta}z/(z {sub spec} + 1) {approx}more » 0.035). We estimate galaxy stellar masses by fitting the multicolor photometry to a grid of composite stellar population models. We quantitatively describe the galaxy morphology by fitting point-spread function convolved Sersic profiles to the galaxy surface brightness distributions down to F814 = 24 mag for a sample of 41,300 objects. We confirm an evolution of the morphological mix with redshift: the higher the redshift the more disk-dominated galaxies become important. We find that the morphological mix is a function of the local comoving density: the morphology density relation extends up to the highest redshift explored. The stellar mass function of disk-dominated galaxies is consistent with being constant with redshift. Conversely, the stellar mass function of bulge-dominated systems shows a decline in normalization with redshift. Such different behaviors of late-types and early-types stellar mass functions naturally set the redshift evolution of the transition mass. We find a population of relatively massive, early-type galaxies, having high specific star formation rate (SSFR) and blue colors which live preferentially in low-density environments. The bulk of massive (>7 x 10{sup 10} M {sub sun}) early-type galaxies have similar characteristic ages, colors, and SSFRs independently of the environment they belong to, with those hosting the oldest stars in the universe preferentially belonging to the highest density regions. The whole catalog including morphological information and stellar mass estimates analyzed in this work is made publicly available.« less

The accelerated build-up of the red sequence in high-redshift galaxy clusters

NASA Astrophysics Data System (ADS)

Cerulo, P.; Couch, W. J.; Lidman, C.; Demarco, R.; Huertas-Company, M.; Mei, S.; Sánchez-Janssen, R.; Barrientos, L. F.; Muñoz, R. P.

2016-04-01

We analyse the evolution of the red sequence in a sample of galaxy clusters at redshifts 0.8 < z < 1.5 taken from the HAWK-I Cluster Survey (HCS). The comparison with the low-redshift (0.04 < z < 0.08) sample of the WIde-field Nearby Galaxy-cluster Survey (WINGS) and other literature results shows that the slope and intrinsic scatter of the cluster red sequence have undergone little evolution since z = 1.5. We find that the luminous-to-faint ratio and the slope of the faint end of the luminosity distribution of the HCS red sequence are consistent with those measured in WINGS, implying that there is no deficit of red galaxies at magnitudes fainter than M_V^{ast } at high redshifts. We find that the most massive HCS clusters host a population of bright red sequence galaxies at MV < -22.0 mag, which are not observed in low-mass clusters. Interestingly, we also note the presence of a population of very bright (MV < -23.0 mag) and massive (log (M*/M⊙) > 11.5) red sequence galaxies in the WINGS clusters, which do not include only the brightest cluster galaxies and which are not present in the HCS clusters, suggesting that they formed at epochs later than z = 0.8. The comparison with the luminosity distribution of a sample of passive red sequence galaxies drawn from the COSMOS/UltraVISTA field in the photometric redshift range 0.8 < zphot < 1.5 shows that the red sequence in clusters is more developed at the faint end, suggesting that halo mass plays an important role in setting the time-scales for the build-up of the red sequence.

2dFLenS and KiDS: determining source redshift distributions with cross-correlations

NASA Astrophysics Data System (ADS)

Johnson, Andrew; Blake, Chris; Amon, Alexandra; Erben, Thomas; Glazebrook, Karl; Harnois-Deraps, Joachim; Heymans, Catherine; Hildebrandt, Hendrik; Joudaki, Shahab; Klaes, Dominik; Kuijken, Konrad; Lidman, Chris; Marin, Felipe A.; McFarland, John; Morrison, Christopher B.; Parkinson, David; Poole, Gregory B.; Radovich, Mario; Wolf, Christian

2017-03-01

We develop a statistical estimator to infer the redshift probability distribution of a photometric sample of galaxies from its angular cross-correlation in redshift bins with an overlapping spectroscopic sample. This estimator is a minimum-variance weighted quadratic function of the data: a quadratic estimator. This extends and modifies the methodology presented by McQuinn & White. The derived source redshift distribution is degenerate with the source galaxy bias, which must be constrained via additional assumptions. We apply this estimator to constrain source galaxy redshift distributions in the Kilo-Degree imaging survey through cross-correlation with the spectroscopic 2-degree Field Lensing Survey, presenting results first as a binned step-wise distribution in the range z < 0.8, and then building a continuous distribution using a Gaussian process model. We demonstrate the robustness of our methodology using mock catalogues constructed from N-body simulations, and comparisons with other techniques for inferring the redshift distribution.

An AzTEC 1.1mm survey of the GOODS-N field - II. Multiwavelength identifications and redshift distribution

NASA Astrophysics Data System (ADS)

Chapin, Edward L.; Pope, Alexandra; Scott, Douglas; Aretxaga, Itziar; Austermann, Jason E.; Chary, Ranga-Ram; Coppin, Kristen; Halpern, Mark; Hughes, David H.; Lowenthal, James D.; Morrison, Glenn E.; Perera, Thushara A.; Scott, Kimberly S.; Wilson, Grant W.; Yun, Min S.

2009-10-01

We present results from a multiwavelength study of 29 sources (false detection probabilities <5 per cent) from a survey of the Great Observatories Origins Deep Survey-North (GOODS-N) field at 1.1mm using the Astronomical Thermal Emission Camera (AzTEC). Comparing with existing 850μm Submillimetre Common-User Bolometer Array (SCUBA) studies in the field, we examine differences in the source populations selected at the two wavelengths. The AzTEC observations uniformly cover the entire survey field to a 1σ depth of ~1mJy. Searching deep 1.4GHz Very Large Array (VLA) and Spitzer 3-24μm catalogues, we identify robust counterparts for 21 1.1mm sources, and tentative associations for the remaining objects. The redshift distribution of AzTEC sources is inferred from available spectroscopic and photometric redshifts. We find a median redshift of z = 2.7, somewhat higher than z = 2.0 for 850μm selected sources in the same field, and our lowest redshift identification lies at a spectroscopic redshift z = 1.1460. We measure the 850μm to 1.1mm colour of our sources and do not find evidence for `850μm dropouts', which can be explained by the low signal-to-noise ratio of the observations. We also combine these observed colours with spectroscopic redshifts to derive the range of dust temperatures T, and dust emissivity indices β for the sample, concluding that existing estimates T ~ 30K and β ~ 1.75 are consistent with these new data.

The mass function of black holes 1

NASA Astrophysics Data System (ADS)

Natarajan, Priyamvada; Volonteri, Marta

2012-05-01

In this paper, we compare the observationally derived black hole mass function (BHMF) of luminous (>1045-1046 erg s-1) broad-line quasars (BLQSOs) at 1 < z < 4.5 drawn from the Sloan Digital Sky Survey (SDSS) presented by Kelly et al., with models of merger-driven black hole (BH) growth in the context of standard hierarchical structure formation models. In these models, we explore two distinct black hole seeding prescriptions at the highest redshifts: 'light seeds'- remnants of Population III stars and 'massive seeds' that form from the direct collapse of pre-galactic discs. The subsequent merger triggered mass build-up of the black hole population is tracked over cosmic time under the assumption of a fixed accretion rate as well as rates drawn from the distribution derived by Merloni & Heinz. Four model snapshots at z= 1.25, 2, 3.25 and 4.25 are compared with the SDSS-derived BHMFs of BLQSOs. We find that the light seed models fall short of reproducing the observationally derived mass function of BLQSOs at MBH > 109 M⊙ throughout the redshift range; the massive seed models with a fixed accretion rate of 0.3 Edd, or with accretion rates drawn from the Merloni & Heinz distribution provide the best fit to the current observational data at z > 2, although they overestimate the high-mass end of the mass function at lower redshifts. At low redshifts, a drastic drop in the accretion rate is observed and this is explained as arising due to the diminished gas supply available due to consumption by star formation or changes in the geometry of the inner feeding regions. Therefore, the overestimate at the high-mass end of the black hole mass function for the massive seed models can be easily modified, as the accretion rate is likely significantly lower at these epochs than what we assume. For the Merloni & Heinz model, examining the Eddington ratio distributions fEdd, we find that they are almost uniformly sampled from fEdd= 10-2 to 1 at z≃ 1, while at high redshift, current observations suggest accretion rates close to Eddington, if not mildly super-Eddington, at least for these extremely luminous quasars. Our key findings are that the duty cycle of super-massive black holes powering BLQSOs increases with increasing redshift for all models and models with Population III remnants as black hole seeds are unable to fit the observationally derived BHMFs for BLQSOs, lending strong support for the massive seeding model.

The VIMOS Ultra Deep Survey first data release: Spectra and spectroscopic redshifts of 698 objects up to zspec 6 in CANDELS

NASA Astrophysics Data System (ADS)

Tasca, L. A. M.; Le Fèvre, O.; Ribeiro, B.; Thomas, R.; Moreau, C.; Cassata, P.; Garilli, B.; Le Brun, V.; Lemaux, B. C.; Maccagni, D.; Pentericci, L.; Schaerer, D.; Vanzella, E.; Zamorani, G.; Zucca, E.; Amorin, R.; Bardelli, S.; Cassarà, L. P.; Castellano, M.; Cimatti, A.; Cucciati, O.; Durkalec, A.; Fontana, A.; Giavalisco, M.; Grazian, A.; Hathi, N. P.; Ilbert, O.; Paltani, S.; Pforr, J.; Scodeggio, M.; Sommariva, V.; Talia, M.; Tresse, L.; Vergani, D.; Capak, P.; Charlot, S.; Contini, T.; de la Torre, S.; Dunlop, J.; Fotopoulou, S.; Guaita, L.; Koekemoer, A.; López-Sanjuan, C.; Mellier, Y.; Salvato, M.; Scoville, N.; Taniguchi, Y.; Wang, P. W.

2017-04-01

This paper describes the first data release (DR1) of the VIMOS Ultra Deep Survey (VUDS). The VUDS-DR1 is the release of all low-resolution spectroscopic data obtained in 276.9 arcmin2 of the CANDELS-COSMOS and CANDELS-ECDFS survey areas, including accurate spectroscopic redshifts zspec and individual spectra obtained with VIMOS on the ESO-VLT. A total of 698 objects have a measured redshift, with 677 galaxies, two type-I AGN, and a small number of 19 contaminating stars. The targets of the spectroscopic survey are selected primarily on the basis of their photometric redshifts to ensure a broad population coverage. About 500 galaxies have zspec > 2, 48of which have zspec > 4; the highest reliable redshifts reach beyond zspec = 6. This data set approximately doubles the number of galaxies with spectroscopic redshifts at z > 3 in these fields. We discuss the general properties of the VUDS-DR1 sample in terms of the spectroscopic redshift distribution, the distribution of Lyman-α equivalent widths, and physical properties including stellar masses M⋆ and star formation rates derived from spectral energy distribution fitting with the knowledge of zspec. We highlight the properties of the most massive star-forming galaxies, noting the wide range in spectral properties, with Lyman-α in emission or in absorption, and in imaging properties with compact, multi-component, or pair morphologies. We present the catalogue database and data products. All VUDS-DR1 data are publicly available and can be retrieved from a dedicated query-based database. Future VUDS data releases will follow this VUDS-DR1 to give access to the spectra and associated measurement of 8000 objects in the full 1 square degree of the VUDS survey. Based on data obtained with the European Southern Observatory Very Large Telescope, Paranal, Chile, under Large Program 185.A-0791. http://cesam.lam.fr/vuds

The Multiwavelength Survey by Yale-Chile (MUSYC): Deep Near-Infrared Imaging and the Selection of Distant Galaxies

NASA Astrophysics Data System (ADS)

Quadri, Ryan; Marchesini, Danilo; van Dokkum, Pieter; Gawiser, Eric; Franx, Marijn; Lira, Paulina; Rudnick, Gregory; Urry, C. Megan; Maza, José; Kriek, Mariska; Barrientos, L. Felipe; Blanc, Guillermo A.; Castander, Francisco J.; Christlein, Daniel; Coppi, Paolo S.; Hall, Patrick B.; Herrera, David; Infante, Leopoldo; Taylor, Edward N.; Treister, Ezequiel; Willis, Jon P.

2007-09-01

We present deep near-infrared JHK imaging of four 10' × 10' fields. The observations were carried out as part of the Multiwavelength Survey by Yale-Chile (MUSYC) with ISPI on the CTIO 4 m telescope. The typical point-source limiting depths are J ~ 22.5, H ~ 21.5, and K ~ 21 (5 σ Vega). The effective seeing in the final images is ~1.0″. We combine these data with MUSYC UBVRIz imaging to create K-selected catalogs that are unique for their uniform size, depth, filter coverage, and image quality. We investigate the rest-frame optical colors and photometric redshifts of galaxies that are selected using common color selection techniques, including distant red galaxies (DRGs), star-forming and passive BzKs, and the rest-frame UV-selected BM, BX, and Lyman break galaxies (LBGs). These techniques are effective at isolating large samples of high-redshift galaxies, but none provide complete or uniform samples across the targeted redshift ranges. The DRG and BM/BX/LBG criteria identify populations of red and blue galaxies, respectively, as they were designed to do. The star-forming BzKs have a very wide redshift distribution, extending down to z ~ 1, a wide range of colors, and may include galaxies with very low specific star formation rates. In comparison, the passive BzKs are fewer in number, have a different distribution of K magnitudes, and have a somewhat different redshift distribution. By combining either the DRG and BM/BX/LBG criteria, or the star-forming and passive BzK criteria, it appears possible to define a reasonably complete sample of galaxies to our flux limit over specific redshift ranges. However, the redshift dependence of both the completeness and sampled range of rest-frame colors poses an ultimate limit to the usefulness of these techniques.

THE STELLAR MASS FUNDAMENTAL PLANE AND COMPACT QUIESCENT GALAXIES AT z < 0.6

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

Zahid, H. Jabran; Damjanov, Ivana; Geller, Margaret J.

2016-04-20

We examine the evolution of the relation between stellar mass surface density, velocity dispersion, and half-light radius—the stellar mass fundamental plane (MFP)—for quiescent galaxies at z < 0.6. We measure the local relation from galaxies in the Sloan Digital Sky Survey and the intermediate redshift relation from ∼500 quiescent galaxies with stellar masses 10 ≲ log( M {sub *}/ M {sub ⊙}) ≲ 11.5. Nearly half of the quiescent galaxies in our intermediate redshift sample are compact. After accounting for important selection and systematic effects, the velocity dispersion distribution of galaxies at intermediate redshifts is similar to that of galaxiesmore » in the local universe. Galaxies at z < 0.6 appear to be smaller (≲0.1 dex) than galaxies in the local sample. The orientation of the stellar MFP is independent of redshift for massive quiescent galaxies at z < 0.6 and the zero-point evolves by ∼0.04 dex. Compact quiescent galaxies fall on the same relation as the extended objects. We confirm that compact quiescent galaxies are the tail of the size and mass distribution of the normal quiescent galaxy population.« less

Red nuggets grow inside-out: evidence from gravitational lensing

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

Oldham, Lindsay; Auger, Matthew W.; Fassnacht, Christopher D.

Here, we present a new sample of strong gravitational lens systems where both the foreground lenses and background sources are early-type galaxies. Using imaging from Hubble Space Telescope (HST)/Advanced Camera for Studies (ACS) and Keck/NIRC2, we model the surface brightness distributions and show that the sources form a distinct population of massive, compact galaxies at redshifts 0.4 ≲ z ≲ 0.7, lying systematically below the size–mass relation of the global elliptical galaxy population at those redshifts. These may therefore represent relics of high-redshift red nuggets or their partly evolved descendants. We exploit the magnifying effect of lensing to investigate themore » structural properties, stellar masses and stellar populations of these objects with a view to understanding their evolution. We model these objects parametrically and find that they generally require two Sérsic components to properly describe their light profiles, with one more spheroidal component alongside a more envelope-like component, which is slightly more extended though still compact. This is consistent with the hypothesis of the inside-out growth of these objects via minor mergers. Lastly, we also find that the sources can be characterized by red-to-blue colour gradients as a function of radius which are stronger at low redshift – indicative of ongoing accretion – but that their environments generally appear consistent with that of the general elliptical galaxy population, contrary to recent suggestions that these objects are pre-dominantly associated with clusters.« less

Red nuggets grow inside-out: evidence from gravitational lensing

DOE PAGES

Oldham, Lindsay; Auger, Matthew W.; Fassnacht, Christopher D.; ...

2016-11-03

Here, we present a new sample of strong gravitational lens systems where both the foreground lenses and background sources are early-type galaxies. Using imaging from Hubble Space Telescope (HST)/Advanced Camera for Studies (ACS) and Keck/NIRC2, we model the surface brightness distributions and show that the sources form a distinct population of massive, compact galaxies at redshifts 0.4 ≲ z ≲ 0.7, lying systematically below the size–mass relation of the global elliptical galaxy population at those redshifts. These may therefore represent relics of high-redshift red nuggets or their partly evolved descendants. We exploit the magnifying effect of lensing to investigate themore » structural properties, stellar masses and stellar populations of these objects with a view to understanding their evolution. We model these objects parametrically and find that they generally require two Sérsic components to properly describe their light profiles, with one more spheroidal component alongside a more envelope-like component, which is slightly more extended though still compact. This is consistent with the hypothesis of the inside-out growth of these objects via minor mergers. Lastly, we also find that the sources can be characterized by red-to-blue colour gradients as a function of radius which are stronger at low redshift – indicative of ongoing accretion – but that their environments generally appear consistent with that of the general elliptical galaxy population, contrary to recent suggestions that these objects are pre-dominantly associated with clusters.« less

CFHTLenS and RCSLenS: testing photometric redshift distributions using angular cross-correlations with spectroscopic galaxy surveys

NASA Astrophysics Data System (ADS)

Choi, A.; Heymans, C.; Blake, C.; Hildebrandt, H.; Duncan, C. A. J.; Erben, T.; Nakajima, R.; Van Waerbeke, L.; Viola, M.

2016-12-01

We determine the accuracy of galaxy redshift distributions as estimated from photometric redshift probability distributions p(z). Our method utilizes measurements of the angular cross-correlation between photometric galaxies and an overlapping sample of galaxies with spectroscopic redshifts. We describe the redshift leakage from a galaxy photometric redshift bin j into a spectroscopic redshift bin I using the sum of the p(z) for the galaxies residing in bin j. We can then predict the angular cross-correlation between photometric and spectroscopic galaxies due to intrinsic galaxy clustering when I ≠ j as a function of the measured angular cross-correlation when I = j. We also account for enhanced clustering arising from lensing magnification using a halo model. The comparison of this prediction with the measured signal provides a consistency check on the validity of using the summed p(z) to determine galaxy redshift distributions in cosmological analyses, as advocated by the Canada-France-Hawaii Telescope Lensing Survey (CFHTLenS). We present an analysis of the photometric redshifts measured by CFHTLenS, which overlaps the Baryon Oscillation Spectroscopic Survey (BOSS). We also analyse the Red-sequence Cluster Lensing Survey, which overlaps both BOSS and the WiggleZ Dark Energy Survey. We find that the summed p(z) from both surveys are generally biased with respect to the true underlying distributions. If unaccounted for, this bias would lead to errors in cosmological parameter estimation from CFHTLenS by less than ˜4 per cent. For photometric redshift bins which spatially overlap in 3D with our spectroscopic sample, we determine redshift bias corrections which can be used in future cosmological analyses that rely on accurate galaxy redshift distributions.

The Herschel Virgo Cluster Survey. XIX. Physical properties of low luminosity FIR sources at z < 0.5

NASA Astrophysics Data System (ADS)

Pappalardo, Ciro; Bizzocchi, Luca; Fritz, Jacopo; Boselli, Alessandro; Boquien, Mederic; Boissier, Samuel; Baes, Maarten; Ciesla, Laure; Bianchi, Simone; Clemens, Marcel; Viaene, Sebastien; Bendo, George J.; De Looze, Ilse; Smith, Matthew W. L.; Davies, Jonathan

2016-05-01

Context. The star formation rate is a crucial parameter for the investigation galaxy evolution. At low redshift the cosmic star formation rate density declines smoothly, and massive active galaxies become passive, reducing their star formation activity. This implies that the bulk of the star formation rate density at low redshift is mainly driven by low mass objects. Aims: We investigate the properties of a sample of low luminosity far-infrared sources selected at 250 μm. We have collected data from ultraviolet to far-infrared in order to perform a multiwavelengths analysis. The main goal is to investigate the correlation between star formation rate, stellar mass, and dust mass for a galaxy population with a wide range in dust content and stellar mass, including the low mass regime that most probably dominates the star formation rate density at low redshift. Methods: We define a main sample of ~800 sources with full spectral energy distribution coverage between 0.15 <λ< 500 μm and an extended sample with ~5000 sources in which we remove the constraints on the ultraviolet and near-infrared bands. We analyze both samples with two different spectral energy distribution fitting methods: MAGPHYS and CIGALE, which interpret a galaxy spectral energy distribution as a combination of different simple stellar population libraries and dust emission templates. Results: In the star formation rate versus stellar mass plane our samples occupy a region included between local spirals and higher redshift star forming galaxies. These galaxies represent the population that at z< 0.5 quenches their star formation activity and reduces their contribution to the cosmic star formation rate density. The subsample of galaxies with the higher masses (M∗> 3 × 1010 M⊙) do not lie on the main sequence, but show a small offset as a consequence of the decreased star formation. Low mass galaxies (M∗< 1 × 1010 M⊙) settle in the main sequence with star formation rate and stellar mass consistent with local spirals. Conclusions: Deep Herschel data allow the identification of a mixed galaxy population with galaxies still in an assembly phase or galaxies at the beginning of their passive evolution. We find that the dust luminosity is the parameter that allow us to discriminate between these two galaxy populations. The median spectral energy distribution shows that even at low star formation rate our galaxy sample has a higher mid-infrared emission than previously predicted. Herschel is an ESA space observatory with science instruments provided by a European-led principal investigator consortia and with an important participation from NASA.

Evolution of clustering length, large-scale bias, and host halo mass at 2 < z < 5 in the VIMOS Ultra Deep Survey (VUDS)⋆

NASA Astrophysics Data System (ADS)

Durkalec, A.; Le Fèvre, O.; Pollo, A.; de la Torre, S.; Cassata, P.; Garilli, B.; Le Brun, V.; Lemaux, B. C.; Maccagni, D.; Pentericci, L.; Tasca, L. A. M.; Thomas, R.; Vanzella, E.; Zamorani, G.; Zucca, E.; Amorín, R.; Bardelli, S.; Cassarà, L. P.; Castellano, M.; Cimatti, A.; Cucciati, O.; Fontana, A.; Giavalisco, M.; Grazian, A.; Hathi, N. P.; Ilbert, O.; Paltani, S.; Ribeiro, B.; Schaerer, D.; Scodeggio, M.; Sommariva, V.; Talia, M.; Tresse, L.; Vergani, D.; Capak, P.; Charlot, S.; Contini, T.; Cuby, J. G.; Dunlop, J.; Fotopoulou, S.; Koekemoer, A.; López-Sanjuan, C.; Mellier, Y.; Pforr, J.; Salvato, M.; Scoville, N.; Taniguchi, Y.; Wang, P. W.

2015-11-01

We investigate the evolution of galaxy clustering for galaxies in the redshift range 2.0

The Las Campanas Infrared Survey - II. Photometric redshifts, comparison with models and clustering evolution

NASA Astrophysics Data System (ADS)

Firth, A. E.; Somerville, R. S.; McMahon, R. G.; Lahav, O.; Ellis, R. S.; Sabbey, C. N.; McCarthy, P. J.; Chen, H.-W.; Marzke, R. O.; Wilson, J.; Abraham, R. G.; Beckett, M. G.; Carlberg, R. G.; Lewis, J. R.; Mackay, C. D.; Murphy, D. C.; Oemler, A. E.; Persson, S. E.

2002-05-01

The Las Campanas Infrared (LCIR) Survey, using the Cambridge Infra-Red Survey Instrument (CIRSI), reaches H ~21 over nearly 1deg2 . In this paper we present results from 744arcmin2 centred on the Hubble Deep Field South for which UBVRI optical data are publicly available. Making conservative magnitude cuts to ensure spatial uniformity, we detect 3177 galaxies to H =20.0 in 744arcmin2 and a further 842 to H =20.5 in a deeper subregion of 407arcmin2 . We compare the observed optical-infrared (IR) colour distributions with the predictions of semi-analytic hierarchical models and find reasonable agreement. We also determine photometric redshifts, finding a median redshift of ~0.55. We compare the redshift distributions N (z ) of E, Sbc, Scd and Im spectral types with models, showing that the observations are inconsistent with simple passive-evolution models while semi-analytic models provide a reasonable fit to the total N (z ) but underestimate the number of z ~1 red spectral types relative to bluer spectral types. We also present N (z ) for samples of extremely red objects (EROs) defined by optical-IR colours. We find that EROs with R -H >4 and H <20.5 have a median redshift z m ~1 while redder colour cuts have slightly higher z m . In the magnitude range 194 comprise ~18 per cent of the observed galaxy population, while in semi-analytic models they contribute only ~4 per cent. We also determine the angular correlation function w (θ ) for magnitude, colour, spectral type and photometric redshift-selected subsamples of the data and use the photometric redshift distributions to derive the spatial clustering statistic ξ (r ) as a function of spectral type and redshift out to z ~1.2. Parametrizing ξ (r ) by ξ (r c ,z )=[r c /r *(z )]-1.8 , where r c is in comoving coordinates, we find that r *(z ) increases by a factor of 1.5-2 from z =0 to z ~1.2. We interpret this as a selection effect - the galaxies selected at z ~1.2 are intrinsically very luminous, about 1-1.5mag brighter than L *. When galaxies are selected by absolute magnitude, we find no evidence for evolution in r * over this redshift range. Extrapolated to z =0, we find r *(z =0)~6.5h -1 Mpc for red galaxies and r *(z =0)~2-4h -1 Mpc for blue galaxies. We also find that, while the angular clustering amplitude of EROs with R -H >4 or I -H >3 is up to four times that of the whole galaxy population, the spatial clustering length r *(z =1) is ~7.5-10.5h -1 Mpc, which is only a factor of ~1.7 times r *(z =1) for R -H <4 and I -H <3 galaxies lying in a similar redshift and luminosity range. This difference is similar to that observed between red and blue galaxies at low redshifts.

Dusty Star Forming Galaxies and Supermassive Black Holes at High Redshifts: In- Situ Coevolution

NASA Astrophysics Data System (ADS)

Mancuso, Claudia

2016-10-01

We have exploited the continuity equation approach and the star-formation timescales derived from the observed 'main sequence' relation (Star Formation Rate vs Stellar Mass), to show that the observed high abundance of galaxies with stellar masses ≥ a few 10^10 M⊙ at redshift z ≥ 4 implies the existence of a galaxy population featuring large star formation rates (SFRs) ψ ≥ 10^2 M⊙ yr^-1 in heavily dust-obscured conditions. These galaxies constitute the high-redshift counterparts of the dusty star-forming population already surveyed for z ≤ 3 in the Far-InfraRed (FIR) band by the Herschel space observatory. We work out specific predictions for the evolution of the corresponding stellar mass and SFR functions out to z ∼10, elucidating that the number density at z ≤ 8 for SFRs ψ ≥ 30 M⊙ yr^-1 cannot be estimated relying on the UltraViolet (UV) luminosity function alone, even when standard corrections for dust extinction based on the UV slope are applied. We compute the number counts and redshift distributions (including galaxy-scale gravitational lensing) of this galaxy population, and show that current data from AzTEC-LABOCA, SCUBA-2 and ALMA-SPT surveys are already digging into it. We substantiate how an observational strategy based on a color preselection in the far-IR or (sub-)mm band with Herschel and SCUBA-2, supplemented by photometric data via on-source observations with ALMA, can allow to reconstruct the bright end of the SFR functions out to z ≤ 8. In parallel, such a challenging task can be managed by exploiting current UV surveys in combination with (sub-)mm observations by ALMA and NIKA2. The same could be done with radio observations by SKA and its precursors. In particular we have worked out predictions for the radio counts of star-forming galaxies down to nJy levels, along with redshift distributions down to the detection limits of the phase 1 Square Kilometer Array MID telescope (SKA1-MID) and of its precursors. To do that we exploited our SFR functions with relations between SFR and radio (synchrotron and free-free) emission. Our results show that the deepest SKA1- MID surveys will detect high-z galaxies with SFRs two orders of magnitude lower compared to Herschel surveys. The highest redshift tails of the distributions at the detection limits of planned SKA1-MID surveys comprise a substantial fraction of strongly lensed galaxies. The SKA1-MID will thus provide a comprehensive view of the star formation history throughout the re-ionization epoch, unaffected by dust extinction. We have also provided specific predictions for the EMU/ASKAP and MIGHTEE/MeerKAT surveys. We finally provide a novel, unifying physical interpretation on the origin, the average shape, the scatter, and the cosmic evolution for the main sequences (MS) of star-forming galaxies and active galactic nuclei at high redshift z ≥ 1. We achieve this goal in a model-independent way by exploiting the redshift-dependent SFR functions, and the deterministic evolutionary tracks for the history of star formation and black hole accretion, gauged on a wealth of multiwavelength observations including the observed Eddington ratio distribution. We further validate these ingredients by showing their consistency with the observed galaxy stellar mass functions and active galactic nucleus (AGN) bolometric luminosity functions at different redshifts via, again, the continuity equation approach. Our analysis of the main sequence for high-redshift galaxies and AGNs highlights that the present data strongly support a scenario of in situ coevolution for star formation and black hole accretion, envisaging these as local, time coordinated processes.

Percolation galaxy groups and clusters in the sdss redshift survey: identification, catalogs, and the multiplicity function

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

Berlind, Andreas A.; Frieman, Joshua A.; Weinberg, David H.

2006-01-01

We identify galaxy groups and clusters in volume-limited samples of the SDSS redshift survey, using a redshift-space friends-of-friends algorithm. We optimize the friends-of-friends linking lengths to recover galaxy systems that occupy the same dark matter halos, using a set of mock catalogs created by populating halos of N-body simulations with galaxies. Extensive tests with these mock catalogs show that no combination of perpendicular and line-of-sight linking lengths is able to yield groups and clusters that simultaneously recover the true halo multiplicity function, projected size distribution, and velocity dispersion. We adopt a linking length combination that yields, for galaxy groups withmore » ten or more members: a group multiplicity function that is unbiased with respect to the true halo multiplicity function; an unbiased median relation between the multiplicities of groups and their associated halos; a spurious group fraction of less than {approx}1%; a halo completeness of more than {approx}97%; the correct projected size distribution as a function of multiplicity; and a velocity dispersion distribution that is {approx}20% too low at all multiplicities. These results hold over a range of mock catalogs that use different input recipes of populating halos with galaxies. We apply our group-finding algorithm to the SDSS data and obtain three group and cluster catalogs for three volume-limited samples that cover 3495.1 square degrees on the sky. We correct for incompleteness caused by fiber collisions and survey edges, and obtain measurements of the group multiplicity function, with errors calculated from realistic mock catalogs. These multiplicity function measurements provide a key constraint on the relation between galaxy populations and dark matter halos.« less

The red and blue galaxy populations in the GOODS field: evidence for an excess of red dwarfs

NASA Astrophysics Data System (ADS)

Salimbeni, S.; Giallongo, E.; Menci, N.; Castellano, M.; Fontana, A.; Grazian, A.; Pentericci, L.; Trevese, D.; Cristiani, S.; Nonino, M.; Vanzella, E.

2008-01-01

Aims: We study the evolution of the galaxy population up to z˜ 3 as a function of its colour properties. In particular, luminosity functions and luminosity densities were derived as a function of redshift for the blue/late and red/early populations. Methods: We use data from the GOODS-MUSIC catalogue, which have typical magnitude limits z850≤ 26 and K_s≤ 23.5 for most of the sample. About 8% of the galaxies have spectroscopic redshifts; the remaining have well calibrated photometric redshifts derived from the extremely wide multi-wavelength coverage in 14 bands (from the U band to the Spitzer 8~ μm band). We have derived a catalogue of galaxies complete in the rest-frame B-band, which has been divided into two subsamples according to their rest-frame U-V colour (or derived specific star formation rate) properties. Results: We confirm a bimodality in the U-V colour and specific star formation rate of the galaxy sample up to z˜ 3. This bimodality is used to compute the luminosity functions of the blue/late and red/early subsamples. The luminosity functions of the blue/late and total samples are well represented by steep Schechter functions evolving in luminosity with increasing redshifts. The volume density of the luminosity functions of the red/early populations decreases with increasing redshift. The shape of the red/early luminosity functions shows an excess of faint red dwarfs with respect to the extrapolation of a flat Schechter function and can be represented by the sum of two Schechter functions. Our model for galaxy formation in the hierarchical clustering scenario, which also includes external feedback due to a diffuse UV background, shows a general broad agreement with the luminosity functions of both populations, the larger discrepancies being present at the faint end for the red population. Hints on the nature of the red dwarf population are given on the basis of their stellar mass and spatial distributions.

BL Lacertae Objects Beyond Redshift 1.3 - UV-to-NIR Photometry and Photometric Redshift for Fermi/LAT Blazars

NASA Technical Reports Server (NTRS)

Rau, A.; Schady, P.; Greiner, J.; Salvato, M.; Ajello, M.; Bottacini, E.; Gehrels, N.; Afonso, P. M. J.; Elliott, J.; Filgas, R.;

Dark Energy Survey Year 1 results: cross-correlation redshifts - methods and systematics characterization

NASA Astrophysics Data System (ADS)

Gatti, M.; Vielzeuf, P.; Davis, C.; Cawthon, R.; Rau, M. M.; DeRose, J.; De Vicente, J.; Alarcon, A.; Rozo, E.; Gaztanaga, E.; Hoyle, B.; Miquel, R.; Bernstein, G. M.; Bonnett, C.; Carnero Rosell, A.; Castander, F. J.; Chang, C.; da Costa, L. N.; Gruen, D.; Gschwend, J.; Hartley, W. G.; Lin, H.; MacCrann, N.; Maia, M. A. G.; Ogando, R. L. C.; Roodman, A.; Sevilla-Noarbe, I.; Troxel, M. A.; Wechsler, R. H.; Asorey, J.; Davis, T. M.; Glazebrook, K.; Hinton, S. R.; Lewis, G.; Lidman, C.; Macaulay, E.; Möller, A.; O'Neill, C. R.; Sommer, N. E.; Uddin, S. A.; Yuan, F.; Zhang, B.; Abbott, T. M. C.; Allam, S.; Annis, J.; Bechtol, K.; Brooks, D.; Burke, D. L.; Carollo, D.; Carrasco Kind, M.; Carretero, J.; Cunha, C. E.; D'Andrea, C. B.; DePoy, D. L.; Desai, S.; Eifler, T. F.; Evrard, A. E.; Flaugher, B.; Fosalba, P.; Frieman, J.; García-Bellido, J.; Gerdes, D. W.; Goldstein, D. A.; Gruendl, R. A.; Gutierrez, G.; Honscheid, K.; Hoormann, J. K.; Jain, B.; James, D. J.; Jarvis, M.; Jeltema, T.; Johnson, M. W. G.; Johnson, M. D.; Krause, E.; Kuehn, K.; Kuhlmann, S.; Kuropatkin, N.; Li, T. S.; Lima, M.; Marshall, J. L.; Melchior, P.; Menanteau, F.; Nichol, R. C.; Nord, B.; Plazas, A. A.; Reil, K.; Rykoff, E. S.; Sako, M.; Sanchez, E.; Scarpine, V.; Schubnell, M.; Sheldon, E.; Smith, M.; Smith, R. C.; Soares-Santos, M.; Sobreira, F.; Suchyta, E.; Swanson, M. E. C.; Tarle, G.; Thomas, D.; Tucker, B. E.; Tucker, D. L.; Vikram, V.; Walker, A. R.; Weller, J.; Wester, W.; Wolf, R. C.

2018-06-01

We use numerical simulations to characterize the performance of a clustering-based method to calibrate photometric redshift biases. In particular, we cross-correlate the weak lensing source galaxies from the Dark Energy Survey Year 1 sample with redMaGiC galaxies (luminous red galaxies with secure photometric redshifts) to estimate the redshift distribution of the former sample. The recovered redshift distributions are used to calibrate the photometric redshift bias of standard photo-z methods applied to the same source galaxy sample. We apply the method to two photo-z codes run in our simulated data: Bayesian Photometric Redshift and Directional Neighbourhood Fitting. We characterize the systematic uncertainties of our calibration procedure, and find that these systematic uncertainties dominate our error budget. The dominant systematics are due to our assumption of unevolving bias and clustering across each redshift bin, and to differences between the shapes of the redshift distributions derived by clustering versus photo-zs. The systematic uncertainty in the mean redshift bias of the source galaxy sample is Δz ≲ 0.02, though the precise value depends on the redshift bin under consideration. We discuss possible ways to mitigate the impact of our dominant systematics in future analyses.

The Rise and Fall of Star Formation Histories of Blue Galaxies at Redshifts 0.2 < z < 1.4

NASA Technical Reports Server (NTRS)

Pacifici, Camilla; Kassin, Susan A.; Weiner, Benjamin; Charlot, Stephane; Gardner, Jonathan P.

2012-01-01

Popular cosmological scenarios predict that galaxies form hierarchically from the merger of many progenitor, each with their own unique star formation history (SFH). We use the approach recently developed by Pacifici et al. to constrain the SFHs of 4517 blue (presumably star-forming) galaxies with spectroscopic redshifts in the range O.2 < z < 1:4 from the All-Wavelength Extended Groth Strip International Survey (AEGIS). This consists in the Bayesian analysis of the observed galaxy spectral ' energy distributions with a comprehensive library of synthetic spectra assembled using state-of-the-art models of star formation and chemical enrichment histories, stellar population synthesis, nebular emission and attenuation by dust. We constrain the SFH of each galaxy in our sample by comparing the observed fluxes in the B, R,l and K(sub s) bands and rest-frame optical emission-line luminosities with those of one million model spectral energy distributions. We explore the dependence of the resulting SFH on galaxy stellar mass and redshift. We find that the average SFHs of high-mass galaxies rise and fall in a roughly symmetric bell-shaped manner, while those of low-mass galaxies rise progressively in time, consistent with the typically stronger activity of star formation in low-mass compared to high-mass galaxies. For galaxies of all masses, the star formation activity rises more rapidly at high than at low redshift. These findings imply that the standard approximation of exponentially declining SFHs wIdely used to interpret observed galaxy spectral energy distributions is not appropriate to constrain the physical parameters of star-forming galaxies at intermediate redshifts.

Non-equilibrium populations of hydrogen in high-redshift galaxies

NASA Astrophysics Data System (ADS)

Pomerantz, Brian B.; Redmond, Kayla; Strelnitski, Vladimir

2014-07-01

We investigate the possibility of maser amplification in hydrogen recombination lines from the galaxies of first generation, at z≲ 30. Combining analytical and computational approaches, we show that the transitions between the hydrogen Rydberg energy levels induced by the radiation from the ionizing star and by the (warmer than currently) cosmic microwave background can produce noticeable differences in the population distribution, as compared with previous computations for contemporary H+ regions, most of which ignored the processes induced by the ionizing star's radiation. In particular, the low (n≲ 30) α-transitions show an increased tendency towards population inversion, when ionization of the H+ region is caused by a very hot star at high redshift. The resulting maser/laser amplification can increase the brightness of the emitted lines and make them detectable. However, the limiting effects of maser saturation will probably not allow maser gains to exceed one or two orders of magnitude.

RECONSTRUCTING REDSHIFT DISTRIBUTIONS WITH CROSS-CORRELATIONS: TESTS AND AN OPTIMIZED RECIPE

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

Matthews, Daniel J.; Newman, Jeffrey A., E-mail: djm70@pitt.ed, E-mail: janewman@pitt.ed

2010-09-20

Many of the cosmological tests to be performed by planned dark energy experiments will require extremely well-characterized photometric redshift measurements. Current estimates for cosmic shear are that the true mean redshift of the objects in each photo-z bin must be known to better than 0.002(1 + z), and the width of the bin must be known to {approx}0.003(1 + z) if errors in cosmological measurements are not to be degraded significantly. A conventional approach is to calibrate these photometric redshifts with large sets of spectroscopic redshifts. However, at the depths probed by Stage III surveys (such as DES), let alonemore » Stage IV (LSST, JDEM, and Euclid), existing large redshift samples have all been highly (25%-60%) incomplete, with a strong dependence of success rate on both redshift and galaxy properties. A powerful alternative approach is to exploit the clustering of galaxies to perform photometric redshift calibrations. Measuring the two-point angular cross-correlation between objects in some photometric redshift bin and objects with known spectroscopic redshift, as a function of the spectroscopic z, allows the true redshift distribution of a photometric sample to be reconstructed in detail, even if it includes objects too faint for spectroscopy or if spectroscopic samples are highly incomplete. We test this technique using mock DEEP2 Galaxy Redshift survey light cones constructed from the Millennium Simulation semi-analytic galaxy catalogs. From this realistic test, which incorporates the effects of galaxy bias evolution and cosmic variance, we find that the true redshift distribution of a photometric sample can, in fact, be determined accurately with cross-correlation techniques. We also compare the empirical error in the reconstruction of redshift distributions to previous analytic predictions, finding that additional components must be included in error budgets to match the simulation results. This extra error contribution is small for surveys that sample large areas of sky (>{approx}10{sup 0}-100{sup 0}), but dominant for {approx}1 deg{sup 2} fields. We conclude by presenting a step-by-step, optimized recipe for reconstructing redshift distributions from cross-correlation information using standard correlation measurements.« less

Spatial and kinematic distributions of transition populations in intermediate redshift galaxy clusters

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

Crawford, Steven M.; Wirth, Gregory D.; Bershady, Matthew A., E-mail: crawford@saao.ac.za, E-mail: wirth@keck.hawaii.edu, E-mail: mab@astro.wisc.edu

2014-05-01

We analyze the spatial and velocity distributions of confirmed members in five massive clusters of galaxies at intermediate redshift (0.5 < z < 0.9) to investigate the physical processes driving galaxy evolution. Based on spectral classifications derived from broad- and narrow-band photometry, we define four distinct galaxy populations representing different evolutionary stages: red sequence (RS) galaxies, blue cloud (BC) galaxies, green valley (GV) galaxies, and luminous compact blue galaxies (LCBGs). For each galaxy class, we derive the projected spatial and velocity distribution and characterize the degree of subclustering. We find that RS, BC, and GV galaxies in these clusters havemore » similar velocity distributions, but that BC and GV galaxies tend to avoid the core of the two z ≈ 0.55 clusters. GV galaxies exhibit subclustering properties similar to RS galaxies, but their radial velocity distribution is significantly platykurtic compared to the RS galaxies. The absence of GV galaxies in the cluster cores may explain their somewhat prolonged star-formation history. The LCBGs appear to have recently fallen into the cluster based on their larger velocity dispersion, absence from the cores of the clusters, and different radial velocity distribution than the RS galaxies. Both LCBG and BC galaxies show a high degree of subclustering on the smallest scales, leading us to conclude that star formation is likely triggered by galaxy-galaxy interactions during infall into the cluster.« less

Dark Energy Survey Year 1 Results: Cross-Correlation Redshifts in the DES -- Calibration of the Weak Lensing Source Redshift Distributions

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

Davis, C.; et al.

We present the calibration of the Dark Energy Survey Year 1 (DES Y1) weak lensing source galaxy redshift distributions from clustering measurements. By cross-correlating the positions of source galaxies with luminous red galaxies selected by the redMaGiC algorithm we measure the redshift distributions of the source galaxies as placed into different tomographic bins. These measurements constrain any such shifts to an accuracy ofmore » $$\\sim0.02$$ and can be computed even when the clustering measurements do not span the full redshift range. The highest-redshift source bin is not constrained by the clustering measurements because of the minimal redshift overlap with the redMaGiC galaxies. We compare our constraints with those obtained from $$\\texttt{COSMOS}$$ 30-band photometry and find that our two very different methods produce consistent constraints.« less

ON THE RADIO AND OPTICAL LUMINOSITY EVOLUTION OF QUASARS

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

Singal, J.; Petrosian, V.; Lawrence, A.

2011-12-20

We calculate simultaneously the radio and optical luminosity evolutions of quasars, and the distribution in radio loudness R defined as the ratio of radio and optical luminosities, using a flux-limited data set containing 636 quasars with radio and optical fluxes from White et al. We first note that when dealing with multi-variate data it is imperative to first determine the true correlations among the variables, not those introduced by the observational selection effects, before obtaining the individual distributions of the variables. We use the methods developed by Efron and Petrosian which are designed to obtain unbiased correlations, distributions, and evolutionmore » with redshift from a data set truncated due to observational biases. It is found that the population of quasars exhibits strong positive correlation between the radio and optical luminosities. With this correlation, whether intrinsic or observationally induced accounted for, we find that there is a strong luminosity evolution with redshift in both wavebands, with significantly higher radio than optical evolution. We conclude that the luminosity evolution obtained by arbitrarily separating the sources into radio-loud (R > 10) and radio-quiet (R < 10) populations introduces significant biases that skew the result considerably. We also construct the local radio and optical luminosity functions and the density evolution. Finally, we consider the distribution of the radio-loudness parameter R obtained from careful treatment of the selection effects and luminosity evolutions with that obtained from the raw data without such considerations. We find a significant difference between the two distributions and no clear sign of bi-modality in the true distribution for the range of R values considered. Our results indicate therefore, somewhat surprisingly, that there is no critical switch in the efficiency of the production of disk outflows/jets between very radio-quiet and very radio-loud quasars, but rather a smooth transition. Also, this efficiency seems higher for the high-redshift and more luminous sources in the sample considered.« less

ULTRA STEEP SPECTRUM RADIO SOURCES IN THE LOCKMAN HOLE: SERVS IDENTIFICATIONS AND REDSHIFT DISTRIBUTION AT THE FAINTEST RADIO FLUXES

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

Afonso, J.; Bizzocchi, L.; Grossi, M.

2011-12-20

Ultra steep spectrum (USS) radio sources have been successfully used to select powerful radio sources at high redshifts (z {approx}> 2). Typically restricted to large-sky surveys and relatively bright radio flux densities, it has gradually become possible to extend the USS search to sub-mJy levels, thanks to the recent appearance of sensitive low-frequency radio facilities. Here a first detailed analysis of the nature of the faintest USS sources is presented. By using Giant Metrewave Radio Telescope and Very Large Array radio observations of the Lockman Hole at 610 MHz and 1.4 GHz, a sample of 58 USS sources, with 610more » MHz integrated fluxes above 100 {mu}Jy, is assembled. Deep infrared data at 3.6 and 4.5 {mu}m from the Spitzer Extragalactic Representative Volume Survey (SERVS) are used to reliably identify counterparts for 48 (83%) of these sources, showing an average total magnitude of [3.6]{sub AB} = 19.8 mag. Spectroscopic redshifts for 14 USS sources, together with photometric redshift estimates, improved by the use of the deep SERVS data, for a further 19 objects, show redshifts ranging from z = 0.1 to z = 2.8, peaking at z {approx} 0.6 and tailing off at high redshifts. The remaining 25 USS sources, with no redshift estimate, include the faintest [3.6] magnitudes, with 10 sources undetected at 3.6 and 4.5 {mu}m (typically [3.6] {approx}> 22-23 mag from local measurements), which suggests the likely existence of higher redshifts among the sub-mJy USS population. The comparison with the Square Kilometre Array Design Studies Simulated Skies models indicates that Fanaroff-Riley type I radio sources and radio-quiet active galactic nuclei may constitute the bulk of the faintest USS population, and raises the possibility that the high efficiency of the USS technique for the selection of high-redshift sources remains even at the sub-mJy level.« less

A cross-correlation-based estimate of the galaxy luminosity function

NASA Astrophysics Data System (ADS)

van Daalen, Marcel P.; White, Martin

2018-06-01

We extend existing methods for using cross-correlations to derive redshift distributions for photometric galaxies, without using photometric redshifts. The model presented in this paper simultaneously yields highly accurate and unbiased redshift distributions and, for the first time, redshift-dependent luminosity functions, using only clustering information and the apparent magnitudes of the galaxies as input. In contrast to many existing techniques for recovering unbiased redshift distributions, the output of our method is not degenerate with the galaxy bias b(z), which is achieved by modelling the shape of the luminosity bias. We successfully apply our method to a mock galaxy survey and discuss improvements to be made before applying our model to real data.

Comparison of z-known GRBs with the Main Groups of Bright BATSE Events

NASA Technical Reports Server (NTRS)

Mitrofanov, Igor G.; Sanin, Anton B.; Anfimov, Dmitrij S.; Litvak, Maxim L.; Briggs, Michael S.; Paciesas, William S.; Pendleton, Geoffrey N.; Preece, Robert D.; Meegan, Charles A.; Whitaker, Ann F. (Technical Monitor)

2001-01-01

The small reference sample of six BATSE gamma-ray bursts with known redshifts from optical afterglows is compared with a comparison group of the 218 brightest BATSE bursts. These two groups are shown to be consistent both with respect to the distributions of the spectral peak parameter in the observer's frame and also with respect to the distributions of the frame-independent cosmological invariant parameter (CIP). Using the known values of the redshifts z for the reference sample, the rest-frame distribution of spectral parameters is built. The de-redshifted distribution of the spectral parameters of the reference sample is compared with distribution of these parameters for the comparison group after de-redshifting by the factor 1/(1+z), with z a free parameter. Requiring consistency between these two distributions produces a collective estimation of the best fitting redshifts z for the comparison group, z=1.8--3.6. These values can be considered as the average cosmological redshift of the sources of the brightest BATSE bursts. The most probable value of the peak energy of the spectrum in the rest frame is 920 keV, close to the rest mass of an electron-positron pair.

The luminosity function for different morphological types in the CfA Redshift Survey

NASA Technical Reports Server (NTRS)

Marzke, Ronald O.; Geller, Margaret J.; Huchra, John P.; Corwin, Harold G., Jr.

1994-01-01

We derive the luminosity function for different morphological types in the original CfA Redshift Survey (CfA1) and in the first two slices of the CfA Redshift Survey Extension (CfA2). CfA1 is a complete sample containing 2397 galaxies distributed over 2.7 steradians with m(sub z) less than or equal 14.5. The first two complete slices of CfA2 contain 1862 galaxies distributed over 0.42 steradians with m(sub z)=15.5. The shapes of the E-S0 and spiral luminosity functions (LF) are indistinguishable. We do not confirm the steeply decreasing faint end in the E-S0 luminosity function found by Loveday et al. for an independent sample in the southern hemisphere. We demonstrate that incomplete classification in deep redshift surveys can lead to underestimates of the faint end of the elliptical luminosity function and could be partially responsible for the difference between the CfA survey and other local field surveys. The faint end of the LF for the Magellanic spirals and irregulars is very steep. The Sm-Im luminosity function is well fit by a Schechter function with M*=-18.79, alpha=-1.87, and phi*=0.6x10(exp -3) for M(sub z) less than or equal to -13. These galaxies are largely responsible for the excess at the faint end of the general CfA luminosity function. The abundance of intrinsically faint, blue galaxies nearby affects the interpretation of deep number counts. The dwarf population increases the expected counts at B=25 in a no-evolution, q(sub 0)=0.05 model by a factor of two over standard no-evolution estimates. These dwarfs change the expected median redshift in deep redshift surveys by less than 10 percent . Thus the steep Sm-Im LF may contribute to the reconciliation of deep number counts with deep redshift surveys.

Intra-cluster Globular Clusters in a Simulated Galaxy Cluster

NASA Astrophysics Data System (ADS)

Ramos-Almendares, Felipe; Abadi, Mario; Muriel, Hernán; Coenda, Valeria

2018-01-01

Using a cosmological dark matter simulation of a galaxy-cluster halo, we follow the temporal evolution of its globular cluster population. To mimic the red and blue globular cluster populations, we select at high redshift (z∼ 1) two sets of particles from individual galactic halos constrained by the fact that, at redshift z = 0, they have density profiles similar to observed ones. At redshift z = 0, approximately 60% of our selected globular clusters were removed from their original halos building up the intra-cluster globular cluster population, while the remaining 40% are still gravitationally bound to their original galactic halos. As the blue population is more extended than the red one, the intra-cluster globular cluster population is dominated by blue globular clusters, with a relative fraction that grows from 60% at redshift z = 0 up to 83% for redshift z∼ 2. In agreement with observational results for the Virgo galaxy cluster, the blue intra-cluster globular cluster population is more spatially extended than the red one, pointing to a tidally disrupted origin.

Dark Energy Survey Year 1 Results: galaxy mock catalogues for BAO

NASA Astrophysics Data System (ADS)

Avila, S.; Crocce, M.; Ross, A. J.; García-Bellido, J.; Percival, W. J.; Banik, N.; Camacho, H.; Kokron, N.; Chan, K. C.; Andrade-Oliveira, F.; Gomes, R.; Gomes, D.; Lima, M.; Rosenfeld, R.; Salvador, A. I.; Friedrich, O.; Abdalla, F. B.; Annis, J.; Benoit-Lévy, A.; Bertin, E.; Brooks, D.; Carrasco Kind, M.; Carretero, J.; Castander, F. J.; Cunha, C. E.; da Costa, L. N.; Davis, C.; De Vicente, J.; Doel, P.; Fosalba, P.; Frieman, J.; Gerdes, D. W.; Gruen, D.; Gruendl, R. A.; Gutierrez, G.; Hartley, W. G.; Hollowood, D.; Honscheid, K.; James, D. J.; Kuehn, K.; Kuropatkin, N.; Miquel, R.; Plazas, A. A.; Sanchez, E.; Scarpine, V.; Schindler, R.; Schubnell, M.; Sevilla-Noarbe, I.; Smith, M.; Sobreira, F.; Suchyta, E.; Swanson, M. E. C.; Tarle, G.; Thomas, D.; Walker, A. R.; Dark Energy Survey Collaboration

2018-05-01

Mock catalogues are a crucial tool in the analysis of galaxy surveys data, both for the accurate computation of covariance matrices, and for the optimisation of analysis methodology and validation of data sets. In this paper, we present a set of 1800 galaxy mock catalogues designed to match the Dark Energy Survey Year-1 BAO sample (Crocce et al. 2017) in abundance, observational volume, redshift distribution and uncertainty, and redshift dependent clustering. The simulated samples were built upon HALOGEN (Avila et al. 2015) halo catalogues, based on a 2LPT density field with an empirical halo bias. For each of them, a lightcone is constructed by the superposition of snapshots in the redshift range 0.45 < z < 1.4. Uncertainties introduced by so-called photometric redshifts estimators were modelled with a double-skewed-Gaussian curve fitted to the data. We populate halos with galaxies by introducing a hybrid Halo Occupation Distribution - Halo Abundance Matching model with two free parameters. These are adjusted to achieve a galaxy bias evolution b(zph) that matches the data at the 1-σ level in the range 0.6 < zph < 1.0. We further analyse the galaxy mock catalogues and compare their clustering to the data using the angular correlation function w(θ), the comoving transverse separation clustering ξμ < 0.8(s⊥) and the angular power spectrum Cℓ, finding them in agreement. This is the first large set of three-dimensional {ra,dec,z} galaxy mock catalogues able to simultaneously accurately reproduce the photometric redshift uncertainties and the galaxy clustering.

Evolution of the luminosity function of extragalactic objects

NASA Technical Reports Server (NTRS)

Petrosian, V.

1985-01-01

A nonparametric procedure for determination of the evolution of the luminosity function of extragalactic objects and use of this for prediction of expected redshift and luminosity distribution of objects is described. The relation between this statistical evolution of the population and their physical evolution, such as the variation with cosmological epoch of their luminosity and formation rate is presented. This procedure when applied to a sample of optically selected quasars with redshifts less than two shows that the luminosity function evolves more strongly for higher luminosities, indicating a larger quasar activity at earlier epochs and a more rapid evolution of the objects during their higher luminosity phases. It is also shown that absence of many quasars at redshifts greater than three implies slowing down of this evolution in the conventional cosmological models, perhaps indicating that this is near the epoch of the birth of the quasar (and galaxies).

The 5-10 keV AGN luminosity function at 0.01 < z < 4.0

NASA Astrophysics Data System (ADS)

Fotopoulou, S.; Buchner, J.; Georgantopoulos, I.; Hasinger, G.; Salvato, M.; Georgakakis, A.; Cappelluti, N.; Ranalli, P.; Hsu, L. T.; Brusa, M.; Comastri, A.; Miyaji, T.; Nandra, K.; Aird, J.; Paltani, S.

2016-03-01

The active galactic nuclei (AGN) X-ray luminosity function traces actively accreting supermassive black holes and is essential for the study of the properties of the AGN population, black hole evolution, and galaxy-black hole coevolution. Up to now, the AGN luminosity function has been estimated several times in soft (0.5-2 keV) and hard X-rays (2-10 keV). AGN selection in these energy ranges often suffers from identification and redshift incompleteness and, at the same time, photoelectric absorption can obscure a significant amount of the X-ray radiation. We estimate the evolution of the luminosity function in the 5-10 keV band, where we effectively avoid the absorbed part of the spectrum, rendering absorption corrections unnecessary up to NH ~ 1023 cm-2. Our dataset is a compilation of six wide, and deep fields: MAXI, HBSS, XMM-COSMOS, Lockman Hole, XMM-CDFS, AEGIS-XD, Chandra-COSMOS, and Chandra-CDFS. This extensive sample of ~1110 AGN (0.01 < z < 4.0, 41 < log Lx < 46) is 98% redshift complete with 68% spectroscopic redshifts. For sources lacking a spectroscopic redshift estimation we use the probability distribution function of photometric redshift estimation specifically tuned for AGN, and a flat probability distribution function for sources with no redshift information. We use Bayesian analysis to select the best parametric model from simple pure luminosity and pure density evolution to more complicated luminosity and density evolution and luminosity-dependent density evolution (LDDE). We estimate the model parameters that describe best our dataset separately for each survey and for the combined sample. We show that, according to Bayesian model selection, the preferred model for our dataset is the LDDE. Our estimation of the AGN luminosity function does not require any assumption on the AGN absorption and is in good agreement with previous works in the 2-10 keV energy band based on X-ray hardness ratios to model the absorption in AGN up to redshift three. Our sample does not show evidence of a rapid decline of the AGN luminosity function up to redshift four.

Dark Energy Survey Year 1 Results: Cross-Correlation Redshifts - Methods and Systematics Characterization

DOE PAGES

Gatti, M.

2018-02-22

We use numerical simulations to characterize the performance of a clustering-based method to calibrate photometric redshift biases. In particular, we cross-correlate the weak lensing (WL) source galaxies from the Dark Energy Survey Year 1 (DES Y1) sample with redMaGiC galaxies (luminous red galaxies with secure photometric red- shifts) to estimate the redshift distribution of the former sample. The recovered redshift distributions are used to calibrate the photometric redshift bias of standard photo-z methods applied to the same source galaxy sample. We also apply the method to three photo-z codes run in our simulated data: Bayesian Photometric Redshift (BPZ), Directional Neighborhoodmore » Fitting (DNF), and Random Forest-based photo-z (RF). We characterize the systematic uncertainties of our calibration procedure, and find that these systematic uncertainties dominate our error budget. The dominant systematics are due to our assumption of unevolving bias and clustering across each redshift bin, and to differences between the shapes of the redshift distributions derived by clustering vs photo-z's. The systematic uncertainty in the mean redshift bias of the source galaxy sample is z ≲ 0.02, though the precise value depends on the redshift bin under consideration. Here, we discuss possible ways to mitigate the impact of our dominant systematics in future analyses.« less

Dark Energy Survey Year 1 Results: Cross-Correlation Redshifts - Methods and Systematics Characterization

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

Gatti, M.

We use numerical simulations to characterize the performance of a clustering-based method to calibrate photometric redshift biases. In particular, we cross-correlate the weak lensing (WL) source galaxies from the Dark Energy Survey Year 1 (DES Y1) sample with redMaGiC galaxies (luminous red galaxies with secure photometric red- shifts) to estimate the redshift distribution of the former sample. The recovered redshift distributions are used to calibrate the photometric redshift bias of standard photo-z methods applied to the same source galaxy sample. We also apply the method to three photo-z codes run in our simulated data: Bayesian Photometric Redshift (BPZ), Directional Neighborhoodmore » Fitting (DNF), and Random Forest-based photo-z (RF). We characterize the systematic uncertainties of our calibration procedure, and find that these systematic uncertainties dominate our error budget. The dominant systematics are due to our assumption of unevolving bias and clustering across each redshift bin, and to differences between the shapes of the redshift distributions derived by clustering vs photo-z's. The systematic uncertainty in the mean redshift bias of the source galaxy sample is z ≲ 0.02, though the precise value depends on the redshift bin under consideration. Here, we discuss possible ways to mitigate the impact of our dominant systematics in future analyses.« less

Obscuration-dependent Evolution of Active Galactic Nuclei

NASA Astrophysics Data System (ADS)

Buchner, Johannes; Georgakakis, Antonis; Nandra, Kirpal; Brightman, Murray; Menzel, Marie-Luise; Liu, Zhu; Hsu, Li-Ting; Salvato, Mara; Rangel, Cyprian; Aird, James; Merloni, Andrea; Ross, Nicholas

2015-04-01

We aim to constrain the evolution of active galactic nuclei (AGNs) as a function of obscuration using an X-ray-selected sample of ~2000 AGNs from a multi-tiered survey including the CDFS, AEGIS-XD, COSMOS, and XMM-XXL fields. The spectra of individual X-ray sources are analyzed using a Bayesian methodology with a physically realistic model to infer the posterior distribution of the hydrogen column density and intrinsic X-ray luminosity. We develop a novel non-parametric method that allows us to robustly infer the distribution of the AGN population in X-ray luminosity, redshift, and obscuring column density, relying only on minimal smoothness assumptions. Our analysis properly incorporates uncertainties from low count spectra, photometric redshift measurements, association incompleteness, and the limited sample size. We find that obscured AGNs with N H > 1022 cm-2 account for {77}+4-5% of the number density and luminosity density of the accretion supermassive black hole population with L X > 1043 erg s-1, averaged over cosmic time. Compton-thick AGNs account for approximately half the number and luminosity density of the obscured population, and {38}+8-7% of the total. We also find evidence that the evolution is obscuration dependent, with the strongest evolution around N H ≈ 1023 cm-2. We highlight this by measuring the obscured fraction in Compton-thin AGNs, which increases toward z ~ 3, where it is 25% higher than the local value. In contrast, the fraction of Compton-thick AGNs is consistent with being constant at ≈35%, independent of redshift and accretion luminosity. We discuss our findings in the context of existing models and conclude that the observed evolution is, to first order, a side effect of anti-hierarchical growth.

the-wizz: clustering redshift estimation for everyone

NASA Astrophysics Data System (ADS)

Morrison, C. B.; Hildebrandt, H.; Schmidt, S. J.; Baldry, I. K.; Bilicki, M.; Choi, A.; Erben, T.; Schneider, P.

2017-05-01

We present the-wizz, an open source and user-friendly software for estimating the redshift distributions of photometric galaxies with unknown redshifts by spatially cross-correlating them against a reference sample with known redshifts. The main benefit of the-wizz is in separating the angular pair finding and correlation estimation from the computation of the output clustering redshifts allowing anyone to create a clustering redshift for their sample without the intervention of an 'expert'. It allows the end user of a given survey to select any subsample of photometric galaxies with unknown redshifts, match this sample's catalogue indices into a value-added data file and produce a clustering redshift estimation for this sample in a fraction of the time it would take to run all the angular correlations needed to produce a clustering redshift. We show results with this software using photometric data from the Kilo-Degree Survey (KiDS) and spectroscopic redshifts from the Galaxy and Mass Assembly survey and the Sloan Digital Sky Survey. The results we present for KiDS are consistent with the redshift distributions used in a recent cosmic shear analysis from the survey. We also present results using a hybrid machine learning-clustering redshift analysis that enables the estimation of clustering redshifts for individual galaxies. the-wizz can be downloaded at http://github.com/morriscb/The-wiZZ/.

Galaxy populations in massive galaxy clusters to $z$ = 1.1: Color distribution, concentration, halo occupation number and red sequence fraction

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

Hennig, C.; Mohr, Joseph J.; Zenteno, A.

We study the galaxy populations in 74 Sunyaev–Zeldovich effect selected clusters from the South Pole Telescope survey, which have been imaged in the science verification phase of the Dark Energy Survey. The sample extends up to z ~ 1.1 with 4 × 10 14 M⊙ ≤ M200 ≤ 3 × 10 15M⊙. Using the band containing the 4000 Å break and its redward neighbour, we study the colour–magnitude distributions of cluster galaxies to ~m* + 2, finding that: (1)The intrinsic rest frame g – r colour width of the red sequence (RS) population is ~0.03 out to z ~ 0.85 with a preference for an increase to ~0.07 at z = 1, and (2) the prominence of the RS declines beyond z ~ 0.6. The spatial distribution of cluster galaxies is well described by the NFW profile out to 4R200 with a concentration of c g = 3.59more » $$+0.20\\atop{–0.18}$$, 5.37$$+0.27\\atop{-0.24}$$ and 1.38$$+0.21\\atop{-0.19}$$ for the full, the RS and the blue non-RS populations, respectively, but with ~40 per cent to 55 per cent cluster to cluster variation and no statistically significant redshift or mass trends. The number of galaxies within the virial region N200 exhibits a mass trend indicating that the number of galaxies per unit total mass is lower in the most massive clusters, and shows no significant redshift trend. The RS fraction within R200 is (68 ± 3) per cent at z = 0.46, varies from ~55 per cent at z = 1 to ~80 per cent at z = 0.1 and exhibits intrinsic variation among clusters of ~14 per cent. Finally, we discuss a model that suggests that the observed redshift trend in RS fraction favours a transformation time-scale for infalling field galaxies to become RS galaxies of 2–3 Gyr.« less

Galaxy populations in massive galaxy clusters to $z$ = 1.1: Color distribution, concentration, halo occupation number and red sequence fraction

DOE PAGES

Hennig, C.; Mohr, Joseph J.; Zenteno, A.; ...

2017-01-23

We study the galaxy populations in 74 Sunyaev–Zeldovich effect selected clusters from the South Pole Telescope survey, which have been imaged in the science verification phase of the Dark Energy Survey. The sample extends up to z ~ 1.1 with 4 × 10 14 M⊙ ≤ M200 ≤ 3 × 10 15M⊙. Using the band containing the 4000 Å break and its redward neighbour, we study the colour–magnitude distributions of cluster galaxies to ~m* + 2, finding that: (1)The intrinsic rest frame g – r colour width of the red sequence (RS) population is ~0.03 out to z ~ 0.85 with a preference for an increase to ~0.07 at z = 1, and (2) the prominence of the RS declines beyond z ~ 0.6. The spatial distribution of cluster galaxies is well described by the NFW profile out to 4R200 with a concentration of c g = 3.59more » $$+0.20\\atop{–0.18}$$, 5.37$$+0.27\\atop{-0.24}$$ and 1.38$$+0.21\\atop{-0.19}$$ for the full, the RS and the blue non-RS populations, respectively, but with ~40 per cent to 55 per cent cluster to cluster variation and no statistically significant redshift or mass trends. The number of galaxies within the virial region N200 exhibits a mass trend indicating that the number of galaxies per unit total mass is lower in the most massive clusters, and shows no significant redshift trend. The RS fraction within R200 is (68 ± 3) per cent at z = 0.46, varies from ~55 per cent at z = 1 to ~80 per cent at z = 0.1 and exhibits intrinsic variation among clusters of ~14 per cent. Finally, we discuss a model that suggests that the observed redshift trend in RS fraction favours a transformation time-scale for infalling field galaxies to become RS galaxies of 2–3 Gyr.« less

An improved probabilistic approach for linking progenitor and descendant galaxy populations using comoving number density

NASA Astrophysics Data System (ADS)

Wellons, Sarah; Torrey, Paul

2017-06-01

Galaxy populations at different cosmic epochs are often linked by cumulative comoving number density in observational studies. Many theoretical works, however, have shown that the cumulative number densities of tracked galaxy populations not only evolve in bulk, but also spread out over time. We present a method for linking progenitor and descendant galaxy populations which takes both of these effects into account. We define probability distribution functions that capture the evolution and dispersion of galaxy populations in number density space, and use these functions to assign galaxies at redshift zf probabilities of being progenitors/descendants of a galaxy population at another redshift z0. These probabilities are used as weights for calculating distributions of physical progenitor/descendant properties such as stellar mass, star formation rate or velocity dispersion. We demonstrate that this probabilistic method provides more accurate predictions for the evolution of physical properties than the assumption of either a constant number density or an evolving number density in a bin of fixed width by comparing predictions against galaxy populations directly tracked through a cosmological simulation. We find that the constant number density method performs least well at recovering galaxy properties, the evolving method density slightly better and the probabilistic method best of all. The improvement is present for predictions of stellar mass as well as inferred quantities such as star formation rate and velocity dispersion. We demonstrate that this method can also be applied robustly and easily to observational data, and provide a code package for doing so.

CANDELS/GOODS-S, CDFS, and ECDFS: photometric redshifts for normal and X-ray-detected galaxies

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

Hsu, Li-Ting; Salvato, Mara; Nandra, Kirpal

2014-11-20

We present photometric redshifts and associated probability distributions for all detected sources in the Extended Chandra Deep Field South (ECDFS). This work makes use of the most up-to-date data from the Cosmic Assembly Near-IR Deep Legacy Survey (CANDELS) and the Taiwan ECDFS Near-Infrared Survey (TENIS) in addition to other data. We also revisit multi-wavelength counterparts for published X-ray sources from the 4 Ms CDFS and 250 ks ECDFS surveys, finding reliable counterparts for 1207 out of 1259 sources (∼96%). Data used for photometric redshifts include intermediate-band photometry deblended using the TFIT method, which is used for the first time inmore » this work. Photometric redshifts for X-ray source counterparts are based on a new library of active galactic nuclei/galaxy hybrid templates appropriate for the faint X-ray population in the CDFS. Photometric redshift accuracy for normal galaxies is 0.010 and for X-ray sources is 0.014 and outlier fractions are 4% and 5.2%, respectively. The results within the CANDELS coverage area are even better, as demonstrated both by spectroscopic comparison and by galaxy-pair statistics. Intermediate-band photometry, even if shallow, is valuable when combined with deep broadband photometry. For best accuracy, templates must include emission lines.« less

Measuring the Stellar Populations of Individual Lyman Alpha Emitters During the Epoch of Peak Star Formation

NASA Astrophysics Data System (ADS)

Reddy, Naveen

2010-09-01

Selecting galaxies by their strong Lyman-alpha emission provides a powerful means of probing the reionization epoch and the faint/low-mass galaxies that dominate star formation at high redshift. Yet, our understanding of high-redshift Lyman-alpha emitters {LAEs} has lagged behind that of other well-studied populations {e.g., Lyman break galaxies} due to their continuum faintness and the shifting of age/mass-sensitive features into the near-IR where the high terrestrial background inhibits deep observations. All existing studies of LAEs at z>2 have used stacked optical and/or Spitzer infrared data to discern their median properties, but the actual distributions of ages, reddenings, and stellar masses for these populations are poorly characterized. To fill this glaring gap in the observations and advance our understanding of this important population, we propose WFC3/IR+F160W imaging of fields where we have conducted a survey of low redshift {z 1.9} Lyman-alpha emitters {LAEs}, in order to measure their ages and stellar masses at an epoch where such observations directly probe the age-sensitive Balmer/4000 AA breaks. The targeted sample will include 45-50 spectroscopically confirmed LAEs at z=1.7-2.1 and roughly twice as many candidates, making it the largest sample of homogeneously selected LAEs with individual measurements of the ages, masses, and dust extinction. With these data we will {1} carefully take into account the age-dependence of the extinction curve to make robust comparisons between LAEs and continuum-selected galaxies at the same redshifts; {2} combine clustering and stellar mass measurements to infer the duty cycles of LAEs and determine if they are triggered in the presence of large-scale structures; and {3} quantify the importance of the LAE phase at different galaxy luminosity and mass scales, over a large dynamic range in these properties. An economical investment of just 12 orbits will allow us to accomplish these goals, and remains the only hope of efficiently studying such low luminosity high-redshift galaxies in the near-IR prior to the JWST-era.

Cross-correlation redshift calibration without spectroscopic calibration samples in DES Science Verification Data

NASA Astrophysics Data System (ADS)

Davis, C.; Rozo, E.; Roodman, A.; Alarcon, A.; Cawthon, R.; Gatti, M.; Lin, H.; Miquel, R.; Rykoff, E. S.; Troxel, M. A.; Vielzeuf, P.; Abbott, T. M. C.; Abdalla, F. B.; Allam, S.; Annis, J.; Bechtol, K.; Benoit-Lévy, A.; Bertin, E.; Brooks, D.; Buckley-Geer, E.; Burke, D. L.; Carnero Rosell, A.; Carrasco Kind, M.; Carretero, J.; Castander, F. J.; Crocce, M.; Cunha, C. E.; D'Andrea, C. B.; da Costa, L. N.; Desai, S.; Diehl, H. T.; Doel, P.; Drlica-Wagner, A.; Fausti Neto, A.; Flaugher, B.; Fosalba, P.; Frieman, J.; García-Bellido, J.; Gaztanaga, E.; Gerdes, D. W.; Giannantonio, T.; Gruen, D.; Gruendl, R. A.; Gutierrez, G.; Honscheid, K.; Jain, B.; James, D. J.; Jeltema, T.; Krause, E.; Kuehn, K.; Kuhlmann, S.; Kuropatkin, N.; Lahav, O.; Li, T. S.; Lima, M.; March, M.; Marshall, J. L.; Martini, P.; Melchior, P.; Ogando, R. L. C.; Plazas, A. A.; Romer, A. K.; Sanchez, E.; Scarpine, V.; Schindler, R.; Schubnell, M.; Sevilla-Noarbe, I.; Smith, M.; Soares-Santos, M.; Sobreira, F.; Suchyta, E.; Swanson, M. E. C.; Tarle, G.; Thomas, D.; Vikram, V.; Walker, A. R.; Wechsler, R. H.

2018-06-01

Galaxy cross-correlations with high-fidelity redshift samples hold the potential to precisely calibrate systematic photometric redshift uncertainties arising from the unavailability of complete and representative training and validation samples of galaxies. However, application of this technique in the Dark Energy Survey (DES) is hampered by the relatively low number density, small area, and modest redshift overlap between photometric and spectroscopic samples. We propose instead using photometric catalogues with reliable photometric redshifts for photo-z calibration via cross-correlations. We verify the viability of our proposal using redMaPPer clusters from the Sloan Digital Sky Survey (SDSS) to successfully recover the redshift distribution of SDSS spectroscopic galaxies. We demonstrate how to combine photo-z with cross-correlation data to calibrate photometric redshift biases while marginalizing over possible clustering bias evolution in either the calibration or unknown photometric samples. We apply our method to DES Science Verification (DES SV) data in order to constrain the photometric redshift distribution of a galaxy sample selected for weak lensing studies, constraining the mean of the tomographic redshift distributions to a statistical uncertainty of Δz ˜ ±0.01. We forecast that our proposal can, in principle, control photometric redshift uncertainties in DES weak lensing experiments at a level near the intrinsic statistical noise of the experiment over the range of redshifts where redMaPPer clusters are available. Our results provide strong motivation to launch a programme to fully characterize the systematic errors from bias evolution and photo-z shapes in our calibration procedure.

Cross-correlation redshift calibration without spectroscopic calibration samples in DES Science Verification Data

DOE PAGES

Davis, C.; Rozo, E.; Roodman, A.; ...

2018-03-26

Galaxy cross-correlations with high-fidelity redshift samples hold the potential to precisely calibrate systematic photometric redshift uncertainties arising from the unavailability of complete and representative training and validation samples of galaxies. However, application of this technique in the Dark Energy Survey (DES) is hampered by the relatively low number density, small area, and modest redshift overlap between photometric and spectroscopic samples. We propose instead using photometric catalogs with reliable photometric redshifts for photo-z calibration via cross-correlations. We verify the viability of our proposal using redMaPPer clusters from the Sloan Digital Sky Survey (SDSS) to successfully recover the redshift distribution of SDSS spectroscopic galaxies. We demonstrate how to combine photo-z with cross-correlation data to calibrate photometric redshift biases while marginalizing over possible clustering bias evolution in either the calibration or unknown photometric samples. We apply our method to DES Science Verification (DES SV) data in order to constrain the photometric redshift distribution of a galaxy sample selected for weak lensing studies, constraining the mean of the tomographic redshift distributions to a statistical uncertainty ofmore » $$\\Delta z \\sim \\pm 0.01$$. We forecast that our proposal can in principle control photometric redshift uncertainties in DES weak lensing experiments at a level near the intrinsic statistical noise of the experiment over the range of redshifts where redMaPPer clusters are available. Here, our results provide strong motivation to launch a program to fully characterize the systematic errors from bias evolution and photo-z shapes in our calibration procedure.« less

Cross-correlation redshift calibration without spectroscopic calibration samples in DES Science Verification Data

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

Davis, C.; Rozo, E.; Roodman, A.

Galaxy cross-correlations with high-fidelity redshift samples hold the potential to precisely calibrate systematic photometric redshift uncertainties arising from the unavailability of complete and representative training and validation samples of galaxies. However, application of this technique in the Dark Energy Survey (DES) is hampered by the relatively low number density, small area, and modest redshift overlap between photometric and spectroscopic samples. We propose instead using photometric catalogs with reliable photometric redshifts for photo-z calibration via cross-correlations. We verify the viability of our proposal using redMaPPer clusters from the Sloan Digital Sky Survey (SDSS) to successfully recover the redshift distribution of SDSS spectroscopic galaxies. We demonstrate how to combine photo-z with cross-correlation data to calibrate photometric redshift biases while marginalizing over possible clustering bias evolution in either the calibration or unknown photometric samples. We apply our method to DES Science Verification (DES SV) data in order to constrain the photometric redshift distribution of a galaxy sample selected for weak lensing studies, constraining the mean of the tomographic redshift distributions to a statistical uncertainty ofmore » $$\\Delta z \\sim \\pm 0.01$$. We forecast that our proposal can in principle control photometric redshift uncertainties in DES weak lensing experiments at a level near the intrinsic statistical noise of the experiment over the range of redshifts where redMaPPer clusters are available. Here, our results provide strong motivation to launch a program to fully characterize the systematic errors from bias evolution and photo-z shapes in our calibration procedure.« less

The VIMOS Public Extragalactic Redshift Survey (VIPERS). Star formation history of passive red galaxies

NASA Astrophysics Data System (ADS)

Siudek, M.; Małek, K.; Scodeggio, M.; Garilli, B.; Pollo, A.; Haines, C. P.; Fritz, A.; Bolzonella, M.; de la Torre, S.; Granett, B. R.; Guzzo, L.; Abbas, U.; Adami, C.; Bottini, D.; Cappi, A.; Cucciati, O.; De Lucia, G.; Davidzon, I.; Franzetti, P.; Iovino, A.; Krywult, J.; Le Brun, V.; Le Fèvre, O.; Maccagni, D.; Marchetti, A.; Marulli, F.; Polletta, M.; Tasca, L. A. M.; Tojeiro, R.; Vergani, D.; Zanichelli, A.; Arnouts, S.; Bel, J.; Branchini, E.; Ilbert, O.; Gargiulo, A.; Moscardini, L.; Takeuchi, T. T.; Zamorani, G.

2017-01-01

Aims: We trace the evolution and the star formation history of passive red galaxies, using a subset of the VIMOS Public Extragalactic Redshift Survey (VIPERS). The detailed spectral analysis of stellar populations of intermediate-redshift passive red galaxies allows the build up of their stellar content to be followed over the last 8 billion years. Methods: We extracted a sample of passive red galaxies in the redshift range 0.4

TYPE Ia SUPERNOVA DISTANCE MODULUS BIAS AND DISPERSION FROM K-CORRECTION ERRORS: A DIRECT MEASUREMENT USING LIGHT CURVE FITS TO OBSERVED SPECTRAL TIME SERIES

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

Saunders, C.; Aldering, G.; Aragon, C.

2015-02-10

We estimate systematic errors due to K-corrections in standard photometric analyses of high-redshift Type Ia supernovae. Errors due to K-correction occur when the spectral template model underlying the light curve fitter poorly represents the actual supernova spectral energy distribution, meaning that the distance modulus cannot be recovered accurately. In order to quantify this effect, synthetic photometry is performed on artificially redshifted spectrophotometric data from 119 low-redshift supernovae from the Nearby Supernova Factory, and the resulting light curves are fit with a conventional light curve fitter. We measure the variation in the standardized magnitude that would be fit for a givenmore » supernova if located at a range of redshifts and observed with various filter sets corresponding to current and future supernova surveys. We find significant variation in the measurements of the same supernovae placed at different redshifts regardless of filters used, which causes dispersion greater than ∼0.05 mag for measurements of photometry using the Sloan-like filters and a bias that corresponds to a 0.03 shift in w when applied to an outside data set. To test the result of a shift in supernova population or environment at higher redshifts, we repeat our calculations with the addition of a reweighting of the supernovae as a function of redshift and find that this strongly affects the results and would have repercussions for cosmology. We discuss possible methods to reduce the contribution of the K-correction bias and uncertainty.« less

The Quest for Dusty Star-forming Galaxies at High Redshift z ≳ 4

NASA Astrophysics Data System (ADS)

Mancuso, C.; Lapi, A.; Shi, J.; Gonzalez-Nuevo, J.; Aversa, R.; Danese, L.

2016-06-01

We exploit the continuity equation approach and “main-sequence” star formation timescales to show that the observed high abundance of galaxies with stellar masses ≳ a few 1010 M ⊙ at redshift z ≳ 4 implies the existence of a galaxy population featuring large star formation rates (SFRs) ψ ≳ 102 M ⊙ yr-1 in heavily dust-obscured conditions. These galaxies constitute the high-redshift counterparts of the dusty star-forming population already surveyed for z ≲ 3 in the far-IR band by the Herschel Space Observatory. We work out specific predictions for the evolution of the corresponding stellar mass and SFR functions out to z ˜ 10, determining that the number density at z ≲ 8 for SFRs ψ ≳ 30 M ⊙ yr-1 cannot be estimated relying on the UV luminosity function alone, even when standard corrections for dust extinction based on the UV slope are applied. We compute the number counts and redshift distributions (including galaxy-scale gravitational lensing) of this galaxy population, and show that current data from the AzTEC-LABOCA, SCUBA-2, and ALMA-SPT surveys are already addressing it. We demonstrate how an observational strategy based on color preselection in the far-IR or (sub-)millimeter band with Herschel and SCUBA-2, supplemented by photometric data from on-source observations with ALMA, can allow us to reconstruct the bright end of the SFR functions out to z ≲ 8. In parallel, such a challenging task can be managed by exploiting current UV surveys in combination with (sub-)millimeter observations by ALMA and NIKA2 and/or radio observations by SKA and its precursors.

Modeling the evolution of infrared galaxies: a parametric backward evolution model

NASA Astrophysics Data System (ADS)

Béthermin, M.; Dole, H.; Lagache, G.; Le Borgne, D.; Penin, A.

2011-05-01

Aims: We attempt to model the infrared galaxy evolution in as simple a way as possible and reproduce statistical properties such as the number counts between 15 μm and 1.1 mm, the luminosity functions, and the redshift distributions. We then use the fitted model to interpret observations from Spitzer, AKARI, BLAST, LABOCA, AzTEC, SPT, and Herschel, and make predictions for Planck and future experiments such as CCAT or SPICA. Methods: This model uses an evolution in density and luminosity of the luminosity function parametrized by broken power-laws with two breaks at redshift ~0.9 and 2, and contains the two populations of the Lagache model: normal and starburst galaxies. We also take into account the effect of the strong lensing of high-redshift sub-millimeter galaxies. This effect is significant in the sub-mm and mm range near 50 mJy. It has 13 free parameters and eight additional calibration parameters. We fit the parameters to the IRAS, Spitzer, Herschel, and AzTEC measurements with a Monte Carlo Markov chain. Results: The model adjusted to deep counts at key wavelengths reproduces the counts from mid-infrared to millimeter wavelengths, as well as the mid-infrared luminosity functions. We discuss the contribution to both the cosmic infrared background (CIB) and the infrared luminosity density of the different populations. We also estimate the effect of the lensing on the number counts, and discuss the discovery by the South Pole Telescope (SPT) of a very bright population lying at high redshift. We predict the contribution of the lensed sources to the Planck number counts, the confusion level for future missions using a P(D) formalism, and the Universe opacity to TeV photons caused by the CIB. Material of the model (software, tables and predictions) is available online.

THE QUEST FOR DUSTY STAR-FORMING GALAXIES AT HIGH REDSHIFT z ≳ 4

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

Mancuso, C.; Lapi, A.; Shi, J.

2016-06-01

We exploit the continuity equation approach and “main-sequence” star formation timescales to show that the observed high abundance of galaxies with stellar masses ≳ a few 10{sup 10} M {sub ⊙} at redshift z ≳ 4 implies the existence of a galaxy population featuring large star formation rates (SFRs) ψ ≳ 10{sup 2} M {sub ⊙} yr{sup −1} in heavily dust-obscured conditions. These galaxies constitute the high-redshift counterparts of the dusty star-forming population already surveyed for z ≲ 3 in the far-IR band by the Herschel Space Observatory . We work out specific predictions for the evolution of the correspondingmore » stellar mass and SFR functions out to z ∼ 10, determining that the number density at z ≲ 8 for SFRs ψ ≳ 30 M {sub ⊙} yr{sup −1} cannot be estimated relying on the UV luminosity function alone, even when standard corrections for dust extinction based on the UV slope are applied. We compute the number counts and redshift distributions (including galaxy-scale gravitational lensing) of this galaxy population, and show that current data from the AzTEC - LABOCA , SCUBA-2 , and ALMA - SPT surveys are already addressing it. We demonstrate how an observational strategy based on color preselection in the far-IR or (sub-)millimeter band with Herschel and SCUBA-2 , supplemented by photometric data from on-source observations with ALMA , can allow us to reconstruct the bright end of the SFR functions out to z ≲ 8. In parallel, such a challenging task can be managed by exploiting current UV surveys in combination with (sub-)millimeter observations by ALMA and NIKA2 and/or radio observations by SKA and its precursors.« less

A steep slope and small scatter for the high-mass end of the L–σ relation at z ~ 0.55

DOE PAGES

Montero-Dorta, Antonio D.; Shu, Yiping; Bolton, Adam S.; ...

2016-01-07

We measure the intrinsic relation between velocity dispersion (σ) and luminosity (L) for massive, luminous red galaxies at redshift z ~ 0.55. Here, we achieve unprecedented precision by using a sample of 600 000 galaxies with spectra from the Baryon Oscillation Spectroscopic Survey of the third Sloan Digital Sky Survey (SDSS-III), covering a range of stellar masses M* ≳ 10 11M ⊙. We deconvolve the effects of photometric errors, limited spectroscopic signal-to-noise ratio, and red–blue galaxy confusion using a novel hierarchical Bayesian formalism that is generally applicable to any combination of photometric and spectroscopic observables. For an L–σ relation ofmore » the form L ∝ σ β, we find β = 7.8 ± 1.1 for σ corrected to the effective radius, and a very small intrinsic scatter of s = 0.047 ± 0.004 in log10σ at fixed L. No significant redshift evolution is found for these parameters. The evolution of the zero-point within the redshift range considered is consistent with the passive evolution of a galaxy population that formed at redshift z = 2–3, assuming single stellar populations. An analysis of previously reported results seems to indicate that the passively evolved high-mass L–σ relation at z ~ 0.55 is consistent with the one measured at z = 0.1. Finally, our results, in combination with those presented in the LF work of Montero-Dorta et al., provide a detailed description of the high-mass end of the red sequence (RS) at z ~ 0.55. This characterization, in the light of previous literature, suggest that the high-mass RS distribution corresponds to the ‘core’ elliptical population.« less

The LOFAR window on star-forming galaxies and AGNs - curved radio SEDs and IR-radio correlation at 0

NASA Astrophysics Data System (ADS)

Calistro Rivera, G.; Williams, W. L.; Hardcastle, M. J.; Duncan, K.; Röttgering, H. J. A.; Best, P. N.; Brüggen, M.; Chyży, K. T.; Conselice, C. J.; de Gasperin, F.; Engels, D.; Gürkan, G.; Intema, H. T.; Jarvis, M. J.; Mahony, E. K.; Miley, G. K.; Morabito, L. K.; Prandoni, I.; Sabater, J.; Smith, D. J. B.; Tasse, C.; van der Werf, P. P.; White, G. J.

2017-08-01

We present a study of the low-frequency radio properties of star-forming (SF) galaxies and active galactic nuclei (AGNs) up to redshift z = 2.5. The new spectral window probed by the Low Frequency Array (LOFAR) allows us to reconstruct the radio continuum emission from 150 MHz to 1.4 GHz to an unprecedented depth for a radio-selected sample of 1542 galaxies in ˜ 7 deg2 of the LOFAR Boötes field. Using the extensive multiwavelength data set available in Boötes and detailed modelling of the far-infrared to ultraviolet spectral energy distribution (SED), we are able to separate the star formation (N = 758) and the AGN (N = 784) dominated populations. We study the shape of the radio SEDs and their evolution across cosmic time and find significant differences in the spectral curvature between the SF galaxy and AGN populations. While the radio spectra of SF galaxies exhibit a weak but statistically significant flattening, AGN SEDs show a clear trend to become steeper towards lower frequencies. No evolution of the spectral curvature as a function of redshift is found for SF galaxies or AGNs. We investigate the redshift evolution of the infrared-radio correlation for SF galaxies and find that the ratio of total infrared to 1.4-GHz radio luminosities decreases with increasing redshift: q1.4 GHz = (2.45 ± 0.04) (1 + z)-0.15 ± 0.03. Similarly, q150 MHz shows a redshift evolution following q150 GHz = (1.72 ± 0.04) (1 + z)-0.22 ± 0.05. Calibration of the 150 MHz radio luminosity as a star formation rate tracer suggests that a single power-law extrapolation from q1.4 GHz is not an accurate approximation at all redshifts.

Simulations of deep galaxy fields. 1: Monte Carlo simulations of optical and near-infrared counts

NASA Technical Reports Server (NTRS)

Chokshi, Arati; Lonsdale, Carol J.; Mazzei, Paola; De Zotti, Gianfranco

1994-01-01

Monte Carlo simulations of three-dimensional galaxy distributions are performed, following the 1988 prescription of Chokshi & Wright, to study the photometric properties of evolving galaxy populations in the optical and near-infrared bands to high redshifts. In this paper, the first of a series, we present our baseline model in which galaxy numbers are conserved, and in which no explicit 'starburst' population is included. We use the model in an attempt to simultaneously fit published blue and near-infrared photometric and spectroscopic observations of deep fields. We find that our baseline models, with a formation redshift, z(sub f), of 1000, and H(sub 0) = 50, are able to reproduce the blue counts to b(sub j) = 22, independent of the value of Omega(sub 0), and also to provide a satisfactory fit to the observed blue-band redshift distributions, but for no value of Omega(sub 0) do we achieve an acceptable fit to the fainter blue counts. In the K band, we fit the number counts to the limit of the present-day surveys only for an Omega(sub 0) = 0 cosmology. We investigate the effect on the model fits of varying the cosmological parameters H(sub 0), the formation red-shift z(sub f), and the local luminosity function. Changing H(sub 0) does not improve the fits to the observations. However, reducing the epoch of a galaxy formation used in our simulations has a substantial effect. In particular, a model with z(sub f) approximately equal to 5 in a low Omega(sub 0) universe improves the fit to the faintest photometric blue data without any need to invoke a new population of galaxies, substantial merging, or a significant starburst galaxy population. For an Omega(sub 0) = 1 universe, however, reducing z(sub f) is less successful at fitting the blue-band counts and has little effect at all at K. Varying the parameters of the local luminosity function can also have a significant effect. In particular the steep low end slope of the local luminosity function of Franceschini et al. allows an acceptable fit to the b(sub j) less than or equal to 25 counts for Omega(sub 0) = 1, but is incompatible with Omega(sub 0) = 0.

Short gamma-ray bursts at the dawn of the gravitational wave era

NASA Astrophysics Data System (ADS)

Ghirlanda, G.; Salafia, O. S.; Pescalli, A.; Ghisellini, G.; Salvaterra, R.; Chassande-Mottin, E.; Colpi, M.; Nappo, F.; D'Avanzo, P.; Melandri, A.; Bernardini, M. G.; Branchesi, M.; Campana, S.; Ciolfi, R.; Covino, S.; Götz, D.; Vergani, S. D.; Zennaro, M.; Tagliaferri, G.

2016-10-01

We derive the luminosity function φ(L) and redshift distribution Ψ(z) of short gamma-ray bursts (SGRBs) using all the available observer-frame constraints (I.e. peak flux, fluence, peak energy and duration distributions) of the large population of Fermi SGRBs and the rest-frame properties of a complete sample of SGRBs detected by Swift. We show that a steep φ(L) ∝ L- α with α ≥ 2.0 is excluded if the full set of constraints is considered. We implement a Markov chain Monte Carlo method to derive the φ(L) and Ψ(z) functions assuming intrinsic Ep-Liso and Ep-Eiso correlations to hold or, alternatively, that the distributions of intrinsic peak energy, luminosity, and duration are independent. To make our results independent from assumptions on the progenitor (NS-NS binary mergers or other channels) and from uncertainties on the star formation history, we assume a parametric form for the redshift distribution of the population of SGRBs. We find that a relatively flat luminosity function with slope ~0.5 below a characteristic break luminosity ~3 × 1052 erg s-1 and a redshift distribution of SGRBs peaking at z ~ 1.5-2 satisfy all our constraints. These results also hold if no Ep-Liso and Ep-Eiso correlations are assumed and they do not depend on the choice of the minimum luminosity of the SGRB population. We estimate, within ~200 Mpc (I.e. the design aLIGO range for the detection of gravitational waves produced by NS-NS merger events), that there should be 0.007-0.03 SGRBs yr-1 detectable as γ-ray events. Assuming current estimates of NS-NS merger rates and that all NS-NS mergers lead to a SGRB event, we derive a conservative estimate of the average opening angle of SGRBs ⟨ θjet ⟩ ~ 3°-6°. The luminosity function implies a prompt emission average luminosity ⟨L⟩ ~ 1.5 × 1052 erg s-1, higher by nearly two orders of magnitude than previous findings in the literature, which greatly enhances the chance of observing SGRB "orphan" afterglows. Effort should go in the direction of finding and identifying such orphan afterglows as counterparts of GW events.

AN EVOLVING STELLAR INITIAL MASS FUNCTION AND THE GAMMA-RAY BURST REDSHIFT DISTRIBUTION

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

Wang, F. Y.; Dai, Z. G.

2011-02-01

Recent studies suggest that Swift gamma-ray bursts (GRBs) may not trace an ordinary star formation history (SFH). Here, we show that the GRB rate turns out to be consistent with the SFH with an evolving stellar initial mass function (IMF). We first show that the latest Swift sample of GRBs reveals an increasing evolution in the GRB rate relative to the ordinary star formation rate at high redshifts. We then assume only massive stars with masses greater than the critical value to produce GRBs and use an evolving stellar IMF suggested by Dave to fit the latest GRB redshift distribution.more » This evolving IMF would increase the relative number of massive stars, which could lead to more GRB explosions at high redshifts. We find that the evolving IMF can well reproduce the observed redshift distribution of Swift GRBs.« less

Analytic halo approach to the bispectrum of galaxies in redshift space

NASA Astrophysics Data System (ADS)

Yamamoto, Kazuhiro; Nan, Yue; Hikage, Chiaki

2017-02-01

We present an analytic formula for the galaxy bispectrum in redshift space on the basis of the halo approach description with the halo occupation distribution of central galaxies and satellite galaxies. This work is an extension of a previous work on the galaxy power spectrum, which illuminated the significant contribution of satellite galaxies to the higher multipole spectrum through the nonlinear redshift space distortions of their random motions. Behaviors of the multipoles of the bispectrum are compared with results of numerical simulations assuming a halo occupation distribution of the low-redshift (LOWZ) sample of the Sloan Digital Sky Survey (SDSS) III baryon oscillation spectroscopic survey (BOSS) survey. Also presented are analytic approximate formulas for the multipoles of the bispectrum, which is useful to understanding their characteristic properties. We demonstrate that the Fingers of God effect is quite important for the higher multipoles of the bispectrum in redshift space, depending on the halo occupation distribution parameters.

X-rays across the galaxy population - I. Tracing the main sequence of star formation

NASA Astrophysics Data System (ADS)

Aird, J.; Coil, A. L.; Georgakakis, A.

2017-03-01

We use deep Chandra imaging to measure the distribution of X-ray luminosities (LX) for samples of star-forming galaxies as a function of stellar mass and redshift, using a Bayesian method to push below the nominal X-ray detection limits. Our luminosity distributions all show narrow peaks at LX ≲ 1042 erg s-1 that we associate with star formation, as opposed to AGN that are traced by a broad tail to higher LX. Tracking the luminosity of these peaks as a function of stellar mass reveals an 'X-ray main sequence' with a constant slope ≈0.63 ± 0.03 over 8.5 ≲ log {M}_{ast }/M_{⊙} ≲ 11.5 and 0.1 ≲ z ≲ 4, with a normalization that increases with redshift as (1 + z)3.79 ± 0.12. We also compare the peak X-ray luminosities with UV-to-IR tracers of star formation rates (SFRs) to calibrate the scaling between LX and SFR. We find that LX ∝ SFR0.83 × (1 + z)1.3, where the redshift evolution and non-linearity likely reflect changes in high-mass X-ray binary populations of star-forming galaxies. Using galaxies with a broader range of SFR, we also constrain a stellar-mass-dependent contribution to LX, likely related to low-mass X-ray binaries. Using this calibration, we convert our X-ray main sequence to SFRs and measure a star-forming main sequence with a constant slope ≈0.76 ± 0.06 and a normalization that evolves with redshift as (1 + z)2.95 ± 0.33. Based on the X-ray emission, there is no evidence for a break in the main sequence at high stellar masses, although we cannot rule out a turnover given the uncertainties in the scaling of LX to SFR.

Accreting binary population synthesis and feedback prescriptions

NASA Astrophysics Data System (ADS)

Fragos, Tassos

2016-04-01

Studies of extagalactic X-ray binary populations have shown that the characteristics of these populations depend strongly on the characteristics of the host galaxy's parent stellar population (e.g. star-formation history and metallicity). These dependencies not only make X-ray binaries promising for aiding in the measurement of galaxy properties themselves, but they also have important astrophysical and cosmological implications. For example, due to the relatively young stellar ages and primordial metallicities in the early Universe (z > 3), it is predicted that X-ray binaries were more luminous than today. The more energetic X-ray photons, because of their long mean-free paths, can escape the galaxies where they are produced, and interact at long distances with the intergalactic medium. This could result in a smoother spatial distribution of ionized regions, and more importantly in an overall warmer intergalactic medium. The energetic X-ray photons emitted from X-ray binaries dominate the X-ray radiation field over active galactic nuclei at z > 6 - 8, and hence Χ-ray binary feedback can be a non-negligible contributor to the heating and reionization of the inter-galactic medium in the early universe. The spectral energy distribution shape of the XRB emission does not change significantly with redshift, suggesting that the same XRB subpopulation, namely black-hole XRBs in the high-soft state, dominates the cumulative emission at all times. On the contrary, the normalization of the spectral energy distribution does evolve with redshift. To zeroth order, this evolution is driven by the cosmic star-formation rate evolution. However, the metallicity evolution of the universe and the mean stellar population age are two important factors that affect the X-ray emission from high-mass and low-mass XRBs, respectively. In this talk, I will review recent studies on the potential feedback from accreting binary populations in galactic and cosmological scales. Furthermore, I will discuss which are the next steps towards a more physically realisitc modelling of accreting compact object populations in the early Universe.

Dark Energy Survey Year 1 Results: Calibration of redMaGiC Redshift Distributions in DES and SDSS from Cross-Correlations

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

Cawthon, R.; et al.

We present calibrations of the redshift distributions of redMaGiC galaxies in the Dark Energy Survey Year 1 (DES Y1) and Sloan Digital Sky Survey (SDSS) DR8 data. These results determine the priors of the redshift distribution of redMaGiC galaxies, which were used for galaxy clustering measurements and as lenses for galaxy-galaxy lensing measurements in DES Y1 cosmological analyses. We empirically determine the bias in redMaGiC photometric redshift estimates using angular cross-correlations with Baryon Oscillation Spectroscopic Survey (BOSS) galaxies. For DES, we calibrate a single parameter redshift bias in three photometric redshift bins:more » $$z \\in[0.15,0.3]$$, [0.3,0.45], and [0.45,0.6]. Our best fit results in each bin give photometric redshift biases of $$|\\Delta z|<0.01$$. To further test the redMaGiC algorithm, we apply our calibration procedure to SDSS redMaGiC galaxies, where the statistical precision of the cross-correlation measurement is much higher due to a greater overlap with BOSS galaxies. For SDSS, we also find best fit results of $$|\\Delta z|<0.01$$. We compare our results to other analyses of redMaGiC photometric redshifts.« less

Redshift surveys

NASA Technical Reports Server (NTRS)

Geller, Margaret J.; Huchra, J. P.

1991-01-01

Present-day understanding of the large-scale galaxy distribution is reviewed. The statistics of the CfA redshift survey are briefly discussed. The need for deeper surveys to clarify the issues raised by recent studies of large-scale galactic distribution is addressed.

A Ks-band-selected catalogue of objects in the ALHAMBRA survey

NASA Astrophysics Data System (ADS)

Nieves-Seoane, L.; Fernandez-Soto, A.; Arnalte-Mur, P.; Molino, A.; Stefanon, M.; Ferreras, I.; Ascaso, B.; Ballesteros, F. J.; Cristóbal-Hornillos, D.; López-Sanjuán, C.; Hurtado-Gil, Ll.; Márquez, I.; Masegosa, J.; Aguerri, J. A. L.; Alfaro, E.; Aparicio-Villegas, T.; Benítez, N.; Broadhurst, T.; Cabrera-Caño, J.; Castander, F. J.; Cepa, J.; Cerviño, M.; González Delgado, R. M.; Husillos, C.; Infante, L.; Martínez, V. J.; Moles, M.; Olmo, A. del; Perea, J.; Pović, M.; Prada, F.; Quintana, J. M.; Troncoso-Iribarren, P.; Viironen, K.

2017-02-01

The original ALHAMBRA catalogue contained over 400 000 galaxies selected using a synthetic F814W image, to the magnitude limit AB(F814W) ≈ 24.5. Given the photometric redshift depth of the ALHAMBRA multiband data ( = 0.86) and the approximately I-band selection, there is a noticeable bias against red objects at moderate redshift. We avoid this bias by creating a new catalogue selected in the Ks band. This newly obtained catalogue is certainly shallower in terms of apparent magnitude, but deeper in terms of redshift, with a significant population of red objects at z > 1. We select objects using the Ks band images, which reach an approximate AB magnitude limit Ks ≈ 22. We generate masks and derive completeness functions to characterize the sample. We have tested the quality of the photometry and photometric redshifts using both internal and external checks. Our final catalogue includes ≈95 000 sources down to Ks ≈ 22, with a significant tail towards high redshift. We have checked that there is a large sample of objects with spectral energy distributions that correspond to that of massive, passively evolving galaxies at z > 1, reaching as far as z ≈ 2.5. We have tested the possibility of combining our data with deep infrared observations at longer wavelengths, particularly Spitzer IRAC data.

Selection biases in empirical p(z) methods for weak lensing

DOE PAGES

Gruen, D.; Brimioulle, F.

2017-02-23

To measure the mass of foreground objects with weak gravitational lensing, one needs to estimate the redshift distribution of lensed background sources. This is commonly done in an empirical fashion, i.e. with a reference sample of galaxies of known spectroscopic redshift, matched to the source population. In this paper, we develop a simple decision tree framework that, under the ideal conditions of a large, purely magnitude-limited reference sample, allows an unbiased recovery of the source redshift probability density function p(z), as a function of magnitude and colour. We use this framework to quantify biases in empirically estimated p(z) caused bymore » selection effects present in realistic reference and weak lensing source catalogues, namely (1) complex selection of reference objects by the targeting strategy and success rate of existing spectroscopic surveys and (2) selection of background sources by the success of object detection and shape measurement at low signal to noise. For intermediate-to-high redshift clusters, and for depths and filter combinations appropriate for ongoing lensing surveys, we find that (1) spectroscopic selection can cause biases above the 10 per cent level, which can be reduced to ≈5 per cent by optimal lensing weighting, while (2) selection effects in the shape catalogue bias mass estimates at or below the 2 per cent level. Finally, this illustrates the importance of completeness of the reference catalogues for empirical redshift estimation.« less

RX J0848.6+4453: The evolution of galaxy sizes and stellar populations in A z = 1.27 cluster

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

Jørgensen, Inger; Chiboucas, Kristin; Schiavon, Ricardo P.

2014-12-01

RX J0848.6+4453 (Lynx W) at redshift 1.27 is part of the Lynx Supercluster of galaxies. We present an analysis of the stellar populations and star formation history for a sample of 24 members of the cluster. Our study is based on deep optical spectroscopy obtained with Gemini North combined with imaging data from Hubble Space Telescope. Focusing on the 13 bulge-dominated galaxies for which we can determine central velocity dispersions, we find that these show a smaller evolution with redshift of sizes and velocity dispersions than reported for field galaxies and galaxies in poorer clusters. Our data show that themore » galaxies in RX J0848.6+4453 populate the fundamental plane (FP) similar to that found for lower-redshift clusters. The zero-point offset for the FP is smaller than expected if the cluster's galaxies are to evolve passively through the location of the FP we established in our previous work for z = 0.8-0.9 cluster galaxies and then to the present-day FP. The FP zero point for RX J0848.6+4453 corresponds to an epoch of last star formation at z{sub form}=1.95{sub −0.15}{sup +0.22}. Further, we find that the spectra of the galaxies in RX J0848.6+4453 are dominated by young stellar populations at all galaxy masses and in many cases show emission indicating low-level ongoing star formation. The average age of the young stellar populations as estimated from the strength of the high-order Balmer line Hζ is consistent with a major star formation episode 1-2 Gyr prior, which in turn agrees with z {sub form} = 1.95. These galaxies dominated by young stellar populations are distributed throughout the cluster. We speculate that low-level star formation has not yet been fully quenched in the center of this cluster, possibly because the cluster is significantly poorer than other clusters previously studied at similar redshifts, which appear to have very little ongoing star formation in their centers. The mixture in RX J0848.6+4453 of passive galaxies with young stellar populations and massive galaxies still experiencing some star formation appears similar to the galaxy populations recently identified in two z ≈ 2 clusters.« less

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

Juneau, Stéphanie; Bournaud, Frédéric; Daddi, Emanuele

Emission line diagnostic diagrams probing the ionization sources in galaxies, such as the Baldwin-Phillips-Terlevich (BPT) diagram, have been used extensively to distinguish active galactic nuclei (AGN) from purely star-forming galaxies. However, they remain poorly understood at higher redshifts. We shed light on this issue with an empirical approach based on a z ∼ 0 reference sample built from ∼300,000 Sloan Digital Sky Survey galaxies, from which we mimic selection effects due to typical emission line detection limits at higher redshift. We combine this low-redshift reference sample with a simple prescription for luminosity evolution of the global galaxy population to predictmore » the loci of high-redshift galaxies on the BPT and Mass-Excitation (MEx) diagnostic diagrams. The predicted bivariate distributions agree remarkably well with direct observations of galaxies out to z ∼ 1.5, including the observed stellar mass-metallicity (MZ) relation evolution. As a result, we infer that high-redshift star-forming galaxies are consistent with having normal interstellar medium (ISM) properties out to z ∼ 1.5, after accounting for selection effects and line luminosity evolution. Namely, their optical line ratios and gas-phase metallicities are comparable to that of low-redshift galaxies with equivalent emission-line luminosities. In contrast, AGN narrow-line regions may show a shift toward lower metallicities at higher redshift. While a physical evolution of the ISM conditions is not ruled out for purely star-forming galaxies and may be more important starting at z ≳ 2, we find that reliably quantifying this evolution is hindered by selections effects. The recipes provided here may serve as a basis for future studies toward this goal. Code to predict the loci of galaxies on the BPT and MEx diagnostic diagrams and the MZ relation as a function of emission line luminosity limits is made publicly available.« less

Planck intermediate results: XXXIX. The Planck list of high-redshift source candidates

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

Ade, P. A. R.; Aghanim, N.; Arnaud, M.

The Planck mission, thanks to its large frequency range and all-sky coverage, has a unique potential for systematically detecting the brightest, and rarest, submillimetre sources on the sky, including distant objects in the high-redshift Universe traced by their dust emission. In this paper, a novel method, based on a component-separation procedure using a combination of Planck and IRAS data, has been validated and characterized on numerous simulations, and applied to select the most luminous cold submillimetre sources with spectral energy distributions peaking between 353 and 857 GHz at 5' resolution. A total of 2151 Planck high-z source candidates (the PHZ)more » have been detected in the cleanest 26% of the sky, with flux density at 545 GHz above 500 mJy. Embedded in the cosmic infrared background close to the confusion limit, these high-z candidates exhibit colder colours than their surroundings, consistent with redshifts z > 2, assuming a dust temperature of T xgal = 35 K and a spectral index of β xgal = 1.5. Exhibiting extremely high luminosities, larger than 10 14L ⊙, the PHZ objects may be made of multiple galaxies or clumps at high redshift, as suggested by a first statistical analysis based on a comparison with number count models. Furthermore, first follow-up observations obtained from optical to submillimetre wavelengths, which can be found in companion papers, have confirmed that this list consists of two distinct populations. A small fraction (around 3%) of the sources have been identified as strongly gravitationally lensed star-forming galaxies at redshift 2 to 4, while the vast majority of the PHZ sources appear as overdensities of dusty star-forming galaxies, having colours consistent with being at z > 2, and may be considered as proto-cluster candidates. The PHZ provides an original sample, which is complementary to the Planck Sunyaev-Zeldovich Catalogue (PSZ2); by extending the population of virialized massive galaxy clusters detected below z < 1.5 through their SZ signal to a population of sources at z > 1.5, the PHZ may contain the progenitors of today’s clusters. Therefore the Planck list of high-redshift source candidates opens a new window on the study of the early stages of structure formation, particularly understanding the intensively star-forming phase at high-z.« less

Planck intermediate results: XXXIX. The Planck list of high-redshift source candidates

DOE PAGES

Ade, P. A. R.; Aghanim, N.; Arnaud, M.; ...

2016-12-12

The Planck mission, thanks to its large frequency range and all-sky coverage, has a unique potential for systematically detecting the brightest, and rarest, submillimetre sources on the sky, including distant objects in the high-redshift Universe traced by their dust emission. In this paper, a novel method, based on a component-separation procedure using a combination of Planck and IRAS data, has been validated and characterized on numerous simulations, and applied to select the most luminous cold submillimetre sources with spectral energy distributions peaking between 353 and 857 GHz at 5' resolution. A total of 2151 Planck high-z source candidates (the PHZ)more » have been detected in the cleanest 26% of the sky, with flux density at 545 GHz above 500 mJy. Embedded in the cosmic infrared background close to the confusion limit, these high-z candidates exhibit colder colours than their surroundings, consistent with redshifts z > 2, assuming a dust temperature of T xgal = 35 K and a spectral index of β xgal = 1.5. Exhibiting extremely high luminosities, larger than 10 14L ⊙, the PHZ objects may be made of multiple galaxies or clumps at high redshift, as suggested by a first statistical analysis based on a comparison with number count models. Furthermore, first follow-up observations obtained from optical to submillimetre wavelengths, which can be found in companion papers, have confirmed that this list consists of two distinct populations. A small fraction (around 3%) of the sources have been identified as strongly gravitationally lensed star-forming galaxies at redshift 2 to 4, while the vast majority of the PHZ sources appear as overdensities of dusty star-forming galaxies, having colours consistent with being at z > 2, and may be considered as proto-cluster candidates. The PHZ provides an original sample, which is complementary to the Planck Sunyaev-Zeldovich Catalogue (PSZ2); by extending the population of virialized massive galaxy clusters detected below z < 1.5 through their SZ signal to a population of sources at z > 1.5, the PHZ may contain the progenitors of today’s clusters. Therefore the Planck list of high-redshift source candidates opens a new window on the study of the early stages of structure formation, particularly understanding the intensively star-forming phase at high-z.« less

The variance of dispersion measure of high-redshift transient objects as a probe of ionized bubble size during reionization

NASA Astrophysics Data System (ADS)

Yoshiura, Shintaro; Takahashi, Keitaro

2018-01-01

The dispersion measure (DM) of high-redshift (z ≳ 6) transient objects such as fast radio bursts can be a powerful tool to probe the intergalactic medium during the Epoch of Reionization. In this paper, we study the variance of the DMs of objects with the same redshift as a potential probe of the size distribution of ionized bubbles. We calculate the DM variance with a simple model with randomly distributed spherical bubbles. It is found that the DM variance reflects the characteristics of the probability distribution of the bubble size. We find that the variance can be measured precisely enough to obtain the information on the typical size with a few hundred sources at a single redshift.

Long High Redshift GRB and Xrt/swift Lightcurves

NASA Astrophysics Data System (ADS)

Arkhangelskaja, Irene

At February of 2010 the volume of Swift GRB subset with known redshift consisted of more than 150 bursts. Long GRB redshift distribution analysis has shown that confidence level of single peak approximation of this distribution is only ˜60%. Moreover, more than 40% of GRB are in very heavy tails outside 3σ level for this fit. More detailed analysis of long GRB redshift distribution reveals that at 97% confidence level at least two subgroups could be separated with following parameters: = 0.9 ± 0.1 and = 2.7 ± 0.2. It allows to make conclusion that Swift long GRB sources subset is not uniform. In the presented article attention is paid on the measure of discrepancy of long GRB with z>3 and subset of other long GRB with known redshifts. XRT/Swift lightcurves for these groups of GRB were considered and it have shown that at least 90% XRT/Swift lightcurves for GRB with z>3 are more complicated and have got a number of maxima.

High-redshift galaxy populations and their descendants

NASA Astrophysics Data System (ADS)

Guo, Qi; White, Simon D. M.

2009-06-01

We study predictions in the concordance Λ cold dark matter cosmology for the abundance and clustering of high-redshift galaxies and for the properties of their descendants. We focus on three high-redshift populations: Lyman break galaxies (LBGs) at z ~ 3, optically selected star-forming galaxies at z ~ 2 (BXs) and distant red galaxies (DRGs) at z ~ 2. We select galaxies from mock catalogues based on the Millennium Simulation using the observational colour and apparent magnitude criteria. With plausible dust assumptions, our galaxy formation model can simultaneously reproduce the abundances, redshift distributions and clustering of all three observed populations. The star formation rates (SFRs) of model LBGs and BXs are lower than those quoted for the real samples, reflecting differing initial mass functions and scatter in model dust properties. About 85 per cent of model galaxies selected as DRGs are star forming, with SFRs in the range 1 to ~100Msolaryr-1. Model LBGs, BXs and DRGs together account for less than half of all star formation over the range 1.5 < z < 3.2; many massive, star-forming galaxies are predicted to be too heavily obscured to appear in these populations. Model BXs have metallicities which agree roughly with observation, but model LBGs are only slightly more metal poor, in disagreement with recent observational results. The model galaxies are predominantly disc dominated. Stellar masses for LBGs and BXs are ~109.9Msolar, and for DRGs are ~1010.7Msolar. Only about 30 per cent of model galaxies with M* > 1011Msolar are classified as LBGs or BXs at the relevant redshifts, while 65 per cent are classified as DRGs. Almost all model LBGs and BXs are the central galaxies of their dark haloes, but fewer than half of the haloes of any given mass have an LBG or BX central galaxy. Half of all LBG descendants at z = 2 would be identified as BXs, but very few as DRGs. Clustering increases with decreasing redshift for descendants of all three populations, becoming stronger than that of L* galaxies by z = 0, when many have become satellite galaxies and their typical stellar mass has increased by a factor of 10 for LBGs and BXs and by a factor of 3 for DRGs. This growth is dominated by star formation until z ~ 1 and thereafter by mergers. Merging is predicted to be more important for LBG and DRG descendants than for BX descendants. Most LBGs and DRGs end up as red ellipticals, while BXs have a more varied fate. Over 70 per cent of local galaxies with M* > 1011Msolar are predicted to have at least one LBG/BX/DRG progenitor.

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

NASA Astrophysics Data System (ADS)

Fang, Guan-Wen; Ma, Zhong-Yang; Chen, Yang; Kong, Xu

2015-04-01

Using the high-resolution F160W images observed by the HST WFC3 (Hubble Space Telescope Wide Field Camera 3) in the CANDELS-EGS (Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey-Extended Groth Strip) field, we have studied the morphological and structural features of 9 ultraluminous infrared galaxies (ULIRGs) at z ∼ 2. We find a wide range of morphological diversity for these ULIRGs, from ellipsoids to multiple bright nuclei or diffuse structures, e.g., the double nuclei, gaseous bridges, dual asym- metries, irregular or elliptical structures. In order to study the morphology of these ULIRGs quantitatively, their morphological parameters (the Gini coeffcient G and moment index M20) are measured in the rest-frame optical wave- band. Compared with the low-redshift counterparts, the high-redshift ULIRGs show a smaller value of G and a larger value of M20, indicating a less concen- tricity and a larger asymmetry of the stellar population distribution in these ULIRGs. Based on a 2-D fitting of the brightness profiles of these ULIRGs, we have derived their effective radii, which are distributed in a range from 2.4 to kpc, with a mean value of (3.9 ± 1.1) kpc. Moreover, we find that in average the sizes of the high-redshift ULIRGs are one to two times smaller than those of the nearby star-forming galaxies of analogous stellar mass. Our results are consistent with those of other studies under the similar conditions of redshift and infrared luminosity.

The metallicity of the intracluster medium over cosmic time: further evidence for early enrichment

NASA Astrophysics Data System (ADS)

Mantz, Adam B.; Allen, Steven W.; Morris, R. Glenn; Simionescu, Aurora; Urban, Ondrej; Werner, Norbert; Zhuravleva, Irina

2017-12-01

We use Chandra X-ray data to measure the metallicity of the intracluster medium (ICM) in 245 massive galaxy clusters selected from X-ray and Sunyaev-Zel'dovich (SZ) effect surveys, spanning redshifts 0 < z < 1.2. Metallicities were measured in three different radial ranges, spanning cluster cores through their outskirts. We explore trends in these measurements as a function of cluster redshift, temperature and surface brightness 'peakiness' (a proxy for gas cooling efficiency in cluster centres). The data at large radii (0.5-1 r500) are consistent with a constant metallicity, while at intermediate radii (0.1-0.5 r500) we see a late-time increase in enrichment, consistent with the expected production and mixing of metals in cluster cores. In cluster centres, there are strong trends of metallicity with temperature and peakiness, reflecting enhanced metal production in the lowest entropy gas. Within the cool-core/sharply peaked cluster population, there is a large intrinsic scatter in central metallicity and no overall evolution, indicating significant astrophysical variations in the efficiency of enrichment. The central metallicity in clusters with flat surface brightness profiles is lower, with a smaller intrinsic scatter, but increases towards lower redshifts. Our results are consistent with other recent measurements of ICM metallicity as a function of redshift. They reinforce the picture implied by observations of uniform metal distributions in the outskirts of nearby clusters, in which most of the enrichment of the ICM takes place before cluster formation, with significant later enrichment taking place only in cluster centres, as the stellar populations of the central galaxies evolve.

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

Mantz, Adam B.; Allen, Steven W.; Morris, R. Glenn

Here, we use Chandra X-ray data to measure the metallicity of the intracluster medium (ICM) in 245 massive galaxy clusters selected from X-ray and Sunyaev–Zel'dovich (SZ) effect surveys, spanning redshifts 0 < z < 1.2. Metallicities were measured in three different radial ranges, spanning cluster cores through their outskirts. We explore trends in these measurements as a function of cluster redshift, temperature and surface brightness ‘peakiness’ (a proxy for gas cooling efficiency in cluster centres). The data at large radii (0.5–1 r500) are consistent with a constant metallicity, while at intermediate radii (0.1–0.5 r500) we see a late-time increase inmore » enrichment, consistent with the expected production and mixing of metals in cluster cores. In cluster centres, there are strong trends of metallicity with temperature and peakiness, reflecting enhanced metal production in the lowest entropy gas. Within the cool-core/sharply peaked cluster population, there is a large intrinsic scatter in central metallicity and no overall evolution, indicating significant astrophysical variations in the efficiency of enrichment. The central metallicity in clusters with flat surface brightness profiles is lower, with a smaller intrinsic scatter, but increases towards lower redshifts. Our results are consistent with other recent measurements of ICM metallicity as a function of redshift. They reinforce the picture implied by observations of uniform metal distributions in the outskirts of nearby clusters, in which most of the enrichment of the ICM takes place before cluster formation, with significant later enrichment taking place only in cluster centres, as the stellar populations of the central galaxies evolve.« less

EVOLUTION OF THE VELOCITY-DISPERSION FUNCTION OF LUMINOUS RED GALAXIES: A HIERARCHICAL BAYESIAN MEASUREMENT

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

Shu Yiping; Bolton, Adam S.; Dawson, Kyle S.

2012-04-15

We present a hierarchical Bayesian determination of the velocity-dispersion function of approximately 430,000 massive luminous red galaxies observed at relatively low spectroscopic signal-to-noise ratio (S/N {approx} 3-5 per 69 km s{sup -1}) by the Baryon Oscillation Spectroscopic Survey (BOSS) of the Sloan Digital Sky Survey III. We marginalize over spectroscopic redshift errors, and use the full velocity-dispersion likelihood function for each galaxy to make a self-consistent determination of the velocity-dispersion distribution parameters as a function of absolute magnitude and redshift, correcting as well for the effects of broadband magnitude errors on our binning. Parameterizing the distribution at each point inmore » the luminosity-redshift plane with a log-normal form, we detect significant evolution in the width of the distribution toward higher intrinsic scatter at higher redshifts. Using a subset of deep re-observations of BOSS galaxies, we demonstrate that our distribution-parameter estimates are unbiased regardless of spectroscopic S/N. We also show through simulation that our method introduces no systematic parameter bias with redshift. We highlight the advantage of the hierarchical Bayesian method over frequentist 'stacking' of spectra, and illustrate how our measured distribution parameters can be adopted as informative priors for velocity-dispersion measurements from individual noisy spectra.« less

The DESI Experiment Part I: Science,Targeting, and Survey Design

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

Aghamousa, Amir; et al.

DESI (Dark Energy Spectroscopic Instrument) is a Stage IV ground-based dark energy experiment that will study baryon acoustic oscillations (BAO) and the growth of structure through redshift-space distortions with a wide-area galaxy and quasar redshift survey. To trace the underlying dark matter distribution, spectroscopic targets will be selected in four classes from imaging data. We will measure luminous red galaxies up tomore » $z=1.0$. To probe the Universe out to even higher redshift, DESI will target bright [O II] emission line galaxies up to $z=1.7$. Quasars will be targeted both as direct tracers of the underlying dark matter distribution and, at higher redshifts ($ 2.1 < z < 3.5$), for the Ly-$$\\alpha$$ forest absorption features in their spectra, which will be used to trace the distribution of neutral hydrogen. When moonlight prevents efficient observations of the faint targets of the baseline survey, DESI will conduct a magnitude-limited Bright Galaxy Survey comprising approximately 10 million galaxies with a median $$z\\approx 0.2$$. In total, more than 30 million galaxy and quasar redshifts will be obtained to measure the BAO feature and determine the matter power spectrum, including redshift space distortions.« less

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.

High redshift galaxies in the ALHAMBRA survey . I. Selection method and number counts based on redshift PDFs

NASA Astrophysics Data System (ADS)

Viironen, K.; Marín-Franch, A.; López-Sanjuan, C.; Varela, J.; Chaves-Montero, J.; Cristóbal-Hornillos, D.; Molino, A.; Fernández-Soto, A.; Vilella-Rojo, G.; Ascaso, B.; Cenarro, A. J.; Cerviño, M.; Cepa, J.; Ederoclite, A.; Márquez, I.; Masegosa, J.; Moles, M.; Oteo, I.; Pović, M.; Aguerri, J. A. L.; Alfaro, E.; Aparicio-Villegas, T.; Benítez, N.; Broadhurst, T.; Cabrera-Caño, J.; Castander, J. F.; Del Olmo, A.; González Delgado, R. M.; Husillos, C.; Infante, L.; Martínez, V. J.; Perea, J.; Prada, F.; Quintana, J. M.

2015-04-01

Context. Most observational results on the high redshift restframe UV-bright galaxies are based on samples pinpointed using the so-called dropout technique or Ly-α selection. However, the availability of multifilter data now allows the dropout selections to be replaced by direct methods based on photometric redshifts. In this paper we present the methodology to select and study the population of high redshift galaxies in the ALHAMBRA survey data. Aims: Our aim is to develop a less biased methodology than the traditional dropout technique to study the high redshift galaxies in ALHAMBRA and other multifilter data. Thanks to the wide area ALHAMBRA covers, we especially aim at contributing to the study of the brightest, least frequent, high redshift galaxies. Methods: The methodology is based on redshift probability distribution functions (zPDFs). It is shown how a clean galaxy sample can be obtained by selecting the galaxies with high integrated probability of being within a given redshift interval. However, reaching both a complete and clean sample with this method is challenging. Hence, a method to derive statistical properties by summing the zPDFs of all the galaxies in the redshift bin of interest is introduced. Results: Using this methodology we derive the galaxy rest frame UV number counts in five redshift bins centred at z = 2.5,3.0,3.5,4.0, and 4.5, being complete up to the limiting magnitude at mUV(AB) = 24, where mUV refers to the first ALHAMBRA filter redwards of the Ly-α line. With the wide field ALHAMBRA data we especially contribute to the study of the brightest ends of these counts, accurately sampling the surface densities down to mUV(AB) = 21-22. Conclusions: We show that using the zPDFs it is easy to select a very clean sample of high redshift galaxies. We also show that it is better to do statistical analysis of the properties of galaxies using a probabilistic approach, which takes into account both the incompleteness and contamination issues in a natural way. Based on observations collected at the German-Spanish Astronomical Center, Calar Alto, jointly operated by the Max-Planck-Institut für Astronomie (MPIA) at Heidelberg and the Instituto de Astrofísica de Andalucía (CSIC).

Dark Energy Survey Year 1 Results: redshift distributions of the weak-lensing source galaxies

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

Hoyle, B.; Gruen, D.; Bernstein, G. M.

We describe the derivation and validation of redshift distribution estimates and their uncertainties for the galaxies used as weak lensing sources in the Dark Energy Survey (DES) Year 1 cosmological analyses. The Bayesian Photometric Redshift (BPZ) code is used to assign galaxies to four redshift bins between z=0.2 and 1.3, and to produce initial estimates of the lensing-weighted redshift distributionsmore » $$n^i_{PZ}(z)$$ for bin i. Accurate determination of cosmological parameters depends critically on knowledge of $n^i$ but is insensitive to bin assignments or redshift errors for individual galaxies. The cosmological analyses allow for shifts $$n^i(z)=n^i_{PZ}(z-\\Delta z^i)$$ to correct the mean redshift of $n^i(z)$ for biases in $$n^i_{\\rm PZ}$$. The $$\\Delta z^i$$ are constrained by comparison of independently estimated 30-band photometric redshifts of galaxies in the COSMOS field to BPZ estimates made from the DES griz fluxes, for a sample matched in fluxes, pre-seeing size, and lensing weight to the DES weak-lensing sources. In companion papers, the $$\\Delta z^i$$ are further constrained by the angular clustering of the source galaxies around red galaxies with secure photometric redshifts at 0.15« less

Dark Energy Survey Year 1 Results: redshift distributions of the weak-lensing source galaxies

DOE PAGES

Hoyle, B.; Gruen, D.; Bernstein, G. M.; ...

2018-04-18

We describe the derivation and validation of redshift distribution estimates and their uncertainties for the galaxies used as weak lensing sources in the Dark Energy Survey (DES) Year 1 cosmological analyses. The Bayesian Photometric Redshift (BPZ) code is used to assign galaxies to four redshift bins between z=0.2 and 1.3, and to produce initial estimates of the lensing-weighted redshift distributionsmore » $$n^i_{PZ}(z)$$ for bin i. Accurate determination of cosmological parameters depends critically on knowledge of $n^i$ but is insensitive to bin assignments or redshift errors for individual galaxies. The cosmological analyses allow for shifts $$n^i(z)=n^i_{PZ}(z-\\Delta z^i)$$ to correct the mean redshift of $n^i(z)$ for biases in $$n^i_{\\rm PZ}$$. The $$\\Delta z^i$$ are constrained by comparison of independently estimated 30-band photometric redshifts of galaxies in the COSMOS field to BPZ estimates made from the DES griz fluxes, for a sample matched in fluxes, pre-seeing size, and lensing weight to the DES weak-lensing sources. In companion papers, the $$\\Delta z^i$$ are further constrained by the angular clustering of the source galaxies around red galaxies with secure photometric redshifts at 0.15« less

Dark Energy Survey Year 1 Results: Redshift distributions of the weak lensing source galaxies

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

Hoyle, B.; et al.

2017-08-04

We describe the derivation and validation of redshift distribution estimates and their uncertainties for the galaxies used as weak lensing sources in the Dark Energy Survey (DES) Year 1 cosmological analyses. The Bayesian Photometric Redshift (BPZ) code is used to assign galaxies to four redshift bins between z=0.2 and 1.3, and to produce initial estimates of the lensing-weighted redshift distributionsmore » $$n^i_{PZ}(z)$$ for bin i. Accurate determination of cosmological parameters depends critically on knowledge of $n^i$ but is insensitive to bin assignments or redshift errors for individual galaxies. The cosmological analyses allow for shifts $$n^i(z)=n^i_{PZ}(z-\\Delta z^i)$$ to correct the mean redshift of $n^i(z)$ for biases in $$n^i_{\\rm PZ}$$. The $$\\Delta z^i$$ are constrained by comparison of independently estimated 30-band photometric redshifts of galaxies in the COSMOS field to BPZ estimates made from the DES griz fluxes, for a sample matched in fluxes, pre-seeing size, and lensing weight to the DES weak-lensing sources. In companion papers, the $$\\Delta z^i$$ are further constrained by the angular clustering of the source galaxies around red galaxies with secure photometric redshifts at 0.15« less

A quantitative study of peculiarities in galaxy morphology

NASA Astrophysics Data System (ADS)

Wu, Katherine Liang-Kai

I have developed a refined version of the asymmetry parameter first presented by Abraham et al. (1996). Coupled with a simple concentration index, this pair of indices, AW-CW, is compared to Abraham et al.'s log(AA)-log(C A) algorithm. These indices are then applied to a large sample of galaxies in the Hubble Deep Field with photometric redshifts from Connolly (1999). This allows investigation of trends at redshifts which have been largely inaccessible until now. The final sample consists of ~350 objects detected by the AW-CW algorithms with first-moment radii, r1 >= 0'.2 (corresponding to F814WAB ~ 26). The distribution of objects in the AW- CW plane is found to change with redshift. The region of the AW - CW plane populated by objects out to z ~ 1.2 is roughly constant. Accounting for bandpass shifting effects, this region resembles that populated by local bright galaxies (Frei et al. 1996) cosmologically simulated at z = 0.8. Beyond z ~ 1.2, the distribution of galaxies undergoes a significant change. Highly concentrated objects disappear from the AW-C W plane, while high asymmetry objects appear. The high concentration objects below z ~ 1.2 all have early-type morphologies. Very low resolution SEDs of these galaxies created using colors from Williams et al. (1996) are used to calculate the expected appearance of these objects at higher redshifts (z = 1.5 and 2.3). Assuming their luminosities and SEDs have not changed, one-third of the z ~ 0.8 objects would be undetected at z = 1.5, and 97% would disappear by z = 2.3. Any true drop in the number density of these objects would be completely masked by such strong selection effects. An increase in the number and degree of asymmetric objects is also seen beyond z ~ 1.2. Many of these objects exhibit multiple condensations, consistent with merging. Though the shifting of the ultraviolet galaxy spectrum into the F814W-band may be partially responsible, the majority of the increase in both number and degree of asymmetry appears to reflect a genuinely higher number density of asymmetric objects at earlier epochs. AW and CW are shown to be useful tools for exploring galaxy morphology over a wide range of redshifts. Future refinements combined with better SEDs and evolutionary models will undoubtedly reveal valuable insight into galaxy evolution.

Galaxy clusters in the cosmic web

NASA Astrophysics Data System (ADS)

Acebrón, A.; Durret, F.; Martinet, N.; Adami, C.; Guennou, L.

2014-12-01

Simulations of large scale structure formation in the universe predict that matter is essentially distributed along filaments at the intersection of which lie galaxy clusters. We have analysed 9 clusters in the redshift range 0.4

Absorption line indices in the UV. I. Empirical and theoretical stellar population models

NASA Astrophysics Data System (ADS)

Maraston, C.; Nieves Colmenárez, L.; Bender, R.; Thomas, D.

2009-01-01

Aims: Stellar absorption lines in the optical (e.g. the Lick system) have been extensively studied and constitute an important stellar population diagnostic for galaxies in the local universe and up to moderate redshifts. Proceeding towards higher look-back times, galaxies are younger and the ultraviolet becomes the relevant spectral region where the dominant stellar populations shine. A comprehensive study of ultraviolet absorption lines of stellar population models is however still lacking. With this in mind, we study absorption line indices in the far and mid-ultraviolet in order to determine age and metallicity indicators for UV-bright stellar populations in the local universe as well as at high redshift. Methods: We explore empirical and theoretical spectral libraries and use evolutionary population synthesis to compute synthetic line indices of stellar population models. From the empirical side, we exploit the IUE-low resolution library of stellar spectra and system of absorption lines, from which we derive analytical functions (fitting functions) describing the strength of stellar line indices as a function of gravity, temperature and metallicity. The fitting functions are entered into an evolutionary population synthesis code in order to compute the integrated line indices of stellar populations models. The same line indices are also directly evaluated on theoretical spectral energy distributions of stellar population models based on Kurucz high-resolution synthetic spectra, In order to select indices that can be used as age and/or metallicity indicators for distant galaxies and globular clusters, we compare the models to data of template globular clusters from the Magellanic Clouds with independently known ages and metallicities. Results: We provide synthetic line indices in the wavelength range ~1200 Å to ~3000 Å for stellar populations of various ages and metallicities.This adds several new indices to the already well-studied CIV and SiIV absorptions. Based on the comparison with globular cluster data, we select a set of 11 indices blueward of the 2000 Å rest-frame that allows us to recover well the ages and the metallicities of the clusters. These indices are ideal to study ages and metallicities of young galaxies at high redshift. We also provide the synthetic high-resolution stellar population SEDs.

"A Richness Study of 14 Distant X-Ray Clusters from the 160 Square Degree Survey"

NASA Technical Reports Server (NTRS)

Jones, Christine; West, Donald (Technical Monitor)

2001-01-01

We have measured the surface density of galaxies toward 14 X-ray-selected cluster candidates at redshifts z(sub i) 0.46, and we show that they are associated with rich galaxy concentrations. These clusters, having X-ray luminosities of Lx(0.5-2 keV) approx. (0.5 - 2.6) x 10(exp 44) ergs/ sec are among the most distant and luminous in our 160 deg(exp 2) ROSAT Position Sensitive Proportional Counter cluster survey. We find that the clusters range between Abell richness classes 0 and 2 and have a most probable richness class of 1. We compare the richness distribution of our distant clusters to those for three samples of nearby clusters with similar X-ray luminosities. We find that the nearby and distant samples have similar richness distributions, which shows that clusters have apparently not evolved substantially in richness since redshift z=0.5. There is, however, a marginal tendency for the distant clusters to be slightly poorer than nearby clusters, although deeper multicolor data for a large sample would be required to confirm this trend. We compare the distribution of distant X-ray clusters in the L(sub X)-richness plane to the distribution of optically selected clusters from the Palomar Distant Cluster Survey. The optically selected clusters appear overly rich for their X-ray luminosities, when compared to X-ray-selected clusters. Apparently, X-ray and optical surveys do not necessarily sample identical mass concentrations at large redshifts. This may indicate the existence of a population of optically rich clusters with anomalously low X-ray emission, More likely, however, it reflects the tendency for optical surveys to select unvirialized mass concentrations, as might be expected when peering along large-scale filaments.

Three-dimensional Identification and Reconstruction of Galaxy Systems within Flux-limited Redshift Surveys

NASA Astrophysics Data System (ADS)

Marinoni, Christian; Davis, Marc; Newman, Jeffrey A.; Coil, Alison L.

2002-11-01

We have developed a new geometrical method for identifying and reconstructing a homogeneous and highly complete set of galaxy groups within flux-limited redshift surveys. Our method combines information from the three-dimensional Voronoi diagram and its dual, the Delaunay triangulation, to obtain group and cluster catalogs that are remarkably robust over wide ranges in redshift and degree of density enhancement. As free by-products, this Voronoi-Delaunay method (VDM) provides a nonparametric measurement of the galaxy density around each object observed and a quantitative measure of the distribution of cosmological voids in the survey volume. In this paper, we describe the VDM algorithm in detail and test its effectiveness using a family of mock catalogs that simulate the Deep Extragalactic Evolutionary Probe (DEEP2) Redshift Survey, which should present at least as much challenge to cluster reconstruction methods as any other near-future survey that is capable of resolving their velocity dispersions. Using these mock DEEP2 catalogs, we demonstrate that the VDM algorithm can be used to identify a homogeneous set of groups in a magnitude-limited sample throughout the survey redshift window 0.7~400 km s-1. Finally, we argue that the bivariate distribution of systems as a function of redshift and velocity dispersion reconstructed with these techniques reproduces with high fidelity the underlying real space distribution and can thus be used robustly to constrain cosmological parameters. We expect that the VDM algorithm, which has performed so well when faced with the challenges posed by the DEEP2 survey, should only be more effective when applied to the better sampled, larger surveys of the local universe now underway.

A CONSTANT LIMITING MASS SCALE FOR FLAT EARLY-TYPE GALAXIES FROM z {approx} 1 TO z = 0: DENSITY EVOLVES BUT SHAPES DO NOT

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

Holden, Bradford P.; Van der Wel, Arjen; Rix, Hans-Walter

2012-04-20

We measure the evolution in the intrinsic shape distribution of early-type galaxies from z {approx} 1 to z {approx} 0 by analyzing their projected axis-ratio distributions. We extract a low-redshift sample (0.04 < z < 0.08) of early-type galaxies with very low star formation rates from the Sloan Digital Sky Survey, based on a color-color selection scheme and verified through the absence of emission lines in the spectra. The inferred intrinsic shape distribution of these early-type galaxies is strongly mass dependent: the typical short-to-long intrinsic axis ratio of high-mass early-type galaxies (>10{sup 11} M{sub Sun }) is 2:3, whereas atmore » masses below 10{sup 11} M{sub Sun} this ratio narrows to 1:3, or more flattened galaxies. In an entirely analogous manner, we select a high-redshift sample (0.6 < z < 0.8) from two deep-field surveys with multi-wavelength and Hubble Space Telescope/Advanced Camera for Surveys imaging: GEMS and COSMOS. We find a seemingly universal mass of {approx}10{sup 11} M{sub Sun} for highly flattened early-type systems at all redshifts. This implies that the process that grows an early-type galaxy above this ceiling mass, irrespective of cosmic epoch, involves forming round systems. Using both parametric and non-parametric tests, we find no evolution in the projected axis-ratio distribution for galaxies with masses >3 Multiplication-Sign 10{sup 10} M{sub Sun} with redshift. At the same time, our samples imply an increase of 2-3 Multiplication-Sign in comoving number density for early-type galaxies at masses >3 Multiplication-Sign 10{sup 10} M{sub Sun }, in agreement with previous studies. Given the direct connection between the axis-ratio distribution and the underlying bulge-to-disk ratio distribution, our findings imply that the number density evolution of early-type galaxies is not exclusively driven by the emergence of either bulge- or disk-dominated galaxies, but rather by a balanced mix that depends only on the stellar mass of the galaxy. The challenge for galaxy formation models is to reproduce this overall non-evolving ratio of flattened to round early-type galaxies in the context of a continually growing population.« less

Testing the Gamma-Ray Burst Energy Relationships

NASA Technical Reports Server (NTRS)

Band, David L.; Preece, Robert D.

2005-01-01

Building on Nakar & Piran's analysis of the Amati relation relating gamma-ray burst peak energies E(sub p) and isotropic energies E(sub iso ) we test the consistency of a large sample of BATSE bursts with the Amati and Ghirlanda (which relates peak energies and actual gamma-ray energies E(sub gamma)) relations. Each of these relations can be exp ressed as a ratio of the different energies that is a function of red shift (for both the Amati and Ghirlanda relations) and beaming fraction f(sub B) (for the Ghirlanda relation). The most rigorous test, whic h allows bursts to be at any redshift, corroborates Nakar & Piran's r esult - 88% of the BATSE bursts are inconsistent with the Amati relat ion - while only l.6% of the bursts are inconsistent with the Ghirlan da relation if f(sub B) = 1. Modelling the redshift distribution resu lts in an energy ratio distribution for the Amati relation that is sh ifted by an order of magnitude relative to the observed distributions; any sub-population satisfying the Amati relation can comprise at mos t approx. 18% of our burst sample. A similar analysis of the Ghirland a relation depends sensitively on the beaming fraction distribution f or small values of f(sub B); for reasonable estimates of this distrib ution about a third of the burst sample is inconsistent with the Ghir landa relation. Our results indicate that these relations are an artifact of the selection effects of the burst sample in which they were f ound; these selection effects may favor sub-populations for which the se relations are valid.

High-redshift Galaxies and Black Holes Detectable with the JWST: A Population Synthesis Model from Infrared to X-Rays

NASA Astrophysics Data System (ADS)

Volonteri, Marta; Reines, Amy E.; Atek, Hakim; Stark, Daniel P.; Trebitsch, Maxime

2017-11-01

The first billion years of the Universe has been a pivotal time: stars, black holes (BHs), and galaxies formed and assembled, sowing the seeds of galaxies as we know them today. Detecting, identifying, and understanding the first galaxies and BHs is one of the current observational and theoretical challenges in galaxy formation. In this paper we present a population synthesis model aimed at galaxies, BHs, and active galactic nuclei (AGNs) at high redshift. The model builds a population based on empirical relations. The spectral energy distribution of galaxies is determined by age and metallicity, and that of AGNs by BH mass and accretion rate. We validate the model against observations, and predict properties of galaxies and AGN in other wavelength and/or luminosity ranges, estimating the contamination of stellar populations (normal stars and high-mass X-ray binaries) for AGN searches from the infrared to X-rays, and vice versa for galaxy searches. For high-redshift galaxies with stellar ages < 1 {Gyr}, we find that disentangling stellar and AGN emission is challenging at restframe UV/optical wavelengths, while high-mass X-ray binaries become more important sources of confusion in X-rays. We propose a color-color selection in the James Webb Space Telescope bands to separate AGN versus star-dominated galaxies in photometric observations. We also estimate the AGN contribution, with respect to massive, hot, and metal-poor stars, at driving high-ionization lines, such as C IV and He II. Finally, we test the influence of the minimum BH mass and occupation fraction of BHs in low-mass galaxies on the restframe UV/near-IR and X-ray AGN luminosity function.

Investigations of gain redshift in high peak power Ti:sapphire laser systems

NASA Astrophysics Data System (ADS)

Wu, Fenxiang; Yu, Linpeng; Zhang, Zongxin; Li, Wenkai; Yang, Xiaojun; Wu, Yuanfeng; Li, Shuai; Wang, Cheng; Liu, Yanqi; Lu, Xiaoming; Xu, Yi; Leng, Yuxin

2018-07-01

Gain redshift in high peak power Ti:sapphire laser systems can result in narrowband spectral output and hence lengthen the compressed pulse duration. In order to realize broadband spectral output in 10 PW-class Ti:sapphire lasers, the influence on gain redshift induced by spectral pre-shaping, gain distribution of cascaded amplifiers and Extraction During Pumping (EDP) technique have been investigated. The theoretical and experimental results show that the redshift of output spectrum is sensitive to the spectral pre-shaping and the gain distribution of cascaded amplifiers, while insensitive to the pumping scheme with or without EDP. Moreover, the output spectrum from our future 10 PW Ti:sapphire laser is theoretically analyzed based on the investigations above, which indicates that a Fourier-transform limited (FTL) pulse duration of 21 fs can be achieved just by optimizing the spectral pre-shaping and gain distribution in 10 PW-class Ti:sapphire lasers.

Stochastic Order Redshift Technique (SORT): a simple, efficient and robust method to improve cosmological redshift measurements

NASA Astrophysics Data System (ADS)

Tejos, Nicolas; Rodríguez-Puebla, Aldo; Primack, Joel R.

2018-01-01

We present a simple, efficient and robust approach to improve cosmological redshift measurements. The method is based on the presence of a reference sample for which a precise redshift number distribution (dN/dz) can be obtained for different pencil-beam-like sub-volumes within the original survey. For each sub-volume we then impose that: (i) the redshift number distribution of the uncertain redshift measurements matches the reference dN/dz corrected by their selection functions and (ii) the rank order in redshift of the original ensemble of uncertain measurements is preserved. The latter step is motivated by the fact that random variables drawn from Gaussian probability density functions (PDFs) of different means and arbitrarily large standard deviations satisfy stochastic ordering. We then repeat this simple algorithm for multiple arbitrary pencil-beam-like overlapping sub-volumes; in this manner, each uncertain measurement has multiple (non-independent) 'recovered' redshifts which can be used to estimate a new redshift PDF. We refer to this method as the Stochastic Order Redshift Technique (SORT). We have used a state-of-the-art N-body simulation to test the performance of SORT under simple assumptions and found that it can improve the quality of cosmological redshifts in a robust and efficient manner. Particularly, SORT redshifts (zsort) are able to recover the distinctive features of the so-called 'cosmic web' and can provide unbiased measurement of the two-point correlation function on scales ≳4 h-1Mpc. Given its simplicity, we envision that a method like SORT can be incorporated into more sophisticated algorithms aimed to exploit the full potential of large extragalactic photometric surveys.

Infrared surface photometry of 3C 65: Stellar evolution and the Tolman signal

NASA Astrophysics Data System (ADS)

Rigler, M. A.; Lilly, S. J.

1994-06-01

We present an analysis of the infrared surface brightness profile of the high-redshift radio galaxy 3C 65 (z = 1.176), which is well fitted by a de Vaucouleurs r1/4 law. A model surface fitting routine yields characteristic photometric parameters comparable to those of low-redshift radio galaxies and brightest cluster members (BCMs) in standard cosmologies. The small displacement of this galaxy from the locus of low-redshift systems on the mur - log(re) plane suggests that little or no luminosity evolution is required in a cosmological model with (Omega0, lambda0 = (1,0), while a modest degree of luminosity evolution, accountable by passive evolution of the stellar population, is implied in models with (0, 0) or (0.1, 0.9). A nonexpanding cosmology is unlikely because it would require 3C 65 to lie at the extreme end of the distribution of properties of local gE galaxies, and the effects of plausible stellar and/or dynamic evolution would make 3C 65 even more extreme by the present epoch.

Populating dark matter haloes with galaxies: comparing the 2dFGRS with mock galaxy redshift surveys

NASA Astrophysics Data System (ADS)

Yang, Xiaohu; Mo, H. J.; Jing, Y. P.; van den Bosch, Frank C.; Chu, YaoQuan

2004-06-01

In two recent papers, we developed a powerful technique to link the distribution of galaxies to that of dark matter haloes by considering halo occupation numbers as a function of galaxy luminosity and type. In this paper we use these distribution functions to populate dark matter haloes in high-resolution N-body simulations of the standard ΛCDM cosmology with Ωm= 0.3, ΩΛ= 0.7 and σ8= 0.9. Stacking simulation boxes of 100 h-1 Mpc and 300 h-1 Mpc with 5123 particles each we construct mock galaxy redshift surveys out to a redshift of z= 0.2 with a numerical resolution that guarantees completeness down to 0.01L*. We use these mock surveys to investigate various clustering statistics. The predicted two-dimensional correlation function ξ(rp, π) reveals clear signatures of redshift space distortions. The projected correlation functions for galaxies with different luminosities and types, derived from ξ(rp, π), match the observations well on scales larger than ~3 h-1 Mpc. On smaller scales, however, the model overpredicts the clustering power by about a factor two. Modelling the `finger-of-God' effect on small scales reveals that the standard ΛCDM model predicts pairwise velocity dispersions (PVD) that are ~400 km s-1 too high at projected pair separations of ~1 h-1 Mpc. A strong velocity bias in massive haloes, with bvel≡σgal/σdm~ 0.6 (where σgal and σdm are the velocity dispersions of galaxies and dark matter particles, respectively) can reduce the predicted PVD to the observed level, but does not help to resolve the overprediction of clustering power on small scales. Consistent results can be obtained within the standard ΛCDM model only when the average mass-to-light ratio of clusters is of the order of 1000 (M/L)solar in the B-band. Alternatively, as we show by a simple approximation, a ΛCDM model with σ8~= 0.75 may also reproduce the observational results. We discuss our results in light of the recent WMAP results and the constraints on σ8 obtained independently from other observations.

The dark side of galaxy colour

NASA Astrophysics Data System (ADS)

Hearin, Andrew P.; Watson, Douglas F.

2013-10-01

We present age distribution matching, a theoretical formalism for predicting how galaxies of luminosity L and colour C occupy dark matter haloes. Our model supposes that there are just two fundamental properties of a halo that determine the colour and brightness of the galaxy it hosts: the maximum circular velocity Vmax and the redshift zstarve that correlates with the epoch at which the star formation in the galaxy ceases. The halo property zstarve is intended to encompass physical characteristics of halo mass assembly that may deprive the galaxy of its cold gas supply and, ultimately, quench its star formation. The new, defining feature of the model is that, at fixed luminosity, galaxy colour is in monotonic correspondence with zstarve, with the larger values of zstarve being assigned redder colours. We populate an N-body simulation with a mock galaxy catalogue based on age distribution matching and show that the resulting mock galaxy distribution accurately describes a variety of galaxy statistics. Our model suggests that halo and galaxy assembly are indeed correlated. We make publicly available our low-redshift, Sloan Digital Sky Survey Mr < -19 mock galaxy catalogue, and main progenitor histories of all z = 0 haloes, at http://logrus.uchicago.edu/~aphearin

How Dead are Dead Galaxies? Mid-Infrared Fluxes of Quiescent Galaxies at Redshift 0.3< Z< 2.5: Implications for Star Formation Rates and Dust Heating

NASA Technical Reports Server (NTRS)

Fumagalli, Mattia; Labbe, Ivo; Patel, Shannon G.; Franx, Marijn; vanDokkum, Pieter; Brammer, Gabriel; DaCunha, Elisabete; FoersterSchreiber, Natascha M.; Kriek, Mariska; Quadri, Ryan;

Unveiling the Galaxy Population at 1.3 < z < 4: the HUDF05 NICMOS Parallel Fields

NASA Technical Reports Server (NTRS)

Petty, Sara M.; deMello, Duilia F.; Wiklind, Tomy; Gardner, Jonathan P.; Mountain, Matt

2010-01-01

Using the Hubble Ultra Deep Field Near Infrared Camera and Multi-Object Spectrometer (HUDF-NICMOS) UDF05 parallel fields, we cross-matched 301 out of 630 galaxies with the ACS filters V606 and z850, NICMOS filters J110 and H160, and Spitzer IRAC filters at 3.6, 4.5, 5.8 , and 8.0 (mu)m. We modeled the spectral energy distributions (SEDs) to estimate: photometric redshifts, dust extinction, stellar mass, bolometric luminosity, starburst age and metallicity. To validate the photometric redshifts, comparisons with 16 spectroscopic redshifts give 75% within Delta < 0.2, which agrees with the sensitivities expected from the Balmer-break in our dataset. Five parallel fields observed by NICMOS have sensitivities in the H160-band of 80% at mAB = 25.4 and 50% at mAB = 26.7. Because the sample is H160-band selected, it is sensitive to stellar mass rather than UV luminosities. We also use Monte Carlo simulations to determine that the parameters from the best-fit SEDs are robust for the redshift ranges z > or approx. 1.3. Based on the robustness of the photometric redshifts, we analyze a subsample of the 301 galaxies at 1.3 < or = z < or = 2 (35 objects) and 3 < or = z < or = 4 (31 objects) and determine that L(BoI) and the star formation rate increase significantly from z approx. 1.5 to 4. The Balmer decrement is indicative of more evolved galaxies, and at high redshifts, they serve as records of some of the first galaxies. Therefore, the galaxies in this sample are great candidates for future surveys with the James Webb Space Telescope and Atacama Large Millimeter Array.

The Atacama Cosmology Telescope: Physical Properties and Purity of a Galaxy Cluster Sample Selected Via the Sunyaev-Zel'Dovich Effect

NASA Technical Reports Server (NTRS)

Menanteau, Felipe; Gonzalez, Jorge; Juin, Jean-Baptiste; Marriage, Tobias; Reese, Erik D.; Acquaviva, Viviana; Aguirre, Paula; Appel, John Willam; Baker, Andrew J.; Barrientos, L. Felipe;

Degradation analysis in the estimation of photometric redshifts from non-representative training sets

NASA Astrophysics Data System (ADS)

Rivera, J. D.; Moraes, B.; Merson, A. I.; Jouvel, S.; Abdalla, F. B.; Abdalla, M. C. B.

2018-07-01

We perform an analysis of photometric redshifts estimated by using a non-representative training sets in magnitude space. We use the ANNz2 and GPz algorithms to estimate the photometric redshift both in simulations and in real data from the Sloan Digital Sky Survey (DR12). We show that for the representative case, the results obtained by using both algorithms have the same quality, using either magnitudes or colours as input. In order to reduce the errors when estimating the redshifts with a non-representative training set, we perform the training in colour space. We estimate the quality of our results by using a mock catalogue which is split samples cuts in the r band between 19.4 < r < 20.8. We obtain slightly better results with GPz on single point z-phot estimates in the complete training set case, however the photometric redshifts estimated with ANNz2 algorithm allows us to obtain mildly better results in deeper r-band cuts when estimating the full redshift distribution of the sample in the incomplete training set case. By using a cumulative distribution function and a Monte Carlo process, we manage to define a photometric estimator which fits well the spectroscopic distribution of galaxies in the mock testing set, but with a larger scatter. To complete this work, we perform an analysis of the impact on the detection of clusters via density of galaxies in a field by using the photometric redshifts obtained with a non-representative training set.

Degradation analysis in the estimation of photometric redshifts from non-representative training sets

NASA Astrophysics Data System (ADS)

Rivera, J. D.; Moraes, B.; Merson, A. I.; Jouvel, S.; Abdalla, F. B.; Abdalla, M. C. B.

2018-04-01

We perform an analysis of photometric redshifts estimated by using a non-representative training sets in magnitude space. We use the ANNz2 and GPz algorithms to estimate the photometric redshift both in simulations as well as in real data from the Sloan Digital Sky Survey (DR12). We show that for the representative case, the results obtained by using both algorithms have the same quality, either using magnitudes or colours as input. In order to reduce the errors when estimating the redshifts with a non-representative training set, we perform the training in colour space. We estimate the quality of our results by using a mock catalogue which is split samples cuts in the r-band between 19.4 < r < 20.8. We obtain slightly better results with GPz on single point z-phot estimates in the complete training set case, however the photometric redshifts estimated with ANNz2 algorithm allows us to obtain mildly better results in deeper r-band cuts when estimating the full redshift distribution of the sample in the incomplete training set case. By using a cumulative distribution function and a Monte-Carlo process, we manage to define a photometric estimator which fits well the spectroscopic distribution of galaxies in the mock testing set, but with a larger scatter. To complete this work, we perform an analysis of the impact on the detection of clusters via density of galaxies in a field by using the photometric redshifts obtained with a non-representative training set.

First Results on the Cluster Galaxy Population from the Subaru Hyper Suprime-Cam Survey. III. Brightest Cluster Galaxies, Stellar Mass Distribution, and Active Galaxies

NASA Astrophysics Data System (ADS)

Lin, Yen-Ting; Hsieh, Bau-Ching; Lin, Sheng-Chieh; Oguri, Masamune; Chen, Kai-Feng; Tanaka, Masayuki; Chiu, I.-Non; Huang, Song; Kodama, Tadayuki; Leauthaud, Alexie; More, Surhud; Nishizawa, Atsushi J.; Bundy, Kevin; Lin, Lihwai; Miyazaki, Satoshi

2017-12-01

The unprecedented depth and area surveyed by the Subaru Strategic Program with the Hyper Suprime-Cam (HSC-SSP) have enabled us to construct and publish the largest distant cluster sample out to z∼ 1 to date. In this exploratory study of cluster galaxy evolution from z = 1 to z = 0.3, we investigate the stellar mass assembly history of brightest cluster galaxies (BCGs), the evolution of stellar mass and luminosity distributions, the stellar mass surface density profile, as well as the population of radio galaxies. Our analysis is the first high-redshift application of the top N richest cluster selection, which is shown to allow us to trace the cluster galaxy evolution faithfully. Over the 230 deg2 area of the current HSC-SSP footprint, selecting the top 100 clusters in each of the four redshift bins allows us to observe the buildup of galaxy population in descendants of clusters whose z≈ 1 mass is about 2× {10}14 {M}ȯ . Our stellar mass is derived from a machine-learning algorithm, which is found to be unbiased and accurate with respect to the COSMOS data. We find very mild stellar mass growth in BCGs (about 35% between z = 1 and 0.3), and no evidence for evolution in both the total stellar mass–cluster mass correlation and the shape of the stellar mass surface density profile. We also present the first measurement of the radio luminosity distribution in clusters out to z∼ 1, and show hints of changes in the dominant accretion mode powering the cluster radio galaxies at z∼ 0.8.

The Quest for Dusty Primeval Galaxies

NASA Astrophysics Data System (ADS)

Mancuso, C.; Lapi, A.; Danese, L.

2016-06-01

We exploit the continuity equation approach and the 'main sequence' star-formation timescales to show that the observed high abundance of galaxies with stellar masses ? a few >10^10 M_⊙ at redshift z >? 4 implies the existence of a galaxy population featuring large star formation rates (SFRs) ψ >? 10^2 M_⊙ yr^-1 in heavily dust-obscured conditions. These galaxies constitute the high-redshift counterparts of the dusty star-forming population already surveyed for z<3 in the far-IR band by the Herschel space observatory. We work out specific predictions for the evolution of the corresponding stellar mass and SFR functions out to z ˜ 10, elucidating that the number density at z 30 M_⊙ yr^-1 cannot be estimated relying on the UV luminosity function alone, even when standard corrections for dust extinction based on the UV slope are applied. We compute the number counts and redshift distributions (including galaxy-scale gravitational lensing) of this galaxy population, and show that current data from AzTEC-LABOCA, SCUBA-2 and ALMA-SPT surveys are already digging into it. We substantiate how an observational strategy based on a color preselection in the far-IR or (sub-)mm band with Herschel and SCUBA-2, supplemented by photometric data via on-source observations with ALMA, can allow to reconstruct the bright end of the SFR functions out to z ? 8. In parallel, such a challenging task can be managed by exploiting current UV surveys in combination with (sub-)mm observations by ALMA and NIKA2 and/or radio observations by SKA and its precursors.

The VIMOS Public Extragalactic Redshift Survey (VIPERS). The distinct build-up of dense and normal massive passive galaxies

NASA Astrophysics Data System (ADS)

Gargiulo, A.; Bolzonella, M.; Scodeggio, M.; Krywult, J.; De Lucia, G.; Guzzo, L.; Garilli, B.; Granett, B. R.; de la Torre, S.; Abbas, U.; Adami, C.; Arnouts, S.; Bottini, D.; Cappi, A.; Cucciati, O.; Davidzon, I.; Franzetti, P.; Fritz, A.; Haines, C.; Hawken, A. J.; Iovino, A.; Le Brun, V.; Le Fèvre, O.; Maccagni, D.; Małek, K.; Marulli, F.; Moutard, T.; Polletta, M.; Pollo, A.; Tasca, L. A. M.; Tojeiro, R.; Vergani, D.; Zanichelli, A.; Zamorani, G.; Bel, J.; Branchini, E.; Coupon, J.; Ilbert, O.; Moscardini, L.; Peacock, J. A.

2017-10-01

We have used the final data from the VIPERS redshift survey to extract an unparalleled sample of more than 2000 massive ℳ≥1011 M⊙ passive galaxies (MPGs) at redshift 0.5≤z≤1.0, based on their NUVrK colours. This has enabled us to investigate how the population of these objects was built up over cosmic time. We find that the evolution of the number density depends on the galaxy mean surface stellar mass density, Σ. In particular, dense (Σ≥2000 M⊙ pc-2) MPGs show a constant comoving number density over this redshift range, whilst this increases by a factor of approximately four for the least dense objects, defined as having Σ < 1000 M⊙ pc-2. We estimated stellar ages for the MPG population both fitting the spectral energy distribution (SED) and through the D4000n index, obtaining results in good agreement. Our findings are consistent with passive ageing of the stellar content of dense MPGs. We show that at any redshift the less dense MPGs are younger than dense ones and that their stellar populations evolve at a slower rate than predicted by passive evolution. This points to a scenario in which the overall population of MPGs was built up over the cosmic time by continuous addition of less dense galaxies: on top of an initial population of dense objects that passively evolves, new, larger, and younger MPGs continuously join the population at later epochs. Finally, we demonstrate that the observed increase in the number density of MPGs is totally accounted for by the observed decrease in the number density of correspondingly massive star forming galaxies (I.e. all the non-passive ℳ≥1011 M⊙ objects). Such systems observed at z ≃ 1 in VIPERS, therefore, represent the most plausible progenitors of the subsequent emerging class of larger MPGs. Based on observations collected at the European Southern Observatory, Cerro Paranal, Chile, using the Very Large Telescope under programs 182.A-0886 and partly 070.A-9007. Also based on observations obtained with MegaPrime/MegaCam, a joint project of CFHT and CEA/DAPNIA, at the Canada-France-Hawaii Telescope (CFHT), which is operated by the National Research Council (NRC) of Canada, the Institut National des Sciences de l'Univers of the Centre National de la Recherche Scientifique (CNRS) of France, and the University of Hawaii. This work is based in part on data products produced at TERAPIX and the Canadian Astronomy Data Centre as part of the Canada-France-Hawaii Telescope Legacy Survey, a collaborative project of NRC and CNRS. The VIPERS web site is http://www.vipers.inaf.it/

The metallicity of the intracluster medium over cosmic time: further evidence for early enrichment

DOE PAGES

Mantz, Adam B.; Allen, Steven W.; Morris, R. Glenn; ...

2017-08-26

Here, we use Chandra X-ray data to measure the metallicity of the intracluster medium (ICM) in 245 massive galaxy clusters selected from X-ray and Sunyaev–Zel'dovich (SZ) effect surveys, spanning redshifts 0 < z < 1.2. Metallicities were measured in three different radial ranges, spanning cluster cores through their outskirts. We explore trends in these measurements as a function of cluster redshift, temperature and surface brightness ‘peakiness’ (a proxy for gas cooling efficiency in cluster centres). The data at large radii (0.5–1 r500) are consistent with a constant metallicity, while at intermediate radii (0.1–0.5 r500) we see a late-time increase inmore » enrichment, consistent with the expected production and mixing of metals in cluster cores. In cluster centres, there are strong trends of metallicity with temperature and peakiness, reflecting enhanced metal production in the lowest entropy gas. Within the cool-core/sharply peaked cluster population, there is a large intrinsic scatter in central metallicity and no overall evolution, indicating significant astrophysical variations in the efficiency of enrichment. The central metallicity in clusters with flat surface brightness profiles is lower, with a smaller intrinsic scatter, but increases towards lower redshifts. Our results are consistent with other recent measurements of ICM metallicity as a function of redshift. They reinforce the picture implied by observations of uniform metal distributions in the outskirts of nearby clusters, in which most of the enrichment of the ICM takes place before cluster formation, with significant later enrichment taking place only in cluster centres, as the stellar populations of the central galaxies evolve.« less

New insights on the accuracy of photometric redshift measurements

NASA Astrophysics Data System (ADS)

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

2001-12-01

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

AGN Populations in Large-volume X-Ray Surveys: Photometric Redshifts and Population Types Found in the Stripe 82X Survey

NASA Astrophysics Data System (ADS)

Ananna, Tonima Tasnin; Salvato, Mara; LaMassa, Stephanie; Urry, C. Megan; Cappelluti, Nico; Cardamone, Carolin; Civano, Francesca; Farrah, Duncan; Gilfanov, Marat; Glikman, Eilat; Hamilton, Mark; Kirkpatrick, Allison; Lanzuisi, Giorgio; Marchesi, Stefano; Merloni, Andrea; Nandra, Kirpal; Natarajan, Priyamvada; Richards, Gordon T.; Timlin, John

2017-11-01

Multiwavelength surveys covering large sky volumes are necessary to obtain an accurate census of rare objects such as high-luminosity and/or high-redshift active galactic nuclei (AGNs). Stripe 82X is a 31.3 X-ray survey with Chandra and XMM-Newton observations overlapping the legacy Sloan Digital Sky Survey Stripe 82 field, which has a rich investment of multiwavelength coverage from the ultraviolet to the radio. The wide-area nature of this survey presents new challenges for photometric redshifts for AGNs compared to previous work on narrow-deep fields because it probes different populations of objects that need to be identified and represented in the library of templates. Here we present an updated X-ray plus multiwavelength matched catalog, including Spitzer counterparts, and estimated photometric redshifts for 5961 (96% of a total of 6181) X-ray sources that have a normalized median absolute deviation, σnmad=0.06, and an outlier fraction, η = 13.7%. The populations found in this survey and the template libraries used for photometric redshifts provide important guiding principles for upcoming large-area surveys such as eROSITA and 3XMM (in X-ray) and the Large Synoptic Survey Telescope (optical).

A revised and updated catalog of quasi-stellar objects

NASA Technical Reports Server (NTRS)

Hewitt, A.; Burbidge, G.

1993-01-01

The paper contains a catalog of all known quasi-stellar objects (QSOs) with measured emission redshifts, and BL Lac objects, complete to 1992 December 31. The catalog contains 7315 objects, nearly all QSOs including about 90 BL Lac objects. The catalog and references contain extensive information on names, positions, magnitudes, colors, emission-line redshifts, absorption, variability, polarization, and X-ray, radio, and infrared data. A key in the form of subsidiary tables enables the reader to relate the name of a given object to its coordinate name, which is used throughout the compilation. Plots of the Hubble diagram, the apparent magnitude distribution, the emission redshift distribution, and the distribution of the QSOs on the sky are also given.

Planck intermediate results. XXXIX. The Planck list of high-redshift source candidates

NASA Astrophysics Data System (ADS)

Planck Collaboration; Ade, P. A. R.; Aghanim, N.; Arnaud, M.; Aumont, J.; Baccigalupi, C.; Banday, A. J.; Barreiro, R. B.; Bartolo, N.; Battaner, E.; Benabed, K.; Benoit-Lévy, A.; Bernard, J.-P.; Bersanelli, M.; Bielewicz, P.; Bonaldi, A.; Bonavera, L.; Bond, J. R.; Borrill, J.; Bouchet, F. R.; Boulanger, F.; Burigana, C.; Butler, R. C.; Calabrese, E.; Catalano, A.; Chiang, H. C.; Christensen, P. R.; Clements, D. L.; Colombo, L. P. L.; Couchot, F.; Coulais, A.; Crill, B. P.; Curto, A.; Cuttaia, F.; Danese, L.; Davies, R. D.; Davis, R. J.; de Bernardis, P.; de Rosa, A.; de Zotti, G.; Delabrouille, J.; Dickinson, C.; Diego, J. M.; Dole, H.; Doré, O.; Douspis, M.; Ducout, A.; Dupac, X.; Elsner, F.; Enßlin, T. A.; Eriksen, H. K.; Falgarone, E.; Finelli, F.; Flores-Cacho, I.; Frailis, M.; Fraisse, A. A.; Franceschi, E.; Galeotta, S.; Galli, S.; Ganga, K.; Giard, M.; Giraud-Héraud, Y.; Gjerløw, E.; González-Nuevo, J.; Górski, K. M.; Gregorio, A.; Gruppuso, A.; Gudmundsson, J. E.; Hansen, F. K.; Harrison, D. L.; Helou, G.; Hernández-Monteagudo, C.; Herranz, D.; Hildebrandt, S. R.; Hivon, E.; Hobson, M.; Hornstrup, A.; Hovest, W.; Huffenberger, K. M.; Hurier, G.; Jaffe, A. H.; Jaffe, T. R.; Keihänen, E.; Keskitalo, R.; Kisner, T. S.; Kneissl, R.; Knoche, J.; Kunz, M.; Kurki-Suonio, H.; Lagache, G.; Lamarre, J.-M.; Lasenby, A.; Lattanzi, M.; Lawrence, C. R.; Leonardi, R.; Levrier, F.; Liguori, M.; Lilje, P. B.; Linden-Vørnle, M.; López-Caniego, M.; Lubin, P. M.; Macías-Pérez, J. F.; Maffei, B.; Maggio, G.; Maino, D.; Mandolesi, N.; Mangilli, A.; Maris, M.; Martin, P. G.; Martínez-González, E.; Masi, S.; Matarrese, S.; Melchiorri, A.; Mennella, A.; Migliaccio, M.; Mitra, S.; Miville-Deschênes, M.-A.; Moneti, A.; Montier, L.; Morgante, G.; Mortlock, D.; Munshi, D.; Murphy, J. A.; Nati, F.; Natoli, P.; Nesvadba, N. P. H.; Noviello, F.; Novikov, D.; Novikov, I.; Oxborrow, C. A.; Pagano, L.; Pajot, F.; Paoletti, D.; Partridge, B.; Pasian, F.; Pearson, T. J.; Perdereau, O.; Perotto, L.; Pettorino, V.; Piacentini, F.; Piat, M.; Plaszczynski, S.; Pointecouteau, E.; Polenta, G.; Pratt, G. W.; Prunet, S.; Puget, J.-L.; Rachen, J. P.; Reinecke, M.; Remazeilles, M.; Renault, C.; Renzi, A.; Ristorcelli, I.; Rocha, G.; Rosset, C.; Rossetti, M.; Roudier, G.; Rubiño-Martín, J. A.; Rusholme, B.; Sandri, M.; Santos, D.; Savelainen, M.; Savini, G.; Scott, D.; Spencer, L. D.; Stolyarov, V.; Stompor, R.; Sudiwala, R.; Sunyaev, R.; Suur-Uski, A.-S.; Sygnet, J.-F.; Tauber, J. A.; Terenzi, L.; Toffolatti, L.; Tomasi, M.; Tristram, M.; Tucci, M.; Türler, M.; Umana, G.; Valenziano, L.; Valiviita, J.; Van Tent, F.; Vielva, P.; Villa, F.; Wade, L. A.; Wandelt, B. D.; Wehus, I. K.; Welikala, N.; Yvon, D.; Zacchei, A.; Zonca, A.

2016-12-01

The Planck mission, thanks to its large frequency range and all-sky coverage, has a unique potential for systematically detecting the brightest, and rarest, submillimetre sources on the sky, including distant objects in the high-redshift Universe traced by their dust emission. A novel method, based on a component-separation procedure using a combination of Planck and IRAS data, has been validated and characterized on numerous simulations, and applied to select the most luminous cold submillimetre sources with spectral energy distributions peaking between 353 and 857 GHz at 5' resolution. A total of 2151 Planck high-z source candidates (the PHZ) have been detected in the cleanest 26% of the sky, with flux density at 545 GHz above 500 mJy. Embedded in the cosmic infrared background close to the confusion limit, these high-z candidates exhibit colder colours than their surroundings, consistent with redshifts z > 2, assuming a dust temperature of Txgal = 35 K and a spectral index of βxgal = 1.5. Exhibiting extremely high luminosities, larger than 1014L⊙, the PHZ objects may be made of multiple galaxies or clumps at high redshift, as suggested by a first statistical analysis based on a comparison with number count models. Furthermore, first follow-up observations obtained from optical to submillimetre wavelengths, which can be found in companion papers, have confirmed that this list consists of two distinct populations. A small fraction (around 3%) of the sources have been identified as strongly gravitationally lensed star-forming galaxies at redshift 2 to 4, while the vast majority of the PHZ sources appear as overdensities of dusty star-forming galaxies, having colours consistent with being at z > 2, and may be considered as proto-cluster candidates. The PHZ provides an original sample, which is complementary to the Planck Sunyaev-Zeldovich Catalogue (PSZ2); by extending the population of virialized massive galaxy clusters detected below z < 1.5 through their SZ signal to a population of sources at z > 1.5, the PHZ may contain the progenitors of today's clusters. Hence the Planck list of high-redshift source candidates opens a new window on the study of the early stages of structure formation, particularly understanding the intensively star-forming phase at high-z. The catalogue 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/596/A100

Herschel Far Infrared Spectra of Dusty Star-Forming Galaxies

NASA Astrophysics Data System (ADS)

Wilson, Derek; Cooray, Asantha R.; Nayyeri, Hooshang

2017-01-01

We stack archival spectra from the Herschel Space Observatory's SPIRE Spectrometer in three redshift bins from low redshifts (z < 0.2), through intermediate redshifts (0.2 < z < 1), and up to high redshifts (z > 1) in order to determine the average properties of the gas and dust in dusty, star-forming galaxies and (U)LIRGs. In the lower-redshift stack, we detect a host of water and carbon monoxide rotational transition lines, as well as some fine structure lines such as [NII]. At intermediate redshifts, only a [CII] line appears. The high-redshift stack displays strong [CII] emission, as well as faint emission from [OI] and [OIII]. The observed emission lines are used to model the average number density and radiation field strength in the photodissociation regions of our high-redshift sample, and the spectral line energy distributions of CO rotational transitions from the low-redshift stack are presented.

Spectroscopic Needs for Imaging Dark Energy Experiments

DOE PAGES

Newman, Jeffrey A.; Slosar, Anze; Abate, Alexandra; ...

2015-03-15

Ongoing and near-future imaging-based dark energy experiments are critically dependent upon photometric redshifts (a.k.a. photo-z’s): i.e., estimates of the redshifts of objects based only on flux information obtained through broad filters. Higher-quality, lower-scatter photo-z’s will result in smaller random errors on cosmological parameters; while systematic errors in photometric redshift estimates, if not constrained, may dominate all other uncertainties from these experiments. The desired optimization and calibration is dependent upon spectroscopic measurements for secure redshift information; this is the key application of galaxy spectroscopy for imaging-based dark energy experiments. Hence, to achieve their full potential, imaging-based experiments will require large setsmore » of objects with spectroscopically-determined redshifts, for two purposes: Training: Objects with known redshift are needed to map out the relationship between object color and z (or, equivalently, to determine empirically-calibrated templates describing the rest-frame spectra of the full range of galaxies, which may be used to predict the color-z relation). The ultimate goal of training is to minimize each moment of the distribution of differences between photometric redshift estimates and the true redshifts of objects, making the relationship between them as tight as possible. The larger and more complete our “training set” of spectroscopic redshifts is, the smaller the RMS photo-z errors should be, increasing the constraining power of imaging experiments; Requirements: Spectroscopic redshift measurements for ~30,000 objects over >~15 widely-separated regions, each at least ~20 arcmin in diameter, and reaching the faintest objects used in a given experiment, will likely be necessary if photometric redshifts are to be trained and calibrated with conventional techniques. Larger, more complete samples (i.e., with longer exposure times) can improve photo-z algorithms and reduce scatter further, enhancing the science return from planned experiments greatly (increasing the Dark Energy Task Force figure of merit by up to ~50%); Options: This spectroscopy will most efficiently be done by covering as much of the optical and near-infrared spectrum as possible at modestly high spectral resolution (λ/Δλ > ~3000), while maximizing the telescope collecting area, field of view on the sky, and multiplexing of simultaneous spectra. The most efficient instrument for this would likely be either the proposed GMACS/MANIFEST spectrograph for the Giant Magellan Telescope or the OPTIMOS spectrograph for the European Extremely Large Telescope, depending on actual properties when built. The PFS spectrograph at Subaru would be next best and available considerably earlier, c. 2018; the proposed ngCFHT and SSST telescopes would have similar capabilities but start later. Other key options, in order of increasing total time required, are the WFOS spectrograph at TMT, MOONS at the VLT, and DESI at the Mayall 4 m telescope (or the similar 4MOST and WEAVE projects); of these, only DESI, MOONS, and PFS are expected to be available before 2020. Table 2-3 of this white paper summarizes the observation time required at each facility for strawman training samples. To attain secure redshift measurements for a high fraction of targeted objects and cover the full redshift span of future experiments, additional near-infrared spectroscopy will also be required; this is best done from space, particularly with WFIRST-2.4 and JWST; Calibration: The first several moments of redshift distributions (the mean, RMS redshift dispersion, etc.), must be known to high accuracy for cosmological constraints not to be systematics-dominated (equivalently, the moments of the distribution of differences between photometric and true redshifts could be determined instead). The ultimate goal of calibration is to characterize these moments for every subsample used in analyses - i.e., to minimize the uncertainty in their mean redshift, RMS dispersion, etc. – rather than to make the moments themselves small. Calibration may be done with the same spectroscopic dataset used for training if that dataset is extremely high in redshift completeness (i.e., no populations of galaxies to be used in analyses are systematically missed). Accurate photo-z calibration is necessary for all imaging experiments; Requirements: If extremely low levels of systematic incompleteness (<~0.1%) are attained in training samples, the same datasets described above should be sufficient for calibration. However, existing deep spectroscopic surveys have failed to yield secure redshifts for 30–60% of targets, so that would require very large improvements over past experience. This incompleteness would be a limiting factor for training, but catastrophic for calibration. If <~0.1% incompleteness is not attainable, the best known option for calibration of photometric redshifts is to utilize cross-correlation statistics in some form. The most direct method for this uses cross-correlations between positions on the sky of bright objects of known spectroscopic redshift with the sample of objects that we wish to calibrate the redshift distribution for, measured as a function of spectroscopic z. For such a calibration, redshifts of ~100,000 objects over at least several hundred square degrees, spanning the full redshift range of the samples used for dark energy, would be necessary; and Options: The proposed BAO experiment eBOSS would provide sufficient spectroscopy for basic calibrations, particularly for ongoing and near-future imaging experiments. The planned DESI experiment would provide excellent calibration with redundant cross-checks, but will start after the conclusion of some imaging projects. An extension of DESI to the Southern hemisphere would provide the best possible calibration from cross-correlation methods for DES and LSST. We thus anticipate that our two primary needs for spectroscopy – training and calibration of photometric redshifts – will require two separate solutions. For ongoing and future projects to reach their full potential, new spectroscopic samples of faint objects will be needed for training; those new samples may be suitable for calibration, but the latter possibility is uncertain. In contrast, wide-area samples of bright objects are poorly suited for training, but can provide high-precision calibrations via cross-correlation techniques. Additional training/calibration redshifts and/or host galaxy spectroscopy would enhance the use of supernovae and galaxy clusters for cosmology. We also summarize additional work on photometric redshift techniques that will be needed to prepare for data from ongoing and future dark energy experiments.« less

Deep, wide-field, multi-band imaging of z approximately equal to 0.4 clusters and their environs

NASA Technical Reports Server (NTRS)

Silva, David R.; Pierce, Michael J.

1993-01-01

The existence of an excess population of blue galaxies in the cores of distant, rich clusters of galaxies, commonly referred to as the 'Butcher-Oemler' effect is now well established. Spectroscopy of clusters at z = 0.2-0.4 has confirmed that the luminous blue populations comprise as much as 20 percent of these clusters. This fraction is much higher that the 2 percent blue fraction found for nearby rich clusters, such as Coma, indicating that rapid galaxy evolution has occurred on a relatively short time scale. Spectroscopy has also shown that the 'blue' galaxies can basically be divided into three classes: 'starburst' galaxies with large (O II) equivalent widths, 'post-starburst' E+A galaxies (i.e. galaxies with strong Balmer lines shortward of 4000A but elliptical-like colors, and normal spiral/irregulars. Unfortunately, it is difficult to obtain enough spectra of individual galaxies in these intermediate redshift clusters to say anything statistically meaningful. Thus, limited information is available about the relative numbers of these three classes of 'blue' galaxies and the associated E/SO population in these intermediate redshift clusters. More statistically meaningful results can be derived from deep imaging of these clusters. However, the best published data to date (e.g. MacLaren et al. 1988; Dressler & Gunn 1992) are limited to the cluster cores and do not sample the galaxy luminosity functions very deeply at the bluest wavelengths. Furthermore, only limited spectro-energy distribution data is available below 4000A in the observed cluster rest frame providing limited sensitivity to 'recent' star formation activity. To improve this situation, we are currently obtaining deep, wide-field UBRI images of all known rich clusters at z approx. equals 0.4. Our main objective is to obtain the necessary color information to distinguish between the E+SO, 'E+A', and spiral/irregular galaxy populations throughout the cluster/supercluster complex. At this redshift, UBRI correspond to rest-frame 2500A/UVR bandpasses. The rest-frame UVR system provides a powerful 'blue' galaxy discriminate given the expected color distribution. Moreover, since 'hot' stars peak near 2500A, that bandpass is a powerful probe of recent star formation activity in all classes of galaxies. In particular, it is sensitive to ellipticals with 'UV excess' populations (MacLaren et al. 1988).

The Complete Calibration of the Color-Redshift Relation (C3R2) survey for Euclid

NASA Astrophysics Data System (ADS)

Cohen, Judith; Masters, Daniel; C3R2 Team

2018-06-01

The complete calibration of the color-redshift relation (C3R2) survey is a multi-institution, mutli-instrument survey with the Keck telescopes that aims to map out the empirical galaxy color-redshift relation in preparation for the Stage IV dark energy missions Euclid and WFIRST. A key challenge for weak lensing cosmology with these missions will be measuring highly accurate redshift distributions for billions of faint galaxies using only broad-band photometric observations. Well-calibrated photometric redshifts will thus be critical to their success. C3R2 uses an innovative technique that maps the color distribution of galaxies in the high-dimensional color space (u-g, ..., J-H) expected for Euclid and WFIRST, allowng us to focus spectroscopic effort on those regions of galaxy color space which are currently unexplored. C3R2 is a joint effort involving all of the Keck partners, with 44.5 nights allocated thus far. DR1 is published (Masters, Stern, Cohen et al, ApJ, 841, 111), and DR2, with > 3000 new redshifts, will be submitted in mid 2018.

Investigating the Impact of Optical Selection Effects on Observed Rest-frame Prompt GRB Properties

NASA Astrophysics Data System (ADS)

Turpin, D.; Heussaff, V.; Dezalay, J.-P.; Atteia, J.-L.; Klotz, A.; Dornic, D.

2016-11-01

Measuring gamma-ray burst (GRB) properties in their rest frame is crucial for understanding the physics at work in GRBs. This can only be done for GRBs with known redshifts. Since redshifts are usually measured from the optical spectrum of the afterglow, correlations between prompt and afterglow emissions may introduce biases into the distribution of the rest-frame properties of the prompt emission, especially considering that we measure the redshift of only one-third of Swift GRBs. In this paper, we study the optical flux of GRB afterglows and its connection to various intrinsic properties of GRBs. We also discuss the impact of the optical selection effect on the distribution of rest-frame prompt properties of GRBs. Our analysis is based on a sample of 90 GRBs with good optical follow-up and well-measured prompt emission. Seventy-six of them have a measure of redshift and 14 have no redshift. We compare the rest-frame prompt properties of GRBs with different afterglow optical fluxes in order to check for possible correlations between the promt properties and the optical flux of the afterglow. The optical flux is measured two hours after the trigger, which is a typical time for the measure of the redshift. We find that the optical flux of GRB afterglows in our sample is mainly driven by their optical luminosity and depends only slightly on their redshift. We show that GRBs with low and high afterglow optical fluxes have similar E {}{{pi}}, E {}{{iso}}, and L {}{{iso}}, indicating that the rest-frame distributions computed from GRBs with a redshift are not significantly distorted by optical selection effects. However, we found that the {T}90{rest} distribution is not immune to optical selection effects, which favor the selection of GRBs with longer durations. Finally, we note that GRBs well above the E {}{{pi}}-E {}{{iso}} relation have lower optical fluxes and we show that optical selection effects favor the detection of GRBs with bright optical afterglows located close to or below the best-fit E {}{{pi}}-E {}{{iso}} relation (Amati relation), whose redshift is easily measurable. With more than 300 GRBs with a redshift, we now have a much better view of the intrinsic properties of these remarkable events. At the same time, increasing statistics allow us to understand the biases acting on the measurements. The optical selection effects induced by the redshift measurement strategies cannot be neglected when we study the properties of GRBs in their rest frame, even for studies focused on prompt emission.

THE AGE SPREAD OF QUIESCENT GALAXIES WITH THE NEWFIRM MEDIUM-BAND SURVEY: IDENTIFICATION OF THE OLDEST GALAXIES OUT TO z {approx} 2

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

Whitaker, Katherine E.; Van Dokkum, Pieter G.; Brammer, Gabriel

2010-08-20

With a complete, mass-selected sample of quiescent galaxies from the NEWFIRM Medium-Band Survey, we study the stellar populations of the oldest and most massive galaxies (>10{sup 11} M{sub sun}) to high redshift. The sample includes 570 quiescent galaxies selected based on their extinction-corrected U - V colors out to z = 2.2, with accurate photometric redshifts, {sigma} {sub z}/(1 + z) {approx} 2%, and rest-frame colors, {sigma}{sub U-V} {approx} 0.06 mag. We measure an increase in the intrinsic scatter of the rest-frame U - V colors of quiescent galaxies with redshift. This scatter in color arises from the spread inmore » ages of the quiescent galaxies, where we see both relatively quiescent red, old galaxies and quiescent blue, younger galaxies toward higher redshift. The trends between color and age are consistent with the observed composite rest-frame spectral energy distributions (SEDs) of these galaxies. The composite SEDs of the reddest and bluest quiescent galaxies are fundamentally different, with remarkably well-defined 4000 A and Balmer breaks, respectively. Some of the quiescent galaxies may be up to four times older than the average age and up to the age of the universe, if the assumption of solar metallicity is correct. By matching the scatter predicted by models that include growth of the red sequence by the transformation of blue galaxies to the observed intrinsic scatter, the data indicate that most early-type galaxies formed their stars at high redshift with a burst of star formation prior to migrating to the red sequence. The observed U - V color evolution with redshift is weaker than passive evolution predicts; possible mechanisms to slow the color evolution include increasing amounts of dust in quiescent galaxies toward higher redshift, red mergers at z {approx}< 1, and a frosting of relatively young stars from star formation at later times.« less

Morpho-z: improving photometric redshifts with galaxy morphology

NASA Astrophysics Data System (ADS)

Soo, John Y. H.; Moraes, Bruno; Joachimi, Benjamin; Hartley, William; Lahav, Ofer; Charbonnier, Aldée; Makler, Martín; Pereira, Maria E. S.; Comparat, Johan; Erben, Thomas; Leauthaud, Alexie; Shan, Huanyuan; Van Waerbeke, Ludovic

2018-04-01

We conduct a comprehensive study of the effects of incorporating galaxy morphology information in photometric redshift estimation. Using machine learning methods, we assess the changes in the scatter and outlier fraction of photometric redshifts when galaxy size, ellipticity, Sérsic index, and surface brightness are included in training on galaxy samples from the SDSS and the CFHT Stripe-82 Survey (CS82). We show that by adding galaxy morphological parameters to full ugriz photometry, only mild improvements are obtained, while the gains are substantial in cases where fewer passbands are available. For instance, the combination of grz photometry and morphological parameters almost fully recovers the metrics of 5-band photometric redshifts. We demonstrate that with morphology it is possible to determine useful redshift distribution N(z) of galaxy samples without any colour information. We also find that the inclusion of quasar redshifts and associated object sizes in training improves the quality of photometric redshift catalogues, compensating for the lack of a good star-galaxy separator. We further show that morphological information can mitigate biases and scatter due to bad photometry. As an application, we derive both point estimates and posterior distributions of redshifts for the official CS82 catalogue, training on morphology and SDSS Stripe-82 ugriz bands when available. Our redshifts yield a 68th percentile error of 0.058(1 + z), and a outlier fraction of 5.2 per cent. We further include a deep extension trained on morphology and single i-band CS82 photometry.

Multiple Streaming and the Probability Distribution of Density in Redshift Space

NASA Astrophysics Data System (ADS)

Hui, Lam; Kofman, Lev; Shandarin, Sergei F.

2000-07-01

We examine several aspects of redshift distortions by expressing the redshift-space density in terms of the eigenvalues and orientation of the local Lagrangian deformation tensor. We explore the importance of multiple streaming using the Zeldovich approximation (ZA), and compute the average number of streams in both real and redshift space. We find that multiple streaming can be significant in redshift space but negligible in real space, even at moderate values of the linear fluctuation amplitude (σl<~1). Moreover, unlike their real-space counterparts, redshift-space multiple streams can flow past each other with minimal interactions. Such nonlinear redshift-space effects, which are physically distinct from the fingers-of-God due to small-scale virialized motions, might in part explain the well-known departure of redshift distortions from the classic linear prediction by Kaiser, even at relatively large scales where the corresponding density field in real space is well described by linear perturbation theory. We also compute, using the ZA, the probability distribution function (PDF) of the density, as well as S3, in real and redshift space, and compare it with the PDF measured from N-body simulations. The role of caustics in defining the character of the high-density tail is examined. We find that (non-Lagrangian) smoothing, due to both finite resolution or discreteness and small-scale velocity dispersions, is very effective in erasing caustic structures, unless the initial power spectrum is sufficiently truncated.

Using cross correlations to calibrate lensing source redshift distributions: Improving cosmological constraints from upcoming weak lensing surveys

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

De Putter, Roland; Doré, Olivier; Das, Sudeep

2014-01-10

Cross correlations between the galaxy number density in a lensing source sample and that in an overlapping spectroscopic sample can in principle be used to calibrate the lensing source redshift distribution. In this paper, we study in detail to what extent this cross-correlation method can mitigate the loss of cosmological information in upcoming weak lensing surveys (combined with a cosmic microwave background prior) due to lack of knowledge of the source distribution. We consider a scenario where photometric redshifts are available and find that, unless the photometric redshift distribution p(z {sub ph}|z) is calibrated very accurately a priori (bias andmore » scatter known to ∼0.002 for, e.g., EUCLID), the additional constraint on p(z {sub ph}|z) from the cross-correlation technique to a large extent restores the cosmological information originally lost due to the uncertainty in dn/dz(z). Considering only the gain in photo-z accuracy and not the additional cosmological information, enhancements of the dark energy figure of merit of up to a factor of four (40) can be achieved for a SuMIRe-like (EUCLID-like) combination of lensing and redshift surveys, where SuMIRe stands for Subaru Measurement of Images and Redshifts). However, the success of the method is strongly sensitive to our knowledge of the galaxy bias evolution in the source sample and we find that a percent level bias prior is needed to optimize the gains from the cross-correlation method (i.e., to approach the cosmology constraints attainable if the bias was known exactly).« less

CHEMICAL ENRICHMENT OF DAMPED Ly{alpha} SYSTEMS AS A DIRECT CONSTRAINT ON POPULATION III STAR FORMATION

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

Kulkarni, Girish; Hennawi, Joseph F.; Rollinde, Emmanuel

2013-08-01

Observations of damped Ly{alpha} absorbers (DLAs) can be used to measure gas-phase metallicities at large cosmological look-back times with high precision. Furthermore, relative abundances can still be measured accurately deep into the reionization epoch (z > 6) using transitions redward of Ly{alpha}, even though Gunn-Peterson absorption precludes measurement of neutral hydrogen. In this paper, we study the chemical evolution of DLAs using a model for the coupled evolution of galaxies and the intergalactic medium (IGM), which is constrained by a variety of observations. Our goal is to explore the influence of Population III stars on the abundance patterns of DLAsmore » to determine the degree to which abundance measurements can discriminate between different Population III stellar initial mass functions (IMFs). We include effects, such as inflows onto galaxies due to cosmological accretion and outflows from galaxies due to supernova feedback. A distinct feature of our model is that it self-consistently calculates the effect of Population III star formation on the reionization of an inhomogeneous IGM, thus allowing us to calculate the thermal evolution of the IGM and implement photoionization feedback on low-mass galaxy formation. We find that if the critical metallicity of Population III to II/I transition is {approx}< 10{sup -4} Z{sub Sun }, then the cosmic Population III star formation rate drops to zero for z < 8. Nevertheless, at high redshift (z {approx} 6), chemical signatures of Population III stars remain in low-mass galaxies (halo mass {approx}< 10{sup 9} M{sub Sun }). This is because photoionization feedback suppresses star formation in these galaxies until relatively low redshift (z {approx} 10), and the chemical record of their initial generation of Population III stars is retained. We model DLAs as these low-mass galaxies, and assign to them a mass-dependent H I absorption cross-section in order to predict the expected distribution of DLA abundance ratios. We find that these distributions are anchored toward abundance ratios set by Population II supernova yields, but they exhibit a tail which depends significantly on the Population III IMF for z > 5. Thus, a sample of DLA metallicity and relative abundance measurements at high redshift holds the promise to constrain Population III enrichment and the Population III IMF. We find that a sample of just 10 DLAs with relative abundances measured to an accuracy of 0.1 dex is sufficient to constrain the Population III IMF at 4{sigma}. These constraints may prove stronger than other probes of Population III enrichment, such as metal-poor stars and individual metal-poor DLAs. Our results provide a global picture of the thermal, ionization, and chemical evolution of the universe, and have the potential to rule out certain Population III scenarios.« less

Photometric redshifts as a tool for studying the Coma cluster galaxy populations

NASA Astrophysics Data System (ADS)

Adami, C.; Ilbert, O.; Pelló, R.; Cuillandre, J. C.; Durret, F.; Mazure, A.; Picat, J. P.; Ulmer, M. P.

2008-12-01

Aims: We apply photometric redshift techniques to an investigation of the Coma cluster galaxy luminosity function (GLF) at faint magnitudes, in particular in the u* band where basically no studies are presently available at these magnitudes. Methods: Cluster members were selected based on probability distribution function from photometric redshift calculations applied to deep u^*, B, V, R, I images covering a region of almost 1 deg2 (completeness limit R ~ 24). In the area covered only by the u* image, the GLF was also derived after a statistical background subtraction. Results: Global and local GLFs in the B, V, R, and I bands obtained with photometric redshift selection are consistent with our previous results based on a statistical background subtraction. The GLF in the u* band shows an increase in the faint end slope towards the outer regions of the cluster. The analysis of the multicolor type spatial distribution reveals that late type galaxies are distributed in clumps in the cluster outskirts, where X-ray substructures are also detected and where the GLF in the u* band is steeper. Conclusions: We can reproduce the GLFs computed with classical statistical subtraction methods by applying a photometric redshift technique. The u* GLF slope is steeper in the cluster outskirts, varying from α ~ -1 in the cluster center to α ~ -2 in the cluster periphery. The concentrations of faint late type galaxies in the cluster outskirts could explain these very steep slopes, assuming a short burst of star formation in these galaxies when entering the cluster. Based on observations obtained with MegaPrime/MegaCam, a joint project of CFHT and CEA/DAPNIA, at the Canada-France-Hawaii Telescope (CFHT) which is operated by the National Research Council (NRC) of Canada, the Institut National des Sciences de l'Univers of the Centre National de la Recherche Scientifique (CNRS) of France, and the University of Hawaii. This work is also partly based on data products produced at TERAPIX and the Canadian Astronomy Data Centre as part of the Canada-France-Hawaii Telescope Legacy Survey, a collaborative project of NRC and CNRS. Also based on data from W. M. Keck Observatory which is operated as a scientific partnership between the California Institute of Technology, the University of California, and NASA. It was made possible by the generous financial support of the W. M. Keck Foundation.

Dusty Quasars at High Redshifts

NASA Astrophysics Data System (ADS)

Weedman, Daniel; Sargsyan, Lusine

2016-09-01

A population of quasars at z ˜ 2 is determined based on dust luminosities νL ν (7.8 μm) that includes unobscured, partially obscured, and obscured quasars. Quasars are classified by the ratio νL ν (0.25 μm)/νL ν (7.8 μm) = UV/IR, assumed to measure obscuration of UV luminosity by the dust that produces IR luminosity. Quasar counts at rest-frame 7.8 μm are determined for quasars in the Boötes field of the NOAO Deep Wide Field Survey using 24 μm sources with optical redshifts from the AGN and Galaxy Evolution Survey (AGES) or infrared redshifts from the Spitzer Infrared Spectrograph. Spectral energy distributions are extended to far-infrared wavelengths using observations from the Herschel Space Observatory Spectral and Photometric Imaging Receiver (SPIRE), and new SPIRE photometry is presented for 77 high-redshift quasars from the Sloan Digital Sky Survey. It is found that unobscured and obscured quasars have similar space densities at rest-frame 7.8 μm, but the ratio L ν (100 μm)/L ν (7.8 μm) is about three times higher for obscured quasars than for unobscured, so that far-infrared or submillimeter quasar detections are dominated by obscured quasars. We find that only ˜5% of high-redshift submillimeter sources are quasars and that existing 850 μm surveys or 2 mm surveys should already have detected sources at z ˜ 10 if quasar and starburst luminosity functions remain the same from z = 2 until z = 10.

The Number Density of Quiescent Compact Galaxies at Intermediate Redshift

NASA Astrophysics Data System (ADS)

Damjanov, Ivana; Hwang, Ho Seong; Geller, Margaret J.; Chilingarian, Igor

2014-09-01

Massive compact systems at 0.2 < z < 0.6 are the missing link between the predominantly compact population of massive quiescent galaxies at high redshift and their analogs and relics in the local volume. The evolution in number density of these extreme objects over cosmic time is the crucial constraining factor for the models of massive galaxy assembly. We select a large sample of ~200 intermediate-redshift massive compacts from the Baryon Oscillation Spectroscopic Survey (BOSS) spectroscopy by identifying point-like Sloan Digital Sky Survey photometric sources with spectroscopic signatures of evolved redshifted galaxies. A subset of our targets have publicly available high-resolution ground-based images that we use to augment the dynamical and stellar population properties of these systems by their structural parameters. We confirm that all BOSS compact candidates are as compact as their high-redshift massive counterparts and less than half the size of similarly massive systems at z ~ 0. We use the completeness-corrected numbers of BOSS compacts to compute lower limits on their number densities in narrow redshift bins spanning the range of our sample. The abundance of extremely dense quiescent galaxies at 0.2 < z < 0.6 is in excellent agreement with the number densities of these systems at high redshift. Our lower limits support the models of massive galaxy assembly through a series of minor mergers over the redshift range 0 < z < 2.

The distribution of galaxies within the 'Great Wall'

NASA Technical Reports Server (NTRS)

Ramella, Massimo; Geller, Margaret J.; Huchra, John P.

1992-01-01

The galaxy distribution within the 'Great Wall', the most striking feature in the first three 'slices' of the CfA redshift survey extension is examined. The Great Wall is extracted from the sample and is analyzed by counting galaxies in cells. The 'local' two-point correlation function within the Great Wall is computed and the local correlation length, is estimated 15/h Mpc, about 3 times larger than the correlation length for the entire sample. The redshift distribution of galaxies in the pencil-beam survey by Broadhurst et al. (1990) shows peaks separated about by large 'voids', at least to a redshift of about 0.3. The peaks might represent the intersections of their about 5/h Mpc pencil beams with structures similar to the Great Wall. Under this hypothesis, sampling of the Great Walls shows that l approximately 12/h Mpc is the minimum projected beam size required to detect all the 'walls' at redshifts between the peak of the selection function and the effective depth of the survey.

Evolution of the real-space correlation function from next generation cluster surveys. Recovering the real-space correlation function from photometric redshifts

NASA Astrophysics Data System (ADS)

Sridhar, Srivatsan; Maurogordato, Sophie; Benoist, Christophe; Cappi, Alberto; Marulli, Federico

2017-04-01

Context. The next generation of galaxy surveys will provide cluster catalogues probing an unprecedented range of scales, redshifts, and masses with large statistics. Their analysis should therefore enable us to probe the spatial distribution of clusters with high accuracy and derive tighter constraints on the cosmological parameters and the dark energy equation of state. However, for the majority of these surveys, redshifts of individual galaxies will be mostly estimated by multiband photometry which implies non-negligible errors in redshift resulting in potential difficulties in recovering the real-space clustering. Aims: We investigate to which accuracy it is possible to recover the real-space two-point correlation function of galaxy clusters from cluster catalogues based on photometric redshifts, and test our ability to detect and measure the redshift and mass evolution of the correlation length r0 and of the bias parameter b(M,z) as a function of the uncertainty on the cluster redshift estimate. Methods: We calculate the correlation function for cluster sub-samples covering various mass and redshift bins selected from a 500 deg2 light-cone limited to H < 24. In order to simulate the distribution of clusters in photometric redshift space, we assign to each cluster a redshift randomly extracted from a Gaussian distribution having a mean equal to the cluster cosmological redshift and a dispersion equal to σz. The dispersion is varied in the range σ(z=0)=\\frac{σz{1+z_c} = 0.005,0.010,0.030} and 0.050, in order to cover the typical values expected in forthcoming surveys. The correlation function in real-space is then computed through estimation and deprojection of wp(rp). Four mass ranges (from Mhalo > 2 × 1013h-1M⊙ to Mhalo > 2 × 1014h-1M⊙) and six redshift slices covering the redshift range [0, 2] are investigated, first using cosmological redshifts and then for the four photometric redshift configurations. Results: From the analysis of the light-cone in cosmological redshifts we find a clear increase of the correlation amplitude as a function of redshift and mass. The evolution of the derived bias parameter b(M,z) is in fair agreement with theoretical expectations. We calculate the r0-d relation up to our highest mass, highest redshift sample tested (z = 2,Mhalo > 2 × 1014h-1M⊙). From our pilot sample limited to Mhalo > 5 × 1013h-1M⊙(0.4 < z < 0.7), we find that the real-space correlation function can be recovered by deprojection of wp(rp) within an accuracy of 5% for σz = 0.001 × (1 + zc) and within 10% for σz = 0.03 × (1 + zc). For higher dispersions (besides σz > 0.05 × (1 + zc)), the recovery becomes noisy and difficult. The evolution of the correlation in redshift and mass is clearly detected for all σz tested, but requires a large binning in redshift to be detected significantly between individual redshift slices when increasing σz. The best-fit parameters (r0 and γ) as well as the bias obtained from the deprojection method for all σz are within the 1σ uncertainty of the zc sample.

SPECTROSCOPY OF LUMINOUS COMPACT BLUE GALAXIES IN DISTANT CLUSTERS. II. PHYSICAL PROPERTIES OF dE PROGENITOR CANDIDATES

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

Crawford, S. M.; Wirth, Gregory D.; Bershady, M. A.

2016-02-01

Luminous Compact Blue Galaxies (LCBGs) are an extreme star-bursting population of galaxies that were far more common at earlier epochs than today. Based on spectroscopic and photometric measurements of LCBGs in massive (M > 10{sup 15} M{sub ⊙}), intermediate redshift (0.5 < z < 0.9) galaxy clusters, we present their rest-frame properties including star formation rate, dynamical mass, size, luminosity, and metallicity. The appearance of these small, compact galaxies in clusters at intermediate redshift helps explain the observed redshift evolution in the size–luminosity relationship among cluster galaxies. In addition, we find the rest-frame properties of LCBGs appearing in galaxy clusters are indistinguishable from field LCBGs atmore » the same redshift. Up to 35% of the LCBGs show significant discrepancies between optical and infrared indicators of star formation, suggesting that star formation occurs in obscured regions. Nonetheless, the star formation for LCBGs shows a decrease toward the center of the galaxy clusters. Based on their position and velocity, we estimate that up to 10% of cluster LCBGs are likely to merge with another cluster galaxy. Finally, the observed properties and distributions of the LCBGs in these clusters lead us to conclude that we are witnessing the quenching of the progenitors of dwarf elliptical galaxies that dominate the number density of present-epoch galaxy clusters.« less

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

Mao, Peiyuan; Urry, C. Megan

We investigate a sample of 622 blazars with measured fluxes at 12 wavebands across the radio-to-gamma-ray spectrum but without spectroscopic or photometric redshifts. This sample includes hundreds of sources with newly analyzed X-ray spectra reported here. From the synchrotron peak frequencies, estimated by fitting the broadband spectral energy distributions (SEDs), we find that the fraction of high-synchrotron-peaked blazars in these 622 sources is roughly the same as in larger samples of blazars that do have redshifts. We characterize the no-redshift blazars using their infrared colors, which lie in the distinct locus called the WISE blazar strip, then estimate their redshiftsmore » using a KNN regression based on the redshifts of the closest blazars in the WISE color–color plot. Finally, using randomly drawn values from plausible redshift distributions, we simulate the SEDs of these blazars and compare them to known blazar SEDs. Based on all these considerations, we conclude that blazars without redshift estimates are unlikely to be high-luminosity, high-synchrotron-peaked objects, which had been suggested in order to explain the “blazar sequence”—an observed trend of SED shape with luminosity—as a selection effect. Instead, the observed properties of no-redshift blazars are compatible with a causal connection between jet power and electron cooling, i.e., a true blazar sequence.« less

Quantifying the abundance of faint, low-redshift satellite galaxies in the COSMOS survey

NASA Astrophysics Data System (ADS)

Xi, ChengYu; Taylor, James E.; Massey, Richard J.; Rhodes, Jason; Koekemoer, Anton; Salvato, Mara

2018-06-01

Faint dwarf satellite galaxies are important as tracers of small-scale structure, but remain poorly characterized outside the Local Group, due to the difficulty of identifying them consistently at larger distances. We review a recently proposed method for estimating the average satellite population around a given sample of nearby bright galaxies, using a combination of size and magnitude cuts (to select low-redshift dwarf galaxies preferentially) and clustering measurements (to estimate the fraction of true satellites in the cut sample). We test this method using the high-precision photometric redshift catalog of the COSMOS survey, exploring the effect of specific cuts on the clustering signal. The most effective of the size-magnitude cuts considered recover the clustering signal around low-redshift primaries (z < 0.15) with about two-thirds of the signal and 80% of the signal-to-noise ratio obtainable using the full COSMOS photometric redshifts. These cuts are also fairly efficient, with more than one third of the selected objects being clustered satellites. We conclude that structural selection represents a useful tool in characterizing dwarf populations to fainter magnitudes and/or over larger areas than are feasible with spectroscopic surveys. In reviewing the low-redshift content of the COSMOS field, we also note the existence of several dozen objects that appear resolved or partially resolved in the HST imaging, and are confirmed to be local (at distances of ˜250 Mpc or less) by their photometric or spectroscopic redshifts. This underlines the potential for future space-based surveys to reveal local populations of intrinsically faint galaxies through imaging alone.

Confusion-limited galaxy fields. I - Simulated optical and near-infrared images

NASA Technical Reports Server (NTRS)

Chokshi, Arati; Wright, Edward L.

1988-01-01

Techniques for simulating images of galaxy fields are presented that extend to high redshifts and a surface density of galaxies high enough to produce overlapping images. The observed properties of galaxies and galaxy-ensembles in the 'local' universe are extrapolated to high redshifts using reasonable scenarios for the evolution of galaxies and their spatial distribution. This theoretical framework is then employed with Monte Carlo techniques to create fairly realistic two-dimensional distributions of galaxies plus optical and near-infrared sky images in a variety of model universes, using the appropriate density, luminosity, and angular size versus redshift relations.

A Definitive Optical Detection of a Supercluster at Z ~ 0.91

NASA Astrophysics Data System (ADS)

Lubin, Lori M.; Brunner, Robert; Metzger, Mark R.; Postman, Marc; Oke, J. B.

2000-03-01

We present the results from a multiband optical imaging program that has definitively confirmed the existence of a supercluster at z~0.91. Two massive clusters of galaxies, Cl 1604+4304 at z=0.897 and Cl 1604+4321 at z=0.924, were originally observed in the high-redshift cluster survey of Oke, Postman, & Lubin. They are separated by 4300 km s-1 in radial velocity and 17' on the plane of the sky. Their physical and redshift proximity suggested a promising supercluster candidate. Deep BRi imaging of the region between the two clusters indicates a large population of red galaxies. This population forms a tight, red sequence in the color-magnitude diagram at (R-i)~1.4. The characteristic color is identical to that of the spectroscopically confirmed early-type galaxies in the two member clusters. The red galaxies are spread throughout the 5 h-1 Mpc region between Cl 1604+4304 and Cl 1604+4321. Their spatial distribution delineates the entire large-scale structure with high concentrations at the cluster centers. In addition, we detect a significant overdensity of red galaxies directly between Cl 1604+4304 and Cl 1604+4321 which is the signature of a third, rich cluster associated with this system. The strong sequence of red galaxies and their spatial distribution clearly indicate that we have discovered a supercluster at z~0.91.

ON THE ORIGIN OF THE HIGHEST REDSHIFT GAMMA-RAY BURSTS

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

Belczynski, Krzysztof; Holz, Daniel E.; Fryer, Chris L.

2010-01-01

GRB 080913 and GRB 090423 are the most distant gamma-ray bursts (GRBs) known to date, with spectroscopically determined redshifts of z = 6.7 and z = 8.1, respectively. The detection of bursts at this early epoch of the universe significantly constrains the nature of GRBs and their progenitors. We perform population synthesis studies of the formation and evolution of early stars, and calculate the resulting formation rates of short- and long-duration GRBs at high redshift. The peak of the GRB rate from Population II stars occurs at z approx 7 for a model with efficient/fast mixing of metals, while itmore » is found at z approx 3 for an inefficient/slow metallicity evolution model. We show that in the redshift range 6 approx< z approx< 10, essentially all GRBs originate from Population II stars, regardless of the metallicity evolution model. These stars (having small, but non-zero metallicity) are the most likely progenitors for both long GRBs (collapsars) and short GRBs (neutron star-neutron star or blackhole-neutron star mergers) at this epoch. Although the predicted intrinsic rates of long and short GRBs are similar at these high redshifts, observational selection effects lead to higher (a factor of approx10) observed rates for long GRBs. We conclude that the two recently observed high-z GRB events are most likely long GRBs originating from Population II collapsars.« less

Lens models and magnification maps of the six Hubble Frontier Fields clusters

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

Johnson, Traci L.; Sharon, Keren; Bayliss, Matthew B.

2014-12-10

We present strong-lensing models as well as mass and magnification maps for the cores of the six Hubble Space Telescope (HST) Frontier Fields galaxy clusters. Our parametric lens models are constrained by the locations and redshifts of multiple image systems of lensed background galaxies. We use a combination of photometric redshifts and spectroscopic redshifts of the lensed background sources obtained by us (for A2744 and AS1063), collected from the literature, or kindly provided by the lensing community. Using our results, we (1) compare the derived mass distribution of each cluster to its light distribution, (2) quantify the cumulative magnification powermore » of the HST Frontier Fields clusters, (3) describe how our models can be used to estimate the magnification and image multiplicity of lensed background sources at all redshifts and at any position within the cluster cores, and (4) discuss systematic effects and caveats resulting from our modeling methods. We specifically investigate the effect of the use of spectroscopic and photometric redshift constraints on the uncertainties of the resulting models. We find that the photometric redshift estimates of lensed galaxies are generally in excellent agreement with spectroscopic redshifts, where available. However, the flexibility associated with relaxed redshift priors may cause the complexity of large-scale structure that is needed to account for the lensing signal to be underestimated. Our findings thus underline the importance of spectroscopic arc redshifts, or tight photometric redshift constraints, for high precision lens models. All products from our best-fit lens models (magnification, convergence, shear, deflection field) and model simulations for estimating errors are made available via the Mikulski Archive for Space Telescopes.« less

Multiple Streaming and the Probability Distribution of Density in Redshift Space

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

Hui, Lam; Kofman, Lev; Shandarin, Sergei F.

2000-07-01

We examine several aspects of redshift distortions by expressing the redshift-space density in terms of the eigenvalues and orientation of the local Lagrangian deformation tensor. We explore the importance of multiple streaming using the Zeldovich approximation (ZA), and compute the average number of streams in both real and redshift space. We find that multiple streaming can be significant in redshift space but negligible in real space, even at moderate values of the linear fluctuation amplitude ({sigma}{sub l}(less-or-similar sign)1). Moreover, unlike their real-space counterparts, redshift-space multiple streams can flow past each other with minimal interactions. Such nonlinear redshift-space effects, which aremore » physically distinct from the fingers-of-God due to small-scale virialized motions, might in part explain the well-known departure of redshift distortions from the classic linear prediction by Kaiser, even at relatively large scales where the corresponding density field in real space is well described by linear perturbation theory. We also compute, using the ZA, the probability distribution function (PDF) of the density, as well as S{sub 3}, in real and redshift space, and compare it with the PDF measured from N-body simulations. The role of caustics in defining the character of the high-density tail is examined. We find that (non-Lagrangian) smoothing, due to both finite resolution or discreteness and small-scale velocity dispersions, is very effective in erasing caustic structures, unless the initial power spectrum is sufficiently truncated. (c) 2000 The American Astronomical Society.« less

A simulation-based analytic model of radio galaxies

NASA Astrophysics Data System (ADS)

Hardcastle, M. J.

2018-04-01

I derive and discuss a simple semi-analytical model of the evolution of powerful radio galaxies which is not based on assumptions of self-similar growth, but rather implements some insights about the dynamics and energetics of these systems derived from numerical simulations, and can be applied to arbitrary pressure/density profiles of the host environment. The model can qualitatively and quantitatively reproduce the source dynamics and synchrotron light curves derived from numerical modelling. Approximate corrections for radiative and adiabatic losses allow it to predict the evolution of radio spectral index and of inverse-Compton emission both for active and `remnant' sources after the jet has turned off. Code to implement the model is publicly available. Using a standard model with a light relativistic (electron-positron) jet, subequipartition magnetic fields, and a range of realistic group/cluster environments, I simulate populations of sources and show that the model can reproduce the range of properties of powerful radio sources as well as observed trends in the relationship between jet power and radio luminosity, and predicts their dependence on redshift and environment. I show that the distribution of source lifetimes has a significant effect on both the source length distribution and the fraction of remnant sources expected in observations, and so can in principle be constrained by observations. The remnant fraction is expected to be low even at low redshift and low observing frequency due to the rapid luminosity evolution of remnants, and to tend rapidly to zero at high redshift due to inverse-Compton losses.

Stellar mass and velocity functions of galaxies. Backward evolution and the fate of Milky Way siblings

NASA Astrophysics Data System (ADS)

Boissier, S.; Buat, V.; Ilbert, O.

2010-11-01

Context. In recent years, stellar mass functions of both star-forming and quiescent galaxies have been observed at different redshifts in various fields. In addition, star formation rate (SFR) distributions (e.g. in the form of far infrared luminosity functions) were also obtained. Taken together, they offer complementary pieces of information concerning the evolution of galaxies. Aims: We attempt in this paper to check the consistency of the observed stellar mass functions, SFR functions, and the cosmic SFR density with simple backward evolutionary models. Methods: Starting from observed stellar mass functions for star-forming galaxies, we use backwards models to predict the evolution of a number of quantities, such as the SFR function, the cosmic SFR density and the velocity function. Because the velocity is a parameter attached to a galaxy during its history (contrary to the stellar mass), this approach allows us to quantify the number density evolution of galaxies of a given velocity, e.g. of the Milky Way siblings. Results: Observations suggest that the stellar mass function of star-forming galaxies is constant between redshift 0 and 1. To reproduce this result, we must quench star formation in a number of star-forming galaxies. The stellar mass function of these “quenched” galaxies is consistent with available data concerning the increase in the population of quiescent galaxies in the same redshift interval. The stellar mass function of quiescent galaxies is then mainly determined by the distribution of active galaxies that must stop star formation, with a modest mass redistribution during mergers. The cosmic SFR density and the evolution of the SFR functions are recovered relatively well, although they provide some clues to a minor evolution of the stellar mass function of star forming galaxies at the lowest redshifts. We thus consider that we have obtained in a simple way a relatively consistent picture of the evolution of galaxies at intermediate redshifts. If this picture is correct, 50% of the Milky-Way sisters (galaxies with the same velocity as our Galaxy, i.e. 220 km s-1) have quenched their star formation since redshift 1 (and an even higher fraction for higher velocities). We discuss the processes that might be responsible for this transformation.

The AKARI FU-HYU galaxy evolution program: first results from the GOODS-N field

NASA Astrophysics Data System (ADS)

Pearson, C. P.; Serjeant, S.; Negrello, M.; Takagi, T.; Jeong, W.-S.; Matsuhara, H.; Wada, T.; Oyabu, S.; Lee, H. M.; Im, M. S.

2010-05-01

The AKARI FU-HYU mission program carried out mid-infrared imaging of several well studied Spitzer fields preferentially selecting fields already rich in multi-wavelength data from radio to X-ray wavelengths filling in the wavelength desert between the Spitzer IRAC and MIPS bands. We present the initial results for the FU-HYU survey in the GOODS-N field. We utilize the supreme multiwavelength coverage in the GOODS-N field to produce a multiwavelength catalogue from infrared to ultraviolet wavelengths, containing more than 4393 sources, including photometric redshifts. Using the FU-HYU catalogue we present colour-colour diagrams that map the passage of PAH features through our observation bands. We find that the longer mid-infrared bands from AKARI (IRC-L18W 18 micron band) and Spitzer (MIPS24 24 micron band) provide an accurate measure of the total MIR emission of the sources and therefore their probable total mid-infrared luminosity. We also find that colours incorporating the AKARI IRC-S11 11 micron band produce a bimodal distribution where an excess at 11 microns preferentially selects moderate redshift star-forming galaxies. These powerful colour-colour diagnostics are further used as tools to extract anomalous colour populations, in particular a population of Silicate Break galaxies from the GOODS-N field showing that dusty starbursts can be selected of specific redshift ranges (z = 1.2-1.6) by mid-infrared drop-out techniques. The FU-HYU catalogue will be made publically available to the astronomical community.

The VIMOS Public Extragalactic Redshift Survey (VIPERS). The coevolution of galaxy morphology and colour to z 1

NASA Astrophysics Data System (ADS)

Krywult, J.; Tasca, L. A. M.; Pollo, A.; Vergani, D.; Bolzonella, M.; Davidzon, I.; Iovino, A.; Gargiulo, A.; Haines, C. P.; Scodeggio, M.; Guzzo, L.; Zamorani, G.; Garilli, B.; Granett, B. R.; de la Torre, S.; Abbas, U.; Adami, C.; Bottini, D.; Cappi, A.; Cucciati, O.; Franzetti, P.; Fritz, A.; Le Brun, V.; Le Fèvre, O.; Maccagni, D.; Małek, K.; Marulli, F.; Polletta, M.; Tojeiro, R.; Zanichelli, A.; Arnouts, S.; Bel, J.; Branchini, E.; Coupon, J.; De Lucia, G.; Ilbert, O.; McCracken, H. J.; Moscardini, L.; Takeuchi, T. T.

2017-02-01

Context. The study of the separation of galaxy types into different classes that share the same characteristics, and of the evolution of the specific parameters used in the classification are fundamental for understanding galaxy evolution. Aims: We explore the evolution of the statistical distribution of galaxy morphological properties and colours combining high-quality imaging data from the CFHT Legacy Survey with the large number of redshifts and extended photometry from the VIPERS survey. Methods: Galaxy structural parameters were combined with absolute magnitudes, colours and redshifts in order to trace evolution in a multi-parameter space. Using a new method we analysed the combination of colours and structural parameters of early- and late-type galaxies in luminosity-redshift space. Results: We find that both the rest-frame colour distributions in the (U-B) vs. (B-V) plane and the Sérsic index distributions are well fitted by a sum of two Gaussians, with a remarkable consistency of red-spheroidal and blue-disky galaxy populations, over the explored redshift (0.5 < z < 1) and luminosity (-1.5 < B-B∗ < 1.0) ranges. The combination of the rest-frame colour and Sérsic index as a function of redshift and luminosity allows us to present the structure of both galaxy types and their evolution. We find that early-type galaxies display only a slow change in their concentrations after z = 1. Their high concentrations were already established at z 1 and depend much more strongly on their luminosity than redshift. In contrast, late-type galaxies clearly become more concentrated with cosmic time with only little evolution in colour, which remains dependent mainly on their luminosity. Conclusions: The combination of rest-frame colours and Sérsic index as a function of redshift and luminosity leads to a precise statistical description of the structure of galaxies and their evolution. Additionally, the proposed method provides a robust way to split galaxies into early and late types. Based on observations collected at the European Southern Observatory, Cerro Paranal, Chile, using the Very Large Telescope under programs 182.A-0886 and partly 070.A-9007. Also based on observations obtained with MegaPrime/MegaCam, a joint project of CFHT and CEA/DAPNIA, at the Canada-France-Hawaii Telescope (CFHT), which is operated by the National Research Council (NRC) of Canada, the Institut National des Sciences de l'Univers of the Centre National de la Recherche Scientifique (CNRS) of France, and the University of Hawaii. This work is based in part on data products produced at TERAPIX and the Canadian Astronomy Data Centre as part of the Canada-France-Hawaii Telescope Legacy Survey, a collaborative project of NRC and CNRS. The VIPERS web site is http://vipers.inaf.it/A table of the fitted parameters 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/598/A120

Implications of the Low Binary Black Hole Aligned Spins Observed by LIGO

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

Hotokezaka, Kenta; Piran, Tsvi

We explore the implications of the low-spin components along the orbital axis observed in an Advanced LIGO O1 run on binary black hole (BBH) merger scenarios in which the merging BBHs have evolved from field binaries. The coalescence time determines the initial orbital separation of BBHs. This, in turn, determines whether the stars are synchronized before collapse, and hence determines their projected spins. Short coalescence times imply synchronization and large spins. Among known stellar objects, Wolf–Rayet (WR) stars seem to be the only progenitors consistent with the low aligned spins observed in LIGO’s O1, provided that the orbital axis maintainsmore » its direction during the collapse. We calculate the spin distribution of BBH mergers in the local universe, and its redshift evolution for WR progenitors. Assuming that the BBH formation rate peaks around a redshift of ∼2–3, we show that BBH mergers in the local universe are dominated by low-spin events. The high-spin population starts to dominate at a redshift of ∼0.5–1.5. WR stars are also progenitors of long gamma-ray bursts that take place at a comparable rate to BBH mergers. We discuss the possible connection between the two phenomena. Additionally, we show that hypothetical Population III star progenitors are also possible. Although WR and Population III progenitors are consistent with the current data, both models predict a non-vanishing fraction of high positive values of the BBHs’ aligned spin. If those are not detected within the coming LIGO/Virgo runs, it will be unlikely that the observed BBHs formed via field binaries.« less

Evolution of star formation conditions from high-redshift to low-redshift

NASA Astrophysics Data System (ADS)

Shirazi, Maryam

2015-08-01

There are some hints indicating extreme interstellar medium (ISM) conditions at high redshift e.g., harder ionsing radiation fields and higher electron densities. By analysing the ionisation state of galaxies using their [OIII]5007/[OII]3727 line ratios we recently showed that star-forming galaxies at z~ 1. 5 -- 3. 5 have higher ionisation parameters and higher gas densities relative to that of local galaxies with similar global properties (Shirazi et al. 2014). This means the intrinsic properties e.g., the density of star forming regions at high redshift is different from what we observe in the local Universe. Based on the distribution of galaxies in the BPT diagram, it is proposed that the transition to nearby like conditions happen at 0. 8 < z < 1. 5 (Kewley et al 2013). However, we do not know how star-forming regions of the intermediate redshift galaxies are compared to that of high redshift galaxies that have higher gas fractions and are close to the peak of star formation activity in the Universe. We use the unique capability of the MUSE to indirectly trace the ISM conditions at those redshifts. We measure the spatially-resolved ionisation parameter using [OIII ]5007/ [O II]3727 ratio and we measure the spatially resolved gas density using the [OII] 3727,3729 doublet. We probe the spatial distributions of the ionisation parameter and gas density and search for systematic differences between high, intermediate and low redshift galaxies in terms of their global galaxy properties.

Infrared/optical energy distributions of high redshifted quasars

NASA Technical Reports Server (NTRS)

Soifer, B. T.; Neugebauer, G.; Oke, J. B.; Matthews, K.; Lacy, J. H.

1982-01-01

Measurements at 1.2, 1.6 and 2.2 microns were combined with visual spectrophotometry of 21 quasars having redshifts z or = 2.66. The primary result is that the rest frame visual/ultraviolet continua of the high redshift quasars are well described by a sum of a power law continuum with slope of approximately -0.4 and a 3000 A bump. The rest frame visual/ultraviolet continua of these quasars are quite similar to that of 3C273, the archetype of low redshift quasars. There does not appear to be any visual/ultraviolet properties distinguishing high redshift quasars selected via visual or radio techniques.

The active galactic nucleus population in X-ray-selected galaxy groups at 0.5 < Z < 1.1

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

Oh, Semyeong; Woo, Jong-Hak; Matsuoka, Kenta

2014-07-20

We use Chandra data to study the incidence and properties of active galactic nuclei (AGNs) in 16 intermediate redshift (0.5 < z < 1.1) X-ray-selected galaxy groups in the Chandra Deep Field-South. We measure an AGN fraction of f(L{sub X,H}>10{sup 42};M{sub R}<−20)=8.0{sub −2.3}{sup +3.0}% at z-bar ∼0.74, approximately a factor of two higher than the AGN fraction found for rich clusters at comparable redshift. This extends the trend found at low redshift for groups to have higher AGN fractions than clusters. Our estimate of the AGN fraction is also more than a factor of three higher than that of lowmore » redshift X-ray-selected groups. Using optical spectra from various surveys, we also constrain the properties of emission-line selected AGNs in these groups. In contrast to the large population of X-ray AGNs (N(L{sub X,{sub H}} > 10{sup 41} erg s{sup –1}) = 25), we find only four emission-line AGNs, three of which are also X-ray bright. Furthermore, most of the X-ray AGNs in our groups are optically dull (i.e., lack strong emission-lines), similar to those found in low redshift X-ray groups and clusters of galaxies. This contrasts with the AGN population found in low redshift optically selected groups which are dominated by emission-line AGNs. The differences between the optically and X-ray-selected AGNs populations in groups are consistent with a scenario where most AGNs in the densest environments are currently in a low accretion state.« less

The DEIMOS 10K Spectroscopic Survey Catalog of the COSMOS Field

NASA Astrophysics Data System (ADS)

Hasinger, G.; Capak, P.; Salvato, M.; Barger, A. J.; Cowie, L. L.; Faisst, A.; Hemmati, S.; Kakazu, Y.; Kartaltepe, J.; Masters, D.; Mobasher, B.; Nayyeri, H.; Sanders, D.; Scoville, N. Z.; Suh, H.; Steinhardt, C.; Yang, Fengwei

2018-05-01

We present a catalog of 10,718 objects in the COSMOS field, observed through multi-slit spectroscopy with the Deep Imaging Multi-Object Spectrograph (DEIMOS) on the Keck II telescope in the wavelength range ∼5500–9800 Å. The catalog contains 6617 objects with high-quality spectra (two or more spectral features), and 1798 objects with a single spectroscopic feature confirmed by the photometric redshift. For 2024 typically faint objects, we could not obtain reliable redshifts. The objects have been selected from a variety of input catalogs based on multi-wavelength observations in the field, and thus have a diverse selection function, which enables the study of the diversity in the galaxy population. The magnitude distribution of our objects is peaked at I AB ∼ 23 and K AB ∼ 21, with a secondary peak at K AB ∼ 24. We sample a broad redshift distribution in the range 0 < z < 6, with one peak at z ∼ 1, and another one around z ∼ 4. We have identified 13 redshift spikes at z > 0.65 with chance probabilities < 4 × 10‑4, some of which are clearly related to protocluster structures of sizes >10 Mpc. An object-to-object comparison with a multitude of other spectroscopic samples in the same field shows that our DEIMOS sample is among the best in terms of fraction of spectroscopic failures and relative redshift accuracy. We have determined the fraction of spectroscopic blends to about 0.8% in our sample. This is likely a lower limit and at any rate well below the most pessimistic expectations. Interestingly, we find evidence for strong lensing of Lyα background emitters within the slits of 12 of our target galaxies, increasing their apparent density by about a factor of 4. 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 role of submillimetre galaxies in galaxy evolution

NASA Astrophysics Data System (ADS)

Pope, Erin Alexandra

2007-08-01

This thesis presents a comprehensive study of high redshift submillimetre galaxies (SMGs) using the deepest multi-wavelength observations. The submm sample consists of galaxies detected at 850 mm with the Submillimetre Common User Bolometer Array (SCUBA) in the Great Observatories Origins Deep Survey- North region. Using the deep Spitzer Space Telescope images and new data and reductions of the Very Large Array radio data, I find statistically secure counterparts for 60% of the submm sample, and identify tentative counterparts for most of the remaining objects. This is the largest sample of submm galaxies with statistically secure counterparts detected in the radio and with Spitzer . This thesis presents spectral energy distributions (SEDs), Spitzer colours, and infrared (IR) luminosities for the SMGs. A composite rest-frame SED shows that the submm sources peak at longer wavelengths than those of local ultraluminous IR galaxies (ULIRGs), i.e. they appear to be cooler than local ULIRGs of the same luminosity. This demonstrates the strong selection effects, both locally and at high redshift, which may lead to an incomplete census of the ULIRG population. The SEDs of submm galaxies are also different from those of their high redshift neighbours, the near-IR selected BzK galaxies, whose mid-IR to radio SEDs are more like those of local ULIRGs. I fit templates that span the mid-IR through radio to derive the integrated 1R luminosities of the submm galaxies and find a median value of L IR (8-1000 mm) = 6.0 x 10 12 [Special characters omitted.] . I also find that submm flux densities by themselves systematically overpredict L IR when using templates which obey the local ULIRG temperature-luminosity relation. The SED fits show that SMGs are consistent with the correlation between radio and IR luminosity observed in local galaxies. Because the shorter Spitzer wavelengths sample the stellar bump at the redshifts of the submm sources, one can obtain a model independent estimate of the redshift, s(D z /(1 + z )) = 0.07. The median redshift of the secure submm counterparts is 2.0. Using X-ray and mid-IR imaging data, only 5% of the secure counterparts show strong evidence for an active galactic nucleus (AGN) dominating the IR luminosity. This thesis also presents deep Spitzer mid-IR spectroscopy of 13 of these SMGs in order to determine the contribution from AGN and starburst emission to the IR luminosity. I find strong polycyclic aromatic hydrocarbon (PAH) emission features in all of the targets, while only 2/13 SMGs have a significant mid-IR rising power-law component which would indicate an AGN. In the high signal-to- noise ratio composite spectrum of the SMGs I find that the AGN component contributes at most 30% of the mid-IR luminosity, implying that the total LIR in SMGs is dominated by star formation and not AGN emission. I also find that the SMGs lie on the relation between the luminosity of the main PAH features and L IR established for local starburst galaxies, confirming that the PAH luminosity can be used as a proxy for the star formation rate. Interestingly, local ULIRGs, which are often thought to be the low redshift analogues of SMGs, lie off these relations, as they appear deficient in PAH luminosity for a given L IR . In terms of an evolutionary scenario for IR luminous galaxies, SMGs are consistent with being an earlier phase in the massive merger (compared with other local or high redshift ULIRGs) in which the AGN has not yet become strong enough to heat the dust and dilute the PAH emission. I further investigate the overlap between high redshift infrared and submm populations using a statistical stacking analysis to measure the contribution of near- and mid-IR galaxy populations to the 850 mm submm background. For the first time, it is found that the 850 mm background can be completely resolved into individual galaxies and the bulk of these galaxies lie at z [Special characters omitted.] 3. Additionally I present a detailed study of the most distant SMG discovered to date, which I call GN20. This unusually bright source led to the discovery of a high redshift galaxy cluster, which is likely to be lensing the SMG. I discuss the potential for using bright SMGs in future submm surveys to identify high redshift clusters. Finally, for this complete sample of SMGs, I present the cumulative flux distribution at X-ray, optical, IR and radio wavelengths and I determine the depths at which one can expect to detect the majority of submm galaxies in future mm/submm surveys, such as with SCUBA-2, the successor to SCUBA.

Angular power spectrum of galaxies in the 2MASS Redshift Survey

NASA Astrophysics Data System (ADS)

Ando, Shin'ichiro; Benoit-Lévy, Aurélien; Komatsu, Eiichiro

2018-02-01

We present the measurement and interpretation of the angular power spectrum of nearby galaxies in the 2MASS Redshift Survey catalogue with spectroscopic redshifts up to z ≈ 0.1. We detect the angular power spectrum up to a multipole of ℓ ≈ 1000. We find that the measured power spectrum is dominated by galaxies living inside nearby galaxy clusters and groups. We use the halo occupation distribution (HOD) formalism to model the power spectrum, obtaining a fit with reasonable parameters. These HOD parameters are in agreement with the 2MASS galaxy distribution we measure towards the known nearby galaxy clusters, confirming validity of our analysis.

The WFIRST Galaxy Survey Exposure Time Calculator

NASA Technical Reports Server (NTRS)

Hirata, Christopher M.; Gehrels, Neil; Kneib, Jean-Paul; Kruk, Jeffrey; Rhodes, Jason; Wang, Yun; Zoubian, Julien

2013-01-01

This document describes the exposure time calculator for the Wide-Field Infrared Survey Telescope (WFIRST) high-latitude survey. The calculator works in both imaging and spectroscopic modes. In addition to the standard ETC functions (e.g. background and SN determination), the calculator integrates over the galaxy population and forecasts the density and redshift distribution of galaxy shapes usable for weak lensing (in imaging mode) and the detected emission lines (in spectroscopic mode). The source code is made available for public use.

Large-scale clustering measurements with photometric redshifts: comparing the dark matter haloes of X-ray AGN, star-forming and passive galaxies at z ≈ 1

NASA Astrophysics Data System (ADS)

Georgakakis, A.; Mountrichas, G.; Salvato, M.; Rosario, D.; Pérez-González, P. G.; Lutz, D.; Nandra, K.; Coil, A.; Cooper, M. C.; Newman, J. A.; Berta, S.; Magnelli, B.; Popesso, P.; Pozzi, F.

2014-10-01

We combine multi-wavelength data in the AEGIS-XD and C-COSMOS surveys to measure the typical dark matter halo mass of X-ray selected active galactic nuclei (AGN) [LX(2-10 keV) > 1042 erg s- 1] in comparison with far-infrared selected star-forming galaxies detected in the Herschel/PEP survey (PACS Evolutionary Probe; LIR > 1011 L⊙) and quiescent systems at z ≈ 1. We develop a novel method to measure the clustering of extragalactic populations that uses photometric redshift probability distribution functions in addition to any spectroscopy. This is advantageous in that all sources in the sample are used in the clustering analysis, not just the subset with secure spectroscopy. The method works best for large samples. The loss of accuracy because of the lack of spectroscopy is balanced by increasing the number of sources used to measure the clustering. We find that X-ray AGN, far-infrared selected star-forming galaxies and passive systems in the redshift interval 0.6 < z < 1.4 are found in haloes of similar mass, log MDMH/(M⊙ h-1) ≈ 13.0. We argue that this is because the galaxies in all three samples (AGN, star-forming, passive) have similar stellar mass distributions, approximated by the J-band luminosity. Therefore, all galaxies that can potentially host X-ray AGN, because they have stellar masses in the appropriate range, live in dark matter haloes of log MDMH/(M⊙ h-1) ≈ 13.0 independent of their star formation rates. This suggests that the stellar mass of X-ray AGN hosts is driving the observed clustering properties of this population. We also speculate that trends between AGN properties (e.g. luminosity, level of obscuration) and large-scale environment may be related to differences in the stellar mass of the host galaxies.

Galaxy modelling. II. Multi-wavelength faint counts from a semi-analytic model of galaxy formation

NASA Astrophysics Data System (ADS)

Devriendt, J. E. G.; Guiderdoni, B.

2000-11-01

This paper predicts self-consistent faint galaxy counts from the UV to the submm wavelength range. The stardust spectral energy distributions described in Devriendt et al. \\citeparyear{DGS99} (Paper I) are embedded within the explicit cosmological framework of a simple semi-analytic model of galaxy formation and evolution. We begin with a description of the non-dissipative and dissipative collapses of primordial perturbations, and plug in standard recipes for star formation, stellar evolution and feedback. We also model the absorption of starlight by dust and its re-processing in the IR and submm. We then build a class of models which capture the luminosity budget of the universe through faint galaxy counts and redshift distributions in the whole wavelength range spanned by our spectra. In contrast with a rather stable behaviour in the optical and even in the far-IR, the submm counts are dramatically sensitive to variations in the cosmological parameters and changes in the star formation history. Faint submm counts are more easily accommodated within an open universe with a low value of Omega_0 , or a flat universe with a non-zero cosmological constant. We confirm the suggestion of Guiderdoni et al. \\citeparyear{GHBM98} that matching the current multi-wavelength data requires a population of heavily-extinguished, massive galaxies with large star formation rates ( ~ 500 M_sun yr-1) at intermediate and high redshift (z >= 1.5). Such a population of objects probably is the consequence of an increase of interaction and merging activity at high redshift, but a realistic quantitative description can only be obtained through more detailed modelling of such processes. This study illustrates the implementation of multi-wavelength spectra into a semi-analytic model. In spite of its simplicity, it already provides fair fits of the current data of faint counts, and a physically motivated way of interpolating and extrapolating these data to other wavelengths and fainter flux levels.

The Center for Astrophysics Redshift Survey - Recent results

NASA Technical Reports Server (NTRS)

Geller, Margaret J.; Huchra, John P.

1989-01-01

Six strips of the CfA redshift survey extension are now complete. The data continue to support a picture in which galaxies are on thin sheets which nearly surround vast low-density voids. The largest structures are comparable with the extent of the survey. Voids like the one in Bootes are a common feature of the large-scale distribution of galaxies. The issue of fair samples of the galaxy distribution is discussed, examining statistical measures of the galaxy distribution including the two-point correlation functions.

A Catalog of Photometric Redshift and the Distribution of Broad Galaxy Morphologies

NASA Astrophysics Data System (ADS)

Paul, Nicholas; Virag, Nicholas; Shamir, Lior

2018-06-01

We created a catalog of photometric redshift of ~3,000,000 SDSS galaxies annotated by their broad morphology. The photometric redshift was optimized by testing and comparing several pattern recognition algorithms and variable selection strategies, trained and tested on a subset of the galaxies in the catalog that had spectra. The galaxies in the catalog have i magnitude brighter than 18 and Petrosian radius greater than 5.5''. The majority of these objects are not included in previous SDSS photometric redshift catalogs such as the photoz table of SDSS DR12. Analysis of the catalog shows that the number of galaxies in the catalog that are visually spiral increases until redshift of ~0.085, where it peaks and starts to decrease. It also shows that the number of spiral galaxies compared to elliptical galaxies drops as the redshift increases. The catalog is publicly available at https://figshare.com/articles/Morphology_and_photometric_redshift_catalog/4833593

A Photometric redshift galaxy catalog from the Red-Sequence Cluster Survey

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

Hsieh, Bau-Ching; /Taiwan, Natl. Central U. /Taipei, Inst. Astron. Astrophys.; Yee, H.K.C.

2005-02-01

The Red-Sequence Cluster Survey (RCS) provides a large and deep photometric catalog of galaxies in the z' and R{sub c} bands for 90 square degrees of sky, and supplemental V and B data have been obtained for 33.6 deg{sup 2}. They compile a photometric redshift catalog from these 4-band data by utilizing the empirical quadratic polynomial photometric redshift fitting technique in combination with CNOC2 and GOODS/HDF-N redshift data. The training set includes 4924 spectral redshifts. The resulting catalog contains more than one million galaxies with photometric redshifts < 1.5 and R{sub c} < 24, giving an rms scatter {delta}({Delta}z)

The Atacama Cosmology Telescope: Cross-Correlation of Cosmic Microwave Background Lensing and Quasars

NASA Technical Reports Server (NTRS)

Sherwin, Blake D; Das, Sudeep; Haijian, Amir; Addison, Graeme; Bond, Richard; Crichton, Devin; Devlin, Mark J.; Dunkley, Joanna; Gralla, Megan B.; Halpern, Mark;

zBEAMS: a unified solution for supernova cosmology with redshift uncertainties

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

Roberts, Ethan; Lochner, Michelle; Bassett, Bruce A.

Supernova cosmology without spectra will be an important component of future surveys such as LSST. This lack of supernova spectra results in uncertainty in the redshifts which, if ignored, leads to significantly biased estimates of cosmological parameters. Here we present a hierarchical Bayesian formalism— zBEAMS—that addresses this problem by marginalising over the unknown or uncertain supernova redshifts to produce unbiased cosmological estimates that are competitive with supernova data with spectroscopically confirmed redshifts. zBEAMS provides a unified treatment of both photometric redshifts and host galaxy misidentification (occurring due to chance galaxy alignments or faint hosts), effectively correcting the inevitable contamination inmore » the Hubble diagram. Like its predecessor BEAMS, our formalism also takes care of non-Ia supernova contamination by marginalising over the unknown supernova type. We illustrate this technique with simulations of supernovae with photometric redshifts and host galaxy misidentification. A novel feature of the photometric redshift case is the important role played by the redshift distribution of the supernovae.« less

Evidence for Cluster Evolution from an Improved Measurement of the Velocity Dispersion and Morphological Fraction of Cluster 1324+3011 at z=0.76

NASA Astrophysics Data System (ADS)

Lubin, Lori M.; Oke, J. B.; Postman, Marc

2002-10-01

We have carried out additional spectroscopic observations in the field of cluster Cl 1324+3011 at z=0.76. Combined with the spectroscopy recently presented by Postman, Lubin, & Oke, we now have spectroscopically confirmed 47 cluster members. With this significant number of redshifts, we measure accurately the cluster velocity dispersion to be 1016+126-93 km s-1. The distribution of velocity offsets is consistent with a Gaussian, indicating no substantial velocity substructure. As previously noted for other optically selected clusters at redshifts of z>~0.5, a comparison between the X-ray luminosity (LX) and the velocity dispersion (σ) of Cl 1324+3011 implies that this cluster is underluminous in X-rays by a factor of ~3-40 when compared with the LX-σ relation for local and moderate-redshift clusters. We also examine the morphologies of those cluster members that have available high angular resolution imaging with the Hubble Space Telescope (HST). There are 22 spectroscopically confirmed cluster members within the HST field of view. Twelve of these are visually classified as early-type (elliptical or S0) galaxies, implying an early-type fraction of 0.55+0.17-0.14 in this cluster. This fraction is a factor of ~1.5 lower than that observed in nearby rich clusters. Confirming previous cluster studies, the results for cluster Cl 1324+3011, combined with morphological studies of other massive clusters at redshifts of 0<=z<~1, suggest that the galaxy population in massive clusters is strongly evolving with redshift. This evolution implies that early-type galaxies are forming out of the excess of late-type (spiral, irregular, and peculiar) galaxies over the ~7 Gyr timescale.

Spectroscopy of Luminous Compact Blue Galaxies in Distant Clusters. I. Spectroscopic Data

NASA Astrophysics Data System (ADS)

Crawford, Steven M.; Wirth, Gregory D.; Bershady, Matthew A.; Hon, Kimo

2011-11-01

We used the DEIMOS spectrograph on the Keck II Telescope to obtain spectra of galaxies in the fields of five distant, rich galaxy clusters over the redshift range 0.5 < z < 0.9 in a search for luminous compact blue galaxies (LCBGs). Unlike traditional studies of galaxy clusters, we preferentially targeted blue cluster members identified via multi-band photometric pre-selection based on imaging data from the WIYN telescope. Of the 1288 sources that we targeted, we determined secure spectroscopic redshifts for 848 sources, yielding a total success rate of 66%. Our redshift measurements are in good agreement with those previously reported in the literature, except for 11 targets which we believe were previously in error. Within our sample, we confirm the presence of 53 LCBGs in the five galaxy clusters. The clusters all stand out as distinct peaks in the redshift distribution of LCBGs with the average number density of LCBGs ranging from 1.65 ± 0.25 Mpc-3 at z = 0.55 to 3.13 ± 0.65 Mpc-3 at z = 0.8. The number density of LCBGs in clusters exceeds the field density by a factor of 749 ± 116 at z = 0.55; at z = 0.8, the corresponding ratio is E = 416 ± 95. At z = 0.55, this enhancement is well above that seen for blue galaxies or the overall cluster population, indicating that LCBGs are preferentially triggered in high-density environments at intermediate redshifts. Based in part 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.

X-Ray Properties of K-Selected Galaxies at 0.5 Less than z Less than 2.0: Investigating Trends with Stellar Mass, Redshift and Spectral Type

NASA Technical Reports Server (NTRS)

Jones, Therese M.; Kriek, Mariska; vanDokkum, Peter G.; Brammer, Gabriel; Franx, Marijn; Greene, Jenny E.; Labbe, Ivo; Whitaker, Katherine E.

2014-01-01

We examine how the total X-ray luminosity correlates with stellar mass, stellar population, and redshift for a K-band limited sample of approximately 3500 galaxies at 0.5 < z < 2.0 from the NEWFIRM Medium Band Survey in the COSMOS field. The galaxy sample is divided into 32 different galaxy types, based on similarities between the spectral energy distributions. For each galaxy type, we further divide the sample into bins of redshift and stellar mass, and perform an X-ray stacking analysis using the Chandra COSMOS data. We find that full band X-ray luminosity is primarily increasing with stellar mass, and at similar mass and spectral type is higher at larger redshifts. When comparing at the same stellar mass, we find that the X-ray luminosity is slightly higher for younger galaxies (i.e., weaker 4000 angstrom breaks), but the scatter in this relation is large. We compare the observed X-ray luminosities to those expected from low- and high-mass X-ray binaries (XRBs). For blue galaxies, XRBs can almost fully account for the observed emission, while for older galaxies with larger 4000 angstrom breaks, active galactic nuclei (AGN) or hot gas dominate the measured X-ray flux. After correcting for XRBs, the X-ray luminosity is still slightly higher in younger galaxies, although this correlation is not significant. AGN appear to be a larger component of galaxy X-ray luminosity at earlier times, as the hardness ratio increases with redshift. Together with the slight increase in X-ray luminosity this may indicate more obscured AGNs or higher accretion rates at earlier times.

Evolution of HI from Z=5 to the present

NASA Technical Reports Server (NTRS)

Storrie-Lombardi, L. J.

2002-01-01

Studies of damped Lya systems provide us with a good measure of the evolution of the HI column density distribution function and the contribution to the comoving mass density in neutral gas out to redshifts of z = 5 . The column density distribution function at high redshift steepens for the highest column density HI absorbers, though the contribution to the comoving mass density of neutral gas remains fiat from 2 < z < 5 . Results from studies at z < 2 are finding substantial numbers of damped absorbers identified from MgII absorption, compared to previous blind surveys. These results indicate that the contribution to the comoving mass density in neutral gas may be constant from z 0 to z 5. Details of recent work in the redshift range z < 2 work is covered elsewhere in this volume (see D. Nestor). We review here recent results for the redshift range 2 < z < 5.

Gravitational lensing effects in a time-variable cosmological 'constant' cosmology

NASA Technical Reports Server (NTRS)

Ratra, Bharat; Quillen, Alice

1992-01-01

A scalar field phi with a potential V(phi) varies as phi exp -alpha(alpha is greater than 0) has an energy density, behaving like that of a time-variable cosmological 'constant', that redshifts less rapidly than the energy densities of radiation and matter, and so might contribute significantly to the present energy density. We compute, in this spatially flat cosmology, the gravitational lensing optical depth, and the expected lens redshift distribution for fixed source redshift. We find, for the values of alpha of about 4 and baryonic density parameter Omega of about 0.2 consistent with the classical cosmological tests, that the optical depth is significantly smaller than that in a constant-Lambda model with the same Omega. We also find that the redshift of the maximum of the lens distribution falls between that in the constant-Lambda model and that in the Einstein-de Sitter model.

How dead are dead galaxies? Mid-infrared fluxes of quiescent galaxies at redshift 0.3 < z < 2.5: implications for star formation rates and dust heating

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

Fumagalli, Mattia; Labbé, Ivo; Patel, Shannon G.

We investigate star formation rates (SFRs) of quiescent galaxies at high redshift (0.3 < z < 2.5) using 3D-HST WFC3 grism spectroscopy and Spitzer mid-infrared data. We select quiescent galaxies on the basis of the widely used UVJ color-color criteria. Spectral energy distribution (SED) fitting (rest-frame optical and near-IR) indicates very low SFRs for quiescent galaxies (sSFR ∼ 10{sup –12} yr{sup –1}). However, SED fitting can miss star formation if it is hidden behind high dust obscuration and ionizing radiation is re-emitted in the mid-infrared. It is therefore fundamental to measure the dust-obscured SFRs with a mid-IR indicator. We stackmore » the MIPS 24 μm images of quiescent objects in five redshift bins centered on z = 0.5, 0.9, 1.2, 1.7, 2.2 and perform aperture photometry. Including direct 24 μm detections, we find sSFR ∼ 10{sup –11.9} × (1 + z){sup 4} yr{sup –1}. These values are higher than those indicated by SED fitting, but at each redshift they are 20-40 times lower than those of typical star-forming galaxies. The true SFRs of quiescent galaxies might be even lower, as we show that the mid-IR fluxes can be due to processes unrelated to ongoing star formation, such as cirrus dust heated by old stellar populations and circumstellar dust. Our measurements show that star formation quenching is very efficient at every redshift. The measured SFR values are at z > 1.5 marginally consistent with the ones expected from gas recycling (assuming that mass loss from evolved stars refuels star formation) and well below that at lower redshifts.« less

The Infrared Properties of Sources Matched in the Wise All-Sky and Herschel ATLAS Surveys

NASA Technical Reports Server (NTRS)

Bond, Nicholas A.; Benford, Dominic J.; Gardner, Jonathan P.; Amblard, Alexandre; Fleuren, Simone; Blain, Andrew W.; Dunne, Loretta; Smith, Daniel J. B.; Maddox, Steve J.; Hoyos, Carlos;

The Infrared Properties of Sources Matched in the WISE All-Sky and Herschel Atlas Surveys

NASA Technical Reports Server (NTRS)

Bond, Nicholas A.; Benford, Dominic J.; Gardner, Jonathan P.; Eisenhardt, Peter; Amblard, Alexandre; Temi, Pasquale; Fleuren, Simone; Blain, Andrew W.; Dunne, Loretta; Smith, Daniel J.;

FAST: Fitting and Assessment of Synthetic Templates

NASA Astrophysics Data System (ADS)

Kriek, Mariska; van Dokkum, Pieter G.; Labbé, Ivo; Franx, Marijn; Illingworth, Garth D.; Marchesini, Danilo; Quadri, Ryan F.; Aird, James; Coil, Alison L.; Georgakakis, Antonis

2018-03-01

FAST (Fitting and Assessment of Synthetic Templates) fits stellar population synthesis templates to broadband photometry and/or spectra. FAST is compatible with the photometric redshift code EAzY (ascl:1010.052) when fitting broadband photometry; it uses the photometric redshifts derived by EAzY, and the input files (for examply, photometric catalog and master filter file) are the same. FAST fits spectra in combination with broadband photometric data points or simultaneously fits two components, allowing for an AGN contribution in addition to the host galaxy light. Depending on the input parameters, FAST outputs the best-fit redshift, age, dust content, star formation timescale, metallicity, stellar mass, star formation rate (SFR), and their confidence intervals. Though some of FAST's functions overlap with those of HYPERZ (ascl:1108.010), it differs by fitting fluxes instead of magnitudes, allows the user to completely define the grid of input stellar population parameters and easily input photometric redshifts and their confidence intervals, and calculates calibrated confidence intervals for all parameters. Note that FAST is not a photometric redshift code, though it can be used as one.

Broad Redshifted Line as a Signature of Outflow

NASA Astrophysics Data System (ADS)

Titarchuk, Lev; Kazanas, Demos; Becker, Peter A.

2003-11-01

We formulate and solve the diffusion problem of line photon propagation in a bulk outflow from a compact object (black hole or neutron star) using a generic assumption regarding the distribution of line photons within the outflow. Thomson scattering of the line photons within the expanding flow leads to a decrease of their energy which is of first order in v/c, where v is the outflow velocity and c is the speed of light. We demonstrate that the emergent line profile is closely related to the time distribution of photons diffusing through the flow (the light curve) and consists of a broad redshifted feature. We analyzed the line profiles for the general case of outflow density distribution. We emphasize that the redshifted lines are intrinsic properties of the powerful outflow that are supposed to be in many compact objects.

Broad Red-Shifted Lines as a Signature of Outflow

NASA Astrophysics Data System (ADS)

Kazanas, Demosthenes; Titarchuk, Lev; Becker, Peter A.

2004-07-01

We formulate and solve the diffusion problem of line photon propagation in a bulk outflow from a compact object (black hole or neutron star) using a generic assumption regarding the distribution of line photons within the outflow. Thomson scattering of the line photons within the expanding flow leads to a decrease of their energy which is of first order in v/c, where v is the outflow velocity and c the speed of light. We demonstrate that the emergent line profile is closely related to the time distribution of photons diffusing through the flow (the light curve) and consists of a broad redshifted feature. We analyzed the line profiles for the general case of outflow density distribution. We emphasize that the redshifted lines are intrinsic properties of the powerful outflow that are supposed to be in many compact objects.

Broad Red-Shifted Lines as a Signature of Outflows

NASA Astrophysics Data System (ADS)

Titarchuck, Lev; Kazanas, Demos; Becker, Peter A.

2006-02-01

We formulate and solve the diffusion problem of line photon propagation in a bulk outflow from a compact object (black hole or neutron star) using a generic assumption regarding the distribution of line photons within the outflow. Thomson scattering of the line photons within the expanding flow leads to a decrease of their energy which is of first order in υ/c, where υ the outflow velocity and c is the speed of light. We demonstrate that the emergent line profile is closely related to the time distribution of photons diffusing through the flow (the light curve) and consists of a broad redshifted feature. We analyzed the line profiles for the general case of outflow density distribution. We emphasize that the redshifted lines are intrinsic properties of the powerful outflow that are supposed to be in many compact objects.

Pixel-by-Pixel SED Fitting of Intermediate Redshift Galaxies

NASA Astrophysics Data System (ADS)

Cohen, Seth H.; Kim, Hwihyun; Petty, Sara M.; Farrah, Duncan

2015-01-01

We select intermediate redshift galaxies from the Hubble Space Telescope CANDELS and GOODS surveys to study their stellar populations on sub-kilo-parsec scales by fitting SED models on a pixel-by-pixel basis. Galaxies are chosen to have measured spectroscopic redshifts (z<1.5), to be bright (H_AB<21 mag), to be relatively face-on (b/a > 0.6), and have a minimum of ten individual resolution elements across the face of the galaxy, as defined by the broadest PSF (F160W-band) in the data. The sample contains ~200 galaxies with BViz(Y)JH band HST photometry. The main goal of the study is to better understand the effects of population blending when using a pixel-by-pixel SED fitting (pSED) approach. We outline our pSED fitting method which gives maps of stellar mass, age, star-formation rate, etc. Several examples of individual pSED-fit maps are presented in detail, as well as some preliminary results on the full sample. The pSED method is necessarily biased by the brightest population in a given pixel outshining the rest of the stars, and, therefore, we intend to study this apparent population blending in a set of artificially redshifted images of nearby galaxies, for which we have star-by-star measurements of their stellar populations. This local sample will be used to better interpret the measurements for the higher redshift galaxies.Based on observations made with the NASA/ESA Hubble Space Telescope, obtained from the Data Archive 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. This archival research is associated with program #13241.

Lensing corrections to features in the angular two-point correlation function and power spectrum

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

LoVerde, Marilena; Department of Physics, Columbia University, New York, New York 10027; Hui, Lam

2008-01-15

It is well known that magnification bias, the modulation of galaxy or quasar source counts by gravitational lensing, can change the observed angular correlation function. We investigate magnification-induced changes to the shape of the observed correlation function w({theta}), and the angular power spectrum C{sub l}, paying special attention to the matter-radiation equality peak and the baryon wiggles. Lensing effectively mixes the correlation function of the source galaxies with that of the matter correlation at the lower redshifts of the lenses distorting the observed correlation function. We quantify how the lensing corrections depend on the width of the selection function, themore » galaxy bias b, and the number count slope s. The lensing correction increases with redshift and larger corrections are present for sources with steep number count slopes and/or broad redshift distributions. The most drastic changes to C{sub l} occur for measurements at high redshifts (z > or approx. 1.5) and low multipole moment (l < or approx. 100). For the source distributions we consider, magnification bias can shift the location of the matter-radiation equality scale by 1%-6% at z{approx}1.5 and by z{approx}3.5 the shift can be as large as 30%. The baryon bump in {theta}{sup 2}w({theta}) is shifted by < or approx. 1% and the width is typically increased by {approx}10%. Shifts of > or approx. 0.5% and broadening > or approx. 20% occur only for very broad selection functions and/or galaxies with (5s-2)/b > or approx. 2. However, near the baryon bump the magnification correction is not constant but is a gently varying function which depends on the source population. Depending on how the w({theta}) data is fitted, this correction may need to be accounted for when using the baryon acoustic scale for precision cosmology.« less

On the Validity of the Streaming Model for the Redshift-Space Correlation Function in the Linear Regime

NASA Astrophysics Data System (ADS)

Fisher, Karl B.

1995-08-01

The relation between the galaxy correlation functions in real-space and redshift-space is derived in the linear regime by an appropriate averaging of the joint probability distribution of density and velocity. The derivation recovers the familiar linear theory result on large scales but has the advantage of clearly revealing the dependence of the redshift distortions on the underlying peculiar velocity field; streaming motions give rise to distortions of θ(Ω0.6/b) while variations in the anisotropic velocity dispersion yield terms of order θ(Ω1.2/b2). This probabilistic derivation of the redshift-space correlation function is similar in spirit to the derivation of the commonly used "streaming" model, in which the distortions are given by a convolution of the real-space correlation function with a velocity distribution function. The streaming model is often used to model the redshift-space correlation function on small, highly nonlinear, scales. There have been claims in the literature, however, that the streaming model is not valid in the linear regime. Our analysis confirms this claim, but we show that the streaming model can be made consistent with linear theory provided that the model for the streaming has the functional form predicted by linear theory and that the velocity distribution is chosen to be a Gaussian with the correct linear theory dispersion.

Neutral hydrogen in the post-reionization universe

NASA Astrophysics Data System (ADS)

Padmanabhan, Hamsa

2018-05-01

The evolution of neutral hydrogen (HI) across redshifts is a powerful probe of cosmology, large scale structure in the universe and the intergalactic medium. Using a data-driven halo model to describe the distribution of HI in the post-reionization universe (z ~ 5 to 0), we obtain the best-fitting parameters from a rich sample of observational data: low redshift 21-cm emission line studies, intermediate redshift intensity mapping experiments, and higher redshift Damped Lyman Alpha (DLA) observations. Our model describes the abundance and clustering of neutral hydrogen across redshifts 0 - 5, and is useful for investigating different aspects of galaxy evolution and for comparison with hydrodynamical simulations. The framework can be applied for forecasting future observations with neutral hydrogen, and extended to the case of intensity mapping with molecular and other line transitions at intermediate redshifts.

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 Chandra Deepest Fields in the Infrared: Making the Connection between Normal Galaxies and AGN

NASA Astrophysics Data System (ADS)

Grogin, N. A.; Ferguson, H. C.; Dickinson, M. E.; Giavalisco, M.; Mobasher, B.; Padovani, P.; Williams, R. E.; Chary, R.; Gilli, R.; Heckman, T. M.; Stern, D.; Winge, C.

2001-12-01

Within each of the two Chandra Deepest Fields (CDFs), there are ~10'x15' regions targeted for non-proprietary, deep SIRTF 3.6--24μ m imaging as part of the Great Observatories Origins Deep Survey (GOODS) Legacy program. In advance of the SIRTF observations, the GOODS team has recently begun obtaining non-proprietary, deep ground-based optical and near-IR imaging and spectroscopy over these regions, which contain virtually all of the current ≈1 Msec CXO coverage in the CDF North and much of the ≈1 Msec coverage in the CDF South. In particular, the planned depth of the near-IR imaging (JAB ~ 25.3; HAB ~ 24.8; KAB ~ 24.4) combined with the deep Chandra data can allow us to trace the evolutionary connection between normal galaxies, starbursts, and AGN out to z ~ 1 and beyond. We describe our CDF Archival program, which is integrating these GOODS-supporting observations together with the CDF archival data and other publicly-available datasets in these regions to create a multi-wavelength deep imaging and spectroscpic database available to the entire community. We highlight progress toward near-term science goals of this program, including: (a) pushing constraints on the redshift distribution and spectral-energy distributions of the faintest X-ray sources to the deepest possible levels via photometric redshifts; and (b) better characterizing the heavily-obscured and the high-redshift populations via both a near-IR search for optically-undetected CDF X-ray sources and also X-ray stacking analyses on the CXO-undetected EROs in these fields.

Metallicity Evolution of Damped Lyα Systems Out to z ~ 5

NASA Astrophysics Data System (ADS)

Rafelski, Marc; Wolfe, Arthur M.; Prochaska, J. Xavier; Neeleman, Marcel; Mendez, Alexander J.

2012-08-01

We present chemical abundance measurements for 47 damped Lyα (DLA) systems, 30 at z > 4, observed with the Echellette Spectrograph and Imager and the High Resolution Echelle Spectrometer on the Keck telescopes. H I column densities of the DLAs are measured with Voigt profile fits to the Lyα profiles, and we find an increased number of false DLA identifications with Sloan Digital Sky Survey at z > 4 due to the increased density of the Lyα forest. Ionic column densities are determined using the apparent optical depth method, and we combine our new metallicity measurements with 195 from previous surveys to determine the evolution of the cosmic metallicity of neutral gas. We find the metallicity of DLAs decreases with increasing redshift, improving the significance of the trend and extending it to higher redshifts, with a linear fit of -0.22 ± 0.03 dex per unit redshift from z = 0.09-5.06. The metallicity "floor" of ≈1/600 solar continues out to z ~ 5, despite our sensitivity for finding DLAs with much lower metallicities. However, this floor is not statistically different from a steep tail to the distribution. We also find that the intrinsic scatter of metallicity among DLAs of ~0.5 dex continues out to z ~ 5. In addition, the metallicity distribution and the α/Fe ratios of z > 2 DLAs are consistent with being drawn from the same parent population with those of halo stars. It is therefore possible that the halo stars in the Milky Way formed out of gas that commonly exhibits DLA absorption at z > 2.

THE RED SEQUENCE AT BIRTH IN THE GALAXY CLUSTER Cl J1449+0856 AT z = 2

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

Strazzullo, V.; Pannella, M.; Daddi, E.

We use Hubble Space Telescope /WFC3 imaging to study the red population in the IR-selected, X-ray detected, low-mass cluster Cl J1449+0856 at z = 2, one of the few bona fide established clusters discovered at this redshift, and likely a typical progenitor of an average massive cluster today. This study explores the presence and significance of an early red sequence in the core of this structure, investigating the nature of red-sequence galaxies, highlighting environmental effects on cluster galaxy populations at high redshift, and at the same time underlining similarities and differences with other distant dense environments. Our results suggest thatmore » the red population in the core of Cl J1449+0856 is made of a mixture of quiescent and dusty star-forming galaxies, with a seedling of the future red sequence already growing in the very central cluster region, and already characterizing the inner cluster core with respect to lower-density environments. On the other hand, the color–magnitude diagram of this cluster is definitely different from that of lower-redshift z ≲ 1 clusters, as well as of some rare particularly evolved massive clusters at similar redshift, and it is suggestive of a transition phase between active star formation and passive evolution occurring in the protocluster and established lower-redshift cluster regimes.« less

The ALHAMBRA survey: B-band luminosity function of quiescent and star-forming galaxies at 0.2 ≤ z < 1 by PDF analysis

NASA Astrophysics Data System (ADS)

López-Sanjuan, C.; Tempel, E.; Benítez, N.; Molino, A.; Viironen, K.; Díaz-García, L. A.; Fernández-Soto, A.; Santos, W. A.; Varela, J.; Cenarro, A. J.; Moles, M.; Arnalte-Mur, P.; Ascaso, B.; Montero-Dorta, A. D.; Pović, M.; Martínez, V. J.; Nieves-Seoane, L.; Stefanon, M.; Hurtado-Gil, Ll.; Márquez, I.; Perea, J.; Aguerri, J. A. L.; Alfaro, E.; Aparicio-Villegas, T.; Broadhurst, T.; Cabrera-Caño, J.; Castander, F. J.; Cepa, J.; Cerviño, M.; Cristóbal-Hornillos, D.; González Delgado, R. M.; Husillos, C.; Infante, L.; Masegosa, J.; del Olmo, A.; Prada, F.; Quintana, J. M.

2017-03-01

Aims: Our goal is to study the evolution of the B-band luminosity function (LF) since z 1 using ALHAMBRA data. Methods: We used the photometric redshift and the I-band selection magnitude probability distribution functions (PDFs) of those ALHAMBRA galaxies with I ≤ 24 mag to compute the posterior LF. We statistically studied quiescent and star-forming galaxies using the template information encoded in the PDFs. The LF covariance matrix in redshift - magnitude - galaxy type space was computed, including the cosmic variance. That was estimated from the intrinsic dispersion of the LF measurements in the 48 ALHAMBRA sub-fields. The uncertainty due to the photometric redshift prior is also included in our analysis. Results: We modelled the LF with a redshift-dependent Schechter function affected by the same selection effects than the data. The measured ALHAMBRA LF at 0.2 ≤ z< 1 and the evolving Schechter parameters both for quiescent and star-forming galaxies agree with previous results in the literature. The estimated redshift evolution of MB* ∝ Qz is QSF = -1.03 ± 0.08 and QQ = -0.80 ± 0.08, and of log 10φ∗ ∝ Pz is PSF = -0.01 ± 0.03 and PQ = -0.41 ± 0.05. The measured faint-end slopes are αSF = -1.29 ± 0.02 and αQ = -0.53 ± 0.04. We find a significant population of faint quiescent galaxies with MB ≳ -18, modelled by a second Schechter function with slope β = -1.31 ± 0.11. Conclusions: We present a robust methodology to compute LFs using multi-filter photometric data. The application to ALHAMBRA shows a factor 2.55 ± 0.14 decrease in the luminosity density jB of star-forming galaxies, and a factor 1.25 ± 0.16 increase in the jB of quiescent ones since z = 1, confirming the continuous build-up of the quiescent population with cosmic time. The contribution of the faint quiescent population to jB increases from 3% at z = 1 to 6% at z = 0. The developed methodology will be applied to future multi-filter surveys such as J-PAS. Based on observations collected at the German-Spanish Astronomical Center, Calar Alto (CAHA), jointly operated by the Max-Planck-Institut für Astronomie (MPIA) at Heidelberg and the Instituto de Astrofísica de Andalucía (CSIC)

Infrared Color Selection of Massive Galaxies at z > 3

NASA Astrophysics Data System (ADS)

Wang, T.; Elbaz, D.; Schreiber, C.; Pannella, M.; Shu, X.; Willner, S. P.; Ashby, M. L. N.; Huang, J.-S.; Fontana, A.; Dekel, A.; Daddi, E.; Ferguson, H. C.; Dunlop, J.; Ciesla, L.; Koekemoer, A. M.; Giavalisco, M.; Boutsia, K.; Finkelstein, S.; Juneau, S.; Barro, G.; Koo, D. C.; Michałowski, M. J.; Orellana, G.; Lu, Y.; Castellano, M.; Bourne, N.; Buitrago, F.; Santini, P.; Faber, S. M.; Hathi, N.; Lucas, R. A.; Pérez-González, P. G.

2016-01-01

We introduce a new color selection technique to identify high-redshift, massive galaxies that are systematically missed by Lyman-break selection. The new selection is based on the H160 (H) and Infrared Array Camera (IRAC) 4.5 μm bands, specifically H-[4.5]\\gt 2.25 mag. These galaxies, called “HIEROs,” include two major populations that can be separated with an additional J - H color. The populations are massive and dusty star-forming galaxies at z\\gt 3 ({JH}-{blue}) and extremely dusty galaxies at z≲ 3 ({JH}-{red}). The 350 arcmin2 of the GOODS-North and GOODS-South fields with the deepest Hubble Space Telescope (HST)/Wide Field Camera 3 (WFC3) near-infrared and IRAC data contain as many as 285 HIEROs down to [4.5]\\lt 24 mag. Inclusion of the most extreme HIEROs, not even detected in the H band, makes this selection particularly complete for the identification of massive high-redshift galaxies. We focus here primarily on {JH}-{blue} (z\\gt 3) HIEROs, which have a median photometric redshift < z> ˜ 4.4 and stellar mass {M}*˜ {10}10.6 {M}⊙ and are much fainter in the rest-frame UV than similarly massive Lyman-break galaxies (LBGs). Their star formation rates (SFRs), derived from their stacked infrared spectral energy distributions (SEDs), reach ˜240 {M}⊙ yr-1, leading to a specific SFR, {{sSFR}}\\equiv {{SFR}}/{M}*˜ 4.2 Gyr-1, suggesting that the sSFRs for massive galaxies continue to grow at z\\gt 2 but at a lower growth rate than from z = 0 to z = 2. With a median half-light radius of 2 kpc, including ˜ 20% as compact as quiescent (QS) galaxies at similar redshifts, {JH}-{blue} HIEROs represent perfect star-forming progenitors of the most massive ({M}*≳ {10}11.2 {M}⊙ ) compact QS galaxies at z˜ 3 and have the right number density. HIEROs make up ˜ 60% of all galaxies with {M}*\\gt {10}10.5 {M}⊙ identified at z\\gt 3 from their photometric redshifts. This is five times more than LBGs with nearly no overlap between the two populations. While HIEROs make up 15%-25% of the total SFR density at z˜ 4-5, they completely dominate the SFR density taking place in {M}*\\gt {10}10.5 {M}⊙ galaxies, and HIEROs are therefore crucial to understanding the very early phase of massive galaxy formation.

Characterizing the WISE-selected heavily obscured quasar population with optical spectroscopy from the Southern African Large Telescope

NASA Astrophysics Data System (ADS)

Hviding, Raphael E.; Hickox, Ryan C.; Hainline, Kevin N.; Carroll, Christopher M.; DiPompeo, Michael A.; Yan, Wei; Jones, Mackenzie L.

2018-02-01

We present the results of an optical spectroscopic survey of 46 heavily obscured quasar candidates. Objects are selected using their mid-infrared (mid-IR) colours and magnitudes from the Wide-Field Infrared Survey Explorer (WISE) anzd their optical magnitudes from the Sloan Digital Sky Survey. Candidate Active Galactic Nuclei (AGNs) are selected to have mid-IR colours indicative of quasar activity and lie in a region of mid-IR colour space outside previously published X-ray based selection regions. We obtain optical spectra for our sample using the Robert Stobie Spectrograph on the Southern African Large Telescope. 30 objects (65 per cent) have identifiable emission lines, allowing for the determination of spectroscopic redshifts. Other than one object at z ˜ 2.6, candidates have moderate redshifts ranging from z = 0.1 to 0.8 with a median of 0.3. 21 (70 per cent) of our objects with identified redshift (46 per cent of the whole sample) are identified as AGNs through common optical diagnostics. We model the spectral energy distributions of our sample and found that all require a strong AGN component, with an average intrinsic AGN fraction at 8 μm of 0.91. Additionally, the fits require large extinction coefficients with an average E(B - V)AGN = 17.8 (average A(V)AGN = 53.4). By focusing on the area outside traditional mid-IR photometric cuts, we are able to capture and characterize a population of deeply buried quasars that were previously unattainable through X-ray surveys alone.

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

Muzzin, Adam; Van der Burg, R. F. J.; McGee, Sean L.

We investigate the velocity versus position phase space of z ∼ 1 cluster galaxies using a set of 424 spectroscopic redshifts in nine clusters drawn from the GCLASS survey. Dividing the galaxy population into three categories, that is, quiescent, star-forming, and poststarburst, we find that these populations have distinct distributions in phase space. Most striking are the poststarburst galaxies, which are commonly found at small clustercentric radii with high clustercentric velocities, and appear to trace a coherent 'ring' in phase space. Using several zoom simulations of clusters, we show that the coherent distribution of the poststarbursts can be reasonably wellmore » reproduced using a simple quenching scenario. Specifically, the phase space is best reproduced if these galaxies are quenched with a rapid timescale (0.1 0.5 Gyr) or by quenching galaxies at larger radii (R ∼ R {sub 200}). We compare this quenching timescale to the timescale implied by the stellar populations of the poststarburst galaxies and find that the poststarburst spectra are well-fit by a rapid quenching (τ {sub Q} = 0.4{sub −0.4}{sup +0.3} Gyr) of a typical star-forming galaxy. The similarity between the quenching timescales derived from these independent indicators is a strong consistency check of the quenching model. Given that the model implies satellite quenching is rapid and occurs well within R {sub 200}, this would suggest that ram-pressure stripping of either the hot or cold gas component of galaxies are the most plausible candidates for the physical mechanism. The high cold gas consumption rates at z ∼ 1 make it difficult to determine whether hot or cold gas stripping is dominant; however, measurements of the redshift evolution of the satellite quenching timescale and location may be capable of distinguishing between the two.« less

GALAXY INFALL BY INTERACTING WITH ITS ENVIRONMENT: A COMPREHENSIVE STUDY OF 340 GALAXY CLUSTERS

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

Gu, Liyi; Wen, Zhonglue; Gandhi, Poshak

To study systematically the evolution of the angular extents of the galaxy, intracluster medium (ICM), and dark matter components in galaxy clusters, we compiled the optical and X-ray properties of a sample of 340 clusters with redshifts <0.5, based on all the available data from the Sloan Digital Sky Survey and Chandra / XMM-Newton . For each cluster, the member galaxies were determined primarily with photometric redshift measurements. The radial ICM mass distribution, as well as the total gravitational mass distribution, was derived from a spatially resolved spectral analysis of the X-ray data. When normalizing the radial profile of galaxymore » number to that of the ICM mass, the relative curve was found to depend significantly on the cluster redshift; it drops more steeply toward the outside in lower-redshift subsamples. The same evolution is found in the galaxy-to-total mass profile, while the ICM-to-total mass profile varies in an opposite way. The behavior of the galaxy-to-ICM distribution does not depend on the cluster mass, suggesting that the detected redshift dependence is not due to mass-related effects, such as sample selection bias. Also, it cannot be ascribed to various redshift-dependent systematic errors. We interpret that the galaxies, the ICM, and the dark matter components had similar angular distributions when a cluster was formed, while the galaxies traveling in the interior of the cluster have continuously fallen toward the center relative to the other components, and the ICM has slightly expanded relative to the dark matter although it suffers strong radiative loss. This cosmological galaxy infall, accompanied by an ICM expansion, can be explained by considering that the galaxies interact strongly with the ICM while they are moving through it. The interaction is considered to create a large energy flow of 10{sup 4445} erg s{sup 1} per cluster from the member galaxies to their environment, which is expected to continue over cosmological timescales.« less

Galaxy Infall by Interacting with Its Environment: A Comprehensive Study of 340 Galaxy Clusters

NASA Astrophysics Data System (ADS)

Gu, Liyi; Wen, Zhonglue; Gandhi, Poshak; Inada, Naohisa; Kawaharada, Madoka; Kodama, Tadayuki; Konami, Saori; Nakazawa, Kazuhiro; Xu, Haiguang; Makishima, Kazuo

2016-07-01

To study systematically the evolution of the angular extents of the galaxy, intracluster medium (ICM), and dark matter components in galaxy clusters, we compiled the optical and X-ray properties of a sample of 340 clusters with redshifts <0.5, based on all the available data from the Sloan Digital Sky Survey and Chandra/XMM-Newton. For each cluster, the member galaxies were determined primarily with photometric redshift measurements. The radial ICM mass distribution, as well as the total gravitational mass distribution, was derived from a spatially resolved spectral analysis of the X-ray data. When normalizing the radial profile of galaxy number to that of the ICM mass, the relative curve was found to depend significantly on the cluster redshift; it drops more steeply toward the outside in lower-redshift subsamples. The same evolution is found in the galaxy-to-total mass profile, while the ICM-to-total mass profile varies in an opposite way. The behavior of the galaxy-to-ICM distribution does not depend on the cluster mass, suggesting that the detected redshift dependence is not due to mass-related effects, such as sample selection bias. Also, it cannot be ascribed to various redshift-dependent systematic errors. We interpret that the galaxies, the ICM, and the dark matter components had similar angular distributions when a cluster was formed, while the galaxies traveling in the interior of the cluster have continuously fallen toward the center relative to the other components, and the ICM has slightly expanded relative to the dark matter although it suffers strong radiative loss. This cosmological galaxy infall, accompanied by an ICM expansion, can be explained by considering that the galaxies interact strongly with the ICM while they are moving through it. The interaction is considered to create a large energy flow of 1044-45 erg s-1 per cluster from the member galaxies to their environment, which is expected to continue over cosmological timescales.

Searching for Lyman-alpha Emitters as a Probe of Cosmic Reionization and Peering Inside Galaxies in the First Two Billion Years

NASA Astrophysics Data System (ADS)

Jung, Intae; Finkelstein, Steven; CANDELS team

2018-01-01

In the reionization era an immediately accessible method for studying the intergalactic medium is to measure the equivalent width distribution of Lyman-alpha emission from galaxies with follow-up spectroscopy. To search for Lyman-alpha emission from galaxies at z ~ 5-8, we perform spectroscopic observations of candidate galaxies from the Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey (CANDELS). We utilize data from the Keck DEIMOS (optical) and MOSFIRE (near-infrared) spectrographs, ensuring a comprehensive wavelength coverage of Lyman-alpha emission at z ~ 5-8. We have a total of 1170 object-hours of spectroscopic integration of galaxies at z > 5: 118 galaxies with DEIMOS and 69 galaxies with MOSFIRE. The equivalent width distribution of Lyman-alpha emission is constrained with the number of detected objects from our dataset by constructing detailed simulations of mock emission lines, which consider observational conditions and the photometric redshift probability distribution function. We present our robust measure of the evolution of the Lyman-alpha emission equivalent width distribution at z ~ 5-8.Understanding what drives star-formation quenching in the early universe is a long-standing puzzle. To reveal the hidden relation of quenching with galaxy structural properties, particularly central stellar mass density, we perform the first spatially resolved stellar population study of galaxies at z ~ 4, utilizing the CANDELS imaging data set over the GOODS-S field. We examine 166 photometric-redshift-selected galaxies at 3.5 < z < 4.0 with additional deep K-band survey data from the HAWK-I UDS and GOODS Survey which covers the 4000Å break at these redshifts. We estimate the stellar mass, star formation rate, and dust extinction for galaxy inner and outer regions via spatially resolved spectral energy distribution fitting based on a Markov Chain Monte Carlo algorithm. By comparing specific star formation rates (sSFRs) between inner and outer parts of the galaxies we find that the majority of galaxies with high central mass densities show evidence for a preferentially lower sSFR in their centers than in their outer regions, indicative of reduced sSFRs in their central regions.

Analyzing the Signatures of High Red-shift Hydrogen: The Lyman Alpha and 21cm Emission Lines

NASA Astrophysics Data System (ADS)

Hansen, Matthew

Hydrogen line emission is an important window on galaxy formation due to the large abundance of neutral hydrogen in the early Universe. This dissertation comprises two theoretical/computational studies of two types of hydrogen line emission: Lyman alpha emission and escape from young stellar populations, and 21cm radiation from neutral hydrogen clouds at the time of the first luminous objects. The Lyman alpha research concerns the radiative transfer of resonant line radiation from a central source escaping from a multi-phase medium appropriate to young star forming regions. To analyze the properties of this novel radiative transfer problem I develop new theoretical formulations of the problem, substantiated by physically accurate monte carlo simulations of photon scattering and absorption through multi-phase gas geometries. I find that the escape fraction of resonant line photons from young star forming regions--ionized gas filled with neutral hydrogen clouds with low dust content--can exceed the continuum photon escape fraction by up to an order of magnitude. Additionally, I study the effect of gas outflow on the line profile of escaping resonant photons. In light of these results, I discuss why a young normal stellar populations surrounded by a clumpy multi-phase gas outflow can explain the Lyman alpha spectra seen from high red-shift Lyman Alpha Emitters (LAEs). The 21cm research concerns the ionization evolution of the Intergalactic Medium (IGM) during the era of the first luminous objects in the Universe. Large radio-array observatories are currently being built to specifically detect the red-shifted 21cm radiation from neutral hydrogen at red-shifts z ˜ 12 - - 6; the output will be three dimensional maps of ionized regions across the plane of the sky at various red-shift depths. The signal in the resulting ionization maps will be limited by observational noise, mainly from foreground galactic emission in radio frequencies. The research presented here is a unique approach to data mining the planned observational ionization map data. I develop the one-point statistics of the observed 21cm intensity appropriate for the IGM at high red-shifts using a mixture model technique. I show that physically interesting parameters of such mixture models, such as the total ionized gas fraction at a given red-shift slice, can be estimated by applying Maximum Likelihood Expectation to the mixture model of the observed 21cm intensity distribution. The confidence intervals on the expected model parameters are rigorously calculated, and applied to expected detection capabilities of the planned radio-array observatories. I find that at least one of the observatories, the Low Frequency Array (LOFAR), will be able to statistically detect the evolution of the total ionized gas fraction with good precision.

Supernova Cosmology Inference with Probabilistic Photometric Redshifts (SCIPPR)

NASA Astrophysics Data System (ADS)

Peters, Christina; Malz, Alex; Hlozek, Renée

2018-01-01

The Bayesian Estimation Applied to Multiple Species (BEAMS) framework employs probabilistic supernova type classifications to do photometric SN cosmology. This work extends BEAMS to replace high-confidence spectroscopic redshifts with photometric redshift probability density functions, a capability that will be essential in the era the Large Synoptic Survey Telescope and other next-generation photometric surveys where it will not be possible to perform spectroscopic follow up on every SN. We present the Supernova Cosmology Inference with Probabilistic Photometric Redshifts (SCIPPR) Bayesian hierarchical model for constraining the cosmological parameters from photometric lightcurves and host galaxy photometry, which includes selection effects and is extensible to uncertainty in the redshift-dependent supernova type proportions. We create a pair of realistic mock catalogs of joint posteriors over supernova type, redshift, and distance modulus informed by photometric supernova lightcurves and over redshift from simulated host galaxy photometry. We perform inference under our model to obtain a joint posterior probability distribution over the cosmological parameters and compare our results with other methods, namely: a spectroscopic subset, a subset of high probability photometrically classified supernovae, and reducing the photometric redshift probability to a single measurement and error bar.

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

NASA Astrophysics Data System (ADS)

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

2018-02-01

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

Cluster Mass Calibration at High Redshift: HST Weak Lensing Analysis of 13 Distant Galaxy Clusters from the South Pole Telescope Sunyaev-Zel'dovich Survey

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

Schrabback, T.; et al.

We present an HST/ACS weak gravitational lensing analysis of 13 massive high-redshift (z_median=0.88) galaxy clusters discovered in the South Pole Telescope (SPT) Sunyaev-Zel'dovich Survey. This study is part of a larger campaign that aims to robustly calibrate mass-observable scaling relations over a wide range in redshift to enable improved cosmological constraints from the SPT cluster sample. We introduce new strategies to ensure that systematics in the lensing analysis do not degrade constraints on cluster scaling relations significantly. First, we efficiently remove cluster members from the source sample by selecting very blue galaxies in V-I colour. Our estimate of the sourcemore » redshift distribution is based on CANDELS data, where we carefully mimic the source selection criteria of the cluster fields. We apply a statistical correction for systematic photometric redshift errors as derived from Hubble Ultra Deep Field data and verified through spatial cross-correlations. We account for the impact of lensing magnification on the source redshift distribution, finding that this is particularly relevant for shallower surveys. Finally, we account for biases in the mass modelling caused by miscentring and uncertainties in the mass-concentration relation using simulations. In combination with temperature estimates from Chandra we constrain the normalisation of the mass-temperature scaling relation ln(E(z) M_500c/10^14 M_sun)=A+1.5 ln(kT/7.2keV) to A=1.81^{+0.24}_{-0.14}(stat.) +/- 0.09(sys.), consistent with self-similar redshift evolution when compared to lower redshift samples. Additionally, the lensing data constrain the average concentration of the clusters to c_200c=5.6^{+3.7}_{-1.8}.« less

A New Method to Separate Star-forming from AGN Galaxies at Intermediate Redshift: The Submillijansky Radio Population in the VLA-COSMOS Survey

NASA Astrophysics Data System (ADS)

Smolčić, V.; Schinnerer, E.; Scodeggio, M.; Franzetti, P.; Aussel, H.; Bondi, M.; Brusa, M.; Carilli, C. L.; Capak, P.; Charlot, S.; Ciliegi, P.; Ilbert, O.; Ivezić, Ž.; Jahnke, K.; McCracken, H. J.; Obrić, M.; Salvato, M.; Sanders, D. B.; Scoville, N.; Trump, J. R.; Tremonti, C.; Tasca, L.; Walcher, C. J.; Zamorani, G.

2008-07-01

We explore the properties of the submillijansky radio population at 20 cm by applying a newly developed optical color-based method to separate star-forming (SF) from active galactic nucleus (AGN) galaxies at intermediate redshifts (zlesssim 1.3). Although optical rest-frame colors are used, our separation method is shown to be efficient and not biased against dusty starburst galaxies. This classification method has been calibrated and tested on a local radio-selected optical sample. Given accurate multiband photometry and redshifts, it carries the potential to be generally applicable to any galaxy sample where SF and AGN galaxies are the two dominant populations. In order to quantify the properties of the submillijansky radio population, we have analyzed ~2,400 radio sources, detected at 20 cm in the VLA-COSMOS survey; 90% of these have submillijansky flux densities. We classify the objects into (1) star candidates, (2) quasi-stellar objects, (3) AGN, (4) SF, and (5) high-redshift (z > 1.3) galaxies. We find, for the composition of the submillijansky radio population, that SF galaxies are not the dominant population at submillijansky flux levels, as previously often assumed, but that they make up an approximately constant fraction of 30%-40% in the flux density range of ~50 μJy to 0.7 mJy. In summary, based on the entire VLA-COSMOS radio population at 20 cm, we find that the radio population at these flux densities is a mixture of roughly 30%-40% of SF and 50%-60% of AGN galaxies, with a minor contribution (~10%) of QSOs.

Galaxy luminosity function: evolution at high redshift

NASA Astrophysics Data System (ADS)

Martinet, N.; Durret, F.; Guennou, L.; Adami, C.

2014-12-01

There are some disagreements about the abundance of faint galaxies in high redshift clusters. DAFT/FADA (Dark energy American French Team) is a medium redshift (0.4

Galaxy clustering with photometric surveys using PDF redshift information

DOE PAGES

Asorey, J.; Carrasco Kind, M.; Sevilla-Noarbe, I.; ...

2016-03-28

Here, photometric surveys produce large-area maps of the galaxy distribution, but with less accurate redshift information than is obtained from spectroscopic methods. Modern photometric redshift (photo-z) algorithms use galaxy magnitudes, or colors, that are obtained through multi-band imaging to produce a probability density function (PDF) for each galaxy in the map. We used simulated data to study the effect of using different photo-z estimators to assign galaxies to redshift bins in order to compare their effects on angular clustering and galaxy bias measurements. We found that if we use the entire PDF, rather than a single-point (mean or mode) estimate, the deviations are less biased, especially when using narrow redshift bins. When the redshift bin widths aremore » $$\\Delta z=0.1$$, the use of the entire PDF reduces the typical measurement bias from 5%, when using single point estimates, to 3%.« less

Linear clusters of galaxies - A194

NASA Technical Reports Server (NTRS)

Chapman, G. N. F.; Geller, M. J.; Huchra, J. P.

1988-01-01

New measurements for 160 redshifts and previous measurements for 108 other redshifts are presented for galaxies within 5 deg of A194. The galaxy distribution in A194 is shown to be inconsistent with a spherically symmetric King model. A mass-to-light ratio is derived using the virial theorem which is lower than the mean for the groups in the CfA redshift survey (Huchra and Geller, 1982; Geller, 1984). A nonparametric test for galaxy-cluster alignment and a Chi-squared test are used to search for alignment of galaxy major axes with the axis of A194. Evidence for neither luminosity segregation nor significant differences in the velocity or surface distributions of galaxies as a function of morphological type is found.

The Formation of Milky Way-mass Disk Galaxies in the First 500 Million Years of a Cold Dark Matter Universe

NASA Astrophysics Data System (ADS)

Feng, Yu; Di Matteo, Tiziana; Croft, Rupert; Tenneti, Ananth; Bird, Simeon; Battaglia, Nicholas; Wilkins, Stephen

2015-07-01

Whether or not among the myriad tiny protogalaxies there exists a population with similarities to present-day galaxies is an open question. We show, using BlueTides, the first hydrodynamic simulation large enough to resolve the relevant scales, that the first massive galaxies to form are predicted to have extensive rotationally supported disks. Although their morphology resembles in some ways Milky Way types seen at much lower redshifts, these high-redshift galaxies are smaller, denser, and richer in gas than their low-redshift counterparts. From a kinematic analysis of a statistical sample of 216 galaxies at redshift z = 8-10, we have found that disk galaxies make up 70% of the population of galaxies with stellar mass {10}10{M}⊙ or greater. Cold dark matter cosmology therefore makes specific predictions for the population of large galaxies 500 million years after the Big Bang. We argue that wide-field satellite telescopes (e.g., WFIRST) will in the near future discover these first massive disk galaxies. The simplicity of their structure and formation history should make new tests of cosmology possible.

The cosmic evolution of massive black holes in the Horizon-AGN simulation

NASA Astrophysics Data System (ADS)

Volonteri, M.; Dubois, Y.; Pichon, C.; Devriendt, J.

2016-08-01

We analyse the demographics of black holes (BHs) in the large-volume cosmological hydrodynamical simulation Horizon-AGN. This simulation statistically models how much gas is accreted on to BHs, traces the energy deposited into their environment and, consequently, the back-reaction of the ambient medium on BH growth. The synthetic BHs reproduce a variety of observational constraints such as the redshift evolution of the BH mass density and the mass function. Strong self-regulation via AGN feedback, weak supernova feedback, and unresolved internal processes result in a tight BH-galaxy mass correlation. Starting at z ˜ 2, tidal stripping creates a small population of BHs over-massive with respect to the halo. The fraction of galaxies hosting a central BH or an AGN increases with stellar mass. The AGN fraction agrees better with multi-wavelength studies, than single-wavelength ones, unless obscuration is taken into account. The most massive haloes present BH multiplicity, with additional BHs gained by ongoing or past mergers. In some cases, both a central and an off-centre AGN shine concurrently, producing a dual AGN. This dual AGN population dwindles with decreasing redshift, as found in observations. Specific accretion rate and Eddington ratio distributions are in good agreement with observational estimates. The BH population is dominated in turn by fast, slow, and very slow accretors, with transitions occurring at z = 3 and z = 2, respectively.

Deriving photometric redshifts using fuzzy archetypes and self-organizing maps - I. Methodology

NASA Astrophysics Data System (ADS)

Speagle, Joshua S.; Eisenstein, Daniel J.

2017-07-01

We propose a method to substantially increase the flexibility and power of template fitting-based photometric redshifts by transforming a large number of galaxy spectral templates into a corresponding collection of 'fuzzy archetypes' using a suitable set of perturbative priors designed to account for empirical variation in dust attenuation and emission-line strengths. To bypass widely separated degeneracies in parameter space (e.g. the redshift-reddening degeneracy), we train self-organizing maps (SOMs) on large 'model catalogues' generated from Monte Carlo sampling of our fuzzy archetypes to cluster the predicted observables in a topologically smooth fashion. Subsequent sampling over the SOM then allows full reconstruction of the relevant probability distribution functions (PDFs). This combined approach enables the multimodal exploration of known variation among galaxy spectral energy distributions with minimal modelling assumptions. We demonstrate the power of this approach to recover full redshift PDFs using discrete Markov chain Monte Carlo sampling methods combined with SOMs constructed from Large Synoptic Survey Telescope ugrizY and Euclid YJH mock photometry.

STELLAR POPULATIONS AND EVOLUTION OF EARLY-TYPE CLUSTER GALAXIES: CONSTRAINTS FROM OPTICAL IMAGING AND SPECTROSCOPY OF z = 0.5-0.9 GALAXY CLUSTERS

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

Jorgensen, Inger; Chiboucas, Kristin, E-mail: ijorgensen@gemini.edu, E-mail: kchiboucas@gemini.edu

2013-03-15

We present an analysis of stellar populations and evolutionary history of galaxies in three similarly rich galaxy clusters MS0451.6-0305 (z = 0.54), RXJ0152.7-1357 (z = 0.83), and RXJ1226.9+3332 (z = 0.89). Our analysis is based on high signal-to-noise ground-based optical spectroscopy and Hubble Space Telescope imaging for a total of 17-34 members in each cluster. Using the dynamical masses together with the effective radii and the velocity dispersions, we find no indication of evolution of sizes or velocity dispersions with redshift at a given galaxy mass. We establish the Fundamental Plane (FP) and scaling relations between absorption line indices andmore » velocity dispersions. We confirm that the FP is steeper at z Almost-Equal-To 0.86 compared to the low-redshift FP, indicating that under the assumption of passive evolution the formation redshift, z{sub form}, depends on the galaxy velocity dispersion (or alternatively mass). At a velocity dispersion of {sigma} = 125 km s{sup -1} (Mass = 10{sup 10.55} M{sub Sun }) we find z{sub form} = 1.24 {+-} 0.05, while at {sigma} = 225 km s{sup -1} (Mass = 10{sup 11.36} M{sub Sun }) the formation redshift is z{sub form} = 1.95{sup +0.3}{sub -0.2}, for a Salpeter initial mass function. The three clusters follow similar scaling relations between absorption line indices and velocity dispersions as those found for low-redshift galaxies. The zero point offsets for the Balmer lines depend on cluster redshifts. However, the offsets indicate a slower evolution, and therefore higher formation redshift, than the zero point differences found from the FP, if interpreting the data using a passive evolution model. Specifically, the strength of the higher order Balmer lines H{delta} and H{gamma} implies z{sub form} > 2.8. The scaling relations for the metal indices in general show small and in some cases insignificant zero point offsets, favoring high formation redshifts for a passive evolution model. Based on the absorption line indices and recent stellar population models from Thomas et al., we find that MS0451.6-0305 has a mean metallicity [M/H] approximately 0.2 dex below that of the other clusters and our low-redshift sample. We confirm our previous result that RXJ0152.7-1357 has a mean abundance ratio [{alpha}/Fe] approximately 0.3 dex higher than that of the other clusters. The differences in [M/H] and [{alpha}/Fe] between the high-redshift clusters and the low-redshift sample are inconsistent with a passive evolution scenario for early-type cluster galaxies over the redshift interval studied. Low-level star formation may be able to bring the metallicity of MS0451.6-0305 in agreement with the low-redshift sample, while we speculate whether galaxy mergers can lead to sufficiently large changes in the abundance ratios for the RXJ0152.7-1357 galaxies to allow them to reach the low-redshift sample values in the time available.« less

Measuring our Universe from Galaxy Redshift Surveys.

PubMed

Lahav, Ofer; Suto, Yasushi

2004-01-01

Galaxy redshift surveys have achieved significant progress over the last couple of decades. Those surveys tell us in the most straightforward way what our local Universe looks like. While the galaxy distribution traces the bright side of the Universe, detailed quantitative analyses of the data have even revealed the dark side of the Universe dominated by non-baryonic dark matter as well as more mysterious dark energy (or Einstein's cosmological constant). We describe several methodologies of using galaxy redshift surveys as cosmological probes, and then summarize the recent results from the existing surveys. Finally we present our views on the future of redshift surveys in the era of precision cosmology.

A deep redshift survey of field galaxies. Comments on the reality of the Butcher-Oemler effect

NASA Technical Reports Server (NTRS)

Koo, David C.; Kron, Richard G.

1987-01-01

A spectroscopic survey of over 400 field galaxies has been completed in three fields for which we have deep UBVI photographic photometry. The galaxies typically range from B=20 to 22 and possess redshifts z from 0.1 to 0.5 that are often quite spiky in distribution. Little, if any, luminosity evolution is observed up to redshifts z approx 0.5. By such redshifts, however, an unexpectedly large fraction of luminous galaxies has very blue intrinsic colors that suggest extensive star formation; in contrast, the reddest galaxies still have colors that match those of present-day ellipticals.

Dark Energy Survey Year 1 Results: Measurement of the Baryon Acoustic Oscillation scale in the distribution of galaxies to redshift 1

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

Abbott, T.M.C.; et al.

We present angular diameter distance measurements obtained by locating the BAO scale in the distribution of galaxies selected from the first year of Dark Energy Survey data. We consider a sample of over 1.3 million galaxies distributed over a footprint of 1318 degmore » $^2$ with $$0.6 < z_{\\rm photo} < 1$$ and a typical redshift uncertainty of $0.03(1+z)$. This sample was selected, as fully described in a companion paper, using a color/magnitude selection that optimizes trade-offs between number density and redshift uncertainty. We investigate the BAO signal in the projected clustering using three conventions, the angular separation, the co-moving transverse separation, and spherical harmonics. Further, we compare results obtained from template based and machine learning photometric redshift determinations. We use 1800 simulations that approximate our sample in order to produce covariance matrices and allow us to validate our distance scale measurement methodology. We measure the angular diameter distance, $$D_A$$, at the effective redshift of our sample divided by the true physical scale of the BAO feature, $$r_{\\rm d}$$. We obtain close to a 4 per cent distance measurement of $$D_A(z_{\\rm eff}=0.81)/r_{\\rm d} = 10.75\\pm 0.43 $$. These results are consistent with the flat $$\\Lambda$$CDM concordance cosmological model supported by numerous other recent experimental results.« less

Redshift Space Distortion on the Small Scale Clustering of Structure

NASA Astrophysics Data System (ADS)

Park, Hyunbae; Sabiu, Cristiano; Li, Xiao-dong; Park, Changbom; Kim, Juhan

2018-01-01

The positions of galaxies in comoving Cartesian space varies under different cosmological parameter choices, inducing a redshift-dependent scaling in the galaxy distribution. The shape of the two-point correlation of galaxies exhibits a significant redshift evolution when the galaxy sample is analyzed under a cosmology differing from the true, simulated one. In our previous works, we can made use of this geometrical distortion to constrain the values of cosmological parameters governing the expansion history of the universe. This current work is a continuation of our previous works as a strategy to constrain cosmological parameters using redshift-invariant physical quantities. We now aim to understand the redshift evolution of the full shape of the small scale, anisotropic galaxy clustering and give a firmer theoretical footing to our previous works.

Spatial distribution of the gamma-ray bursts at very high redshift

NASA Astrophysics Data System (ADS)

Mészáros, Attila

2018-05-01

The author - with his collaborators - already in years 1995-96 have shown - purely from the analyses of the observations - that the gamma-ray bursts (GRBs) can be till redshift 20. Since that time several other statistical studies of the spatial distribution of GRBs were provided. Remarkable conclusions concerning the star-formation rate and the validity of the cosmological principle were obtained about the regions of the cosmic dawn. In this contribution these efforts are surveyed.

Bayesian Redshift Classification of Emission-line Galaxies with Photometric Equivalent Widths

NASA Astrophysics Data System (ADS)

Leung, Andrew S.; Acquaviva, Viviana; Gawiser, Eric; Ciardullo, Robin; Komatsu, Eiichiro; Malz, A. I.; Zeimann, Gregory R.; Bridge, Joanna S.; Drory, Niv; Feldmeier, John J.; Finkelstein, Steven L.; Gebhardt, Karl; Gronwall, Caryl; Hagen, Alex; Hill, Gary J.; Schneider, Donald P.

2017-07-01

We present a Bayesian approach to the redshift classification of emission-line galaxies when only a single emission line is detected spectroscopically. We consider the case of surveys for high-redshift Lyα-emitting galaxies (LAEs), which have traditionally been classified via an inferred rest-frame equivalent width (EW {W}{Lyα }) greater than 20 Å. Our Bayesian method relies on known prior probabilities in measured emission-line luminosity functions and EW distributions for the galaxy populations, and returns the probability that an object in question is an LAE given the characteristics observed. This approach will be directly relevant for the Hobby-Eberly Telescope Dark Energy Experiment (HETDEX), which seeks to classify ˜106 emission-line galaxies into LAEs and low-redshift [{{O}} {{II}}] emitters. For a simulated HETDEX catalog with realistic measurement noise, our Bayesian method recovers 86% of LAEs missed by the traditional {W}{Lyα } > 20 Å cutoff over 2 < z < 3, outperforming the EW cut in both contamination and incompleteness. This is due to the method’s ability to trade off between the two types of binary classification error by adjusting the stringency of the probability requirement for classifying an observed object as an LAE. In our simulations of HETDEX, this method reduces the uncertainty in cosmological distance measurements by 14% with respect to the EW cut, equivalent to recovering 29% more cosmological information. Rather than using binary object labels, this method enables the use of classification probabilities in large-scale structure analyses. It can be applied to narrowband emission-line surveys as well as upcoming large spectroscopic surveys including Euclid and WFIRST.

Cosmological Parameter Estimation Using the Genus Amplitude—Application to Mock Galaxy Catalogs

NASA Astrophysics Data System (ADS)

Appleby, Stephen; Park, Changbom; Hong, Sungwook E.; Kim, Juhan

2018-01-01

We study the topology of the matter density field in two-dimensional slices and consider how we can use the amplitude A of the genus for cosmological parameter estimation. Using the latest Horizon Run 4 simulation data, we calculate the genus of the smoothed density field constructed from light cone mock galaxy catalogs. Information can be extracted from the amplitude of the genus by considering both its redshift evolution and magnitude. The constancy of the genus amplitude with redshift can be used as a standard population, from which we derive constraints on the equation of state of dark energy {w}{de}—by measuring A at z∼ 0.1 and z∼ 1, we can place an order {{Δ }}{w}{de}∼ { O }(15 % ) constraint on {w}{de}. By comparing A to its Gaussian expectation value, we can potentially derive an additional stringent constraint on the matter density {{Δ }}{{{Ω }}}{mat}∼ 0.01. We discuss the primary sources of contamination associated with the two measurements—redshift space distortion (RSD) and shot noise. With accurate knowledge of galaxy bias, we can successfully remove the effect of RSD, and the combined effect of shot noise and nonlinear gravitational evolution is suppressed by smoothing over suitably large scales {R}{{G}}≥slant 15 {Mpc}/h. Without knowledge of the bias, we discuss how joint measurements of the two- and three-dimensional genus can be used to constrain the growth factor β =f/b. The method can be applied optimally to redshift slices of a galaxy distribution generated using the drop-off technique.

Galaxy Clusters

NASA Astrophysics Data System (ADS)

Miller, Christopher J. Miller

2012-03-01

There are many examples of clustering in astronomy. Stars in our own galaxy are often seen as being gravitationally bound into tight globular or open clusters. The Solar System's Trojan asteroids cluster at the gravitational Langrangian in front of Jupiter’s orbit. On the largest of scales, we find gravitationally bound clusters of galaxies, the Virgo cluster (in the constellation of Virgo at a distance of ˜50 million light years) being a prime nearby example. The Virgo cluster subtends an angle of nearly 8◦ on the sky and is known to contain over a thousand member galaxies. Galaxy clusters play an important role in our understanding of theUniverse. Clusters exist at peaks in the three-dimensional large-scale matter density field. Their sky (2D) locations are easy to detect in astronomical imaging data and their mean galaxy redshifts (redshift is related to the third spatial dimension: distance) are often better (spectroscopically) and cheaper (photometrically) when compared with the entire galaxy population in large sky surveys. Photometric redshift (z) [Photometric techniques use the broad band filter magnitudes of a galaxy to estimate the redshift. Spectroscopic techniques use the galaxy spectra and emission/absorption line features to measure the redshift] determinations of galaxies within clusters are accurate to better than delta_z = 0.05 [7] and when studied as a cluster population, the central galaxies form a line in color-magnitude space (called the the E/S0 ridgeline and visible in Figure 16.3) that contains galaxies with similar stellar populations [15]. The shape of this E/S0 ridgeline enables astronomers to measure the cluster redshift to within delta_z = 0.01 [23]. The most accurate cluster redshift determinations come from spectroscopy of the member galaxies, where only a fraction of the members need to be spectroscopically observed [25,42] to get an accurate redshift to the whole system. If light traces mass in the Universe, then the locations of galaxy clusters will be at locations of the peaks in the true underlying (mostly) dark matter density field. Kaiser (1984) [19] called this the high-peak model, which we demonstrate in Figure 16.1. We show a two-dimensional representation of a density field created by summing plane-waves with a predetermined power and with random wave-vector directions. In the left panel, we plot only the largest modes, where we see the density peaks (black) and valleys (white) in the combined field. In the right panel, we allow for smaller modes. You can see that the highest density peaks in the left panel contain smaller-scale, but still high-density peaks. These are the locations of future galaxy clusters. The bottom panel shows just these cluster-scale peaks. As you can see, the peaks themselves are clustered, and instead of just one large high-density peak in the original density field (see the left panel), the smaller modes show that six peaks are "born" within the broader, underlying large-scale density modes. This exemplifies the "bias" or amplified structure that is traced by galaxy clusters [19]. Clusters are rare, easy to find, and their member galaxies provide good distance estimates. In combination with their amplified clustering signal described above, galaxy clusters are considered an efficient and precise tracer of the large-scale matter density field in the Universe. Galaxy clusters can also be used to measure the baryon content of the Universe [43]. They can be used to identify gravitational lenses [38] and map the distribution of matter in clusters. The number and spatial distribution of galaxy clusters can be used to constrain cosmological parameters, like the fraction of the energy density in the Universe due to matter (Omega_matter) or the variation in the density field on fixed physical scales (sigma_8) [26,33]. The individual clusters act as “Island Universes” and as such are laboratories here we can study the evolution of the properties of the cluster, like the hot, gaseous intra-cluster medium or shapes, colors, and star-formation histories of the member galaxies [17].

The formation of ultra compact dwarf galaxies and massive globular clusters. Quasar-like objects to test for a variable stellar initial mass function

NASA Astrophysics Data System (ADS)

Jeřábková, T.; Kroupa, P.; Dabringhausen, J.; Hilker, M.; Bekki, K.

2017-12-01

The stellar initial mass function (IMF) has been described as being invariant, bottom-heavy, or top-heavy in extremely dense star-burst conditions. To provide usable observable diagnostics, we calculate redshift dependent spectral energy distributions of stellar populations in extreme star-burst clusters, which are likely to have been the precursors of present day massive globular clusters (GCs) and of ultra compact dwarf galaxies (UCDs). The retention fraction of stellar remnants is taken into account to assess the mass to light ratios of the ageing star-burst. Their redshift dependent photometric properties are calculated as predictions for James Webb Space Telescope (JWST) observations. While the present day GCs and UCDs are largely degenerate concerning bottom-heavy or top-heavy IMFs, a metallicity- and density-dependent top-heavy IMF implies the most massive UCDs, at ages < 100 Myr, to appear as objects with quasar-like luminosities with a 0.1-10% variability on a monthly timescale due to core collapse supernovae.

A compilation of redshifts and velocity dispersions for Abell clusters (Struble and Rood 1987): Documentation for the machine-readable version

NASA Technical Reports Server (NTRS)

Warren, Wayne H., Jr.

1989-01-01

The machine readable version of the compilation, as it is currently being distributed from the Astronomical Data Center, is described. The catalog contains redshifts and velocity dispersions for all Abell clusters for which these data had been published up to 1986 July. Also included are 1950 equatorial coordinates for the centers of the listed clusters, numbers of observations used to determine the redshifts, and bibliographical references citing the data sources.

Pairs of galaxies in low density regions of a combined redshift catalog

NASA Technical Reports Server (NTRS)

Charlton, Jane C.; Salpeter, Edwin E.

1990-01-01

The distributions of projected separations and radial velocity differences of pairs of galaxies in the CfA and Southern Sky Redshift Survey (SSRS) redshift catalogs are examined. The authors focus on pairs that fall in low density environments rather than in clusters or large groups. The projected separation distribution is nearly flat, while uncorrelated galaxies would have given one linearly rising with r sub p. There is no break in this curve even below 50 kpc, the minimum halo size consistent with measured galaxy rotation curves. The significant number of pairs at small separations is inconsistent with the N-body result that galaxies with overlapping halos will rapidly merge, unless there are significant amounts of matter distributed out to a few hundred kpc of the galaxies. This dark matter may either be in distinct halos or more loosely distributed. Large halos would allow pairs at initially large separations to head toward merger, replenishing the distribution at small separations. In the context of this model, the authors estimate that roughly 10 to 25 percent of these low density galaxies are the product of a merger, compared with the elliptical/SO fraction of 18 percent, observed in low density regions of the sample.

Galaxy and Mass Assembly (GAMA): Exploring the WISE Web in G12

NASA Astrophysics Data System (ADS)

Jarrett, T. H.; Cluver, M. E.; Magoulas, C.; Bilicki, M.; Alpaslan, M.; Bland-Hawthorn, J.; Brough, S.; Brown, M. J. I.; Croom, S.; Driver, S.; Holwerda, B. W.; Hopkins, A. M.; Loveday, J.; Norberg, P.; Peacock, J. A.; Popescu, C. C.; Sadler, E. M.; Taylor, E. N.; Tuffs, R. J.; Wang, L.

2017-02-01

We present an analysis of the mid-infrared Wide-field Infrared Survey Explorer (WISE) sources seen within the equatorial GAMA G12 field, located in the North Galactic Cap. Our motivation is to study and characterize the behavior of WISE source populations in anticipation of the deep multiwavelength surveys that will define the next decade, with the principal science goal of mapping the 3D large-scale structures and determining the global physical attributes of the host galaxies. In combination with cosmological redshifts, we identify galaxies from their WISE W1 (3.4 μm) resolved emission, and we also perform a star-galaxy separation using apparent magnitude, colors, and statistical modeling of star counts. The resulting galaxy catalog has ≃590,000 sources in 60 deg2, reaching a W1 5σ depth of 31 μJy. At the faint end, where redshifts are not available, we employ a luminosity function analysis to show that approximately 27% of all WISE extragalactic sources to a limit of 17.5 mag (31 μJy) are at high redshift, z> 1. The spatial distribution is investigated using two-point correlation functions and a 3D source density characterization at 5 Mpc and 20 Mpc scales. For angular distributions, we find that brighter and more massive sources are strongly clustered relative to fainter sources with lower mass; likewise, based on WISE colors, spheroidal galaxies have the strongest clustering, while late-type disk galaxies have the lowest clustering amplitudes. In three dimensions, we find a number of distinct groupings, often bridged by filaments and superstructures. Using special visualization tools, we map these structures, exploring how clustering may play a role with stellar mass and galaxy type.

Measuring the total and baryonic mass profiles of the very massive CASSOWARY 31 strong lens. A fossil system at z ≃ 0.7?

NASA Astrophysics Data System (ADS)

Grillo, C.; Christensen, L.; Gallazzi, A.; Rasmussen, J.

2013-08-01

We investigate the total and baryonic mass distributions in deflector number 31 (CSWA 31) of the Cambridge And Sloan Survey Of Wide ARcs in the skY (CASSOWARY). We confirm spectroscopically a four-image lensing system at redshift 1.4870 with Very Large Telescope/X-shooter observations. The lensed images are distributed around a bright early-type galaxy at redshift 0.683, surrounded by several smaller galaxies at similar photometric redshifts. We use available optical and X-ray data to constrain the deflector total, stellar and hot gas mass through, respectively, strong lensing, stellar population analysis and plasma modelling. We derive a total mass projected within the Einstein radius REin = 70 kpc of (40 ± 1) × 1012 M⊙, and a central logarithmic slope of -1.7 ± 0.2 for the total mass density. Despite a very high stellar mass and velocity dispersion of the central galaxy of (3 ± 1) × 1012 M⊙ and (450 ± 80) km s-1, respectively, the cumulative stellar-to-total mass profile of the deflector implies a remarkably low stellar mass fraction of 20 per cent (3-6 per cent) in projection within the central galaxy effective radius Re = 25 kpc (R = 100 kpc). We also find that the CSWA 31 deflector has properties suggesting it to be among the most distant and massive fossil systems studied so far. The unusually strong central dark matter dominance and the possible fossil nature of this system render it an interesting target for detailed tests of cosmological models and structure formation scenarios.

HectoMAPping the Universe. Karl Schwarzschild Award Lecture 2014

NASA Astrophysics Data System (ADS)

Geller, Margaret J.; Hwang, Ho Seong

2015-06-01

During the last three decades progress in mapping the Universe from an age of 400 000 years to the present has been stunning. Instrument/telescope combinations have naturally determined the sampling of various redshift ranges. Here we outline the impact of the Hectospec on the MMT on exploration of the Universe in the redshift range 0.2 ⪉ z ⪉ 0.8. We focus on dense redshift surveys, SHELS and HectoMAP. SHELS is a complete magnitude limited survey covering 8 square degrees. The HectoMAP survey combines a red-selected dense redshift survey and a weak lensing map covering 50 square degrees. Combining the dense redshift survey with a Subaru HyperSuprimeCam (HSC) weak lensing map will provide a powerful probe of the way galaxies trace the distribution of dark matter on a wide range of physical scales.

Bulge Growth and Quenching Since Z=2.5 in Candels/3D-HST

NASA Technical Reports Server (NTRS)

Lang, Phillip; Wuyts, Stijn; Somerville, Rachel S.; Schreiber, Natascha M. Foerster; Genzel, Reinhard; Bell, Eric F.; Brammer, Gabe; Dekel, Avishai; Faber, Sandra M.; Ferguson, Henry C.;

Energy Feedback from X-ray Binaries in the Early Universe

NASA Technical Reports Server (NTRS)

Fragos, T.; Lehmer, B..; Naoz, S.; Zezas, A.; Basu-Zych, A.

2013-01-01

X-ray photons, because of their long mean-free paths, can easily escape the galactic environments where they are produced, and interact at long distances with the intergalactic medium, potentially having a significant contribution to the heating and reionization of the early universe. The two most important sources of X-ray photons in the universe are active galactic nuclei (AGNs) and X-ray binaries (XRBs). In this Letter we use results from detailed, large scale population synthesis simulations to study the energy feedback of XRBs, from the first galaxies (z (redshift) approximately equal to 20) until today.We estimate that X-ray emission from XRBs dominates over AGN at z (redshift) greater than or approximately equal to 6-8. The shape of the spectral energy distribution of the emission from XRBs shows little change with redshift, in contrast to its normalization which evolves by approximately 4 orders of magnitude, primarily due to the evolution of the cosmic star-formation rate. However, the metallicity and the mean stellar age of a given XRB population affect significantly its X-ray output. Specifically, the X-ray luminosity from high-mass XRBs per unit of star-formation rate varies an order of magnitude going from solar metallicity to less than 10% solar, and the X-ray luminosity from low-mass XRBs per unit of stellar mass peaks at an age of approximately 300 Myr (million years) and then decreases gradually at later times, showing little variation for mean stellar ages 3 Gyr (Giga years, or billion years). Finally, we provide analytical and tabulated prescriptions for the energy output of XRBs, that can be directly incorporated in cosmological simulations.

The size evolution of star-forming and quenched galaxies in the IllustrisTNG simulation

NASA Astrophysics Data System (ADS)

Genel, Shy; Nelson, Dylan; Pillepich, Annalisa; Springel, Volker; Pakmor, Rüdiger; Weinberger, Rainer; Hernquist, Lars; Naiman, Jill; Vogelsberger, Mark; Marinacci, Federico; Torrey, Paul

2018-03-01

We analyse scaling relations and evolution histories of galaxy sizes in TNG100, part of the IllustrisTNG simulation suite. Observational qualitative trends of size with stellar mass, star formation rate and redshift are reproduced, and a quantitative comparison of projected r band sizes at 0 ≲ z ≲ 2 shows agreement to much better than 0.25 dex. We follow populations of z = 0 galaxies with a range of masses backwards in time along their main progenitor branches, distinguishing between main-sequence and quenched galaxies. Our main findings are as follows. (i) At M*, z = 0 ≳ 109.5 M⊙, the evolution of the median main progenitor differs, with quenched galaxies hardly growing in median size before quenching, whereas main-sequence galaxies grow their median size continuously, thus opening a gap from the progenitors of quenched galaxies. This is partly because the main-sequence high-redshift progenitors of quenched z = 0 galaxies are drawn from the lower end of the size distribution of the overall population of main-sequence high-redshift galaxies. (ii) Quenched galaxies with M*, z = 0 ≳ 109.5 M⊙ experience a steep size growth on the size-mass plane after their quenching time, but with the exception of galaxies with M*, z = 0 ≳ 1011 M⊙, the size growth after quenching is small in absolute terms, such that most of the size (and mass) growth of quenched galaxies (and its variation among them) occurs while they are still on the main sequence. After they become quenched, the size growth rate of quenched galaxies as a function of time, as opposed to versus mass, is similar to that of main-sequence galaxies. Hence, the size gap is retained down to z = 0.

The scatter and evolution of the global hot gas properties of simulated galaxy cluster populations

NASA Astrophysics Data System (ADS)

Le Brun, Amandine M. C.; McCarthy, Ian G.; Schaye, Joop; Ponman, Trevor J.

2017-04-01

We use the cosmo-OverWhelmingly Large Simulation (cosmo-OWLS) suite of cosmological hydrodynamical simulations to investigate the scatter and evolution of the global hot gas properties of large simulated populations of galaxy groups and clusters. Our aim is to compare the predictions of different physical models and to explore the extent to which commonly adopted assumptions in observational analyses (e.g. self-similar evolution) are violated. We examine the relations between (true) halo mass and the X-ray temperature, X-ray luminosity, gas mass, Sunyaev-Zel'dovich (SZ) flux, the X-ray analogue of the SZ flux (YX) and the hydrostatic mass. For the most realistic models, which include active galactic nuclei (AGN) feedback, the slopes of the various mass-observable relations deviate substantially from the self-similar ones, particularly at late times and for low-mass clusters. The amplitude of the mass-temperature relation shows negative evolution with respect to the self-similar prediction (I.e. slower than the prediction) for all models, driven by an increase in non-thermal pressure support at higher redshifts. The AGN models predict strong positive evolution of the gas mass fractions at low halo masses. The SZ flux and YX show positive evolution with respect to self-similarity at low mass but negative evolution at high mass. The scatter about the relations is well approximated by log-normal distributions, with widths that depend mildly on halo mass. The scatter decreases significantly with increasing redshift. The exception is the hydrostatic mass-halo mass relation, for which the scatter increases with redshift. Finally, we discuss the relative merits of various hot gas-based mass proxies.

Modeling the Redshift Evolution of the Normal Galaxy X-Ray Luminosity Function

NASA Technical Reports Server (NTRS)

Tremmel, M.; Fragos, T.; Lehmer, B. D.; Tzanavaris, P.; Belczynski, K.; Kalogera, V.; Basu-Zych, A. R.; Farr, W. M.; Hornschemeier, A.; Jenkins, L.;

Is a top-heavy initial mass function needed to reproduce the submillimetre galaxy number counts?

NASA Astrophysics Data System (ADS)

Safarzadeh, Mohammadtaher; Lu, Yu; Hayward, Christopher C.

2017-12-01

Matching the number counts and redshift distribution of submillimetre galaxies (SMGs) without invoking modifications to the initial mass ffunction (IMF) has proved challenging for semi-analytic models (SAMs) of galaxy formation. We adopt a previously developed SAM that is constrained to match the z = 0 galaxy stellar mass function and makes various predictions which agree well with observational constraints; we do not recalibrate the SAM for this work. We implement three prescriptions to predict the submillimetre flux densities of the model galaxies; two depend solely on star formation rate, whereas the other also depends on the dust mass. By comparing the predictions of the models, we find that taking into account the dust mass, which affects the dust temperature and thus influences the far-infrared spectral energy distribution, is crucial for matching the number counts and redshift distribution of SMGs. Moreover, despite using a standard IMF, our model can match the observed SMG number counts and redshift distribution reasonably well, which contradicts the conclusions of some previous studies that a top-heavy IMF, in addition to taking into account the effect of dust mass, is needed to match these observations. Although we have not identified the key ingredient that is responsible for our model matching the observed SMG number counts and redshift distribution without IMF variation - which is challenging given the different prescriptions for physical processes employed in the SAMs of interest - our results demonstrate that in SAMs, IMF variation is degenerate with other physical processes, such as stellar feedback.

CLASH: DISCOVERY OF A BRIGHT z {approx_equal} 6.2 DWARF GALAXY QUADRUPLY LENSED BY MACS J0329.6-0211

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

Zitrin, A.; Moustakas, J.; Bradley, L.

2012-03-15

We report the discovery of a z{sub phot} = 6.18{sup +0.05}{sub -0.07} (95% confidence level) dwarf galaxy, lensed into four images by the galaxy cluster MACS J0329.6-0211 (z{sub l} = 0.45). The galaxy is observed as a high-redshift dropout in HST/ACS/WFC3 CLASH and Spitzer/IRAC imaging. Its redshift is securely determined due to a clear detection of the Lyman break in the 18-band photometry, making this galaxy one of the highest-redshift multiply lensed objects known to date with an observed magnitude of F125W =24.00 {+-} 0.04 AB mag for its most magnified image. We also present the first strong-lensing analysis ofmore » this cluster uncovering 15 additional multiply imaged candidates of five lower-redshift sources spanning the range z{sub s} {approx_equal} 2-4. The mass model independently supports the high photometric redshift and reveals magnifications of 11.6{sup +8.9}{sub -4.1}, 17.6{sup +6.2}{sub -3.9}, 3.9{sup +3.0}{sub -1.7}, and 3.7{sup +1.3}{sub -0.2}, respectively, for the four images of the high-redshift galaxy. By delensing the most magnified image we construct an image of the source with a physical resolution of {approx}200 pc when the universe was {approx}0.9 Gyr old, where the z {approx_equal} 6.2 galaxy occupies a source-plane area of approximately 2.2 kpc{sup 2}. Modeling the observed spectral energy distribution using population synthesis models, we find a demagnified stellar mass of {approx}10{sup 9} M{sub Sun }, subsolar metallicity (Z/Z{sub Sun} {approx} 0.5), low dust content (A{sub V} {approx} 0.1 mag), a demagnified star formation rate (SFR) of {approx}3.2 M{sub Sun} yr{sup -1}, and a specific SFR of {approx}3.4 Gyr{sup -1}, all consistent with the properties of local dwarf galaxies.« less

An ALMA Survey of Submillimeter Galaxies in the Extended Chandra Deep Field South: Spectroscopic Redshifts

NASA Astrophysics Data System (ADS)

Danielson, A. L. R.; Swinbank, A. M.; Smail, Ian; Simpson, J. M.; Casey, C. M.; Chapman, S. C.; da Cunha, E.; Hodge, J. A.; Walter, F.; Wardlow, J. L.; Alexander, D. M.; Brandt, W. N.; de Breuck, C.; Coppin, K. E. K.; Dannerbauer, H.; Dickinson, M.; Edge, A. C.; Gawiser, E.; Ivison, R. J.; Karim, A.; Kovacs, A.; Lutz, D.; Menten, K.; Schinnerer, E.; Weiß, A.; van der Werf, P.

2017-05-01

We present spectroscopic redshifts of {\\text{}}{S}870μ {{m}} ≳ 2 mJy submillimeter galaxies (SMGs), which have been identified from the ALMA follow-up observations of 870 μm detected sources in the Extended Chandra Deep Field South (the ALMA-LESS survey). We derive spectroscopic redshifts for 52 SMGs, with a median of z = 2.4 ± 0.1. However, the distribution features a high-redshift tail, with ˜23% of the SMGs at z≥slant 3. Spectral diagnostics suggest that the SMGs are young starbursts, and the velocity offsets between the nebular emission and UV ISM absorption lines suggest that many are driving winds, with velocity offsets of up to 2000 km s-1. Using the spectroscopic redshifts and the extensive UV-to-radio photometry in this field, we produce optimized spectral energy distributions (SEDs) using Magphys, and use the SEDs to infer a median stellar mass of {M}\\star = (6 ± 1)× 1010 M {}⊙ for our SMGs with spectroscopic redshift. By combining these stellar masses with the star formation rates (measured from the far-infrared SEDs), we show that SMGs (on average) lie a factor of ˜5 above the so-called “main sequence” at z˜ 2. We provide this library of 52 template fits with robust and uniquely well-sampled SEDs as a resource for future studies of SMGs, and also release the spectroscopic catalog of ˜2000 (mostly infrared-selected) galaxies targeted as part of the spectroscopic campaign.

Studying the Evolution of the Contamination of the Sunyaev-Zel'dovich effect due to High-redshift (sub-)mm Galaxies

NASA Astrophysics Data System (ADS)

Montana, Alfredo; Aretxaga, I.; Austermann, J.; Bock, J.; Chapin, E.; Gaztanaga, E.; Hughes, D.; Lowenthal, J.; Mauskopf, P.; Perera, T.; Scott, K.; Wilson, G.; Yun, M.

2007-05-01

We present simulations of the submillimetre/millimetre (sub-mm) sky to study the environment of luminous starburst galaxies, radio galaxies and AGN towards biased-regions (large-scale over-densities) in the high-redshift universe. Guided by recent results from AzTEC extragalactic surveys at 1.1mm, we describe the impact of this population of galaxies, that dominate the sub-mm extragalactic background, on the detectability of the Sunyaev-Zel'dovich effect (SZE) as a function of redshift. These results will be presented in the context of the next generation of wide-area surveys to identify high-redshift clusters via the SZE.

Steps Toward Unveiling the True Population of AGN: Photometric Selection of Broad-Line AGN

NASA Astrophysics Data System (ADS)

Schneider, Evan; Impey, C.

2012-01-01

We present an AGN selection technique that enables identification of broad-line AGN using only photometric data. An extension of infrared selection techniques, our method involves fitting a given spectral energy distribution with a model consisting of three physically motivated components: infrared power law emission, optical accretion disk emission, and host galaxy emission. Each component can be varied in intensity, and a reduced chi-square minimization routine is used to determine the optimum parameters for each object. Using this model, both broad- and narrow-line AGN are seen to fall within discrete ranges of parameter space that have plausible bounds, allowing physical trends with luminosity and redshift to be determined. Based on a fiducial sample of AGN from the catalog of Trump et al. (2009), we find the region occupied by broad-line AGN to be distinct from that of quiescent or star-bursting galaxies. Because this technique relies only on photometry, it will allow us to find AGN at fainter magnitudes than are accessible in spectroscopic surveys, and thus probe a population of less luminous and/or higher redshift objects. With the vast availability of photometric data in large surveys, this technique should have broad applicability and result in large samples that will complement X-ray AGN catalogs.

An Overdensity of Massive, Dusty Starbursts Associated with the High-Redshift Radio Galaxy MRC1138-262 at z = 2.16

NASA Astrophysics Data System (ADS)

Altieri, Bruno; Dannerbauer, Helmut

We present Herschel and APEX LABOCA 870 μm imaging of the field of the high-redshift radio galaxy MRC1138 at z = 2.16. We detect 16 submillimeter galaxies in this ˜140 arcmin2 large bolometer map, with flux densities in the range 3-11 mJy. The pure number counts indicate an overdensity of SMGs by a factor of five compared to blank field surveys. Based on an exquisite multi-wavelength database including VLA 1.4 GHz radio and infrared observations, we verifiy whether these sources are members of the proto-cluster structure at z = 2.2 or not. Based on Herschel PACS+ SPIRE and Spitzer MIPS photometry, we derived reliable far-infrared photometric redshifts for all of our sources. VLT-ISAAC near-infrared spectroscopic observations confirmed redshifts of z ≈ 2.2 for four of these SMGs. We conclude that in total at least seven sources are part of this proto-cluster at z = 2.16. We measure a star formation rate density S FRD ˜ 1500 M⊙ yr-1 Mpc-3, four magntiudes higher compared to the global SFRD at this redshift. Striklingly, these seven sources are concentrated within a region of 2 Mpc (the typical size of clusters in the local universe) and are not distributed in the filaments as predicted by theories and traced by the Hα emitters at z ≈ 2.2. This concentration of massive, dusty starbursts is not centered on the radio galaxy which is submm bright. A significant fraction, six out of 11 SMGs with z ≈ 2.2 Hα imaging coverage are associated with Hα emitters, demonstrating the potential of tracing SMG counterparts with this source population. Our results demonstrate that indeed submm observations enable us to reveal clusters of massive, dusty starbursts and will pave the road for systematic and detailed investigations with this technique in the future.

Integrated HI emission in galaxy groups and clusters

NASA Astrophysics Data System (ADS)

Ai, Mei; Zhu, Ming; Fu, Jian

2017-09-01

The integrated HI emission from hierarchical structures such as groups and clusters of galaxies can be detected by FAST at intermediate redshifts. Here we propose to use FAST to study the evolution of the global HI content of clusters and groups over cosmic time by measuring their integrated HI emissions. We use the Virgo Cluster as an example to estimate the detection limit of FAST, and have estimated the integration time to detect a Virgo type cluster at different redshifts (from z = 0.1 to z = 1.5).We have also employed a semi-analytic model (SAM) to simulate the evolution of HI contents in galaxy clusters. Our simulations suggest that the HI mass of a Virgo-like cluster could be 2-3 times higher and the physical size could be more than 50% smaller when redshift increases from z = 0.3 to z = 1. Thus the integration time could be reduced significantly and gas rich clusters at intermediate redshifts can be detected by FAST in less than 2 hours of integration time. For the local Universe, we have also used SAM simulations to create mock catalogs of clusters to predict the outcomes from FAST all sky surveys. Comparing with the optically selected catalogs derived by cross matching the galaxy catalogs from the SDSS survey and the ALFALFA survey, we find that the HI mass distribution of the mock catalog with 20 s of integration time agrees well with that of observations. However, the mock catalog with 120 s of integration time predicts many more groups and clusters that contain a population of low mass HI galaxies not detected by the ALFALFA survey. A future deep HI blind sky survey with FAST would be able to test such prediction and set constraints on the numerical simulation models. The observational strategy and sample selections for future FAST observations of galaxy clusters at high redshifts are also discussed.

Stellar Populations of Lyman Break Galaxies at z approx. to 1-3 in the HST/WFC3 Early Release Science Observations

NASA Technical Reports Server (NTRS)

Hathi, N. P.; Cohen, S. H.; Ryan, R. E., Jr.; Finkelstein, S. L.; McCarthy, P. J.; Windhorst, R. A.; Yan, H.; Koekemoer, A. M.; Rutkowski, M. J.; OConnell, R. W.;

A search for moderate-redshift survivors from the population of luminous compact passive galaxies at high redshift

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

Stockton, Alan; Shih, Hsin-Yi; Larson, Kirsten

2014-01-10

From a search of a ∼2400 deg{sup 2} region covered by both the Sloan Digital Sky Survey and UKIRT Infrared Deep Sky Survey databases, we have attempted to identify galaxies at z ∼ 0.5 that are consistent with their being essentially unmodified examples of the luminous passive compact galaxies found at z ∼ 2.5. After isolating good candidates via deeper imaging, we further refine the sample with Keck moderate-resolution spectroscopy and laser guide star adaptive-optics imaging. For four of the five galaxies that so far remain after passing through this sieve, we analyze plausible star-formation histories based on our spectramore » in order to identify galaxies that may have survived with little modification from the population formed at high redshift. We find two galaxies that are consistent with having formed ≳ 95% of their mass at z > 5. We attempt to estimate masses both from our stellar population determinations and from velocity dispersions. Given the high frequency of small axial ratios, both in our small sample and among samples found at high redshifts, we tentatively suggest that some of the more extreme examples of passive compact galaxies may have prolate morphologies.« less

THE RISE AND FALL OF THE STAR FORMATION HISTORIES OF BLUE GALAXIES AT REDSHIFTS 0.2 < z < 1.4

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

Pacifici, Camilla; Kassin, Susan A.; Gardner, Jonathan P.

2013-01-01

Popular cosmological scenarios predict that galaxies form hierarchically from the merger of many progenitors, each with their own unique star formation history (SFH). We use a sophisticated approach to constrain the SFHs of 4517 blue (presumably star-forming) galaxies with spectroscopic redshifts in the range 0.2 < z < 1.4 from the All-Wavelength Extended Groth Strip International Survey. This consists in the Bayesian analysis of the observed galaxy spectral energy distributions with a comprehensive library of synthetic spectra assembled using realistic, hierarchical star formation, and chemical enrichment histories from cosmological simulations. We constrain the SFH of each galaxy in our samplemore » by comparing the observed fluxes in the B, R, I, and K{sub s} bands and rest-frame optical emission-line luminosities with those of one million model spectral energy distributions. We explore the dependence of the resulting SFHs on galaxy stellar mass and redshift. We find that the average SFHs of high-mass galaxies rise and fall in a roughly symmetric bell-shaped manner, while those of low-mass galaxies rise progressively in time, consistent with the typically stronger activity of star formation in low-mass compared to high-mass galaxies. For galaxies of all masses, the star formation activity rises more rapidly at high than at low redshift. These findings imply that the standard approximation of exponentially declining SFHs widely used to interpret observed galaxy spectral energy distributions may not be appropriate to constrain the physical parameters of star-forming galaxies at intermediate redshifts.« less

Photometric redshifts for the next generation of deep radio continuum surveys - I. Template fitting

NASA Astrophysics Data System (ADS)

Duncan, Kenneth J.; Brown, Michael J. I.; Williams, Wendy L.; Best, Philip N.; Buat, Veronique; Burgarella, Denis; Jarvis, Matt J.; Małek, Katarzyna; Oliver, S. J.; Röttgering, Huub J. A.; Smith, Daniel J. B.

2018-01-01

We present a study of photometric redshift performance for galaxies and active galactic nuclei detected in deep radio continuum surveys. Using two multiwavelength data sets, over the NOAO Deep Wide Field Survey Boötes and COSMOS fields, we assess photometric redshift (photo-z) performance for a sample of ∼4500 radio continuum sources with spectroscopic redshifts relative to those of ∼63 000 non-radio-detected sources in the same fields. We investigate the performance of three photometric redshift template sets as a function of redshift, radio luminosity and infrared/X-ray properties. We find that no single template library is able to provide the best performance across all subsets of the radio-detected population, with variation in the optimum template set both between subsets and between fields. Through a hierarchical Bayesian combination of the photo-z estimates from all three template sets, we are able to produce a consensus photo-z estimate that equals or improves upon the performance of any individual template set.

First broadband characterization and redshift determination of the VHE blazar MAGIC J2001+439

DOE PAGES

Aleksić, J.; Ansoldi, S.; Antonelli, L. A.; ...

2014-12-09

We aim to characterize the broadband emission from 2FGL J2001.1+4352, which has been associated with the unknown-redshift blazar MG4 J200112+4352. Based on its gamma-ray spectral properties, it was identified as a potential very high energy (VHE; E> 100 GeV) gamma-ray emitter. We investigate whether this object is aVHE emitter, characterize its gamma-ray spectrum, and study the broadband emission within the one-zone synchrotron self-Compton (SSC) scenario, which is commonly used to describe the emission in blazars. Moreover, we also intend to determine the redshift of this object, which is a crucial parameter for its scientific interpretation. Here, the source was observedmore » with MAGIC first in 2009 and later in 2010 within a multi-instrument observation campaign. The MAGIC observations yielded 14.8 h of good quality stereoscopic data. Besides MAGIC, the campaign involved, observations with Fermi-LAT, Swift-XRT/UVOT, the optical telescopes KVA, Goddard Robotic Telescope, Galaxy View observatory, Crimean Astrophysical observatory, St. Petersburg observatory, and the Owens Valley Radio Observatory. The object was monitored at radio, optical and gamma-ray energies during the years 2010 and 2011. We characterize the radio to VHE spectral energy distribution and quantify the multiband variability and correlations over short (few days) and long (many months) timescales. We also organized deep imaging optical observations with the Nordic Optical Telescope in 2013 to determine the source redshift. As a result, the source, named MAGIC J2001+439, is detected for the first time at VHE with MAGIC at a statistical significance of 6.3σ (E > 70 GeV) during a 1.3 h long observation on 2010 July 16. The multi-instrument observations show variability in all energy bands with the highest amplitude of variability in the X-ray and VHE bands. Besides the variability on few-day timescales, the long-term monitoring of MAGIC J2001+439 shows that, the gamma-ray, optical, and radio emissions gradually decreased on few-month timescales from 2010 through 2011, indicating that at least some of the radio, optical and gamma-ray emission is produced in a single region by the same population of particles. We also determine for the first time the redshift of this BL Lac object through the measurement of its host galaxy during low blazar activity. Using the observational evidence that the luminosities of BL Lac host galaxies are confined to a relatively narrow range, we obtain z = 0.18 ± 0.04. In addition, we use the Fermi-LAT and MAGIC gamma-ray spectra to provide an independent redshift estimation, z = 0.17 ± 0.10. Finally, using the former (more accurate) redshift value, we adequately describe the broadband emission with a one-zone SSC model for different activity states and interpret the few-day timescale variability as produced by changes in the high-energy component of the electron energy distribution.« less

Probing the galaxy-halo connection in UltraVISTA to z ˜ 2

NASA Astrophysics Data System (ADS)

McCracken, H. J.; Wolk, M.; Colombi, S.; Kilbinger, M.; Ilbert, O.; Peirani, S.; Coupon, J.; Dunlop, J.; Milvang-Jensen, B.; Caputi, K.; Aussel, H.; Béthermin, M.; Le Fèvre, O.

2015-05-01

We use percent-level precision photometric redshifts in the UltraVISTA-DR1 near-infrared survey to investigate the changing relationship between galaxy stellar mass and the dark matter haloes hosting them to z ˜ 2. We achieve this by measuring the clustering properties and abundances of a series of volume-limited galaxy samples selected by stellar mass and star formation activity. We interpret these results in the framework of a phenomenological halo model and numerical simulations. Our measurements span a uniquely large range in stellar mass and redshift and reach below the characteristic stellar mass to z ˜ 2. Our results are: (1) at fixed redshift and scale, clustering amplitude depends monotonically on sample stellar mass threshold; (2) at fixed angular scale, the projected clustering amplitude decreases with redshift but the comoving correlation length remains constant; (3) characteristic halo masses and galaxy bias increase with increasing median stellar mass of the sample; (4) the slope of these relationships is modified in lower mass haloes; (5) concerning the passive galaxy population, characteristic halo masses are consistent with a simply less-abundant version of the full galaxy sample, but at lower redshifts the fraction of satellite galaxies in the passive population is very different from the full galaxy sample; (6) finally, we find that the ratio between the characteristic halo mass and median stellar mass at each redshift bin reaches a peak at log (Mh/M⊙) ˜ 12.2 and the position of this peak remains constant out to z ˜ 2. The behaviour of the full and passively evolving galaxy samples can be understood qualitatively by considering the slow evolution of the characteristic stellar mass in the redshift range probed by our survey.

Cluster Mass Calibration at High Redshift: HST Weak Lensing Analysis of 13 Distant Galaxy Clusters from the South Pole Telescope Sunyaev-Zel’dovich Survey

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

Schrabback, T.; Applegate, D.; Dietrich, J. P.

Here we present an HST/Advanced Camera for Surveys (ACS) weak gravitational lensing analysis of 13 massive high-redshift (z median = 0.88) galaxy clusters discovered in the South Pole Telescope (SPT) Sunyaev–Zel'dovich Survey. This study is part of a larger campaign that aims to robustly calibrate mass–observable scaling relations over a wide range in redshift to enable improved cosmological constraints from the SPT cluster sample. We introduce new strategies to ensure that systematics in the lensing analysis do not degrade constraints on cluster scaling relations significantly. First, we efficiently remove cluster members from the source sample by selecting very blue galaxies in V-I colour. Our estimate of the source redshift distribution is based on Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey (CANDELS) data, where we carefully mimic the source selection criteria of the cluster fields. We apply a statistical correction for systematic photometric redshift errors as derived from Hubble Ultra Deep Field data and verified through spatial cross-correlations. We account for the impact of lensing magnification on the source redshift distribution, finding that this is particularly relevant for shallower surveys. Finally, we account for biases in the mass modelling caused by miscentring and uncertainties in the concentration–mass relation using simulations. In combination with temperature estimates from Chandra we constrain the normalization of the mass–temperature scaling relation ln (E(z)M 500c/10 14 M ⊙) = A + 1.5ln (kT/7.2 keV) to A=1.81more » $$+0.24\\atop{-0.14}$$(stat.)±0.09(sys.), consistent with self-similar redshift evolution when compared to lower redshift samples. Additionally, the lensing data constrain the average concentration of the clusters to c 200c=5.6$$+3.7\\atop{-1.8}$$.« less

Cluster Mass Calibration at High Redshift: HST Weak Lensing Analysis of 13 Distant Galaxy Clusters from the South Pole Telescope Sunyaev-Zel’dovich Survey

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

Schrabback, T.; Applegate, D.; Dietrich, J. P.

We present an HST/Advanced Camera for Surveys (ACS) weak gravitational lensing analysis of 13 massive high-redshift (z(median) = 0.88) galaxy clusters discovered in the South Pole Telescope (SPT) Sunyaev-Zel'dovich Survey. This study is part of a larger campaign that aims to robustly calibrate mass-observable scaling relations over a wide range in redshift to enable improved cosmological constraints from the SPT cluster sample. We introduce new strategies to ensure that systematics in the lensing analysis do not degrade constraints on cluster scaling relations significantly. First, we efficiently remove cluster members from the source sample by selecting very blue galaxies in Vmore » - I colour. Our estimate of the source redshift distribution is based on Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey (CANDELS) data, where we carefully mimic the source selection criteria of the cluster fields. We apply a statistical correction for systematic photometric redshift errors as derived from Hubble Ultra Deep Field data and verified through spatial cross-correlations. We account for the impact of lensing magnification on the source redshift distribution, finding that this is particularly relevant for shallower surveys. Finally, we account for biases in the mass modelling caused by miscentring and uncertainties in the concentration-mass relation using simulations. In combination with temperature estimates from Chandra we constrain the normalization of the mass-temperature scaling relation ln (E(z) M-500c/10(14)M(circle dot)) = A + 1.5ln (kT/7.2 keV) to A = 1.81(-0.14)(+0.24)(stat.)+/- 0.09(sys.), consistent with self-similar redshift evolution when compared to lower redshift samples. Additionally, the lensing data constrain the average concentration of the clusters to c(200c) = 5.6(-1.8)(+3.7).« less

Cluster Mass Calibration at High Redshift: HST Weak Lensing Analysis of 13 Distant Galaxy Clusters from the South Pole Telescope Sunyaev-Zel’dovich Survey

DOE PAGES

Schrabback, T.; Applegate, D.; Dietrich, J. P.; ...

2017-10-14

Here we present an HST/Advanced Camera for Surveys (ACS) weak gravitational lensing analysis of 13 massive high-redshift (z median = 0.88) galaxy clusters discovered in the South Pole Telescope (SPT) Sunyaev–Zel'dovich Survey. This study is part of a larger campaign that aims to robustly calibrate mass–observable scaling relations over a wide range in redshift to enable improved cosmological constraints from the SPT cluster sample. We introduce new strategies to ensure that systematics in the lensing analysis do not degrade constraints on cluster scaling relations significantly. First, we efficiently remove cluster members from the source sample by selecting very blue galaxies in V-I colour. Our estimate of the source redshift distribution is based on Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey (CANDELS) data, where we carefully mimic the source selection criteria of the cluster fields. We apply a statistical correction for systematic photometric redshift errors as derived from Hubble Ultra Deep Field data and verified through spatial cross-correlations. We account for the impact of lensing magnification on the source redshift distribution, finding that this is particularly relevant for shallower surveys. Finally, we account for biases in the mass modelling caused by miscentring and uncertainties in the concentration–mass relation using simulations. In combination with temperature estimates from Chandra we constrain the normalization of the mass–temperature scaling relation ln (E(z)M 500c/10 14 M ⊙) = A + 1.5ln (kT/7.2 keV) to A=1.81more » $$+0.24\\atop{-0.14}$$(stat.)±0.09(sys.), consistent with self-similar redshift evolution when compared to lower redshift samples. Additionally, the lensing data constrain the average concentration of the clusters to c 200c=5.6$$+3.7\\atop{-1.8}$$.« less

The K-Band Quasar Luminosity Function from an SDSS and UKIDSS Matched Catalog

NASA Astrophysics Data System (ADS)

Peth, Michael; Ross, N. P.; Schneider, D. P.

2010-01-01

We match the 1,015,082 quasars from the Sloan Digital Sky Survey (SDSS) DR6 Photometric Quasar catalog to the UKIRT Infrared Digital Sky Survey (UKIDSS) Large Area Survey (LAS) DR3 to produce a catalog of 130,827 objects with optical (ugriz) and infrared (YJHK) measurements over an area of 1,200 sq. deg. A matching radius of 1'’ is used; the positional standard deviations of SDSS DR6 quasars and UKIDSS LAS is δRA = 0.137'’ and δDec = 0.131''. The catalog contains 74,351 K-band detections and 42,133 objects have coverage in all four NIR bands. In addition to the catalog, we present optical and NIR color-redshift and color-color plots. The photometric vs. spectroscopic redshift plots demonstrate how unreliable high reported photometric redshifts can be. This forces us to focus on z4.6 quasars are compared to our highest redshift objects. The giK color-color plot demonstrates that stellar contamination only affects a small sample of the objects. Distributions for Y,J,H,K and i-bands reveal insights into the flux limits in each magnitude. We investigate the distribution of redshifts from different data sets and investigate the legitimacy of certain measured photometric redshift regions. For in-depth analysis, we focus on the 300 sq. deg area equatorial SDSS region designated as Stripe 82. We measure the observed K-band quasar luminosity function (QLF) for a subset of 9,872, z<2.2 objects. We find the shape of the K-band QLF is very similar to that of the optical QLF, over the considered redshift ranges. Our calculated K-Band QLFs broadly match previous optical QLFs calculated from the SDSS and 2SLAQ QSO surveys and should provide important constraints linking unobscured optical quasars to Mid-Infrared detected, dusty and obscured AGNs at high-redshift.

Gamma-Ray Bursts and Cosmology

NASA Technical Reports Server (NTRS)

Norris, Jay P.

2003-01-01

The unrivalled, extreme luminosities of gamma-ray bursts (GRBs) make them the favored beacons for sampling the high redshift Universe. To employ GRBs to study the cosmic terrain -- e.g., star and galaxy formation history -- GRB luminosities must be calibrated, and the luminosity function versus redshift must be measured or inferred. Several nascent relationships between gamma-ray temporal or spectral indicators and luminosity or total energy have been reported. These measures promise to further our understanding of GRBs once the connections between the luminosity indicators and GRB jets and emission mechanisms are better elucidated. The current distribution of 33 redshifts determined from host galaxies and afterglows peaks near z $\\sim$ 1, whereas for the full BATSE sample of long bursts, the lag-luminosity relation predicts a broad peak z $\\sim$ 1--4 with a tail to z $\\sim$ 20, in rough agreement with theoretical models based on star formation considerations. For some GRB subclasses and apparently related phenomena -- short bursts, long-lag bursts, and X-ray flashes -- the present information on their redshift distributions is sparse or entirely lacking, and progress is expected in Swift era when prompt alerts become numerous.

Peculiar velocity effect on galaxy correlation functions in nonlinear clustering regime

NASA Astrophysics Data System (ADS)

Matsubara, Takahiko

1994-03-01

We studied the distortion of the apparent distribution of galaxies in redshift space contaminated by the peculiar velocity effect. Specifically we obtained the expressions for N-point correlation functions in redshift space with given functional form for velocity distribution f(v) and evaluated two- and three-point correlation functions quantitatively. The effect of velocity correlations is also discussed. When the two-point correlation function in real space has a power-law form, Xir(r) is proportional to r(-gamma), the redshift-space counterpart on small scales also has a power-law form but with an increased power-law index: Xis(s) is proportional to s(1-gamma). When the three-point correlation function has the hierarchical form and the two-point correlation function has the power-law form in real space, the hierarchical form of the three-point correlation function is almost preserved in redshift space. The above analytic results are compared with the direct analysis based on N-body simulation data for cold dark matter models. Implications on the hierarchical clustering ansatz are discussed in detail.

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.

AGES: THE AGN AND GALAXY EVOLUTION SURVEY

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

Kochanek, C. S.; Eisenstein, D. J.; Caldwell, N.

2012-05-01

The AGN and Galaxy Evolution Survey (AGES) is a redshift survey covering, in its standard fields, 7.7 deg{sup 2} of the Booetes field of the NOAO Deep Wide-Field Survey. The final sample consists of 23,745 redshifts. There are well-defined galaxy samples in 10 bands (the B{sub W} , R, I, J, K, IRAC 3.6, 4.5, 5.8, and 8.0 {mu}m, and MIPS 24 {mu}m bands) to a limiting magnitude of I < 20 mag for spectroscopy. For these galaxies, we obtained 18,163 redshifts from a sample of 35,200 galaxies, where random sparse sampling was used to define statistically complete sub-samples inmore » all 10 photometric bands. The median galaxy redshift is 0.31, and 90% of the redshifts are in the range 0.085 < z < 0.66. Active galactic nuclei (AGNs) were selected as radio, X-ray, IRAC mid-IR, and MIPS 24 {mu}m sources to fainter limiting magnitudes (I < 22.5 mag for point sources). Redshifts were obtained for 4764 quasars and galaxies with AGN signatures, with 2926, 1718, 605, 119, and 13 above redshifts of 0.5, 1, 2, 3, and 4, respectively. We detail all the AGES selection procedures and present the complete spectroscopic redshift catalogs and spectral energy distribution decompositions. Photometric redshift estimates are provided for all sources in the AGES samples.« less

The Angular Momentum Distribution and Baryon Content of Star-forming Galaxies at z ˜ 1-3

NASA Astrophysics Data System (ADS)

Burkert, A.; Förster Schreiber, N. M.; Genzel, R.; Lang, P.; Tacconi, L. J.; Wisnioski, E.; Wuyts, S.; Bandara, K.; Beifiori, A.; Bender, R.; Brammer, G.; Chan, J.; Davies, R.; Dekel, A.; Fabricius, M.; Fossati, M.; Kulkarni, S.; Lutz, D.; Mendel, J. T.; Momcheva, I.; Nelson, E. J.; Naab, T.; Renzini, A.; Saglia, R.; Sharples, R. M.; Sternberg, A.; Wilman, D.; Wuyts, E.

2016-08-01

We analyze the angular momenta of massive star-forming galaxies (SFGs) at the peak of the cosmic star formation epoch (z ˜ 0.8-2.6). Our sample of ˜360 log(M */M ⊙) ˜ 9.3-11.8 SFGs is mainly based on the KMOS3D and SINS/zC-SINF surveys of Hα kinematics, and collectively provides a representative subset of the massive star-forming population. The inferred halo scale angular momentum distribution is broadly consistent with that theoretically predicted for their dark matter halos, in terms of mean spin parameter < λ > ˜ 0.037 and its dispersion (σ logλ ˜ 0.2). Spin parameters correlate with the disk radial scale and with their stellar surface density, but do not depend significantly on halo mass, stellar mass, or redshift. Our data thus support the long-standing assumption that on average, even at high redshifts, the specific angular momentum of disk galaxies reflects that of their dark matter halos (j d = j DM). The lack of correlation between λ × (j d /j DM) and the nuclear stellar density Σ*(1 kpc) favors a scenario where disk-internal angular momentum redistribution leads to “compaction” inside massive high-redshift disks. For our sample, the inferred average stellar to dark matter mass ratio is ˜2%, consistent with abundance matching results. Including the molecular gas, the total baryonic disk to dark matter mass ratio is ˜5% for halos near 1012 M ⊙, which corresponds to 31% of the cosmologically available baryons, implying that high-redshift disks are strongly baryon dominated. Based on observations obtained at the Very Large Telescope of the European Southern Observatory, Paranal, Chile (ESO Programme IDs 075.A-0466, 076.A-0527, 079.A-0341, 080.A-0330, 080.A-0339, 080.A-0635, 081.B-0568, 081.A-0672, 082.A-0396, 183.A-0781, 087.A-0081, 088.A-0202, 088.A-0209, 091.A-0126, 092.A-0091, 093.A-0079, 094.A-0217, 095.A-0047, 096.A-0025).

Properties of z ~ 3-6 Lyman break galaxies. II. Impact of nebular emission at high redshift

NASA Astrophysics Data System (ADS)

de Barros, S.; Schaerer, D.; Stark, D. P.

2014-03-01

Context. To gain insight on the mass assembly and place constraints on the star formation history (SFH) of Lyman break galaxies (LBGs), it is important to accurately determine their properties. Aims: We estimate how nebular emission and different SFHs affect parameter estimation of LBGs. Methods: We present a homogeneous, detailed analysis of the spectral energy distribution (SED) of ~1700 LBGs from the GOODS-MUSIC catalogue with deep multi-wavelength photometry from the U band to 8 μm to determine stellar mass, age, dust attenuation, and star formation rate. Using our SED fitting tool, which takes into account nebular emission, we explore a wide parameter space. We also explore a set of different star formation histories. Results: Nebular emission is found to significantly affect the determination of the physical parameters for the majority of z ~ 3-6 LBGs. We identify two populations of galaxies by determining the importance of the contribution of emission lines to broadband fluxes. We find that ~65% of LBGs show detectable signs of emission lines, whereas ~35% show weak or no emission lines. This distribution is found over the entire redshift range. We interpret these groups as actively star-forming and more quiescent LBGs, respectively. We find that it is necessary to considerer SED fits with very young ages (<50 Myr) to reproduce some colours affected by strong emission lines. Other arguments favouring episodic star formation and relatively short star formation timescales are also discussed. Considering nebular emission generally leads to a younger age, lower stellar mass, higher dust attenuation, higher star formation rate, and a large scatter in the SFR-M⋆ relation. Our analysis yields a trend of increasing specific star formation rate with redshift, as predicted by recent galaxy evolution models. Conclusions: The physical parameters of approximately two thirds of high redshift galaxies are significantly modified when we account for nebular emission. The SED models, which include nebular emission shed new light on the properties of LBGs with numerous important implications. Appendix A is available in electronic form at http://www.aanda.org

Galaxies clustering around QSOs with z = 0.9-1.5 and the origin of blue field galaxies

NASA Technical Reports Server (NTRS)

Hintzen, Paul; Romanishin, W.; Valdes, Francisco

1991-01-01

Deep CCD images were obtained in Mould-Cousins R and I passbands of 16 radio quasars with z values between 0.9 and 1.5 and absolute values of b above 35 deg, chosen from the Veron-Cetty and Veron (1984) catalog. Results indicate that, in this population of radio quasars, there is a statistically significant excess of galaxies within 15 arcsec of the quasars and brighter than R = 23 and I = 22. However, contrary to the report of Tyson (1986), no excess was found of galaxies with R less than 21 lying within 30 arcsec of quasars in this redshift range. Data were also obtained for very blue galaxies seen among objects in the general field, all of which are bluer in R-I than Magellanic irregulars at any redshift less than 3. It is suggested that this population might be comprised of low-redshift low-luminosity (H II region) galaxies of the type studied by French (1980) and/or higher redshift galaxies with strong cooling flows and forbidden O II lines.

Herschel-ATLAS: The Angular Correlation Function of Submillimetre Galaxies at High and Low Redshift

NASA Technical Reports Server (NTRS)

Maddox, S. J.; Dunne, L.; Rigby, E.; Eales, S.; Cooray, A.; Scott, D.; Peacock, J. A.; Negrello, M.; Smith, D. J. B.; Benford, D.;

THE SL2S GALAXY-SCALE LENS SAMPLE. V. DARK MATTER HALOS AND STELLAR IMF OF MASSIVE EARLY-TYPE GALAXIES OUT TO REDSHIFT 0.8

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

Sonnenfeld, Alessandro; Treu, Tommaso; Marshall, Philip J.

2015-02-20

We investigate the cosmic evolution of the internal structure of massive early-type galaxies over half of the age of the universe. We perform a joint lensing and stellar dynamics analysis of a sample of 81 strong lenses from the Strong Lensing Legacy Survey and Sloan ACS Lens Survey and combine the results with a hierarchical Bayesian inference method to measure the distribution of dark matter mass and stellar initial mass function (IMF) across the population of massive early-type galaxies. Lensing selection effects are taken into account. We find that the dark matter mass projected within the inner 5 kpc increasesmore » for increasing redshift, decreases for increasing stellar mass density, but is roughly constant along the evolutionary tracks of early-type galaxies. The average dark matter slope is consistent with that of a Navarro-Frenk-White profile, but is not well constrained. The stellar IMF normalization is close to a Salpeter IMF at log M {sub *} = 11.5 and scales strongly with increasing stellar mass. No dependence of the IMF on redshift or stellar mass density is detected. The anti-correlation between dark matter mass and stellar mass density supports the idea of mergers being more frequent in more massive dark matter halos.« less

The SL2S galaxy-scale lens sample. V. dark matter halos and stellar IMF of massive early-type galaxies out to redshift 0.8

DOE PAGES

Sonnenfeld, Alessandro; Treu, Tommaso; Marshall, Philip J.; ...

2015-02-17

Here, we investigate the cosmic evolution of the internal structure of massive early-type galaxies over half of the age of the universe. We also perform a joint lensing and stellar dynamics analysis of a sample of 81 strong lenses from the Strong Lensing Legacy Survey and Sloan ACS Lens Survey and combine the results with a hierarchical Bayesian inference method to measure the distribution of dark matter mass and stellar initial mass function (IMF) across the population of massive early-type galaxies. Lensing selection effects are taken into account. Furthermore, we found that the dark matter mass projected within the innermore » 5 kpc increases for increasing redshift, decreases for increasing stellar mass density, but is roughly constant along the evolutionary tracks of early-type galaxies. The average dark matter slope is consistent with that of a Navarro-Frenk-White profile, but is not well constrained. The stellar IMF normalization is close to a Salpeter IMF at log M * = 11.5 and scales strongly with increasing stellar mass. No dependence of the IMF on redshift or stellar mass density is detected. The anti-correlation between dark matter mass and stellar mass density supports the idea of mergers being more frequent in more massive dark matter halos.« less

FRB strength distribution challenges the cosmological principle

NASA Astrophysics Data System (ADS)

Katz, J. I.

2017-11-01

The distribution of fast radio burst (FRB) fluxes and fluences is characterized by a few very bright events and a deficiency of fainter events, compared to expectations for a homogeneous space-filling distribution. I define a metric to quantify this, and apply it to the 17 presently known Parkes FRB, products of a comparatively homogeneous search. With 98 per cent confidence, we reject the hypothesis of a homogeneous distribution in Euclidean space. Possible explanations include a reduction of fainter events by cosmological redshifts or evolution or a cosmologically local concentration of events. The former is opposed by the small value of the one known FRB redshift. The latter contradicts the Cosmological Principle, but may be explained if the brighter FRB originates in the Local Supercluster.

Galaxy evolution by color-log(n) type since redshift unity in the Hubble Ultra Deep Field

NASA Astrophysics Data System (ADS)

Cameron, E.; Driver, S. P.

2009-01-01

Aims: We explore the use of the color-log(n) (where n is the global Sérsic index) plane as a tool for subdividing the galaxy population in a physically-motivated manner out to redshift unity. We thereby aim to quantify surface brightness evolution by color-log(n) type, accounting separately for the specific selection and measurement biases against each. Methods: We construct (u-r) color-log(n) diagrams for distant galaxies in the Hubble Ultra Deep Field (UDF) within a series of volume-limited samples to z=1.5. The color-log(n) distributions of these high redshift galaxies are compared against that measured for nearby galaxies in the Millennium Galaxy Catalogue (MGC), as well as to the results of visual morphological classification. Based on this analysis we divide our sample into three color-structure classes. Namely, “red, compact”, “blue, diffuse” and “blue, compact”. Luminosity-size diagrams are constructed for members of the two largest classes (“red, compact” and “blue, diffuse”), both in the UDF and the MGC. Artificial galaxy simulations (for systems with exponential and de Vaucouleurs profile shapes alternately) are used to identify “bias-free” regions of the luminosity-size plane in which galaxies are detected with high completeness, and their fluxes and sizes recovered with minimal surface brightness-dependent biases. Galaxy evolution is quantified via comparison of the low and high redshift luminosity-size relations within these “bias-free” regions. Results: We confirm the correlation between color-log(n) plane position and visual morphological type observed locally and in other high redshift studies in the color and/or structure domain. The combined effects of observational uncertainties, the morphological K-correction and cosmic variance preclude a robust statistical comparison of the shape of the MGC and UDF color-log(n) distributions. However, in the interval 0.75 < z <1.0 where the UDF i-band samples close to rest-frame B-band light (i.e., the morphological K-correction between our samples is negligible) we are able to present tentative evidence of bimodality, albiet for a very small sample size (17 galaxies). Our unique approach to quantifying selection and measurement biases in the luminosity-size plane highlights the need to consider errors in the recovery of both magnitudes and sizes, and their dependence on profile shape. Motivated by these results we divide our sample into the three color-structure classes mentioned above and quantify luminosity-size evolution by galaxy type. Specifically, we detect decreases in B-band, surface brightness of 1.57 ± 0.22 mag arcsec-2 and 1.65 ± 0.22 mag arcsec-2 for our “blue, diffuse” and “red, compact” classes respectively between redshift unity and the present day.

Sumo Puff: Tidal debris or disturbed ultra-diffuse galaxy?

NASA Astrophysics Data System (ADS)

Greco, Johnny P.; Greene, Jenny E.; Price-Whelan, Adrian M.; Leauthaud, Alexie; Huang, Song; Goulding, Andy D.; Strauss, Michael A.; Komiyama, Yutaka; Lupton, Robert H.; Miyazaki, Satoshi; Takada, Masahiro; Tanaka, Masayuki; Usuda, Tomonori

2018-01-01

We report the discovery of a diffuse stellar cloud with an angular extent ≳30″, which we term "Sumo Puff", in data from the Hyper Suprime-Cam Subaru Strategic Program (HSC-SSP). While we do not have a redshift for this object, it is in close angular proximity to a post-merger galaxy at redshift z = 0.0431 and is projected within a few virial radii (assuming similar redshifts) of two other ˜L⋆ galaxies, which we use to bracket a potential redshift range of 0.0055 < z < 0.0431. The object's light distribution is flat, as characterized by a low Sérsic index (n ˜ 0.3). It has a low central g-band surface brightness of ˜26.4 mag arcsec-2, large effective radius of ˜13″ (˜11 kpc at z = 0.0431 and ˜1.5 kpc at z = 0.0055), and an elongated morphology (b/a ˜ 0.4). Its red color (g - i ˜ 1) is consistent with a passively evolving stellar population and similar to the nearby post-merger galaxy, and we may see tidal material connecting Sumo Puff with this galaxy. We offer two possible interpretations for the nature of this object: (1) it is an extreme, galaxy-sized tidal feature associated with a recent merger event, or (2) it is a foreground dwarf galaxy with properties consistent with a quenched, disturbed, ultra-diffuse galaxy. We present a qualitative comparison with simulations that demonstrates the feasibility of forming a structure similar to this object in a merger event. Follow-up spectroscopy and/or deeper imaging to confirm the presence of the bridge of tidal material will be necessary to reveal the true nature of this object.

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

Geier, S.; Man, A. W. S.; Krühler, T.

Quiescent massive galaxies at z ∼ 2 are thought to be the progenitors of present-day massive ellipticals. Observations revealed them to be extraordinarily compact. Until now, the determination of stellar ages, star formation rates, and dust properties via spectroscopic measurements has been feasible only for the most luminous and massive specimens (∼3 × M*). Here we present a spectroscopic study of two near-infrared-selected galaxies that are close to the characteristic stellar mass M* (∼0.9 × M* and ∼1.3 × M*) and whose observed brightness has been boosted by the gravitational lensing effect. We measure the redshifts of the two galaxiesmore » to be z = 1.71 ± 0.02 and z = 2.15 ± 0.01. By fitting stellar population synthesis models to their spectrophotometric spectral energy distributions we determine their ages to be 2.4{sup +0.8}{sub -0.6} Gyr and 1.7 ± 0.3 Gyr, respectively, which implies that the two galaxies have higher mass-to-light ratios than most quiescent z ∼ 2 galaxies in other studies. We find no direct evidence for active star formation or active galactic nucleus activity in either of the two galaxies, based on the non-detection of emission lines. Based on the derived redshifts and stellar ages we estimate the formation redshifts to be z=4.3{sup +3.4}{sub -1.2} and z=4.3{sup +1.0}{sub -0.6}, respectively. We use the increased spatial resolution due to the gravitational lensing to derive constraints on the morphology. Fitting Sérsic profiles to the de-lensed images of the two galaxies confirms their compactness, with one of them being spheroid-like and the other providing the first confirmation of a passive lenticular galaxy at a spectroscopically derived redshift of z ∼ 2.« less

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.

The mean star formation rates of unobscured QSOs: searching for evidence of suppressed or enhanced star formation

NASA Astrophysics Data System (ADS)

Stanley, F.; Alexander, D. M.; Harrison, C. M.; Rosario, D. J.; Wang, L.; Aird, J. A.; Bourne, N.; Dunne, L.; Dye, S.; Eales, S.; Knudsen, K. K.; Michałowski, M. J.; Valiante, E.; De Zotti, G.; Furlanetto, C.; Ivison, R.; Maddox, S.; Smith, M. W. L.

2017-12-01

We investigate the mean star formation rates (SFRs) in the host galaxies of ∼3000 optically selected quasi-stellar objects (QSOs) from the Sloan Digital Sky Survey within the Herschel-ATLAS fields, and a radio-luminous subsample covering the redshift range of z = 0.2-2.5. Using Wide-field Infrared Survey Explorer (WISE) and Herschel photometry (12-500 μm) we construct composite spectral energy distributions (SEDs) in bins of redshift and active galactic nucleus (AGN) luminosity. We perform SED fitting to measure the mean infrared luminosity due to star formation, removing the contamination from AGN emission. We find that the mean SFRs show a weak positive trend with increasing AGN luminosity. However, we demonstrate that the observed trend could be due to an increase in black hole (BH) mass (and a consequent increase of inferred stellar mass) with increasing AGN luminosity. We compare to a sample of X-ray selected AGN and find that the two populations have consistent mean SFRs when matched in AGN luminosity and redshift. On the basis of the available virial BH masses, and the evolving BH mass to stellar mass relationship, we find that the mean SFRs of our QSO sample are consistent with those of main sequence star-forming galaxies. Similarly the radio-luminous QSOs have mean SFRs that are consistent with both the overall QSO sample and with star-forming galaxies on the main sequence. In conclusion, on average QSOs reside on the main sequence of star-forming galaxies, and the observed positive trend between the mean SFRs and AGN luminosity can be attributed to BH mass and redshift dependencies.

X-ray constraints on the fraction of obscured active galactic nuclei at high accretion luminosities

NASA Astrophysics Data System (ADS)

Georgakakis, A.; Salvato, M.; Liu, Z.; Buchner, J.; Brandt, W. N.; Ananna, T. Tasnim; Schulze, A.; Shen, Yue; LaMassa, S.; Nandra, K.; Merloni, A.; McGreer, I. D.

2017-08-01

The wide-area XMM-XXL X-ray survey is used to explore the fraction of obscured active galactic nuclei (AGNs) at high accretion luminosities, LX(2-10 keV) ≳ 1044 erg s - 1, and out to redshift z ≈ 1.5. The sample covers an area of about 14 deg2 and provides constraints on the space density of powerful AGNs over a wide range of neutral hydrogen column densities extending beyond the Compton-thick limit, NH ≈ 1024 cm - 2. The fraction of obscured Compton-thin (NH = 1022-1024 cm - 2) AGNs is estimated to be ≈0.35 for luminosities LX(2-10 keV) > 1044 erg s - 1, independent of redshift. For less luminous sources, the fraction of obscured Compton-thin AGNs increases from 0.45 ± 0.10 at z = 0.25 to 0.75 ± 0.05 at z = 1.25. Studies that select AGNs in the infrared via template fits to the observed spectral energy distribution of extragalactic sources estimate space densities at high accretion luminosities consistent with the XMM-XXL constraints. There is no evidence for a large population of AGNs (e.g. heavily obscured) identified in the infrared and missed at X-ray wavelengths. We further explore the mid-infrared colours of XMM-XXL AGNs as a function of accretion luminosity, column density and redshift. The fraction of XMM-XXL sources that lie within the mid-infrared colour wedges defined in the literature to select AGNs is primarily a function of redshift. This fraction increases from about 20-30 per cent at z = 0.25 to about 50-70 per cent at z = 1.5.

The GALEX Ultraviolet Virgo Cluster Survey (GUViCS). VII. Brightest cluster galaxy UV upturn and the FUV-NUV color up to redshift 0.35

NASA Astrophysics Data System (ADS)

Boissier, S.; Cucciati, O.; Boselli, A.; Mei, S.; Ferrarese, L.

2018-03-01

Context. At low redshift, early-type galaxies often exhibit a rising flux with decreasing wavelength in the 1000-2500 Å range, called "UV upturn". The origin of this phenomenon is debated, and its evolution with redshift is poorly constrained. The observed GALEX FUV-NUV color can be used to probe the UV upturn approximately to redshift 0.5. Aim. We provide constraints on the existence of the UV upturn up to redshift 0.4 in the brightest cluster galaxies (BCG) located behind the Virgo cluster, using data from the GUViCS survey. Methods: We estimate the GALEX far-UV (FUV) and near-UV (NUV) observed magnitudes for BCGs from the maxBCG catalog in the GUViCS fields. We increase the number of nonlocal galaxies identified as BCGs with GALEX photometry from a few tens of galaxies to 166 (64 when restricting this sample to relatively small error bars). We also estimate a central color within a 20 arcsec aperture. By using the r-band luminosity from the maxBCG catalog, we can separate blue FUV-NUV due to recent star formation and candidate upturn cases. We use Lick indices to verify their similarity to redshift 0 upturn cases. Results: We clearly detect a population of blue FUV-NUV BCGs in the redshift range 0.10-0.35, vastly improving the existing constraints at these epochs by increasing the number of galaxies studied, and by exploring a redshift range with no previous data (beyond 0.2), spanning one more Gyr in the past. These galaxies bring new constraints that can help distinguish between assumptions concerning the stellar populations causing the UV upturn phenomenon. The existence of a large number of UV upturns around redshift 0.25 favors the existence of a binary channel among the sources proposed in the literature. Tables 2-5 are 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/611/A42

The shape of the cosmic X-ray background: nuclear starburst discs and the redshift evolution of AGN obscuration

NASA Astrophysics Data System (ADS)

Gohil, R.; Ballantyne, D. R.

2018-04-01

A significant number of active galactic nuclei (AGNs) are observed to be hidden behind dust and gas. The distribution of material around AGNs plays an important role in modelling the cosmic X-ray background (CXB), especially the fraction of type 2 AGNs (f2). One of the possible explanations for obscuration in Seyfert galaxies at intermediate redshifts is dusty starburst discs. We compute the two-dimensional (2D) hydrostatic structure of 768 nuclear starburst discs (NSDs) under various physical conditions and also the distribution of column density along the line of sight (NH) associated with these discs. Then the NH distribution is evolved with redshift by using the redshift-dependent distribution function of input parameters. Parameter f2 shows a strong positive evolution up to z = 2, but only a weak level of enhancement at higher z. The Compton-thin and Compton-thick AGN fractions associated with these starburst regions increase ∝ (1 + z)δ, where δ is estimated to be 1.12 and 1.45, respectively. The reflection parameter Rf associated with column density NH ≥ 1023.5 cm-2 extends from 0.13 at z = 0 to 0.58 at z = 4. A CXB model employing this evolving NH distribution indicates that more compact (Rout < 120 pc) NSDs provide a better fit to the CXB. In addition to `Seyfert-like' AGNs obscured by nuclear starbursts, we predict that 40-60 per cent of quasars must be Compton-thick to produce a peak of the CXB spectrum within the observational uncertainty. The predicted total number counts of AGNs in 8-24 keV bands are in fair agreement with observations from the Nuclear Spectroscopic Telescope Array (NuSTAR).

Cosmic velocity-gravity relation in redshift space

NASA Astrophysics Data System (ADS)

Colombi, Stéphane; Chodorowski, Michał J.; Teyssier, Romain

2007-02-01

We propose a simple way to estimate the parameter β ~= Ω0.6/b from 3D galaxy surveys, where Ω is the non-relativistic matter-density parameter of the Universe and b is the bias between the galaxy distribution and the total matter distribution. Our method consists in measuring the relation between the cosmological velocity and gravity fields, and thus requires peculiar velocity measurements. The relation is measured directly in redshift space, so there is no need to reconstruct the density field in real space. In linear theory, the radial components of the gravity and velocity fields in redshift space are expected to be tightly correlated, with a slope given, in the distant observer approximation, by We test extensively this relation using controlled numerical experiments based on a cosmological N-body simulation. To perform the measurements, we propose a new and rather simple adaptive interpolation scheme to estimate the velocity and the gravity field on a grid. One of the most striking results is that non-linear effects, including `fingers of God', affect mainly the tails of the joint probability distribution function (PDF) of the velocity and gravity field: the 1-1.5 σ region around the maximum of the PDF is dominated by the linear theory regime, both in real and redshift space. This is understood explicitly by using the spherical collapse model as a proxy of non-linear dynamics. Applications of the method to real galaxy catalogues are discussed, including a preliminary investigation on homogeneous (volume-limited) `galaxy' samples extracted from the simulation with simple prescriptions based on halo and substructure identification, to quantify the effects of the bias between the galaxy distribution and the total matter distribution, as well as the effects of shot noise.

Evolution of galaxy structure using visual morphologies in CANDELS and Hydro-ART simulations

NASA Astrophysics Data System (ADS)

Mozena, Mark W.

2013-08-01

The general properties, morphologies, and classes of galaxies in the local Universe are well studied. Most local galaxies are morphologically members of the Hubble sequence and can be crudely separated into elliptical red quiescent galaxies or disky blue star-forming galaxies. This Hubble sequence of relaxed structures has been shown to dominate galaxy populations out to a redshift of z~1. The description of galaxies at earlier times is not well known nor is it understood how and at what epoch the Hubble sequence formed. Of particular interest is the structure of galaxies at z~2. This epoch was an active time for galaxy growth and was the peak epoch for star formation rate, active galactic nuclei activity, and mergers between galaxies. With the installation of the near-infrared Wide Field Camera 3 (WFC3) on the Hubble Space Telescope in 2009, large area photometric surveys of galaxies were able to be performed for the first time at moderate redshifts (z~2) in wavebands that effectively trace the older stellar populations and stellar mass of the galaxies rather than the clumpy star-forming regions. Using WFC3 HST images, an in-depth morphology classification system was developed to probe the galaxy populations at higher redshifts (focusing on z~2). These visual classifications were used with other galaxy parameters (stellar mass, color, star formation rate, radius, Sersic profiles, etc) to identify and quantify the moderate redshift galaxy populations and study how these populations changed with time to form the relaxed Hubble sequence Universe we observe today. Additionally, these same tools that were used to probe galaxy populations at z~2 in the observed Universe were also used on simulated galaxy images produced from state-of-the-art cosmological simulations. These Hydro-ART simulations build artificial galaxies that are compared to observations so as to shed light on the relevant mechanisms in galaxy evolution. By classifying and comparing the populations present in the simulations with our observations, we are able to probe the model's ability to create realistic galaxy populations. The first chapter of this thesis focuses on visually classifying and studying galaxy populations at z~2 and how they change with redshift for a given mass. The second chapter focuses on applying our techniques to Hydro-ART simulations at z~2 and comparing these mock 'observed' simulations with our real WFC3 HST observations. Both of these chapters closely resemble manuscripts in the process of being submitted for independent publication.

A cooperative approach among methods for photometric redshifts estimation: an application to KiDS data

NASA Astrophysics Data System (ADS)

Cavuoti, S.; Tortora, C.; Brescia, M.; Longo, G.; Radovich, M.; Napolitano, N. R.; Amaro, V.; Vellucci, C.; La Barbera, F.; Getman, F.; Grado, A.

2017-04-01

Photometric redshifts (photo-z) are fundamental in galaxy surveys to address different topics, from gravitational lensing and dark matter distribution to galaxy evolution. The Kilo Degree Survey (KiDS), I.e. the European Southern Observatory (ESO) public survey on the VLT Survey Telescope (VST), provides the unprecedented opportunity to exploit a large galaxy data set with an exceptional image quality and depth in the optical wavebands. Using a KiDS subset of about 25000 galaxies with measured spectroscopic redshifts, we have derived photo-z using (I) three different empirical methods based on supervised machine learning; (II) the Bayesian photometric redshift model (or BPZ); and (III) a classical spectral energy distribution (SED) template fitting procedure (LE PHARE). We confirm that, in the regions of the photometric parameter space properly sampled by the spectroscopic templates, machine learning methods provide better redshift estimates, with a lower scatter and a smaller fraction of outliers. SED fitting techniques, however, provide useful information on the galaxy spectral type, which can be effectively used to constrain systematic errors and to better characterize potential catastrophic outliers. Such classification is then used to specialize the training of regression machine learning models, by demonstrating that a hybrid approach, involving SED fitting and machine learning in a single collaborative framework, can be effectively used to improve the accuracy of photo-z estimates.

The Hubble Space Telescope quasar absorption line key project. v. redshift evolution of lyman limit absorption in the spectra of a large sample of quasars

NASA Technical Reports Server (NTRS)

Stengler-Larrea, Erik A.; Boksenberg, Alec; Steidel, Charles, C.; Sargent, W. L. W.; Bacall, John N.; Bergeron, Jacqueline; Hartig, George F.; Jannuzi, Buell T.; Kirhakos, Sofia; Savage, Blair D.

1995-01-01

Using a sample of 119 QSOs, containing objects we have selected having previously available high quality ground-based and IUE spectral observations, together with Hubble Space Telescope (HST) observations of 26 QSOs from Bahcall et al. (1993, 1995) and Impey et al. (1995) and new optical observations of 41 objects by Steidel & Sargent (1995), we study the redshift evolution of Lyman limit absorption systems (LLSs; tau greater than 1.0) over the reshift range 0.32 less than or equal to z(sub LLS) less than or equal to 4.11. The HST observations significantly improve the determination of the low redshift (0.4 less than or equal to z(sub LLS) less than or equal to 1.4) distribution. We find the effect which may have been responsible for the apparent strong evolution at a(sub LLS) greater than or equal to 2.5 found by Lanzetta (1991), which led him to consider a broken, not single power law as a better description of the redshift distribution of LLSs. After removing objects which may bias our sample, leaving a total of 169 QSOs, we find the distribution is well described by a single power law, and obtain for the number density as a function of redshift the form N(z) = N(sub 0)(1 + z)(exp gamma) with gamma = 1.50 =/- 0.39 and N(sub 0) = 0.25(sup -0.10)(sub +0.17), consistent with a constant comoving density of absorbers in a Firedmann universe with q(sub 0) = 0 but indicating evolution if q(sub 0) = 1/2.

The Angular Three-Point Correlation Function in the Quasi-linear Regime

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

Buchalter, Ari; Kamionkowski, Marc; Jaffe, Andrew H.

2000-02-10

We calculate the normalized angular three-point correlation function (3PCF), q, as well as the normalized angular skewness, s{sub 3}, assuming the small-angle approximation, for a biased mass distribution in flat and open cold dark matter (CDM) models with Gaussian initial conditions. The leading-order perturbative results incorporate the explicit dependence on the cosmological parameters, the shape of the CDM transfer function, the linear evolution of the power spectrum, the form of the assumed redshift distribution function, and linear and nonlinear biasing, which may be evolving. Results are presented for different redshift distributions, including that appropriate for the APM Galaxy Survey, asmore » well as for a survey with a mean redshift of z{approx_equal}1 (such as the VLA FIRST Survey). Qualitatively, many of the results found for s{sub 3} and q are similar to those obtained in a related treatment of the spatial skewness and 3PCF, such as a leading-order correction to the standard result for s{sub 3} in the case of nonlinear bias (as defined for unsmoothed density fields), and the sensitivity of the configuration dependence of q to both cosmological and biasing models. We show that since angular correlation functions (CFs) are sensitive to clustering over a range of redshifts, the various evolutionary dependences included in our predictions imply that measurements of q in a deep survey might better discriminate between models with different histories, such as evolving versus nonevolving bias, that can have similar spatial CFs at low redshift. Our calculations employ a derived equation, valid for open, closed, and flat models, to obtain the angular bispectrum from the spatial bispectrum in the small-angle approximation. (c) (c) 2000. The American Astronomical Society.« less

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 (log(M{sub *}/M{sub sun})) {approx} 9.1 and ({tau}{sub *}) {approx} 0.06 Gyr, respectively; their maximal masses are similarly lower, (log(M{sub *}/M{sub sun})) {approx} 9.6, and as expected do not track the galaxy mass function. Most importantly, the two GRB host populations remain distinct even if we consider only the star-forming hosts of short GRBs, supporting our previous findings (based on star formation rates and metallicities) that the progenitors of long and short GRBs in late-type galaxies are distinct. Given the much younger stellar populations of long GRB hosts (and hence of long GRB progenitors), and the substantial differences in host properties, we caution against the use of Type I and II designations for GRBs since this may erroneously imply that all GRBs which track star formation activity share the same massive star progenitors.« less

Selection effects and binary galaxy velocity differences

NASA Technical Reports Server (NTRS)

Schneider, Stephen E.; Salpeter, Edwin E.

1990-01-01

Measurements of the velocity differences (delta v's) in pairs of galaxies from large statistical samples have often been used to estimate the average masses of binary galaxies. A basic prediction of these models is that the delta v distribution ought to decline monotonically. However, some peculiar aspects of the kinematics have been uncovered, with an anomalous preference for delta v approx. equal to 72 km s(sup-1) appearing to be present in the data. The authors examine a large sample of binary galaxies with accurate redshift measurements and confirm that the distribution of delta v's appears to be non-monotonic with peaks at 0 and approx. 72 km s (exp -1). The authors suggest that the non-zero peak results from the isolation criteria employed in defining samples of binaries and that it indicates there are two populations of binary orbits contributing to the observed delta v distribution.

Deriving photometric redshifts using fuzzy archetypes and self-organizing maps - II. Implementation

NASA Astrophysics Data System (ADS)

Speagle, Joshua S.; Eisenstein, Daniel J.

2017-07-01

With an eye towards the computational requirements of future large-scale surveys such as Euclid and Large Synoptic Survey Telescope (LSST) that will require photometric redshifts (photo-z's) for ≳ 109 objects, we investigate a variety of ways that 'fuzzy archetypes' can be used to improve photometric redshifts and explore their respective statistical interpretations. We characterize their relative performance using an idealized LSST ugrizY and Euclid YJH mock catalogue of 10 000 objects spanning z = 0-6 at Y = 24 mag. We find most schemes are able to robustly identify redshift probability distribution functions that are multimodal and/or poorly constrained. Once these objects are flagged and removed, the results are generally in good agreement with the strict accuracy requirements necessary to meet Euclid weak lensing goals for most redshifts between 0.8 ≲ z ≲ 2. These results demonstrate the statistical robustness and flexibility that can be gained by combining template-fitting and machine-learning methods and provide useful insights into how astronomers can further exploit the colour-redshift relation.

THE SLOAN DIGITAL SKY SURVEY REVERBERATION MAPPING PROJECT: BIASES IN z  > 1.46 REDSHIFTS DUE TO QUASAR DIVERSITY

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

Denney, K. D.; Peterson, B. M.; Horne, Keith

We use the coadded spectra of 32 epochs of Sloan Digital Sky Survey (SDSS) Reverberation Mapping Project observations of 482 quasars with z  > 1.46 to highlight systematic biases in the SDSS- and Baryon Oscillation Spectroscopic Survey (BOSS)-pipeline redshifts due to the natural diversity of quasar properties. We investigate the characteristics of this bias by comparing the BOSS-pipeline redshifts to an estimate from the centroid of He ii λ 1640. He ii has a low equivalent width but is often well-defined in high-S/N spectra, does not suffer from self-absorption, and has a narrow component which, when present (the case for aboutmore » half of our sources), produces a redshift estimate that, on average, is consistent with that determined from [O ii] to within the He ii and [O ii] centroid measurement uncertainties. The large redshift differences of ∼1000 km s{sup −1}, on average, between the BOSS-pipeline and He ii-centroid redshifts, suggest there are significant biases in a portion of BOSS quasar redshift measurements. Adopting the He ii-based redshifts shows that C iv does not exhibit a ubiquitous blueshift for all quasars, given the precision probed by our measurements. Instead, we find a distribution of C iv-centroid blueshifts across our sample, with a dynamic range that (i) is wider than that previously reported for this line, and (ii) spans C iv centroids from those consistent with the systemic redshift to those with significant blueshifts of thousands of kilometers per second. These results have significant implications for measurement and use of high-redshift quasar properties and redshifts, and studies based thereon.« less

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.

Environment of Submillimeter Galaxies

NASA Astrophysics Data System (ADS)

Hou, K.-c.; Chen, L.-w.

2013-10-01

To study the environment of high-redshift star-forming galaxies — submillimeter galaxies (SMGs) — and their role during large-scale structure formation, we have estimated the galaxy number density fluctuations around SMGs, and analyzed their cross correlation functions with Lyman alpha emitters (LAEs), and optical-selected galaxies with photometric redshift in the COSMOS and ECDFS fields. Only a marginal cross-correlation between SMGs and optical-selected galaxies at most redshifts intervals is found in our results, except a relatively strong correlation detected in the cases of AzTEC-detected SMGs with galaxies at z ˜2.6 and 3.6. The density fluctuations around SMGs with redshift estimated show most SMGs located in a high-density region. There is no correlation signal between LAEs and SMGs, and the galaxy density fluctuations indicate a slightly anti-correlation on a scale smaller than 2 Mpc. Furthermore, we also investigate the density fluctuations of passive and starforming galaxies selected by optical and near infrared colors at similar redshift around SMGs. Finally the implication from our results to the interconnection between high-redshift galaxy populations is discussed.

The Complete Calibration of the Color–Redshift Relation (C3R2) Survey: Survey Overview and Data Release 1

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

Masters, Daniel C.; Stern, Daniel K.; Rhodes, Jason D.

A key goal of the Stage IV dark energy experiments Euclid , LSST, and WFIRST is to measure the growth of structure with cosmic time from weak lensing analysis over large regions of the sky. Weak lensing cosmology will be challenging: in addition to highly accurate galaxy shape measurements, statistically robust and accurate photometric redshift (photo- z ) estimates for billions of faint galaxies will be needed in order to reconstruct the three-dimensional matter distribution. Here we present an overview of and initial results from the Complete Calibration of the Color–Redshift Relation (C3R2) survey, which is designed specifically to calibratemore » the empirical galaxy color–redshift relation to the Euclid depth. These redshifts will also be important for the calibrations of LSST and WFIRST . The C3R2 survey is obtaining multiplexed observations with Keck (DEIMOS, LRIS, and MOSFIRE), the Gran Telescopio Canarias (GTC; OSIRIS), and the Very Large Telescope (VLT; FORS2 and KMOS) of a targeted sample of galaxies that are most important for the redshift calibration. We focus spectroscopic efforts on undersampled regions of galaxy color space identified in previous work in order to minimize the number of spectroscopic redshifts needed to map the color–redshift relation to the required accuracy. We present the C3R2 survey strategy and initial results, including the 1283 high-confidence redshifts obtained in the 2016A semester and released as Data Release 1.« less

Cosmological Constraints from the Redshift Dependence of the Volume Effect Using the Galaxy 2-point Correlation Function across the Line of Sight

NASA Astrophysics Data System (ADS)

Li, Xiao-Dong; Park, Changbom; Sabiu, Cristiano G.; Park, Hyunbae; Cheng, Cheng; Kim, Juhan; Hong, Sungwook E.

2017-08-01

We develop a methodology to use the redshift dependence of the galaxy 2-point correlation function (2pCF) across the line of sight, ξ ({r}\\perp ), as a probe of cosmological parameters. The positions of galaxies in comoving Cartesian space varies under different cosmological parameter choices, inducing a redshift-dependent scaling in the galaxy distribution. This geometrical distortion can be observed as a redshift-dependent rescaling in the measured ξ ({r}\\perp ). We test this methodology using a sample of 1.75 billion mock galaxies at redshifts 0, 0.5, 1, 1.5, and 2, drawn from the Horizon Run 4 N-body simulation. The shape of ξ ({r}\\perp ) can exhibit a significant redshift evolution when the galaxy sample is analyzed under a cosmology differing from the true, simulated one. Other contributions, including the gravitational growth of structure, galaxy bias, and the redshift space distortions, do not produce large redshift evolution in the shape. We show that one can make use of this geometrical distortion to constrain the values of cosmological parameters governing the expansion history of the universe. This method could be applicable to future large-scale structure surveys, especially photometric surveys such as DES and LSST, to derive tight cosmological constraints. This work is a continuation of our previous works as a strategy to constrain cosmological parameters using redshift-invariant physical quantities.

The 2-degree Field Lensing Survey: design and clustering measurements

NASA Astrophysics Data System (ADS)

Blake, Chris; Amon, Alexandra; Childress, Michael; Erben, Thomas; Glazebrook, Karl; Harnois-Deraps, Joachim; Heymans, Catherine; Hildebrandt, Hendrik; Hinton, Samuel R.; Janssens, Steven; Johnson, Andrew; Joudaki, Shahab; Klaes, Dominik; Kuijken, Konrad; Lidman, Chris; Marin, Felipe A.; Parkinson, David; Poole, Gregory B.; Wolf, Christian

2016-11-01

We present the 2-degree Field Lensing Survey (2dFLenS), a new galaxy redshift survey performed at the Anglo-Australian Telescope. 2dFLenS is the first wide-area spectroscopic survey specifically targeting the area mapped by deep-imaging gravitational lensing fields, in this case the Kilo-Degree Survey. 2dFLenS obtained 70 079 redshifts in the range z < 0.9 over an area of 731 deg2, and is designed to extend the data sets available for testing gravitational physics and promote the development of relevant algorithms for joint imaging and spectroscopic analysis. The redshift sample consists first of 40 531 Luminous Red Galaxies (LRGs), which enable analyses of galaxy-galaxy lensing, redshift-space distortion, and the overlapping source redshift distribution by cross-correlation. An additional 28 269 redshifts form a magnitude-limited (r < 19.5) nearly complete subsample, allowing direct source classification and photometric-redshift calibration. In this paper, we describe the motivation, target selection, spectroscopic observations, and clustering analysis of 2dFLenS. We use power spectrum multipole measurements to fit the redshift-space distortion parameter of the LRG sample in two redshift ranges 0.15 < z < 0.43 and 0.43 < z < 0.7 as β = 0.49 ± 0.15 and β = 0.26 ± 0.09, respectively. These values are consistent with those obtained from LRGs in the Baryon Oscillation Spectroscopic Survey. 2dFLenS data products will be released via our website http://2dflens.swin.edu.au.

Proto-Clusters with Evolved Populations around Radio Galaxies at 2

NASA Astrophysics Data System (ADS)

Kodama, T.; Tanaka, M.; Tanaka, I.; Kajisawa, M.

2007-12-01

We present an on-going near-infrared survey of proto-clusters around high-z radio-loud galaxies at 2 ≲ z ≲ 3 with a new wide-field instrument MOIRCS on Subaru. Most of these field are known to show a large number of Lyα and/or Hα emitters at the same redshifts of the radio galaxies. We see a clear excess of near-infrared selected galaxies (JHK_s-selected galaxies as well as DRG) in these fields, and they are indeed proto-clusters with not only young emitters but also evolved populations. Spatial distribution of such NIR selected galaxies is filamentary and track similar structures traced by the emitters. There is an hint that the bright-end of the red sequence first appeared between z=3 and 2.

Optical Spectroscopy of Distant Red Galaxies

NASA Astrophysics Data System (ADS)

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

2009-11-01

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

Bulge Growth and Quenching since z = 2.5 in CANDELS/3D-HST

NASA Astrophysics Data System (ADS)

Lang, Philipp; Wuyts, Stijn; Somerville, Rachel S.; Förster Schreiber, Natascha M.; Genzel, Reinhard; Bell, Eric F.; Brammer, Gabe; Dekel, Avishai; Faber, Sandra M.; Ferguson, Henry C.; Grogin, Norman A.; Kocevski, Dale D.; Koekemoer, Anton M.; Lutz, Dieter; McGrath, Elizabeth J.; Momcheva, Ivelina; Nelson, Erica J.; Primack, Joel R.; Rosario, David J.; Skelton, Rosalind E.; Tacconi, Linda J.; van Dokkum, Pieter G.; Whitaker, Katherine E.

2014-06-01

Exploiting the deep high-resolution imaging of all five CANDELS fields, and accurate redshift information provided by 3D-HST, we investigate the relation between structure and stellar populations for a mass-selected sample of 6764 galaxies above 1010 M ⊙, spanning the redshift range 0.5 < z < 2.5. For the first time, we fit two-dimensional models comprising a single Sérsic fit and two-component (i.e., bulge + disk) decompositions not only to the H-band light distributions, but also to the stellar mass maps reconstructed from resolved stellar population modeling. We confirm that the increased bulge prominence among quiescent galaxies, as reported previously based on rest-optical observations, remains in place when considering the distributions of stellar mass. Moreover, we observe an increase of the typical Sérsic index and bulge-to-total ratio (with median B/T reaching 40%-50%) among star-forming galaxies above 1011 M ⊙. Given that quenching for these most massive systems is likely to be imminent, our findings suggest that significant bulge growth precedes a departure from the star-forming main sequence. We demonstrate that the bulge mass (and ideally knowledge of the bulge and total mass) is a more reliable predictor of the star-forming versus quiescent state of a galaxy than the total stellar mass. The same trends are predicted by the state-of-the-art, semi-analytic model by Somerville et al. In this model, bulges and black holes grow hand in hand through merging and/or disk instabilities, and feedback from active galactic nuclei shuts off star formation. Further observations will be required to pin down star formation quenching mechanisms, but our results imply that they must be internal to the galaxies and closely associated with bulge growth.

Galaxy gas as obscurer - I. GRBs x-ray galaxies and find an NH3∝ M_{star} relation

NASA Astrophysics Data System (ADS)

Buchner, Johannes; Schulze, Steve; Bauer, Franz E.

2017-02-01

An important constraint for galaxy evolution models is how much gas resides in galaxies, in particular, at the peak of star formation z = 1-3. We attempt a novel approach by letting long-duration gamma ray bursts (LGRBs) x-ray their host galaxies and deliver column densities to us. This requires a good understanding of the obscurer and biases introduced by incomplete follow-up observations. We analyse the X-ray afterglow of all 844 Swift LGRBs to date for their column density NH. To derive the population properties, we propagate all uncertainties in a consistent Bayesian methodology. The NH distribution covers the 1020-23 cm-2 range and shows no evolutionary effect. Higher obscurations, e.g. Compton-thick columns, could have been detected but are not observed. The NH distribution is consistent with sources randomly populating a ellipsoidal gas cloud of major axis {N^{major}H }=10^{23}cm^{-2} with 0.22 dex intrinsic scatter between objects. The unbiased SHOALS survey of afterglows and hosts allows us to constrain the relation between Spitzer-derived stellar masses and X-ray derived column densities NH. We find a well-constrained power-law relation of NH = 1021.7 cm-2 × (M⋆/109.5 M⊙)1/3, with 0.5 dex intrinsic scatter between objects. The Milky Way and the Magellanic clouds also follow this relation. From the geometry of the obscurer, its stellar mass dependence and comparison with local galaxies, we conclude that LGRBs are primarily obscured by galaxy-scale gas. Ray tracing of simulated Illustris galaxies reveals a relation of the same normalization, but a steeper stellar-mass dependence and mild redshift evolution. Our new approach provides valuable insight into the gas residing in high-redshift galaxies.

RCSED—A Value-added Reference Catalog of Spectral Energy Distributions of 800,299 Galaxies in 11 Ultraviolet, Optical, and Near-infrared Bands: Morphologies, Colors, Ionized Gas, and Stellar Population Properties

NASA Astrophysics Data System (ADS)

Chilingarian, Igor V.; Zolotukhin, Ivan Yu.; Katkov, Ivan Yu.; Melchior, Anne-Laure; Rubtsov, Evgeniy V.; Grishin, Kirill A.

2017-02-01

We present RCSED, the value-added Reference Catalog of Spectral Energy Distributions of galaxies, which contains homogenized spectrophotometric data for 800,299 low- and intermediate-redshift galaxies (0.007< z< 0.6) selected from the Sloan Digital Sky Survey spectroscopic sample. Accessible from the Virtual Observatory (VO) and complemented with detailed information on galaxy properties obtained with state-of-the-art data analysis, RCSED enables direct studies of galaxy formation and evolution over the last 5 Gyr. We provide tabulated color transformations for galaxies of different morphologies and luminosities, and analytic expressions for the red sequence shape in different colors. RCSED comprises integrated k-corrected photometry in up to 11 ultraviolet, optical, and near-infrared bands published by the GALEX, SDSS, and UKIDSS wide-field imaging surveys; results of the stellar population fitting of SDSS spectra including best-fitting templates, velocity dispersions, parameterized star formation histories, and stellar metallicities computed for instantaneous starburst and exponentially declining star formation models; parametric and non-parametric emission line fluxes and profiles; and gas phase metallicities. We link RCSED to the Galaxy Zoo morphological classification and galaxy bulge+disk decomposition results of Simard et al. We construct the color-magnitude, Faber-Jackson, and mass-metallicity relations; compare them with the literature; and discuss systematic errors of the galaxy properties presented in our catalog. RCSED is accessible from the project web site and via VO simple spectrum access and table access services using VO-compliant applications. We describe several examples of SQL queries to the database. Finally, we briefly discuss existing and future scientific applications of RCSED and prospective catalog extensions to higher redshifts and different wavelengths. .

correlcalc: Two-point correlation function from redshift surveys

NASA Astrophysics Data System (ADS)

Rohin, Yeluripati

2017-11-01

correlcalc calculates two-point correlation function (2pCF) of galaxies/quasars using redshift surveys. It can be used for any assumed geometry or Cosmology model. Using BallTree algorithms to reduce the computational effort for large datasets, it is a parallelised code suitable for running on clusters as well as personal computers. It takes redshift (z), Right Ascension (RA) and Declination (DEC) data of galaxies and random catalogs as inputs in form of ascii or fits files. If random catalog is not provided, it generates one of desired size based on the input redshift distribution and mangle polygon file (in .ply format) describing the survey geometry. It also calculates different realisations of (3D) anisotropic 2pCF. Optionally it makes healpix maps of the survey providing visualization.

Deep 1.1 mm-wavelength imaging of the GOODS-S field by AzTEC/ASTE - II. Redshift distribution and nature of the submillimetre galaxy population

NASA Astrophysics Data System (ADS)

Yun, Min S.; Scott, K. S.; Guo, Yicheng; Aretxaga, I.; Giavalisco, M.; Austermann, J. E.; Capak, P.; Chen, Yuxi; Ezawa, H.; Hatsukade, B.; Hughes, D. H.; Iono, D.; Johnson, S.; Kawabe, R.; Kohno, K.; Lowenthal, J.; Miller, N.; Morrison, G.; Oshima, T.; Perera, T. A.; Salvato, M.; Silverman, J.; Tamura, Y.; Williams, C. C.; Wilson, G. W.

2012-02-01

We report the results of the counterpart identification and a detailed analysis of the physical properties of the 48 sources discovered in our deep 1.1-mm wavelength imaging survey of the Great Observatories Origins Deep Survey-South (GOODS-S) field using the AzTEC instrument on the Atacama Submillimeter Telescope Experiment. One or more robust or tentative counterpart candidate is found for 27 and 14 AzTEC sources, respectively, by employing deep radio continuum, Spitzer/Multiband Imaging Photometer for Spitzer and Infrared Array Camera, and Large APEX Bolometer Camera 870 μm data. Five of the sources (10 per cent) have two robust counterparts each, supporting the idea that these galaxies are strongly clustered and/or heavily confused. Photometric redshifts and star formation rates (SFRs) are derived by analysing ultraviolet(UV)-to-optical and infrared(IR)-to-radio spectral energy distributions (SEDs). The median redshift of zmed˜ 2.6 is similar to other earlier estimates, but we show that 80 per cent of the AzTEC-GOODS sources are at z≥ 2, with a significant high-redshift tail (20 per cent at z≥ 3.3). Rest-frame UV and optical properties of AzTEC sources are extremely diverse, spanning 10 mag in the i- and K-band photometry (a factor of 104 in flux density) with median values of i= 25.3 and K= 22.6 and a broad range of red colour (i-K= 0-6) with an average value of i-K≈ 3. These AzTEC sources are some of the most luminous galaxies in the rest-frame optical bands at z≥ 2, with inferred stellar masses M*= (1-30) × 1010 M⊙ and UV-derived SFRs of SFRUV≳ 101-3 M⊙ yr-1. The IR-derived SFR, 200-2000 M⊙ yr-1, is independent of z or M*. The resulting specific star formation rates, SSFR ≈ 1-100 Gyr-1, are 10-100 times higher than similar mass galaxies at z= 0, and they extend the previously observed rapid rise in the SSFR with redshift to z= 2-5. These galaxies have a SFR high enough to have built up their entire stellar mass within their Hubble time. We find only marginal evidence for an active galactic nucleus (AGN) contribution to the near-IR and mid-IR SEDs, even among the X-ray detected sources, and the derived M* and SFR show little dependence on the presence of an X-ray bright AGN.

Designing a space-based galaxy redshift survey to probe dark energy

NASA Astrophysics Data System (ADS)

Wang, Yun; Percival, Will; Cimatti, Andrea; Mukherjee, Pia; Guzzo, Luigi; Baugh, Carlton M.; Carbone, Carmelita; Franzetti, Paolo; Garilli, Bianca; Geach, James E.; Lacey, Cedric G.; Majerotto, Elisabetta; Orsi, Alvaro; Rosati, Piero; Samushia, Lado; Zamorani, Giovanni

2010-12-01

A space-based galaxy redshift survey would have enormous power in constraining dark energy and testing general relativity, provided that its parameters are suitably optimized. We study viable space-based galaxy redshift surveys, exploring the dependence of the Dark Energy Task Force (DETF) figure-of-merit (FoM) on redshift accuracy, redshift range, survey area, target selection and forecast method. Fitting formulae are provided for convenience. We also consider the dependence on the information used: the full galaxy power spectrum P(k), P(k) marginalized over its shape, or just the Baryon Acoustic Oscillations (BAO). We find that the inclusion of growth rate information (extracted using redshift space distortion and galaxy clustering amplitude measurements) leads to a factor of ~3 improvement in the FoM, assuming general relativity is not modified. This inclusion partially compensates for the loss of information when only the BAO are used to give geometrical constraints, rather than using the full P(k) as a standard ruler. We find that a space-based galaxy redshift survey covering ~20000deg2 over with σz/(1 + z) <= 0.001 exploits a redshift range that is only easily accessible from space, extends to sufficiently low redshifts to allow both a vast 3D map of the universe using a single tracer population, and overlaps with ground-based surveys to enable robust modelling of systematic effects. We argue that these parameters are close to their optimal values given current instrumental and practical constraints.

Velocity anti-correlation of diametrically opposed galaxy satellites in the low-redshift Universe.

PubMed

Ibata, Neil G; Ibata, Rodrigo A; Famaey, Benoit; Lewis, Geraint F

2014-07-31

Recent work has shown that the Milky Way and the Andromeda galaxies both possess the unexpected property that their dwarf satellite galaxies are aligned in thin and kinematically coherent planar structures. It is interesting to evaluate the incidence of such planar structures in the larger galactic population, because the Local Group may not be a representative environment. Here we report measurements of the velocities of pairs of diametrically opposed satellite galaxies. In the local Universe (redshift z < 0.05), we find that satellite pairs out to a distance of 150 kiloparsecs from the galactic centre are preferentially anti-correlated in their velocities (99.994 per cent confidence level), and that the distribution of galaxies in the larger-scale environment (out to distances of about 2 megaparsecs) is strongly clumped along the axis joining the inner satellite pair (>7σ confidence). This may indicate that planes of co-rotating satellites, similar to those seen around the Andromeda galaxy, are ubiquitous, and their coherent motion suggests that they represent a substantial repository of angular momentum on scales of about 100 kiloparsecs.

Physical Properties of Massive, Star-Forming Galaxies When the Universe Was Only Two Billion Years Old

NASA Astrophysics Data System (ADS)

Fu, Nicole Christina

Due to the finite speed of light and a vast, expanding universe, telescopes are just now receiving the light emitted by galaxies as they were forming in the very early universe. The light from these galaxies has been redshifted (stretched to longer, redder wavelengths) as a result of its journey through expanding space. Using sophisticated techniques and exceptional multi-wavelength optical and infrared data, we isolate a population of 378 galaxies in the process of formation when the Universe was only two billion years old. By matching the distinctive properties of the light spectra of these galaxies to models, the redshift, age, dust content, star formation rate and total stellar mass of each galaxy are determined. Comparing our results to similar surveys of galaxy populations at other redshifts, a picture emerges of the growth and evolution of massive, star-forming galaxies over the course of billions of years.

Galaxy power spectrum in redshift space: Combining perturbation theory with the halo model

NASA Astrophysics Data System (ADS)

Okumura, Teppei; Hand, Nick; Seljak, Uroš; Vlah, Zvonimir; Desjacques, Vincent

2015-11-01

Theoretical modeling of the redshift-space power spectrum of galaxies is crucially important to correctly extract cosmological information from galaxy redshift surveys. The task is complicated by the nonlinear biasing and redshift space distortion (RSD) effects, which change with halo mass, and by the wide distribution of halo masses and their occupations by galaxies. One of the main modeling challenges is the existence of satellite galaxies that have both radial distribution inside the halos and large virial velocities inside halos, a phenomenon known as the Finger-of-God (FoG) effect. We present a model for the redshift-space power spectrum of galaxies in which we decompose a given galaxy sample into central and satellite galaxies and relate different contributions to the power spectrum to 1-halo and 2-halo terms in a halo model. Our primary goal is to ensure that any parameters that we introduce have physically meaningful values, and are not just fitting parameters. For the lowest order 2-halo terms we use the previously developed RSD modeling of halos in the context of distribution function and perturbation theory approach. This term needs to be multiplied by the effect of radial distances and velocities of satellites inside the halo. To this one needs to add the 1-halo terms, which are nonperturbative. We show that the real space 1-halo terms can be modeled as almost constant, with the finite extent of the satellites inside the halo inducing a small k2R2 term over the range of scales of interest, where R is related to the size of the halo given by its halo mass. We adopt a similar model for FoG in redshift space, ensuring that FoG velocity dispersion is related to the halo mass. For FoG k2 type expansions do not work over the range of scales of interest and FoG resummation must be used instead. We test several simple damping functions to model the velocity dispersion FoG effect. Applying the formalism to mock galaxies modeled after the "CMASS" sample of the BOSS survey, we find that our predictions for the redshift-space power spectra are accurate up to k ≃0.4 h Mpc-1 within 1% if the halo power spectrum is measured using N -body simulations and within 3% if it is modeled using perturbation theory.

On the recovery of the local group motion from galaxy redshift surveys

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

Nusser, Adi; Davis, Marc; Branchini, Enzo, E-mail: adi@physics.technion.ac.il, E-mail: mdavis@berkeley.edu, E-mail: branchin@fis.uniroma3.it

2014-06-20

There is an ∼150 km s{sup –1} discrepancy between the measured motion of the Local Group (LG) of galaxies with respect to the cosmic microwave background and the linear theory prediction based on the gravitational force field of the large-scale structure in full-sky redshift surveys. We perform a variety of tests which show that the LG motion cannot be recovered to better than 150-200 km s{sup –1} in amplitude and within ≈10° in direction. The tests rely on catalogs of mock galaxies identified in the Millennium simulation using semi-analytic galaxy formation models. We compare these results to the K{sub s}more » = 11.75 Two-Mass Galaxy Redshift Survey, which provides the deepest and most complete all-sky spatial distribution of galaxies with spectroscopic redshifts available thus far. In our analysis, we use a new concise relation for deriving the LG motion and bulk flow from the true distribution of galaxies in redshift space. Our results show that the main source of uncertainty is the small effective depth of surveys like the Two-Mass Redshift Survey (2MRS), which prevents a proper sampling of the large-scale structure beyond ∼100 h {sup –1} Mpc. Deeper redshift surveys are needed to reach the 'convergence scale' of ≈250 h {sup –1} Mpc in a ΛCDM universe. Deeper surveys would also mitigate the impact of the 'Kaiser rocket' which, in a survey like 2MRS, remains a significant source of uncertainty. Thanks to the quiet and moderate density environment of the LG, purely dynamical uncertainties of the linear predictions are subdominant at the level of ∼90 km s{sup –1}. Finally, we show that deviations from linear galaxy biasing and shot noise errors provide a minor contribution to the total error budget.« less

The AzTEC/SMA Interferometric Imaging Survey of Submillimeter-selected High-redshift Galaxies

NASA Astrophysics Data System (ADS)

Younger, Joshua D.; Fazio, Giovanni G.; Huang, Jia-Sheng; Yun, Min S.; Wilson, Grant W.; Ashby, Matthew L. N.; Gurwell, Mark A.; Peck, Alison B.; Petitpas, Glen R.; Wilner, David J.; Hughes, David H.; Aretxaga, Itziar; Kim, Sungeun; Scott, Kimberly S.; Austermann, Jason; Perera, Thushara; Lowenthal, James D.

2009-10-01

We present results from a continuing interferometric survey of high-redshift submillimeter galaxies (SMGs) with the Submillimeter Array, including high-resolution (beam size ~2 arcsec) imaging of eight additional AzTEC 1.1 mm selected sources in the COSMOS field, for which we obtain six reliable (peak signal-to-noise ratio (S/N) >5 or peak S/N >4 with multiwavelength counterparts within the beam) and two moderate significance (peak S/N >4) detections. When combined with previous detections, this yields an unbiased sample of millimeter-selected SMGs with complete interferometric follow up. With this sample in hand, we (1) empirically confirm the radio-submillimeter association, (2) examine the submillimeter morphology—including the nature of SMGs with multiple radio counterparts and constraints on the physical scale of the far infrared—of the sample, and (3) find additional evidence for a population of extremely luminous, radio-dim SMGs that peaks at higher redshift than previous, radio-selected samples. In particular, the presence of such a population of high-redshift sources has important consequences for models of galaxy formation—which struggle to account for such objects even under liberal assumptions—and dust production models given the limited time since the big bang.

Globular clusters in high-redshift dwarf galaxies: a case study from the Local Group

NASA Astrophysics Data System (ADS)

Zick, Tom O.; Weisz, Daniel R.; Boylan-Kolchin, Michael

2018-06-01

We present the reconstructed evolution of rest-frame ultraviolet (UV) luminosities of the most massive Milky Way dwarf spheroidal satellite galaxy, Fornax, and its five globular clusters (GCs) across redshift, based on analysis of the stellar fossil record and stellar population synthesis modelling. We find that (1) Fornax's (proto-)GCs can generate 10-100 times more UV flux than the field population, despite comprising <˜{5} per cent of the stellar mass at the relevant redshifts; (2) due to their respective surface brightnesses, it is more likely that faint, compact sources in the Hubble Frontier Fields (HFFs) are GCs hosted by faint galaxies, than faint galaxies themselves. This may significantly complicate the construction of a galaxy UV luminosity function at z > 3. (3) GC formation can introduce order-of-magnitude errors in abundance matching. We also find that some compact HFF objects are consistent with the reconstructed properties of Fornax's GCs at the same redshifts (e.g. surface brightness, star formation rate), suggesting we may have already detected proto-GCs in the early Universe. Finally, we discuss the prospects for improving the connections between local GCs and proto-GCs detected in the early Universe.

Cooperative photometric redshift estimation

NASA Astrophysics Data System (ADS)

Cavuoti, S.; Tortora, C.; Brescia, M.; Longo, G.; Radovich, M.; Napolitano, N. R.; Amaro, V.; Vellucci, C.

2017-06-01

In the modern galaxy surveys photometric redshifts play a central role in a broad range of studies, from gravitational lensing and dark matter distribution to galaxy evolution. Using a dataset of ~ 25,000 galaxies from the second data release of the Kilo Degree Survey (KiDS) we obtain photometric redshifts with five different methods: (i) Random forest, (ii) Multi Layer Perceptron with Quasi Newton Algorithm, (iii) Multi Layer Perceptron with an optimization network based on the Levenberg-Marquardt learning rule, (iv) the Bayesian Photometric Redshift model (or BPZ) and (v) a classical SED template fitting procedure (Le Phare). We show how SED fitting techniques could provide useful information on the galaxy spectral type which can be used to improve the capability of machine learning methods constraining systematic errors and reduce the occurrence of catastrophic outliers. We use such classification to train specialized regression estimators, by demonstrating that such hybrid approach, involving SED fitting and machine learning in a single collaborative framework, is capable to improve the overall prediction accuracy of photometric redshifts.

The ASTRODEEP Frontier Fields catalogues. II. Photometric redshifts and rest frame properties in Abell-2744 and MACS-J0416

NASA Astrophysics Data System (ADS)

Castellano, M.; Amorín, R.; Merlin, E.; Fontana, A.; McLure, R. J.; Mármol-Queraltó, E.; Mortlock, A.; Parsa, S.; Dunlop, J. S.; Elbaz, D.; Balestra, I.; Boucaud, A.; Bourne, N.; Boutsia, K.; Brammer, G.; Bruce, V. A.; Buitrago, F.; Capak, P.; Cappelluti, N.; Ciesla, L.; Comastri, A.; Cullen, F.; Derriere, S.; Faber, S. M.; Giallongo, E.; Grazian, A.; Grillo, C.; Mercurio, A.; Michałowski, M. J.; Nonino, M.; Paris, D.; Pentericci, L.; Pilo, S.; Rosati, P.; Santini, P.; Schreiber, C.; Shu, X.; Wang, T.

2016-05-01

Aims: We present the first public release of photometric redshifts, galaxy rest frame properties and associated magnification values in the cluster and parallel pointings of the first two Frontier Fields, Abell-2744 and MACS-J0416. The released catalogues aim to provide a reference for future investigations of extragalactic populations in these legacy fields: from lensed high-redshift galaxies to cluster members themselves. Methods: We exploit a multiwavelength catalogue, ranging from Hubble Space Telescope (HST) to ground-based K and Spitzer IRAC, which is specifically designed to enable detection and measurement of accurate fluxes in crowded cluster regions. The multiband information is used to derive photometric redshifts and physical properties of sources detected either in the H-band image alone, or from a stack of four WFC3 bands. To minimize systematics, median photometric redshifts are assembled from six different approaches to photo-z estimates. Their reliability is assessed through a comparison with available spectroscopic samples. State-of-the-art lensing models are used to derive magnification values on an object-by-object basis by taking into account sources positions and redshifts. Results: We show that photometric redshifts reach a remarkable ~3-5% accuracy. After accounting for magnification, the H-band number counts are found to be in agreement at bright magnitudes with number counts from the CANDELS fields, while extending the presently available samples to galaxies that, intrinsically, are as faint as H ~ 32-33, thanks to strong gravitational lensing. The Frontier Fields allow the galaxy stellar mass distribution to be probed, depending on magnification, at 0.5-1.5 dex lower masses with respect to extragalactic wide fields, including sources at Mstar ~ 107-108 M⊙ at z > 5. Similarly, they allow the detection of objects with intrinsic star formation rates (SFRs) >1 dex lower than in the CANDELS fields reaching 0.1-1 M⊙/yr at z ~ 6-10. The catalogues, together with the final processed images for all HST bands (as well as some diagnostic data and images), are publicly available and can be downloaded from the Astrodeep website at http://www.astrodeep.eu/frontier-fields/ and from a dedicated CDS webpage (http://astrodeep.u-strasbg.fr/ff/index.html). The catalogues are also available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/590/A31

Characterizing the evolution of WISE-selected obscured and unobscured quasars using HOD models.

NASA Astrophysics Data System (ADS)

Myers, Adam D.; DiPompeo, Michael A.; Mitra, Kaustav; Hickox, Ryan C.; Chatterjee, Suchetana; Whalen, Kelly

2018-06-01

Large-area imaging surveys in the infrared are now beginning to unlock the links between the activity of supermassive black holes and the cosmic evolution of dark matter halos during the significant times when black hole growth is enshrouded in dust. With data from the Wide-Field Infrared Survey Explorer (WISE) and complementary optical photometry, we construct samples of nearly half-a-million obscured and unobscured quasars around redshift 1. We study the dark matter halos of these populations using both angular autocorrelation functions and CMB lensing cross-correlations, carefully characterizing the redshift distribution of the obscured quasar sample using cross-correlations. Independent of our measurement technique, we find that obscured quasars occupy dark matter halos a few times more massive than their unobscured counterparts, despite being matched in luminosity at 12 and 22 microns. Modeling the two-point correlation function using a four-parameter Halo Occupation Distribution (HOD) formalism, we determine that purely optically selected quasars reside in dark matter halos that are about half the mass of WISE-selected obscured quasars, and that satellite fractions are somewhat larger for obscured quasars. We investigate scenarios such as merger-driven fueling and Eddington-dependent obscuration to explore what combinations of physical effects can reproduce our observed halo mass measurements. This work was, in part, supported by NASA ADAP award NNX16AN48G.

Star-forming galaxies in intermediate-redshift clusters: stellar versus dynamical masses of luminous compact blue galaxies

NASA Astrophysics Data System (ADS)

Randriamampandry, S. M.; Crawford, S. M.; Bershady, M. A.; Wirth, G. D.; Cress, C. M.

2017-10-01

We investigate the stellar masses of the class of star-forming objects known as luminous compact blue galaxies (LCBGs) by studying a sample of galaxies in the distant cluster MS 0451.6-0305 at z ≈ 0.54 with ground-based multicolour imaging and spectroscopy. For a sample of 16 spectroscopically confirmed cluster LCBGs (colour B - V < 0.5, surface brightness μB < 21 mag arcsec-2 and magnitude MB < -18.5), we measure stellar masses by fitting spectral energy distribution (SED) models to multiband photometry, and compare with dynamical masses [determined from velocity dispersion in the range 10 < σv(km s- 1) < 80] we previously obtained from their emission-line spectra. We compare two different stellar population models that measure stellar mass in star-bursting galaxies, indicating correlations between the stellar age, extinction and stellar mass derived from the two different SED models. The stellar masses of cluster LCBGs are distributed similarly to those of field LCBGs, but the cluster LCBGs show lower dynamical-to-stellar mass ratios (Mdyn/M⋆ = 2.6) than their field LCBG counterparts (Mdyn/M⋆ = 4.8), echoing trends noted previously in low-redshift dwarf elliptical galaxies. Within this limited sample, the specific star formation rate declines steeply with increasing mass, suggesting that these cluster LCBGs have undergone vigorous star formation.

KiDS-450: cosmological parameter constraints from tomographic weak gravitational lensing

NASA Astrophysics Data System (ADS)

Hildebrandt, H.; Viola, M.; Heymans, C.; Joudaki, S.; Kuijken, K.; Blake, C.; Erben, T.; Joachimi, B.; Klaes, D.; Miller, L.; Morrison, C. B.; Nakajima, R.; Verdoes Kleijn, G.; Amon, A.; Choi, A.; Covone, G.; de Jong, J. T. A.; Dvornik, A.; Fenech Conti, I.; Grado, A.; Harnois-Déraps, J.; Herbonnet, R.; Hoekstra, H.; Köhlinger, F.; McFarland, J.; Mead, A.; Merten, J.; Napolitano, N.; Peacock, J. A.; Radovich, M.; Schneider, P.; Simon, P.; Valentijn, E. A.; van den Busch, J. L.; van Uitert, E.; Van Waerbeke, L.

2017-02-01

We present cosmological parameter constraints from a tomographic weak gravitational lensing analysis of ˜450 deg2 of imaging data from the Kilo Degree Survey (KiDS). For a flat Λ cold dark matter (ΛCDM) cosmology with a prior on H0 that encompasses the most recent direct measurements, we find S_8≡ σ _8√{Ω _m/0.3}=0.745± 0.039. This result is in good agreement with other low-redshift probes of large-scale structure, including recent cosmic shear results, along with pre-Planck cosmic microwave background constraints. A 2.3σ tension in S8 and `substantial discordance' in the full parameter space is found with respect to the Planck 2015 results. We use shear measurements for nearly 15 million galaxies, determined with a new improved `self-calibrating' version of lensFIT validated using an extensive suite of image simulations. Four-band ugri photometric redshifts are calibrated directly with deep spectroscopic surveys. The redshift calibration is confirmed using two independent techniques based on angular cross-correlations and the properties of the photometric redshift probability distributions. Our covariance matrix is determined using an analytical approach, verified numerically with large mock galaxy catalogues. We account for uncertainties in the modelling of intrinsic galaxy alignments and the impact of baryon feedback on the shape of the non-linear matter power spectrum, in addition to the small residual uncertainties in the shear and redshift calibration. The cosmology analysis was performed blind. Our high-level data products, including shear correlation functions, covariance matrices, redshift distributions, and Monte Carlo Markov chains are available at http://kids.strw.leidenuniv.nl.

A multicomponent matched filter cluster confirmation tool for eROSITA: initial application to the RASS and DES-SV data sets

NASA Astrophysics Data System (ADS)

Klein, M.; Mohr, J. J.; Desai, S.; Israel, H.; Allam, S.; Benoit-Lévy, A.; Brooks, D.; Buckley-Geer, E.; Carnero Rosell, A.; Carrasco Kind, M.; Cunha, C. E.; da Costa, L. N.; Dietrich, J. P.; Eifler, T. F.; Evrard, A. E.; Frieman, J.; Gruen, D.; Gruendl, R. A.; Gutierrez, G.; Honscheid, K.; James, D. J.; Kuehn, K.; Lima, M.; Maia, M. A. G.; March, M.; Melchior, P.; Menanteau, F.; Miquel, R.; Plazas, A. A.; Reil, K.; Romer, A. K.; Sanchez, E.; Santiago, B.; Scarpine, V.; Schubnell, M.; Sevilla-Noarbe, I.; Smith, M.; Soares-Santos, M.; Sobreira, F.; Suchyta, E.; Swanson, M. E. C.; Tarle, G.; Collaboration, the DES

2018-03-01

We describe a multicomponent matched filter (MCMF) cluster confirmation tool designed for the study of large X-ray source catalogues produced by the upcoming X-ray all-sky survey mission eROSITA. We apply the method to confirm a sample of 88 clusters with redshifts 0.05 < z < 0.8 in the recently published 2RXS catalogue from the ROSAT All-Sky Survey (RASS) over the 208 deg2 region overlapped by the Dark Energy Survey (DES) Science Verification (DES-SV) data set. In our pilot study, we examine all X-ray sources, regardless of their extent. Our method employs a multicolour red sequence (RS) algorithm that incorporates the X-ray count rate and peak position in determining the region of interest for follow-up and extracts the positionally and colour-weighted optical richness λMCMF as a function of redshift for each source. Peaks in the λMCMF-redshift distribution are identified and used to extract photometric redshifts, richness and uncertainties. The significances of all optical counterparts are characterized using the distribution of richnesses defined along random lines of sight. These significances are used to extract cluster catalogues and to estimate the contamination by random superpositions of unassociated optical systems. The delivered photometric redshift accuracy is δz/(1 + z) = 0.010. We find a well-defined X-ray luminosity-λMCMF relation with an intrinsic scatter of δln (λMCMF|Lx) = 0.21. Matching our catalogue with the DES-SV redMaPPer catalogue yields good agreement in redshift and richness estimates; comparing our catalogue with the South Pole Telescope (SPT) selected clusters shows no inconsistencies. SPT clusters in our data set are consistent with the high-mass extension of the RASS-based λMCMF-mass relation.

Quasar Photometric Redshifts and Candidate Selection: A New Algorithm Based on Optical and Mid-infrared Photometric Data

NASA Astrophysics Data System (ADS)

Yang, Qian; Wu, Xue-Bing; Fan, Xiaohui; Jiang, Linhua; McGreer, Ian; Green, Richard; Yang, Jinyi; Schindler, Jan-Torge; Wang, Feige; Zuo, Wenwen; Fu, Yuming

2017-12-01

We present a new algorithm to estimate quasar photometric redshifts (photo-zs), by considering the asymmetries in the relative flux distributions of quasars. The relative flux models are built with multivariate Skew-t distributions in the multidimensional space of relative fluxes as a function of redshift and magnitude. For 151,392 quasars in the SDSS, we achieve a photo-z accuracy, defined as the fraction of quasars with the difference between the photo-z z p and the spectroscopic redshift z s , | {{Δ }}z| =| {z}s-{z}p| /(1+{z}s) within 0.1, of 74%. Combining the WISE W1 and W2 infrared data with the SDSS data, the photo-z accuracy is enhanced to 87%. Using the Pan-STARRS1 or DECaLS photometry with WISE W1 and W2 data, the photo-z accuracies are 79% and 72%, respectively. The prior probabilities as a function of magnitude for quasars, stars, and galaxies are calculated, respectively, based on (1) the quasar luminosity function, (2) the Milky Way synthetic simulation with the Besançon model, and (3) the Bayesian Galaxy Photometric Redshift estimation. The relative fluxes of stars are obtained with the Padova isochrones, and the relative fluxes of galaxies are modeled through galaxy templates. We test our classification method to select quasars using the DECaLS g, r, z, and WISE W1 and W2 photometry. The quasar selection completeness is higher than 70% for a wide redshift range 0.5< z< 4.5, and a wide magnitude range 18< r< 21.5 mag. Our photo-z regression and classification method has the potential to extend to future surveys. The photo-z code will be publicly available.

EVOLUTION OF GALAXIES AND THEIR ENVIRONMENTS AT z = 0.1-3 IN COSMOS

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

Scoville, N.; Benson, A.; Fu, Hai

2013-05-01

Large-scale structures (LSSs) out to z < 3.0 are measured in the Cosmic Evolution Survey (COSMOS) using extremely accurate photometric redshifts (photoz). The K{sub s} -band-selected sample (from Ultra-Vista) is comprised of 155,954 galaxies. Two techniques-adaptive smoothing and Voronoi tessellation-are used to estimate the environmental densities within 127 redshift slices. Approximately 250 statistically significant overdense structures are identified out to z = 3.0 with shapes varying from elongated filamentary structures to more circularly symmetric concentrations. We also compare the densities derived for COSMOS with those based on semi-analytic predictions for a {Lambda}CDM simulation and find excellent overall agreement between themore » mean densities as a function of redshift and the range of densities. The galaxy properties (stellar mass, spectral energy distributions (SEDs), and star formation rates (SFRs)) are strongly correlated with environmental density and redshift, particularly at z < 1.0-1.2. Classifying the spectral type of each galaxy using the rest-frame b - i color (from the photoz SED fitting), we find a strong correlation of early-type galaxies (E-Sa) with high-density environments, while the degree of environmental segregation varies systematically with redshift out to z {approx} 1.3. In the highest density regions, 80% of the galaxies are early types at z = 0.2 compared to only 20% at z = 1.5. The SFRs and the star formation timescales exhibit clear environmental correlations. At z > 0.8, the SFR density is uniformly distributed over all environmental density percentiles, while at lower redshifts the dominant contribution is shifted to galaxies in lower density environments.« less

Galaxy and mass assembly (GAMA): the consistency of GAMA and WISE derived mass-to-light ratios

NASA Astrophysics Data System (ADS)

Kettlety, T.; Hesling, J.; Phillipps, S.; Bremer, M. N.; Cluver, M. E.; Taylor, E. N.; Bland-Hawthorn, J.; Brough, S.; De Propris, R.; Driver, S. P.; Holwerda, B. W.; Kelvin, L. S.; Sutherland, W.; Wright, A. H.

2018-01-01

Recent work has suggested that mid-IR wavelengths are optimal for estimating the mass-to-light ratios of stellar populations and hence the stellar masses of galaxies. We compare stellar masses deduced from spectral energy distribution (SED) models, fitted to multiwavelength optical-NIR photometry, to luminosities derived from WISE photometry in the W1 and W2 bands at 3.6 and 4.5 μm for non-star forming galaxies. The SED-derived masses for a carefully selected sample of low-redshift (z ≤ 0.15) passive galaxies agree with the prediction from stellar population synthesis models such that M*/LW1 ≃ 0.6 for all such galaxies, independent of other stellar population parameters. The small scatter between masses predicted from the optical SED and from the WISE measurements implies that random errors (as opposed to systematic ones such as the use of different initial mass functions) are smaller than previous, deliberately conservative, estimates for the SED fits. This test is subtly different from simultaneously fitting at a wide range of optical and mid-IR wavelengths, which may just generate a compromised fit: we are directly checking that the best-fitting model to the optical data generates an SED whose M*/LW1 is also consistent with separate mid-IR data. We confirm that for passive low-redshift galaxies a fixed M*/LW1 = 0.65 can generate masses at least as accurate as those obtained from more complex methods. Going beyond the mean value, in agreement with expectations from the models, we see a modest change in M*/LW1 with SED fitted stellar population age but an insignificant one with metallicity.

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

NASA Astrophysics Data System (ADS)

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

2014-12-01

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

The FourStar Galaxy Evolution Survey (ZFOURGE): Ultraviolet to Far-infrared Catalogs, Medium-bandwidth Photometric Redshifts with Improved Accuracy, Stellar Masses, and Confirmation of Quiescent Galaxies to z ˜ 3.5

NASA Astrophysics Data System (ADS)

Straatman, Caroline M. S.; Spitler, Lee R.; Quadri, Ryan F.; Labbé, Ivo; Glazebrook, Karl; Persson, S. Eric; Papovich, Casey; Tran, Kim-Vy H.; Brammer, Gabriel B.; Cowley, Michael; Tomczak, Adam; Nanayakkara, Themiya; Alcorn, Leo; Allen, Rebecca; Broussard, Adam; van Dokkum, Pieter; Forrest, Ben; van Houdt, Josha; Kacprzak, Glenn G.; Kawinwanichakij, Lalitwadee; Kelson, Daniel D.; Lee, Janice; McCarthy, Patrick J.; Mehrtens, Nicola; Monson, Andrew; Murphy, David; Rees, Glen; Tilvi, Vithal; Whitaker, Katherine E.

2016-10-01

The FourStar galaxy evolution survey (ZFOURGE) is a 45 night legacy program with the FourStar near-infrared camera on Magellan and one of the most sensitive surveys to date. ZFOURGE covers a total of 400 arcmin2 in cosmic fields CDFS, COSMOS and UDS, overlapping CANDELS. We present photometric catalogs comprising >70,000 galaxies, selected from ultradeep K s -band detection images (25.5-26.5 AB mag, 5σ, total), and >80% complete to K s < 25.3-25.9 AB. We use 5 near-IR medium-bandwidth filters (J 1, J 2, J 3, H s , H l ) as well as broad-band K s at 1.05-2.16 μm to 25-26 AB at a seeing of ˜0.″5. Each field has ancillary imaging in 26-40 filters at 0.3-8 μm. We derive photometric redshifts and stellar population properties. Comparing with spectroscopic redshifts indicates a photometric redshift uncertainty σ z = 0.010, 0.009, and 0.011 in CDFS, COSMOS, and UDS. As spectroscopic samples are often biased toward bright and blue sources, we also inspect the photometric redshift differences between close pairs of galaxies, finding σ z,pairs = 0.01-0.02 at 1 < z < 2.5. We quantify how σ z,pairs depends on redshift, magnitude, spectral energy distribution type, and the inclusion of FourStar medium bands. σ z,pairs is smallest for bright, blue star-forming samples, while red star-forming galaxies have the worst σ z,pairs. Including FourStar medium bands reduces σ z,pairs by 50% at 1.5 < z < 2.5. We calculate star formation rates (SFRs) based on ultraviolet and ultradeep far-IR Spitzer/MIPS and Herschel/PACS data. We derive rest-frame U - V and V - J colors, and illustrate how these correlate with specific SFR and dust emission to z = 3.5. We confirm the existence of quiescent galaxies at z ˜ 3, demonstrating their SFRs are suppressed by > ×15. This paper contains data gathered with the 6.5 meter Magellan Telescopes located at Las Campanas observatory, Chile

The VLA-COSMOS 3 GHz Large Project: The infrared-radio correlation of star-forming galaxies and AGN to z ≲ 6

NASA Astrophysics Data System (ADS)

Delhaize, J.; Smolčić, V.; Delvecchio, I.; Novak, M.; Sargent, M.; Baran, N.; Magnelli, B.; Zamorani, G.; Schinnerer, E.; Murphy, E. J.; Aravena, M.; Berta, S.; Bondi, M.; Capak, P.; Carilli, C.; Ciliegi, P.; Civano, F.; Ilbert, O.; Karim, A.; Laigle, C.; Le Fèvre, O.; Marchesi, S.; McCracken, H. J.; Salvato, M.; Seymour, N.; Tasca, L.

2017-06-01

We examine the behaviour of the infrared-radio correlation (IRRC) over the range 0

Multi-level structure in the large scale distribution of optically luminous galaxies

NASA Astrophysics Data System (ADS)

Deng, Xin-fa; Deng, Zu-gan; Liu, Yong-zhen

1992-04-01

Fractal dimensions in the large scale distribution of galaxies have been calculated with the method given by Wen et al. [1] Samples are taken from CfA redshift survey in northern and southern galactic [2] hemisphere in our analysis respectively. Results from these two regions are compared with each other. There are significant differences between the distributions in these two regions. However, our analyses do show some common features of the distributions in these two regions. All subsamples show multi-level fractal character distinctly. Combining it with the results from analyses of samples given by IRAS galaxies and results from samples given by redshift survey in pencil-beam fields, [3,4] we suggest that multi-level fractal structure is most likely to be a general and important character in the large scale distribution of galaxies. The possible implications of this character are discussed.

The Detection and Statistics of Giant Arcs behind CLASH Clusters

NASA Astrophysics Data System (ADS)

Xu, Bingxiao; Postman, Marc; Meneghetti, Massimo; Seitz, Stella; Zitrin, Adi; Merten, Julian; Maoz, Dani; Frye, Brenda; Umetsu, Keiichi; Zheng, Wei; Bradley, Larry; Vega, Jesus; Koekemoer, Anton

2016-02-01

We developed an algorithm to find and characterize gravitationally lensed galaxies (arcs) to perform a comparison of the observed and simulated arc abundance. Observations are from the Cluster Lensing And Supernova survey with Hubble (CLASH). Simulated CLASH images are created using the MOKA package and also clusters selected from the high-resolution, hydrodynamical simulations, MUSIC, over the same mass and redshift range as the CLASH sample. The algorithm's arc elongation accuracy, completeness, and false positive rate are determined and used to compute an estimate of the true arc abundance. We derive a lensing efficiency of 4 ± 1 arcs (with length ≥6″ and length-to-width ratio ≥7) per cluster for the X-ray-selected CLASH sample, 4 ± 1 arcs per cluster for the MOKA-simulated sample, and 3 ± 1 arcs per cluster for the MUSIC-simulated sample. The observed and simulated arc statistics are in full agreement. We measure the photometric redshifts of all detected arcs and find a median redshift zs = 1.9 with 33% of the detected arcs having zs > 3. We find that the arc abundance does not depend strongly on the source redshift distribution but is sensitive to the mass distribution of the dark matter halos (e.g., the c-M relation). Our results show that consistency between the observed and simulated distributions of lensed arc sizes and axial ratios can be achieved by using cluster-lensing simulations that are carefully matched to the selection criteria used in the observations.

The Dispersion of Fast Radio Bursts from a Structured Intergalactic Medium at Redshifts z < 1.5

NASA Astrophysics Data System (ADS)

Shull, J. Michael; Danforth, Charles W.

2018-01-01

We analyze the sources of free electrons that produce the large dispersion measures, {DM}≈ 300{--}1600 (in units of cm‑3 pc), observed toward fast radio bursts (FRBs). Individual galaxies typically produce {DM}∼ 25{--}60 {{cm}}-3 {pc} from ionized gas in their disk, disk-halo interface, and circumgalactic medium. Toward an FRB source at redshift z, a homogeneous intergalactic medium (IGM) containing a fraction {f}{IGM} of cosmological baryons will produce {DM}=(935 {{cm}}-3 {pc}){f}{IGM} {h}70-1I(z), where I{(z)=(2/3{{{Ω }}}m)[\\{{{{Ω }}}m(1+z)}3+{{{Ω }}}{{Λ }}\\}{}1/2-1]. A structured IGM of photoionized Lyα absorbers in the cosmic web produces similar dispersion, modeled from the observed distribution, {f}b(N,z), of H I (Lyα-forest) absorbers in column density and redshift with ionization corrections and scaling relations from cosmological simulations. An analytic formula for DM(z) applied to observed FRB dispersions suggests that {z}{FRB}≈ 0.2{--}1.5 for an IGM containing a significant baryon fraction, {f}{IGM}=0.6+/- 0.1. Future surveys of the statistical distribution, DM(z), of FRBs identified with specific galaxies and redshifts can be used to calibrate the IGM baryon fraction and distribution of Lyα absorbers. Fluctuations in DM at the level ±10 cm‑3 pc will arise from filaments and voids in the cosmic web.

SEDEBLEND: a new method for deblending spectral energy distributions in confused imaging

NASA Astrophysics Data System (ADS)

MacKenzie, Todd P.; Scott, Douglas; Swinbank, Mark

2016-11-01

For high-redshift submillimetre or millimetre sources detected with single-dish telescopes, interferometric follow-up has shown that many are multiple submillimetre galaxies blended together. Confusion-limited Herschel observations of such targets are also available, and these sample the peak of their spectral energy distribution (SED) in the far-infrared. Many methods for analysing these data have been adopted, but most follow the traditional approach of extracting fluxes before model SEDs are fit, which has the potential to erase important information on degeneracies among fitting parameters and glosses over the intricacies of confusion noise. Here, we adapt the forward-modelling method that we originally developed to disentangle a high-redshift strongly lensed galaxy group, in order to tackle this general problem in a more statistically rigorous way, by combining source deblending and SED fitting into the same procedure. We call this method `SEDeblend'. As an application, we derive constraints on far-infrared luminosities and dust temperatures for sources within the ALMA follow-up of the LABOCA Extended Chandra Deep Field South Submillimetre Survey. We find an average dust temperature for an 870-μm-selected sample of (33.9 ± 2.4) K for the full survey. When selection effects of the sample are considered, we find no evidence that the average dust temperature evolves with redshift for sources with redshifts greater than about 1.5, when compared to those with redshifts between 0.1 and 1.5.

Photometric redshifts for the CFHTLS T0004 deep and wide fields

NASA Astrophysics Data System (ADS)

Coupon, J.; Ilbert, O.; Kilbinger, M.; McCracken, H. J.; Mellier, Y.; Arnouts, S.; Bertin, E.; Hudelot, P.; Schultheis, M.; Le Fèvre, O.; Le Brun, V.; Guzzo, L.; Bardelli, S.; Zucca, E.; Bolzonella, M.; Garilli, B.; Zamorani, G.; Zanichelli, A.; Tresse, L.; Aussel, H.

2009-06-01

Aims: We compute photometric redshifts in the fourth public release of the Canada-France-Hawaii Telescope Legacy Survey. This unique multi-colour catalogue comprises u^*, g', r', i', z' photometry in four deep fields of 1 deg2 each and 35 deg2 distributed over three wide fields. Methods: We used a template-fitting method to compute photometric redshifts calibrated with a large catalogue of 16 983 high-quality spectroscopic redshifts from the VVDS-F02, VVDS-F22, DEEP2, and the zCOSMOS surveys. The method includes correction of systematic offsets, template adaptation, and the use of priors. We also separated stars from galaxies using both size and colour information. Results: Comparing with galaxy spectroscopic redshifts, we find a photometric redshift dispersion, σΔ z/(1+z_s), of 0.028-0.30 and an outlier rate, |Δ z| ≥ 0.15× (1+z_s), of 3-4% in the deep field at i'_AB < 24. In the wide fields, we find a dispersion of 0.037-0.039 and an outlier rate of 3-4% at i'_AB < 22.5. Beyond i'_AB = 22.5 in the wide fields the number of outliers rises from 5% to 10% at i'_AB < 23 and i'_AB < 24, respectively. For the wide sample the systematic redshift bias stays below 1% to i'_AB < 22.5, whereas we find no significant bias in the deep fields. We investigated the effect of tile-to-tile photometric variations and demonstrated that the accuracy of our photometric redshifts is reduced by at most 21%. Application of our star-galaxy classifier reduced the contamination by stars in our catalogues from 60% to 8% at i'_AB < 22.5 in our field with the highest stellar density while keeping a complete galaxy sample. Our CFHTLS T0004 photometric redshifts are distributed to the community. Our release includes 592891 (i'_AB < 22.5) and 244701 (i'_AB < 24) reliable galaxy photometric redshifts in the wide and deep fields, respectively. Based on observations obtained with MegaPrime/MegaCam, a joint project of CFHT and CEA/DAPNIA, at the Canada-France-Hawaii Telescope (CFHT) which is operated by the National Research Council (NRC) of Canada, the Institut National des Sciences de l'Univers of the Centre National de la Recherche Scientifique (CNRS) of France, and the University of Hawaii. This work is based in part on data products produced at Terapix and the Canadian Astronomy Data Centre as part of the Canada-France-Hawaii Telescope Legacy Survey, a collaborative project of NRC and CNRS.

Spectrophotometric Redshifts in the Faint Infrared Grism Survey: Finding Overdensities of Faint Galaxies

NASA Astrophysics Data System (ADS)

Pharo, John; Malhotra, Sangeeta; Rhoads, James; Ryan, Russell; Tilvi, Vithal; Pirzkal, Norbert; Finkelstein, Steven; Windhorst, Rogier; Grogin, Norman; Koekemoer, Anton; Zheng, Zhenya; Hathi, Nimish; Kim, Keunho; Joshi, Bhavin; Yang, Huan; Christensen, Lise; Cimatti, Andrea; Gardner, Jonathan P.; Zakamska, Nadia; Ferreras, Ignacio; Hibon, Pascale; Pasquali, Anna

2018-04-01

We improve the accuracy of photometric redshifts by including low-resolution spectral data from the G102 grism on the Hubble Space Telescope (HST), which assists in redshift determination by further constraining the shape of the broadband spectral energy distribution (SED) and identifying spectral features. The photometry used in the redshift fits includes near-infrared photometry from FIGS+CANDELS, as well as optical data from ground-based surveys and HST ACS, and mid-IR data from Spitzer. We calculated the redshifts through the comparison of measured photometry with template galaxy models, using the EAZY photometric redshift code. For objects with F105W < 26.5 AB mag with a redshift range of 0 < z < 6, we find a typical error of Δz = 0.03 ∗ (1 + z) for the purely photometric redshifts; with the addition of FIGS spectra, these become Δz = 0.02 ∗ (1 + z), an improvement of 50%. Addition of grism data also reduces the outlier rate from 8% to 7% across all fields. With the more accurate spectrophotometric redshifts (SPZs), we searched the FIGS fields for galaxy overdensities. We identified 24 overdensities across the four fields. The strongest overdensity, matching a spectroscopically identified cluster at z = 0.85, has 28 potential member galaxies, of which eight have previous spectroscopic confirmation, and features a corresponding X-ray signal. Another corresponding to a cluster at z = 1.84 has 22 members, 18 of which are spectroscopically confirmed. Additionally, we find four overdensities that are detected at an equal or higher significance in at least one metric to the two confirmed clusters.

The Tolman Surface Brightness Test for the Reality of the Expansion. III. Hubble Space Telescope Profile and Surface Brightness Data for Early-Type Galaxies in Three High-Redshift Clusters

NASA Astrophysics Data System (ADS)

Lubin, Lori M.; Sandage, Allan

2001-09-01

Photometric data for 34 early-type galaxies in the three high-redshift clusters Cl 1324+3011 (z=0.76), Cl 1604+4304 (z=0.90), and Cl 1604+4321 (z=0.92), observed with the Hubble Space Telescope (HST) and with the Keck 10 m telescopes by Oke, Postman, & Lubin, are analyzed to obtain the photometric parameters of mean surface brightness, magnitudes for the growth curves, and angular radii at various Petrosian η radii. The angular radii at η=1.3 mag for the program galaxies are all larger than 0.24". All the galaxies are well resolved at this angular size using HST, whose point-spread function is 0.05", half-width at half-maximum. The data for each of the program galaxies are listed at η=1.0, 1.3, 1.5, 1.7, and 2.0 mag. They are corrected by color equations and K-terms for the effects of redshift to the rest-frame Cape/Cousins I for Cl 1324+3011 and Cl 1604+4304 and R for Cl 1604+4321. The K-corrections are calculated from synthetic spectral energy distributions derived from evolving stellar population models of Bruzual & Charlot, that have been fitted to the observed broadband (BVRI) AB magnitudes of each program galaxy. The listed photometric data are independent of all cosmological parameters. They are the source data for the Tolman surface brightness test made in Paper IV.

Submillimeter Galaxies as Progenitors of Compact Quiescent Galaxies

NASA Technical Reports Server (NTRS)

Toft, S.; Smolcic, V.; Magnelli, B.; Karim, A.; Zirm, A.; Michalowski, M.; Capak, P.; Sheth, K.; Schawinski, K.; Krogager, J.-K.;

Submillimeter Galaxies as Progenitors of Compact Quiescent Galaxies

NASA Astrophysics Data System (ADS)

Toft, S.; Smolčić, V.; Magnelli, B.; Karim, A.; Zirm, A.; Michalowski, M.; Capak, P.; Sheth, K.; Schawinski, K.; Krogager, J.-K.; Wuyts, S.; Sanders, D.; Man, A. W. S.; Lutz, D.; Staguhn, J.; Berta, S.; Mccracken, H.; Krpan, J.; Riechers, D.

2014-02-01

Three billion years after the big bang (at redshift z = 2), half of the most massive galaxies were already old, quiescent systems with little to no residual star formation and extremely compact with stellar mass densities at least an order of magnitude larger than in low-redshift ellipticals, their descendants. Little is known about how they formed, but their evolved, dense stellar populations suggest formation within intense, compact starbursts 1-2 Gyr earlier (at 3 < z < 6). Simulations show that gas-rich major mergers can give rise to such starbursts, which produce dense remnants. Submillimeter-selected galaxies (SMGs) are prime examples of intense, gas-rich starbursts. With a new, representative spectroscopic sample of compact, quiescent galaxies at z = 2 and a statistically well-understood sample of SMGs, we show that z = 3-6 SMGs are consistent with being the progenitors of z = 2 quiescent galaxies, matching their formation redshifts and their distributions of sizes, stellar masses, and internal velocities. Assuming an evolutionary connection, their space densities also match if the mean duty cycle of SMG starbursts is 42^{+40}_{-29} Myr (consistent with independent estimates), which indicates that the bulk of stars in these massive galaxies were formed in a major, early surge of star formation. These results suggest a coherent picture of the formation history of the most massive galaxies in the universe, from their initial burst of violent star formation through their appearance as high stellar-density galaxy cores and to their ultimate fate as giant ellipticals.

Cluster redshifts in five suspected superclusters

NASA Technical Reports Server (NTRS)

Ciardullo, R.; Ford, H.; Harms, R.

1985-01-01

Redshift surveys for rich superclusters were carried out in five regions of the sky containing surface-density enhancements of Abell clusters. While several superclusters are identified, projection effects dominate each field, and no system contains more than five rich clusters. Two systems are found to be especially interesting. The first, field 0136 10, is shown to contain a superposition of at least four distinct superclusters, with the richest system possessing a small velocity dispersion. The second system, 2206 - 22, though a region of exceedingly high Abell cluster surface density, appears to be a remarkable superposition of 23 rich clusters almost uniformly distributed in redshift space between 0.08 and 0.24. The new redshifts significantly increase the three-dimensional information available for the distance class 5 and 6 Abell clusters and allow the spatial correlation function around rich superclusters to be estimated.

Galaxies and large scale structure at high redshifts

PubMed Central

Steidel, Charles C.

1998-01-01

It is now straightforward to assemble large samples of very high redshift (z ∼ 3) field galaxies selected by their pronounced spectral discontinuity at the rest frame Lyman limit of hydrogen (at 912 Å). This makes possible both statistical analyses of the properties of the galaxies and the first direct glimpse of the progression of the growth of their large-scale distribution at such an early epoch. Here I present a summary of the progress made in these areas to date and some preliminary results of and future plans for a targeted redshift survey at z = 2.7–3.4. Also discussed is how the same discovery method may be used to obtain a “census” of star formation in the high redshift Universe, and the current implications for the history of galaxy formation as a function of cosmic epoch. PMID:9419319

Cosmic gamma-ray bursts from BATSE - Another great debate

NASA Technical Reports Server (NTRS)

Hartmann, Dieter H.; The, Lih-Sin; Clayton, Donald D.; Schnepf, Neil G.; Linder, Eric V.

1992-01-01

The BATSE detectors aboard Compton Observatory record about one cosmic gamma-ray burst (GRB) per day. Preliminary data analysis shows a highly isotropic sky map and a nonuniform brightness distribution. Anisotropies expected from a Galactic neutron star population, the most frequently considered source model, did not emerge from the data. Taken at face value, the data seem to suggest a heliocentric solution of the GRB puzzle. The observed isotropy can be achieved if sources are either very near or extragalactic. Pop I neutron stars in the disk do not simultaneously fit sky and brightness distributions. A possibility are sources in an extended Galactic halo with scale length large enough to avoid strong anisotropies due to the solar offset from the Galactic center. If GRBs are located in an extended halo we ask whether the neutron star paradigm can survive. We show that the recently discovered high velocity radio pulsars may provide a natural source population for GRBs. If these pulsars formed in the halo, as suggested by the radio data, the possibility arises that GRBs and high velocity pulsars are two related phenomena that provide observational evidence of the dark Galactic corona. We also discuss cosmological redshift constraints that follow from the observed brightness distribution.

iSEDfit: Bayesian spectral energy distribution modeling of galaxies

NASA Astrophysics Data System (ADS)

Moustakas, John

2017-08-01

iSEDfit uses Bayesian inference to extract the physical properties of galaxies from their observed broadband photometric spectral energy distribution (SED). In its default mode, the inputs to iSEDfit are the measured photometry (fluxes and corresponding inverse variances) and a measurement of the galaxy redshift. Alternatively, iSEDfit can be used to estimate photometric redshifts from the input photometry alone. After the priors have been specified, iSEDfit calculates the marginalized posterior probability distributions for the physical parameters of interest, including the stellar mass, star-formation rate, dust content, star formation history, and stellar metallicity. iSEDfit also optionally computes K-corrections and produces multiple "quality assurance" (QA) plots at each stage of the modeling procedure to aid in the interpretation of the prior parameter choices and subsequent fitting results. The software is distributed as part of the impro IDL suite.

Multipole analysis of redshift-space distortions around cosmic voids

NASA Astrophysics Data System (ADS)

Hamaus, Nico; Cousinou, Marie-Claude; Pisani, Alice; Aubert, Marie; Escoffier, Stéphanie; Weller, Jochen

2017-07-01

We perform a comprehensive redshift-space distortion analysis based on cosmic voids in the large-scale distribution of galaxies observed with the Sloan Digital Sky Survey. To this end, we measure multipoles of the void-galaxy cross-correlation function and compare them with standard model predictions in cosmology. Merely considering linear-order theory allows us to accurately describe the data on the entire available range of scales and to probe void-centric distances down to about 2 h-1Mpc. Common systematics, such as the Fingers-of-God effect, scale-dependent galaxy bias, and nonlinear clustering do not seem to play a significant role in our analysis. We constrain the growth rate of structure via the redshift-space distortion parameter β at two median redshifts, β(bar z=0.32)=0.599+0.134-0.124 and β(bar z=0.54)=0.457+0.056-0.054, with a precision that is competitive with state-of-the-art galaxy-clustering results. While the high-redshift constraint perfectly agrees with model expectations, we observe a mild 2σ deviation at bar z=0.32, which increases to 3σ when the data is restricted to the lowest available redshift range of 0.15

QUANTITATIVE EVALUATION OF THE HYPOTHESIS THAT BL LACERTAE OBJECTS ARE QSO REMNANTS

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

Borra, E. F.

2014-11-20

We evaluate with numerical simulations the hypothesis that BL Lacertae objects (BLLs) are the remnants of quasi-stellar objects. This hypothesis is based on their highly peculiar redshift evolution. They have a comoving space density that increases with decreasing redshift, contrary to all other active galactic nuclei. We assume that relativistic jets are below detection in young radio-quiet quasars and increase in strength with cosmic time so that they eventually are detected as BLLs. Our numerical simulations fit very well the observed redshift distributions of BLLs. There are strong indications that only the high-synchrotron-peaked BLLs could be QSO remnants.

AGN-driven helium reionization and the incidence of extended He III regions at redshift z > 3

NASA Astrophysics Data System (ADS)

Compostella, Michele; Cantalupo, Sebastiano; Porciani, Cristiano

2014-12-01

We use hydrodynamic simulations post-processed with the radiative-transfer code RADAMESH to assess recent claims that the low He II opacity observed in z > 3 quasar spectra may be incompatible with models of He II reionization driven by the observed population of active galactic nuclei (AGNs). In particular, building upon our previous work, we consider an early population of sources and start the radiative-transfer calculation at redshifts z ≥ 5. Our model faithfully reproduces the emissivity of optically selected AGNs as inferred from measurements of their luminosity function. We find that He II reionization is very extended in redshift (Δz ≥ 2) and highly spatially inhomogeneous. In fact, mock spectra extracted from the simulations show a large variability in the evolution of the He II effective optical depth within chunks of size Δz = 0.04. Regions with low opacity (τ_ {He {II}}^eff < 3) can be found at high redshift, in agreement with the most recent observations of UV-transmitting quasars. At the highest redshift currently probed by observations (z ˜ 3.4), our updated model predicts a much lower He II effective optical depth than previous simulations in the literature relieving most of the tension with the current data, that, however, still persists at about the (Gaussian) 1σ to 2σ level. Given the very small number of observed lines of sight, our analysis indicates that current data cannot rule out a purely AGN-driven scenario with high statistical significance.

Photometric Selection of a Massive Galaxy Catalog with z ≥ 0.55

NASA Astrophysics Data System (ADS)

Núñez, Carolina; Spergel, David N.; Ho, Shirley

2017-02-01

We present the development of a photometrically selected massive galaxy catalog, targeting Luminous Red Galaxies (LRGs) and massive blue galaxies at redshifts of z≥slant 0.55. Massive galaxy candidates are selected using infrared/optical color-color cuts, with optical data from the Sloan Digital Sky Survey (SDSS) and infrared data from “unWISE” forced photometry derived from the Wide-field Infrared Survey Explorer (WISE). The selection method is based on previously developed techniques to select LRGs with z> 0.5, and is optimized using receiver operating characteristic curves. The catalog contains 16,191,145 objects, selected over the full SDSS DR10 footprint. The redshift distribution of the resulting catalog is estimated using spectroscopic redshifts from the DEEP2 Galaxy Redshift Survey and photometric redshifts from COSMOS. Restframe U - B colors from DEEP2 are used to estimate LRG selection efficiency. Using DEEP2, the resulting catalog has an average redshift of z = 0.65, with a standard deviation of σ =2.0, and an average restframe of U-B=1.0, with a standard deviation of σ =0.27. Using COSMOS, the resulting catalog has an average redshift of z = 0.60, with a standard deviation of σ =1.8. We estimate 34 % of the catalog to be blue galaxies with z≥slant 0.55. An estimated 9.6 % of selected objects are blue sources with redshift z< 0.55. Stellar contamination is estimated to be 1.8%.

The Herschel Multi-Tiered Extragalactic Survey: SPIRE-mm Photometric Redshifts

NASA Technical Reports Server (NTRS)

Roseboom, I. G.; Ivison, R. J.; Greve, T. R.; Amblard, A.; Arumugam, V.; Auld, R.; Aussel, H.; Bethermin, M.; Blain, A.; Bock, J.;

N-body simulations of gravitational redshifts and other relativistic distortions of galaxy clustering

NASA Astrophysics Data System (ADS)

Zhu, Hongyu; Alam, Shadab; Croft, Rupert A. C.; Ho, Shirley; Giusarma, Elena

2017-10-01

Large redshift surveys of galaxies and clusters are providing the first opportunities to search for distortions in the observed pattern of large-scale structure due to such effects as gravitational redshift. We focus on non-linear scales and apply a quasi-Newtonian approach using N-body simulations to predict the small asymmetries in the cross-correlation function of two galaxy different populations. Following recent work by Bonvin et al., Zhao and Peacock and Kaiser on galaxy clusters, we include effects which enter at the same order as gravitational redshift: the transverse Doppler effect, light-cone effects, relativistic beaming, luminosity distance perturbation and wide-angle effects. We find that all these effects cause asymmetries in the cross-correlation functions. Quantifying these asymmetries, we find that the total effect is dominated by the gravitational redshift and luminosity distance perturbation at small and large scales, respectively. By adding additional subresolution modelling of galaxy structure to the large-scale structure information, we find that the signal is significantly increased, indicating that structure on the smallest scales is important and should be included. We report on comparison of our simulation results with measurements from the SDSS/BOSS galaxy redshift survey in a companion paper.

Predicting the High Redshift Galaxy Population for JWST

NASA Astrophysics Data System (ADS)

Flynn, Zoey; Benson, Andrew

2017-01-01

The James Webb Space Telescope will be launched in Oct 2018 with the goal of observing galaxies in the redshift range of z = 10 - 15. As redshift increases, the age of the Universe decreases, allowing us to study objects formed only a few hundred million years after the Big Bang. This will provide a valuable opportunity to test and improve current galaxy formation theory by comparing predictions for mass, luminosity, and number density to the observed data. We have made testable predictions with the semi-analytical galaxy formation model Galacticus. The code uses Markov Chain Monte Carlo methods to determine viable sets of model parameters that match current astronomical data. The resulting constrained model was then set to match the specifications of the JWST Ultra Deep Field Imaging Survey. Predictions utilizing up to 100 viable parameter sets were calculated, allowing us to assess the uncertainty in current theoretical expectations. We predict that the planned UDF will be able to observe a significant number of objects past redshift z > 9 but nothing at redshift z > 11. In order to detect these faint objects at redshifts z = 11-15 we need to increase exposure time by at least a factor of 1.66.

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

Straatman, Caroline M. S.; Labbé, Ivo; Van Houdt, Josha

The FourStar galaxy evolution survey (ZFOURGE) is a 45 night legacy program with the FourStar near-infrared camera on Magellan and one of the most sensitive surveys to date. ZFOURGE covers a total of 400 arcmin{sup 2} in cosmic fields CDFS, COSMOS and UDS, overlapping CANDELS. We present photometric catalogs comprising >70,000 galaxies, selected from ultradeep K {sub s} -band detection images (25.5–26.5 AB mag, 5 σ , total), and >80% complete to K {sub s} < 25.3–25.9 AB. We use 5 near-IR medium-bandwidth filters ( J {sub 1}, J {sub 2}, J {sub 3}, H {sub s} , H {submore » l} ) as well as broad-band K {sub s} at 1.05–2.16 μ m to 25–26 AB at a seeing of ∼0.″5. Each field has ancillary imaging in 26–40 filters at 0.3–8 μ m. We derive photometric redshifts and stellar population properties. Comparing with spectroscopic redshifts indicates a photometric redshift uncertainty σ {sub z} = 0.010, 0.009, and 0.011 in CDFS, COSMOS, and UDS. As spectroscopic samples are often biased toward bright and blue sources, we also inspect the photometric redshift differences between close pairs of galaxies, finding σ {sub z} {sub ,pairs} = 0.01–0.02 at 1 < z < 2.5. We quantify how σ {sub z} {sub ,pairs} depends on redshift, magnitude, spectral energy distribution type, and the inclusion of FourStar medium bands. σ {sub z} {sub ,pairs} is smallest for bright, blue star-forming samples, while red star-forming galaxies have the worst σ {sub z} {sub ,pairs}. Including FourStar medium bands reduces σ {sub z} {sub ,pairs} by 50% at 1.5 < z < 2.5. We calculate star formation rates (SFRs) based on ultraviolet and ultradeep far-IR Spitzer /MIPS and Herschel /PACS data. We derive rest-frame U − V and V − J colors, and illustrate how these correlate with specific SFR and dust emission to z = 3.5. We confirm the existence of quiescent galaxies at z ∼ 3, demonstrating their SFRs are suppressed by > ×15.« less

The ALHAMBRA survey: accurate merger fractions derived by PDF analysis of photometrically close pairs

NASA Astrophysics Data System (ADS)

López-Sanjuan, C.; Cenarro, A. J.; Varela, J.; Viironen, K.; Molino, A.; Benítez, N.; Arnalte-Mur, P.; Ascaso, B.; Díaz-García, L. A.; Fernández-Soto, A.; Jiménez-Teja, Y.; Márquez, I.; Masegosa, J.; Moles, M.; Pović, M.; Aguerri, J. A. L.; Alfaro, E.; Aparicio-Villegas, T.; Broadhurst, T.; Cabrera-Caño, J.; Castander, F. J.; Cepa, J.; Cerviño, M.; Cristóbal-Hornillos, D.; Del Olmo, A.; González Delgado, R. M.; Husillos, C.; Infante, L.; Martínez, V. J.; Perea, J.; Prada, F.; Quintana, J. M.

2015-04-01

Aims: Our goal is to develop and test a novel methodology to compute accurate close-pair fractions with photometric redshifts. Methods: We improved the currently used methodologies to estimate the merger fraction fm from photometric redshifts by (i) using the full probability distribution functions (PDFs) of the sources in redshift space; (ii) including the variation in the luminosity of the sources with z in both the sample selection and the luminosity ratio constrain; and (iii) splitting individual PDFs into red and blue spectral templates to reliably work with colour selections. We tested the performance of our new methodology with the PDFs provided by the ALHAMBRA photometric survey. Results: The merger fractions and rates from the ALHAMBRA survey agree excellently well with those from spectroscopic work for both the general population and red and blue galaxies. With the merger rate of bright (MB ≤ -20-1.1z) galaxies evolving as (1 + z)n, the power-law index n is higher for blue galaxies (n = 2.7 ± 0.5) than for red galaxies (n = 1.3 ± 0.4), confirming previous results. Integrating the merger rate over cosmic time, we find that the average number of mergers per galaxy since z = 1 is Nmred = 0.57 ± 0.05 for red galaxies and Nmblue = 0.26 ± 0.02 for blue galaxies. Conclusions: Our new methodology statistically exploits all the available information provided by photometric redshift codes and yields accurate measurements of the merger fraction by close pairs from using photometric redshifts alone. Current and future photometric surveys will benefit from this new methodology. Based on observations collected at the German-Spanish Astronomical Center, Calar Alto, jointly operated by the Max-Planck-Institut für Astronomie (MPIA) at Heidelberg and the Instituto de Astrofísica de Andalucía (CSIC).The catalogues, probabilities, and figures of the ALHAMBRA close pairs detected in Sect. 5.1 are available at http://https://cloud.iaa.csic.es/alhambra/catalogues/ClosePairs

High-redshift galaxy populations.

PubMed

Hu, Esther M; Cowie, Lennox L

2006-04-27

We now see many galaxies as they were only 800 million years after the Big Bang, and that limit may soon be exceeded when wide-field infrared detectors are widely available. Multi-wavelength studies show that there was relatively little star formation at very early times and that star formation was at its maximum at about half the age of the Universe. A small number of high-redshift objects have been found by targeting X-ray and radio sources and most recently, gamma-ray bursts. The gamma-ray burst sources may provide a way to reach even higher-redshift galaxies in the future, and to probe the first generation of stars.

Stars and gas in high redshift galaxies

NASA Astrophysics Data System (ADS)

Pettini, Max

Recent advances in instrumentation and observing techniques have made it possible to begin to study in detail the stellar populations and the interstellar media of galaxies at redshift z=3, when the universe was still in its "teen years". In keeping with the theme of this conference, I show how our knowledge of local star-forming regions can be applied directly to these distant galaxies to deduce their ages, metallicities, initial mass function, and masses. I also discuss areas where current limitations in stellar astrophysics have a direct bearing on the interpretation of the data being gathered, at an ever increasing rate, on the high redshift universe.

The Evolution of Normal Galaxy X-Ray Emission Through Cosmic History: Constraints from the 6 MS Chandra Deep Field-South

NASA Technical Reports Server (NTRS)

Lehmer, B. D.; Basu-Zych, A. R.; Mineo, S.; Brandt, W. N.; Eurfrasio, R. T.; Fragos, T.; Hornschemeier, A. E.; Lou, B.; Xue, Y. Q.; Bauer, F. E.;

Dusty Star-forming Galaxies at High Redshift

NASA Astrophysics Data System (ADS)

Su, Ting

2017-02-01

Star-forming galaxies, which convert large amounts of gas into stars at moderate or excessive rates, are a critical population for our understanding of galaxy evolution throughout the cosmic time. A small portion of the star-forming galaxies are defined as starburst galaxies because they have much greater star formation rates (a few hundred to a few thousand of solar masses per year), which are associate with high infrared luminosity. My thesis focuses on starburst galaxies in the intermediate/high redshift universe. In this study, I present various modeling methods of the infrared spectral energy distribution (SED) of starburst galaxies, including modified black-body models and empirical templates based on nearby galaxies. Then, I fit these models to two samples of sources to study galaxy properties and provide a comparison among different SED models. I present galaxy properties derived by the best-fit model -- a modified blackbody model with power-law temperature distribution. The first sample is nine candidate gravitationally-lensed dusty star-forming galaxies (DSFGs) selected at 218 GHz (1.4 mm) from the Atacama Cosmology Telescope (ACT) equatorial survey, with multi-wavelength detections. Among the brightest ACT sources, these represent the subset of the total ACT sample lying in Herschel SPIRE fields, and all nine of the 218 GHz detections were found to have bright Herschel counterparts. We find the sample has a higher redshift distribution (z=4.1+1.1-1.0) than "classical" starburst galaxies, as expected for 218 GHz selection, and an apparent total infrared luminosity of log10(uL_IR/L_sun) = 13.86+0.33-0.30, which suggests that they are either strongly lensed sources or unresolved collections of unlensed DSFGs. The effective apparent diameter of the sample is ud = 4.2+1.7-1.0 kpc, further evidence of strong lensing or multiplicity, since the typical diameter of dusty star-forming galaxies is 1.0-2.5 kpc. We emphasize that the effective apparent diameter derives from SED modeling without the assumption of optically thin dust (as opposed to image morphology). We find that the sources have substantial optical depth (tau = 4.2 +3.7-1.9) around the peak in the modified blackbody spectrum (lambda_obs <= 500 micron), which supports the choice of the optical thick model. The other sample is 30 starburst galaxies with spectroscopically confirmed redshift selected by sub-millimeter surveys in the redshifts range of z 4-6.5. We find that the power-law temperature of optically thick gray-body model is the best fitting method for high-z starburst galaxies. The optically thin model fitting would underestimate the dust temperature and overestimate the dust mass, while nearby starburst templates would overestimate the dust mass by an order of magnitude. For this very high redshift sample, we find a median dust mass of M_d = 2.7e8 Msun and a median infrared luminosity of L_IR = 1.1e13 Lsun which corresponds to a star formation rate of 1180 Msun/yr. The median cold dust component temperature is Tc = 41.7 K, while the median emission region diameter is d=2.4 kpc. We also present the gas mass M_G 2.6e10 Msun and dust-to-gas ratio Zd = 9.1e-3, which are consistent with the local analogues. Additionally, the FIR/radio correlation of the sample is q_IR=2.58, which is consistent with the local galaxies but slightly higher than the intermediate-z starburst galaxies.

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

NASA Technical Reports Server (NTRS)

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

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

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

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

2014-03-01

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

BLACK HOLE MASS AND EDDINGTON RATIO DISTRIBUTION FUNCTIONS OF X-RAY-SELECTED BROAD-LINE AGNs AT z {approx} 1.4 IN THE SUBARU XMM-NEWTON DEEP FIELD

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

Nobuta, K.; Akiyama, M.; Ueda, Y.

2012-12-20

In order to investigate the growth of supermassive black holes (SMBHs), we construct the black hole mass function (BHMF) and Eddington ratio distribution function (ERDF) of X-ray-selected broad-line active galactic nuclei (AGNs) at z {approx} 1.4 in the Subaru XMM-Newton Deep Survey (SXDS) field. A significant part of the accretion growth of SMBHs is thought to take place in this redshift range. Black hole masses of X-ray-selected broad-line AGNs are estimated using the width of the broad Mg II line and 3000 A monochromatic luminosity. We supplement the Mg II FWHM values with the H{alpha} FWHM obtained from our NIRmore » spectroscopic survey. Using the black hole masses of broad-line AGNs at redshifts between 1.18 and 1.68, the binned broad-line AGN BHMFs and ERDFs are calculated using the V{sub max} method. To properly account for selection effects that impact the binned estimates, we derive the corrected broad-line AGN BHMFs and ERDFs by applying the maximum likelihood method, assuming that the ERDF is constant regardless of the black hole mass. We do not correct for the non-negligible uncertainties in virial BH mass estimates. If we compare the corrected broad-line AGN BHMF with that in the local universe, then the corrected BHMF at z = 1.4 has a higher number density above 10{sup 8} M{sub Sun} but a lower number density below that mass range. The evolution may be indicative of a downsizing trend of accretion activity among the SMBH population. The evolution of broad-line AGN ERDFs from z = 1.4 to 0 indicates that the fraction of broad-line AGNs with accretion rates close to the Eddington limit is higher at higher redshifts.« 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.

Emission Features and Source Counts of Galaxies in Mid-Infrared

NASA Technical Reports Server (NTRS)

Xu, C.; Hacking, P. B.; Fang, F.; Shupe, D. L.; Lonsdale, C. J.; Lu, N. Y.; Helou, G.; Stacey, G. J.; Ashby, M. L. N.

1998-01-01

In this work we incorporate the newest ISO results on the mid-infrared spectral-energy-distributions (MIR SEDs) of galaxies into models for the number counts and redshift distributions of MIR surveys.

An AzTEC 1.1-mm survey for ULIRGs in the field of the Galaxy Cluster MS0451.6-0305

NASA Astrophysics Data System (ADS)

Wardlow, J. L.; Smail, Ian; Wilson, G. W.; Yun, M. S.; Coppin, K. E. K.; Cybulski, R.; Geach, J. E.; Ivison, R. J.; Aretxaga, I.; Austermann, J. E.; Edge, A. C.; Fazio, G. G.; Huang, J.; Hughes, D. H.; Kodama, T.; Kang, Y.; Kim, S.; Mauskopf, P. D.; Perera, T. A.; Scott, K. S.

2010-02-01

We have undertaken a deep (σ ~ 1.1 mJy) 1.1-mm survey of the z = 0.54 cluster MS0451.6-0305 using the AzTEC camera on the James Clerk Maxwell Telescope. We detect 36 sources with signal-to-noise ratio (S/N) >= 3.5 in the central 0.10 deg2 and present the AzTEC map, catalogue and number counts. We identify counterparts to 18 sources (50 per cent) using radio, mid-infrared, Spitzer InfraRed Array Camera (IRAC) and Submillimetre Array data. Optical, near- and mid-infrared spectral energy distributions are compiled for the 14 of these galaxies with detectable counterparts, which are expected to contain all likely cluster members. We then use photometric redshifts and colour selection to separate background galaxies from potential cluster members and test the reliability of this technique using archival observations of submillimetre galaxies. We find two potential MS0451-03 members, which, if they are both cluster galaxies, have a total star formation rate (SFR) of ~100Msolaryr-1 - a significant fraction of the combined SFR of all the other galaxies in MS0451-03. We also examine the stacked rest-frame mid-infrared, millimetre and radio emission of cluster members below our AzTEC detection limit, and find that the SFRs of mid-IR-selected galaxies in the cluster and redshift-matched field populations are comparable. In contrast, the average SFR of the morphologically classified late-type cluster population is nearly three times less than the corresponding redshift-matched field galaxies. This suggests that these galaxies may be in the process of being transformed on the red sequence by the cluster environment. Our survey demonstrates that although the environment of MS0451-03 appears to suppress star formation in late-type galaxies, it can support active, dust-obscured mid-IR galaxies and potentially millimetre-detected LIRGs.

The evolution of the cluster optical galaxy luminosity function between z = 0.4 and 0.9 in the DAFT/FADA survey

NASA Astrophysics Data System (ADS)

Martinet, Nicolas; Durret, Florence; Guennou, Loïc; Adami, Christophe; Biviano, Andrea; Ulmer, Melville P.; Clowe, Douglas; Halliday, Claire; Ilbert, Olivier; Márquez, Isabel; Schirmer, Mischa

2015-03-01

Context. There is some disagreement about the abundance of faint galaxies in high-redshift clusters, with contradictory results in the literature arising from studies of the optical galaxy luminosity function (GLF) for small cluster samples. Aims: We compute GLFs for one of the largest medium-to-high-redshift (0.4 ≤ z < 0.9) cluster samples to date in order to probe the abundance of faint galaxies in clusters. We also study how the GLF depends on cluster redshift, mass, and substructure and compare the GLFs of clusters with those of the field. We separately investigate the GLFs of blue and red-sequence (RS) galaxies to understand the evolution of different cluster populations. Methods: We calculated the GLFs for 31 clusters taken from the DAFT/FADA survey in the B,V,R, and I rest-frame bands. We used photometric redshifts computed from BVRIZJ images to constrain galaxy cluster membership. We carried out a detailed estimate of the completeness of our data. We distinguished the red-sequence and blue galaxies using a V - I versus I colour-magnitude diagram. We studied the evolution of these two populations with redshift. We fitted Schechter functions to our stacked GLFs to determine average cluster characteristics. Results: We find that the shapes of our GLFs are similar for the B,V,R, and I bands with a drop at the red GLF faint ends that is more pronounced at high redshift: αred ~ -0.5 at 0.40 ≤ z < 0.65 and αred > 0.1 at 0.65 ≤ z < 0.90. The blue GLFs have a steeper faint end (αblue ~ -1.6) than the red GLFs, which appears to be independent of redshift. For the full cluster sample, blue and red GLFs meet at MV = -20, MR = -20.5, and MI = -20.3. A study of how galaxy types evolve with redshift shows that late-type galaxies appear to become early types between z ~ 0.9 and today. Finally, the faint ends of the red GLFs of more massive clusters appear to be richer than less massive clusters, which is more typical of the lower redshift behaviour. Conclusions: Our results indicate that these clusters form at redshifts higher than z = 0.9 from galaxy structures that already have an established red sequence. Late-type galaxies then appear to evolve into early types, enriching the red sequence between this redshift and today. This effect is consistent with the evolution of the faint-end slope of the red sequence and the galaxy type evolution that we find. Finally, faint galaxies accreted from the field environment at all redshifts might have replaced the blue late-type galaxies that converted into early types, explaining the lack of evolution in the faint-end slopes of the blue GLFs. Appendix is available in electronic form at http://www.aanda.org

Cosmic Reionization on Computers: Properties of the Post-reionization IGM

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

Gnedin, Nickolay Y.; Becker, George D.; Fan, Xiaohui

Here, we present a comparison between several observational tests of the post-reionization IGM and the numerical simulations of reionization completed under the Cosmic Reionization On Computers (CROC) project. The CROC simulations match the gap distribution reasonably well, and also provide a good match for the distribution of peak heights, but there is a notable lack of wide peaks in the simulated spectra and the flux PDFs are poorly matched in the narrow redshift interval 5.5 < z < 5.7, with the match at other redshifts being significantly better, albeit not exact. Both discrepancies are related: simulations show more opacity thanmore » the data.« less

Cosmic Reionization on Computers: Properties of the Post-reionization IGM

DOE PAGES

Gnedin, Nickolay Y.; Becker, George D.; Fan, Xiaohui

2017-05-19

Here, we present a comparison between several observational tests of the post-reionization IGM and the numerical simulations of reionization completed under the Cosmic Reionization On Computers (CROC) project. The CROC simulations match the gap distribution reasonably well, and also provide a good match for the distribution of peak heights, but there is a notable lack of wide peaks in the simulated spectra and the flux PDFs are poorly matched in the narrow redshift interval 5.5 < z < 5.7, with the match at other redshifts being significantly better, albeit not exact. Both discrepancies are related: simulations show more opacity thanmore » the data.« less

Redshift-space distortions with the halo occupation distribution - II. Analytic model

NASA Astrophysics Data System (ADS)

Tinker, Jeremy L.

2007-01-01

We present an analytic model for the galaxy two-point correlation function in redshift space. The cosmological parameters of the model are the matter density Ωm, power spectrum normalization σ8, and velocity bias of galaxies αv, circumventing the linear theory distortion parameter β and eliminating nuisance parameters for non-linearities. The model is constructed within the framework of the halo occupation distribution (HOD), which quantifies galaxy bias on linear and non-linear scales. We model one-halo pairwise velocities by assuming that satellite galaxy velocities follow a Gaussian distribution with dispersion proportional to the virial dispersion of the host halo. Two-halo velocity statistics are a combination of virial motions and host halo motions. The velocity distribution function (DF) of halo pairs is a complex function with skewness and kurtosis that vary substantially with scale. Using a series of collisionless N-body simulations, we demonstrate that the shape of the velocity DF is determined primarily by the distribution of local densities around a halo pair, and at fixed density the velocity DF is close to Gaussian and nearly independent of halo mass. We calibrate a model for the conditional probability function of densities around halo pairs on these simulations. With this model, the full shape of the halo velocity DF can be accurately calculated as a function of halo mass, radial separation, angle and cosmology. The HOD approach to redshift-space distortions utilizes clustering data from linear to non-linear scales to break the standard degeneracies inherent in previous models of redshift-space clustering. The parameters of the occupation function are well constrained by real-space clustering alone, separating constraints on bias and cosmology. We demonstrate the ability of the model to separately constrain Ωm,σ8 and αv in models that are constructed to have the same value of β at large scales as well as the same finger-of-god distortions at small scales.

Cosmological constraints with clustering-based redshifts

NASA Astrophysics Data System (ADS)

Kovetz, Ely D.; Raccanelli, Alvise; Rahman, Mubdi

2017-07-01

We demonstrate that observations lacking reliable redshift information, such as photometric and radio continuum surveys, can produce robust measurements of cosmological parameters when empowered by clustering-based redshift estimation. This method infers the redshift distribution based on the spatial clustering of sources, using cross-correlation with a reference data set with known redshifts. Applying this method to the existing Sloan Digital Sky Survey (SDSS) photometric galaxies, and projecting to future radio continuum surveys, we show that sources can be efficiently divided into several redshift bins, increasing their ability to constrain cosmological parameters. We forecast constraints on the dark-energy equation of state and on local non-Gaussianity parameters. We explore several pertinent issues, including the trade-off between including more sources and minimizing the overlap between bins, the shot-noise limitations on binning and the predicted performance of the method at high redshifts, and most importantly pay special attention to possible degeneracies with the galaxy bias. Remarkably, we find that once this technique is implemented, constraints on dynamical dark energy from the SDSS imaging catalogue can be competitive with, or better than, those from the spectroscopic BOSS survey and even future planned experiments. Further, constraints on primordial non-Gaussianity from future large-sky radio-continuum surveys can outperform those from the Planck cosmic microwave background experiment and rival those from future spectroscopic galaxy surveys. The application of this method thus holds tremendous promise for cosmology.

HI Fluctuations at Large Redshifts: III - Simulating the Signal Expected at GMRT

NASA Astrophysics Data System (ADS)

Bharadwaj, Somnath; Srikant, P. S.

2004-03-01

We simulate the distribution of neutral hydrogen (HI) at the redshifts z D 1:3 and 3:4 using a cosmological N-body simulation along with a prescription for assigning HI masses to the particles. The HI is distributed in clouds whose properties are consistent with those of the damped Lyman- absorption systems (DLAs) seen in quasar spectra. The clustering properties of these clouds are identical to those of the dark matter. We use this to simulate the redshifted HI emission expected at 610 MHzand 325 MHz, two of the observing bands at theGMRT. These are used to predict the correlations expected between the complex visibilities measured at different baselines and frequencies in radio-interferometric observations with the GMRT. The visibility correlations directly probe the power spectrum of HI fluctuations at the epoch when the HI emission originated, and this holds the possibility of using HI observations to study large-scale structures at high z.

Gamma-ray luminosity and photon index evolution of FSRQ blazars and contribution to the gamma-ray background

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

Singal, J.; Ko, A.; Petrosian, V., E-mail: jsingal@richmond.edu

We present the redshift evolutions and distributions of the gamma-ray luminosity and photon spectral index of flat spectrum radio quasar (FSRQ) type blazars, using non-parametric methods to obtain the evolutions and distributions directly from the data. The sample we use for analysis consists of almost all FSRQs observed with a greater than approximately 7σ detection threshold in the first-year catalog of the Fermi Gamma-ray Space Telescope's Large Area Telescope, with redshifts as determined from optical spectroscopy by Shaw et al. We find that FSQRs undergo rapid gamma-ray luminosity evolution, but negligible photon index evolution, with redshift. With these evolutions accountedmore » for we determine the density evolution and luminosity function of FSRQs and calculate their total contribution to the extragalactic gamma-ray background radiation, resolved and unresolved, which is found to be 16(+10/–4)%, in agreement with previous studies.« less

Are some BL Lacs artefacts of gravitational lensing?

PubMed

Ostriker, J P; Vietri, M

1990-03-01

WE suggested in 1985 that a significant fraction of BL Lacertae objects, a kind of lineless quasar, seen in nearby galaxies are in fact images, gravitationally lensed and substantially amplified by stars in the nearby galaxy, of background objects, optically violent variable (OVV) quasars at redshifts z > 1 (ref. 1). This hypothesis was made on the basis of certain general similarities between BL Lacs and O Ws, but for two recently observed BL Lacs(2,3) a strong case can be made that the accompanying elliptical galaxy is a foreground object. In addition, we argue that the distribution of BL Lac redshifts is hard to understand without gravitational lensing, unless we happen to be at a very local maximum of the spatial cosmic distribution of BL Lacs. Our analysis also indicates that the galaxies whose stars are likely to act as microlenses will be found in two peaks, one nearby, with redshift 0.05-0.10, and the other near the distant quasar.

Detecting Massive, High-Redshift Galaxy Clusters Using the Thermal Sunyaev-Zel'dovich Effect

NASA Astrophysics Data System (ADS)

Adams, Carson; Steinhardt, Charles L.; Loeb, Abraham; Karim, Alexander; Staguhn, Johannes; Erler, Jens; Capak, Peter L.

2017-01-01

We develop the thermal Sunyaev-Zel'dovich (SZ) effect as a direct astrophysical measure of the mass distribution of dark matter halos. The SZ effect increases with cosmological distance, a unique astronomical property, and is highly sensitive to halo mass. We find that this presents a powerful methodology for distinguishing between competing models of the halo mass function distribution, particularly in the high-redshift domain just a few hundred million years after the Big Bang. Recent surveys designed to probe this epoch of initial galaxy formation such as CANDELS and SPLASH report an over-abundance of highly massive halos as inferred from stellar ultraviolet (UV) luminosities and the stellar mass to halo mass ratio estimated from nearby galaxies. If these UV luminosity to halo mass relations hold to high-redshift, observations estimate several orders of magnitude more highly massive halos than predicted by hierarchical merging and the standard cosmological paradigm. Strong constraints on the masses of these galaxy clusters are essential to resolving the current tension between observation and theory. We conclude that detections of thermal SZ sources are plausible at high-redshift only for the halo masses inferred from observation. Therefore, future SZ surveys will provide a robust determination between theoretical and observational predictions.

Accurate Emission Line Diagnostics at High Redshift

NASA Astrophysics Data System (ADS)

Jones, Tucker

2017-08-01

How do the physical conditions of high redshift galaxies differ from those seen locally? Spectroscopic surveys have invested hundreds of nights of 8- and 10-meter telescope time as well as hundreds of Hubble orbits to study evolution in the galaxy population at redshifts z 0.5-4 using rest-frame optical strong emission line diagnostics. These surveys reveal evolution in the gas excitation with redshift but the physical cause is not yet understood. Consequently there are large systematic errors in derived quantities such as metallicity.We have used direct measurements of gas density, temperature, and metallicity in a unique sample at z=0.8 to determine reliable diagnostics for high redshift galaxies. Our measurements suggest that offsets in emission line ratios at high redshift are primarily caused by high N/O abundance ratios. However, our ground-based data cannot rule out other interpretations. Spatially resolved Hubble grism spectra are needed to distinguish between the remaining plausible causes such as active nuclei, shocks, diffuse ionized gas emission, and HII regions with escaping ionizing flux. Identifying the physical origin of evolving excitation will allow us to build the necessary foundation for accurate measurements of metallicity and other properties of high redshift galaxies. Only then can we expoit the wealth of data from current surveys and near-future JWST spectroscopy to understand how galaxies evolve over time.

Lyman Break Analogs: Constraints on the Formation of Extreme Starbursts at Low and High Redshift

NASA Technical Reports Server (NTRS)

Goncalves, Thiago S.; Overzier, Roderik; Basu-Zych, Antara; Martin, D. Christopher

2011-01-01

Lyman Break Analogs (LBAs), characterized by high far-UV luminosities and surface brightnesses as detected by GALEX, are intensely star-forming galaxies in the low-redshift universe (z approximately equal to 0.2), with star formation rates reaching up to 50 times that of the Milky Way. These objects present metallicities, morphologies and other physical properties similar to higher redshift Lyman Break Galaxies (LBGs), motivating the detailed study of LBAs as local laboratories of this high-redshift galaxy population. We present results from our recent integral-field spectroscopy survey of LBAs with Keck/OSIRIS, which shows that these galaxies have the same nebular gas kinematic properties as high-redshift LBGs. We argue that such kinematic studies alone are not an appropriate diagnostic to rule out merger events as the trigger for the observed starburst. Comparison between the kinematic analysis and morphological indices from HST imaging illustrates the difficulties of properly identifying (minor or major) merger events, with no clear correlation between the results using either of the two methods. Artificial redshifting of our data indicates that this problem becomes even worse at high redshift due to surface brightness dimming and resolution loss. Whether mergers could generate the observed kinematic properties is strongly dependent on gas fractions in these galaxies. We present preliminary results of a CARMA survey for LBAs and discuss the implications of the inferred molecular gas masses for formation models.

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

NASA Astrophysics Data System (ADS)

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

2018-01-01

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

DERIVATION OF A RELATION FOR THE STEEPENING OF TeV-SELECTED BLAZAR {gamma}-RAY SPECTRA WITH ENERGY AND REDSHIFT

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

Stecker, Floyd William; Scully, Sean T.

2010-02-01

We derive a relation for the steepening of blazar {gamma}-ray spectra between the multi-GeV Fermi energy range and the TeV energy range observed by atmospheric Cerenkov telescopes. The change in spectral index is produced by two effects: (1) an intrinsic steepening, independent of redshift, owing to the properties of emission and absorption in the source and (2) a redshift-dependent steepening produced by intergalactic pair production interactions of blazar {gamma}-rays with low-energy photons of the 'intergalactic background light' (IBL). Given this relation, with good enough data on the mean {gamma}-ray spectral energy distribution of TeV-selected BL Lac objects, the redshift evolutionmore » of the IBL can, in principle, be determined independently of stellar evolution models. We apply our relation to the results of new Fermi observations of TeV-selected blazars.« less

Gravitational Redshift of Deformed Neutron Stars

NASA Astrophysics Data System (ADS)

Romero, Alexis; Zubairi, Omair; Weber, Fridolin

2015-04-01

Non-rotating neutron stars are generally treated in theoretical studies as perfect spheres. Such a treatment, however, may not be correct if strong magnetic fields are present and/or the pressure of the matter in the cores of neutron stars is non-isotropic, leading to neutron stars which are deformed. In this work, we investigate the impact of deformation on the gravitational redshift of neutron stars in the framework of general relativity. Using a parameterized metric to model non-spherical mass distributions, we derive an expression for the gravitational redshift in terms of the mass, radius, and deformity of a neutron star. Numerical solutions for the redshifts of sequences of deformed neutron stars are presented and observational implications are pointed out. This research is funded by the NIH through the Maximizing Access to Research Careers (MARC), under Grant Number: 5T34GM008303-25 and through the National Science Foundation under grant PHY-1411708.

Nep-Akari Evolution with Redshift of Dust Attenuation in 8 ㎛ Selected Galaxies

NASA Astrophysics Data System (ADS)

Buat, V.; Oi, N.; Burgarella, D.; Malek, K.; Matsuhara, H.; Murata, K.; Serjeant, S.; Takeuchi, T. T.; Malkan, M.; Pearson, C.; Wada, T.

2017-03-01

We built a 8um selected sample of galaxies in the NEP-AKARI field by defining 4 redshift bins with the four AKARI bands at 11, 15, 18 and 24 microns (0.15

X-ray morphological study of galaxy cluster catalogues

NASA Astrophysics Data System (ADS)

Democles, Jessica; Pierre, Marguerite; Arnaud, Monique

2016-07-01

Context : The intra-cluster medium distribution as probed by X-ray morphology based analysis gives good indication of the system dynamical state. In the race for the determination of precise scaling relations and understanding their scatter, the dynamical state offers valuable information. Method : We develop the analysis of the centroid-shift so that it can be applied to characterize galaxy cluster surveys such as the XXL survey or high redshift cluster samples. We use it together with the surface brightness concentration parameter and the offset between X-ray peak and brightest cluster galaxy in the context of the XXL bright cluster sample (Pacaud et al 2015) and a set of high redshift massive clusters detected by Planck and SPT and observed by both XMM-Newton and Chandra observatories. Results : Using the wide redshift coverage of the XXL sample, we see no trend between the dynamical state of the systems with the redshift.

PHOTOMETRIC REDSHIFTS OF SUBMILLIMETER GALAXIES

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

Chakrabarti, Sukanya; Magnelli, Benjamin; Lutz, Dieter

2013-08-20

We use the photometric redshift method of Chakrabarti and McKee to infer photometric redshifts of submillimeter galaxies with far-IR (FIR) Herschel data obtained as part of the PACS Evolutionary Probe program. For the sample with spectroscopic redshifts, we demonstrate the validity of this method over a large range of redshifts (4 {approx}> z {approx}> 0.3) and luminosities, finding an average accuracy in (1 + z{sub phot})/(1 + z{sub spec}) of 10%. Thus, this method is more accurate than other FIR photometric redshift methods. This method is different from typical FIR photometric methods in deriving redshifts from the light-to-gas mass (L/M)more » ratio of infrared-bright galaxies inferred from the FIR spectral energy distribution, rather than dust temperatures. To assess the dependence of our photometric redshift method on the data in this sample, we contrast the average accuracy of our method when we use PACS data, versus SPIRE data, versus both PACS and SPIRE data. We also discuss potential selection effects that may affect the Herschel sample. Once the redshift is derived, we can determine physical properties of infrared-bright galaxies, including the temperature variation within the dust envelope, luminosity, mass, and surface density. We use data from the GOODS-S field to calculate the star formation rate density (SFRD) of submillimeter bright sources detected by AzTEC and PACS. The AzTEC-PACS sources, which have a threshold 850 {mu}m flux {approx}> 5 mJy, contribute 15% of the SFRD from all ultraluminous infrared galaxies (L{sub IR} {approx}> 10{sup 12} L{sub Sun }), and 3% of the total SFRD at z {approx} 2.« less

Redshifts for Spitzer-detected galaxies at z 6 - old stars in the first Gyr

NASA Astrophysics Data System (ADS)

Lacy, Mark; Stanway, Elizabeth; Chiu, Kuenley; Douglas, Laura; Eyles, Laurence; Bunker, Andrew

2008-02-01

We have identified a population of star-forming galaxies at z 6 through the i-drop Lyman-break technique using HST/ACS. Using Spitzer/IRAC imaging (tracing the rest-frame optical), we discovered from SED-fitting that some of this population harbour relatively old stars (300-500Myr) with significant Balmer breaks, implying formation epochs of z 10. Our work suggests that UV photons from star formation at z 10 may play a key role in reionizing the Universe. However, these conclusions are drawn from the only field (GOODS-South) which has both deep Spitzer/IRAC imaging and many i-drop spectroscopic redshifts. Hence the global conclusions are compromised by cosmic variance. We have 72-hours on Spitzer to image 6 other sight-lines with deep ACS data; we propose to use GMOS multiobject mode to obtain spectroscopic redshifts, which are crucial to reduce the large uncertainties in fitting the stellar ages and masses, and hence inferring the preceding star formation history and the contribution to reionization.

General relativistic corrections in density-shear correlations

NASA Astrophysics Data System (ADS)

Ghosh, Basundhara; Durrer, Ruth; Sellentin, Elena

2018-06-01

We investigate the corrections which relativistic light-cone computations induce on the correlation of the tangential shear with galaxy number counts, also known as galaxy-galaxy lensing. The standard-approach to galaxy-galaxy lensing treats the number density of sources in a foreground bin as observable, whereas it is in reality unobservable due to the presence of relativistic corrections. We find that already in the redshift range covered by the DES first year data, these currently neglected relativistic terms lead to a systematic correction of up to 50% in the density-shear correlation function for the highest redshift bins. This correction is dominated by the fact that a redshift bin of number counts does not only lens sources in a background bin, but is itself again lensed by all masses between the observer and the counted source population. Relativistic corrections are currently ignored in the standard galaxy-galaxy analyses, and the additional lensing of a counted source populations is only included in the error budget (via the covariance matrix). At increasingly higher redshifts and larger scales, these relativistic and lensing corrections become however increasingly more important, and we here argue that it is then more efficient, and also cleaner, to account for these corrections in the density-shear correlations.

THE AzTEC/SMA INTERFEROMETRIC IMAGING SURVEY OF SUBMILLIMETER-SELECTED HIGH-REDSHIFT GALAXIES

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

Younger, Joshua D.; Fazio, Giovanni G.; Huang Jiasheng

We present results from a continuing interferometric survey of high-redshift submillimeter galaxies (SMGs) with the Submillimeter Array, including high-resolution (beam size approx2 arcsec) imaging of eight additional AzTEC 1.1 mm selected sources in the COSMOS field, for which we obtain six reliable (peak signal-to-noise ratio (S/N) >5 or peak S/N >4 with multiwavelength counterparts within the beam) and two moderate significance (peak S/N >4) detections. When combined with previous detections, this yields an unbiased sample of millimeter-selected SMGs with complete interferometric follow up. With this sample in hand, we (1) empirically confirm the radio-submillimeter association, (2) examine the submillimeter morphology-includingmore » the nature of SMGs with multiple radio counterparts and constraints on the physical scale of the far infrared-of the sample, and (3) find additional evidence for a population of extremely luminous, radio-dim SMGs that peaks at higher redshift than previous, radio-selected samples. In particular, the presence of such a population of high-redshift sources has important consequences for models of galaxy formation-which struggle to account for such objects even under liberal assumptions-and dust production models given the limited time since the big bang.« less

SDSS-IV eBOSS emission-line galaxy pilot survey

DOE PAGES

Comparat, J.; Delubac, T.; Jouvel, S.; ...

2016-08-09

The Sloan Digital Sky Survey IV extended Baryonic Oscillation Spectroscopic Survey (SDSS-IV/eBOSS) will observe 195,000 emission-line galaxies (ELGs) to measure the Baryonic Acoustic Oscillation standard ruler (BAO) at redshift 0.9. To test different ELG selection algorithms, 9,000 spectra were observed with the SDSS spectrograph as a pilot survey based on data from several imaging surveys. First, using visual inspection and redshift quality flags, we show that the automated spectroscopic redshifts assigned by the pipeline meet the quality requirements for a reliable BAO measurement. We also show the correlations between sky emission, signal-to-noise ratio in the emission lines, and redshift error.more » Then we provide a detailed description of each target selection algorithm we tested and compare them with the requirements of the eBOSS experiment. As a result, we provide reliable redshift distributions for the different target selection schemes we tested. Lastly, we determine an target selection algorithms that is best suited to be applied on DECam photometry because they fulfill the eBOSS survey efficiency requirements.« less

The redshift-space neighborhoods of 36 loose groups. 2: Analysis

NASA Technical Reports Server (NTRS)

Ramella, Massimo; Geller, Margaret J.; Hurchra, John P.; Thorstensen, John R.

1995-01-01

We explore the kinematics of 36 rich RGH89 groups identified from the first two complete slices of the CfA redshift survey. These groups have more than five members identified by a friends-of-friends algorithm at a number density contrast delta rho/rho greater than or equal to 80. To examine the stability of the determination of the velocity dispersion for these systems, we compare results for the original 232 members with results for a larger redshift sample, including 334 fainter members in the redshift neighborhoods. On average, we double the number of group members in each system. The observed distribution of velocity dispersions is stable. In fact, the velocity dispersion based on the original members identified in the CfA redshift survey is a reliable predictor of the value for the enlarged sample in an individual group. The velocity dispersion is thus a stable physical parameter for discrimination among systems galaxies. A larger sample of groups, particularly one selected from a distance limited catalog, should provide an interesting constraint on models for the formation of large-scale structure. We take H(sub 0) = km/s/Mpc.

Dusty starburst galaxies in the early Universe as revealed by gravitational lensing.

PubMed

Vieira, J D; Marrone, D P; Chapman, S C; De Breuck, C; Hezaveh, Y D; Weiβ, A; Aguirre, J E; Aird, K A; Aravena, M; Ashby, M L N; Bayliss, M; Benson, B A; Biggs, A D; Bleem, L E; Bock, J J; Bothwell, M; Bradford, C M; Brodwin, M; Carlstrom, J E; Chang, C L; Crawford, T M; Crites, A T; de Haan, T; Dobbs, M A; Fomalont, E B; Fassnacht, C D; George, E M; Gladders, M D; Gonzalez, A H; Greve, T R; Gullberg, B; Halverson, N W; High, F W; Holder, G P; Holzapfel, W L; Hoover, S; Hrubes, J D; Hunter, T R; Keisler, R; Lee, A T; Leitch, E M; Lueker, M; Luong-Van, D; Malkan, M; McIntyre, V; McMahon, J J; Mehl, J; Menten, K M; Meyer, S S; Mocanu, L M; Murphy, E J; Natoli, T; Padin, S; Plagge, T; Reichardt, C L; Rest, A; Ruel, J; Ruhl, J E; Sharon, K; Schaffer, K K; Shaw, L; Shirokoff, E; Spilker, J S; Stalder, B; Staniszewski, Z; Stark, A A; Story, K; Vanderlinde, K; Welikala, N; Williamson, R

2013-03-21

In the past decade, our understanding of galaxy evolution has been revolutionized by the discovery that luminous, dusty starburst galaxies were 1,000 times more abundant in the early Universe than at present. It has, however, been difficult to measure the complete redshift distribution of these objects, especially at the highest redshifts (z > 4). Here we report a redshift survey at a wavelength of three millimetres, targeting carbon monoxide line emission from the star-forming molecular gas in the direction of extraordinarily bright millimetre-wave-selected sources. High-resolution imaging demonstrates that these sources are strongly gravitationally lensed by foreground galaxies. We detect spectral lines in 23 out of 26 sources and multiple lines in 12 of those 23 sources, from which we obtain robust, unambiguous redshifts. At least 10 of the sources are found to lie at z > 4, indicating that the fraction of dusty starburst galaxies at high redshifts is greater than previously thought. Models of lens geometries in the sample indicate that the background objects are ultra-luminous infrared galaxies, powered by extreme bursts of star formation.

The two-point correlation function for groups of galaxies in the Center for Astrophysics redshift survey

NASA Technical Reports Server (NTRS)

Ramella, Massimo; Geller, Margaret J.; Huchra, John P.

1990-01-01

The large-scale distribution of groups of galaxies selected from complete slices of the CfA redshift survey extension is examined. The survey is used to reexamine the contribution of group members to the galaxy correlation function. The relationship between the correlation function for groups and those calculated for rich clusters is discussed, and the results for groups are examined as an extension of the relation between correlation function amplitude and richness. The group correlation function indicates that groups and individual galaxies are equivalent tracers of the large-scale matter distribution. The distribution of group centers is equivalent to random sampling of the galaxy distribution. The amplitude of the correlation function for groups is consistent with an extrapolation of the amplitude-richness relation for clusters. The amplitude scaled by the mean intersystem separation is also consistent with results for richer clusters.

WHEN DID ROUND DISK GALAXIES FORM?

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

Takeuchi, T. M.; Ohta, K.; Yuma, S.

2015-03-01

When and how galaxy morphology, such as the disk and bulge seen in the present-day universe, emerged is still not clear. In the universe at z ≳ 2, galaxies with various morphologies are seen, and star-forming galaxies at z ∼ 2 show the intrinsic shape of bar-like structures. Then, when did the round disk structure form? Here we take a simple and straightforward approach to see the epoch when a round disk galaxy population emerged by constraining the intrinsic shape statistically based on the apparent axial ratio distribution of galaxies. We derived the distributions of the apparent axial ratios inmore » the rest-frame optical light (∼5000 Å) of star-forming main-sequence galaxies at 2.5 > z > 1.4, 1.4 > z > 0.85, and 0.85 > z > 0.5, and found that their apparent axial ratios show peaky distributions at z ≳ 0.85, while a rather flat distribution at the lower redshift. By using a tri-axial model (A > B > C) for the intrinsic shape, we found that the best-fit models give the peaks of the B/A distribution of 0.81 ± 0.04, 0.84 ± 0.04, and 0.92 ± 0.05 at 2.5 > z > 1.4, 1.4 > z > 0.85, and 0.85 > z > 0.5, respectively. The last value is close to the local value of 0.95. Thickness (C/A) is ∼0.25 at all the redshifts and is close to the local value (0.21). The results indicate that the shape of the star-forming galaxies in the main sequence changes gradually, and that the round disk is established at around z ∼ 0.9. The establishment of the round disk may be due to the cessation of a violent interaction between galaxies or the growth of a bulge and/or a supermassive black hole residing at the center of a galaxy that dissolves the bar structure.« less

Infrared-faint radio sources are at high redshifts. Spectroscopic redshift determination of infrared-faint radio sources using the Very Large Telescope

NASA Astrophysics Data System (ADS)

Herzog, A.; Middelberg, E.; Norris, R. P.; Sharp, R.; Spitler, L. R.; Parker, Q. A.

2014-07-01

Context. Infrared-faint radio sources (IFRS) are characterised by relatively high radio flux densities and associated faint or even absent infrared and optical counterparts. The resulting extremely high radio-to-infrared flux density ratios up to several thousands were previously known only for high-redshift radio galaxies (HzRGs), suggesting a link between the two classes of object. However, the optical and infrared faintness of IFRS makes their study difficult. Prior to this work, no redshift was known for any IFRS in the Australia Telescope Large Area Survey (ATLAS) fields which would help to put IFRS in the context of other classes of object, especially of HzRGs. Aims: This work aims at measuring the first redshifts of IFRS in the ATLAS fields. Furthermore, we test the hypothesis that IFRS are similar to HzRGs, that they are higher-redshift or dust-obscured versions of these massive galaxies. Methods: A sample of IFRS was spectroscopically observed using the Focal Reducer and Low Dispersion Spectrograph 2 (FORS2) at the Very Large Telescope (VLT). The data were calibrated based on the Image Reduction and Analysis Facility (IRAF) and redshifts extracted from the final spectra, where possible. This information was then used to calculate rest-frame luminosities, and to perform the first spectral energy distribution modelling of IFRS based on redshifts. Results: We found redshifts of 1.84, 2.13, and 2.76, for three IFRS, confirming the suggested high-redshift character of this class of object. These redshifts and the resulting luminosities show IFRS to be similar to HzRGs, supporting our hypothesis. We found further evidence that fainter IFRS are at even higher redshifts. Conclusions: Considering the similarities between IFRS and HzRGs substantiated in this work, the detection of IFRS, which have a significantly higher sky density than HzRGs, increases the number of active galactic nuclei in the early universe and adds to the problems of explaining the formation of supermassive black holes shortly after the Big Bang.

The impact of galaxy formation on satellite kinematics and redshift-space distortions

NASA Astrophysics Data System (ADS)

Orsi, Álvaro A.; Angulo, Raúl E.

2018-04-01

Galaxy surveys aim to map the large-scale structure of the Universe and use redshift-space distortions to constrain deviations from general relativity and probe the existence of massive neutrinos. However, the amount of information that can be extracted is limited by the accuracy of theoretical models used to analyse the data. Here, by using the L-Galaxies semi-analytical model run over the Millennium-XXL N-body simulation, we assess the impact of galaxy formation on satellite kinematics and the theoretical modelling of redshift-space distortions. We show that different galaxy selection criteria lead to noticeable differences in the radial distributions and velocity structure of satellite galaxies. Specifically, whereas samples of stellar mass selected galaxies feature satellites that roughly follow the dark matter, emission line satellite galaxies are located preferentially in the outskirts of haloes and display net infall velocities. We demonstrate that capturing these differences is crucial for modelling the multipoles of the correlation function in redshift space, even on large scales. In particular, we show how modelling small-scale velocities with a single Gaussian distribution leads to a poor description of the measured clustering. In contrast, we propose a parametrization that is flexible enough to model the satellite kinematics and that leads to an accurate description of the correlation function down to sub-Mpc scales. We anticipate that our model will be a necessary ingredient in improved theoretical descriptions of redshift-space distortions, which together could result in significantly tighter cosmological constraints and a more optimal exploitation of future large data sets.

THE DETECTION AND STATISTICS OF GIANT ARCS BEHIND CLASH CLUSTERS

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

Xu, Bingxiao; Zheng, Wei; Postman, Marc

We developed an algorithm to find and characterize gravitationally lensed galaxies (arcs) to perform a comparison of the observed and simulated arc abundance. Observations are from the Cluster Lensing And Supernova survey with Hubble (CLASH). Simulated CLASH images are created using the MOKA package and also clusters selected from the high-resolution, hydrodynamical simulations, MUSIC, over the same mass and redshift range as the CLASH sample. The algorithm's arc elongation accuracy, completeness, and false positive rate are determined and used to compute an estimate of the true arc abundance. We derive a lensing efficiency of 4 ± 1 arcs (with length ≥6″ andmore » length-to-width ratio ≥7) per cluster for the X-ray-selected CLASH sample, 4 ± 1 arcs per cluster for the MOKA-simulated sample, and 3 ± 1 arcs per cluster for the MUSIC-simulated sample. The observed and simulated arc statistics are in full agreement. We measure the photometric redshifts of all detected arcs and find a median redshift z{sub s} = 1.9 with 33% of the detected arcs having z{sub s} > 3. We find that the arc abundance does not depend strongly on the source redshift distribution but is sensitive to the mass distribution of the dark matter halos (e.g., the c–M relation). Our results show that consistency between the observed and simulated distributions of lensed arc sizes and axial ratios can be achieved by using cluster-lensing simulations that are carefully matched to the selection criteria used in the observations.« less

Redshifted and blueshifted photoluminescence emission of InAs/InP quantum dots upon amorphization of phase change material.

PubMed

Humam, Nurrul Syafawati Binti; Sato, Yu; Takahashi, Motoki; Kanazawa, Shohei; Tsumori, Nobuhiro; Regreny, Philippe; Gendry, Michel; Saiki, Toshiharu

2014-06-16

We present the mechanisms underlying the redshifted and blueshifted photoluminescence (PL) of quantum dots (QDs) upon amorphization of phase change material (PCM). We calculated the stress and energy shift distribution induced by volume expansion using finite element method. Simulation result reveals that redshift is obtained beneath the flat part of amorphous mark, while blueshift is obtained beneath the edge region of amorphous mark. Simulation result is accompanied by two experimental studies; two-dimensional PL intensity mapping of InAs/InP QD sample deposited by a layer of PCM, and an analysis on the relationship between PL intensity ratio and energy shift were performed.

Galaxy power spectrum in redshift space: Combining perturbation theory with the halo model

DOE PAGES

Okumura, Teppei; Hand, Nick; Seljak, Uros; ...

2015-11-19

Theoretical modeling of the redshift-space power spectrum of galaxies is crucially important to correctly extract cosmological information from galaxy redshift surveys. The task is complicated by the nonlinear biasing and redshift space distortion (RSD) effects, which change with halo mass, and by the wide distribution of halo masses and their occupations by galaxies. One of the main modeling challenges is the existence of satellite galaxies that have both radial distribution inside the halos and large virial velocities inside halos, a phenomenon known as the Finger-of-God (FoG) effect. We present a model for the redshift-space power spectrum of galaxies in whichmore » we decompose a given galaxy sample into central and satellite galaxies and relate different contributions to the power spectrum to 1-halo and 2-halo terms in a halo model. Our primary goal is to ensure that any parameters that we introduce have physically meaningful values, and are not just fitting parameters. For the lowest order 2-halo terms we use the previously developed RSD modeling of halos in the context of distribution function and perturbation theory approach. This term needs to be multiplied by the effect of radial distances and velocities of satellites inside the halo. To this one needs to add the 1-halo terms, which are nonperturbative. We show that the real space 1-halo terms can be modeled as almost constant, with the finite extent of the satellites inside the halo inducing a small k 2R 2 term over the range of scales of interest, where R is related to the size of the halo given by its halo mass. Furthermore, we adopt a similar model for FoG in redshift space, ensuring that FoG velocity dispersion is related to the halo mass. For FoG k 2 type expansions do not work over the range of scales of interest and FoG resummation must be used instead. We test several simple damping functions to model the velocity dispersion FoG effect. Applying the formalism to mock galaxies modeled after the “CMASS” sample of the BOSS survey, we find that our predictions for the redshift-space power spectra are accurate up to k ≃ 0.4 h Mpc –1 within 1% if the halo power spectrum is measured using N-body simulations and within 3% if it is modeled using perturbation theory.« less

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

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

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

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

Non-gaussianity versus nonlinearity of cosmological perturbations.

PubMed

Verde, L

2001-06-01

Following the discovery of the cosmic microwave background, the hot big-bang model has become the standard cosmological model. In this theory, small primordial fluctuations are subsequently amplified by gravity to form the large-scale structure seen today. Different theories for unified models of particle physics, lead to different predictions for the statistical properties of the primordial fluctuations, that can be divided in two classes: gaussian and non-gaussian. Convincing evidence against or for gaussian initial conditions would rule out many scenarios and point us toward a physical theory for the origin of structures. The statistical distribution of cosmological perturbations, as we observe them, can deviate from the gaussian distribution in several different ways. Even if perturbations start off gaussian, nonlinear gravitational evolution can introduce non-gaussian features. Additionally, our knowledge of the Universe comes principally from the study of luminous material such as galaxies, but galaxies might not be faithful tracers of the underlying mass distribution. The relationship between fluctuations in the mass and in the galaxies distribution (bias), is often assumed to be local, but could well be nonlinear. Moreover, galaxy catalogues use the redshift as third spatial coordinate: the resulting redshift-space map of the galaxy distribution is nonlinearly distorted by peculiar velocities. Nonlinear gravitational evolution, biasing, and redshift-space distortion introduce non-gaussianity, even in an initially gaussian fluctuation field. I investigate the statistical tools that allow us, in principle, to disentangle the above different effects, and the observational datasets we require to do so in practice.

The Herschel Multi-Tiered Extragalactic Survey: SPIRE-mm Photometric Redshifts

NASA Technical Reports Server (NTRS)

Roseboom, I. G.; Ivison, R. J.; Greve, T. R.; Amblard, A.; Arumugam, V.; Auld, R.; Aussel, H.; Bethermin, M.; Blain, A.; Block, J.;

Photometric Redshifts with the LSST: Evaluating Survey Observing Strategies

NASA Astrophysics Data System (ADS)

Graham, Melissa L.; Connolly, Andrew J.; Ivezić, Željko; Schmidt, Samuel J.; Jones, R. Lynne; Jurić, Mario; Daniel, Scott F.; Yoachim, Peter

2018-01-01

In this paper we present and characterize a nearest-neighbors color-matching photometric redshift estimator that features a direct relationship between the precision and accuracy of the input magnitudes and the output photometric redshifts. This aspect makes our estimator an ideal tool for evaluating the impact of changes to LSST survey parameters that affect the measurement errors of the photometry, which is the main motivation of our work (i.e., it is not intended to provide the “best” photometric redshifts for LSST data). We show how the photometric redshifts will improve with time over the 10 year LSST survey and confirm that the nominal distribution of visits per filter provides the most accurate photo-z results. The LSST survey strategy naturally produces observations over a range of airmass, which offers the opportunity of using an SED- and z-dependent atmospheric affect on the observed photometry as a color-independent redshift indicator. We show that measuring this airmass effect and including it as a prior has the potential to improve the photometric redshifts and can ameliorate extreme outliers, but that it will only be adequately measured for the brightest galaxies, which limits its overall impact on LSST photometric redshifts. We furthermore demonstrate how this airmass effect can induce a bias in the photo-z results, and caution against survey strategies that prioritize high-airmass observations for the purpose of improving this prior. Ultimately, we intend for this work to serve as a guide for the expectations and preparations of the LSST science community with regard to the minimum quality of photo-z as the survey progresses.

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

Kruehler, Thomas; Malesani, Daniele; Milvang-Jensen, Bo

We present simultaneous optical and near-infrared (NIR) spectroscopy of 19 Swift {gamma}-ray burst (GRB) host galaxies observed with the VLT/X-shooter with the aim of measuring their redshifts. Galaxies were selected from The Optically Unbiased GRB Host (TOUGH) survey (15 of the 19 galaxies) or because they hosted GRBs without a bright optical afterglow. Here we provide emission-line redshifts for 13 of the observed galaxies with brightnesses between F606W > 27 mag and R = 22.9 mag (median R-tilde =24.6 mag). The median redshift is z-tilde =2.1 for all hosts and z-tilde =2.3 for the TOUGH hosts. Our new data significantlymore » improve the redshift completeness of the TOUGH survey, which now stands at 77% (53 out of 69 GRBs). They furthermore provide accurate redshifts for nine prototype dark GRBs (e.g., GRB 071021 at z = 2.452 and GRB 080207 at z = 2.086), which are exemplary of GRBs where redshifts are challenging to obtain via afterglow spectroscopy. This establishes X-shooter spectroscopy as an efficient tool for redshift determination of faint, star-forming, high-redshift galaxies such as GRB hosts. It is hence a further step toward removing the bias in GRB samples that is caused by optically dark events, and provides the basis for a better understanding of the conditions in which GRBs form. The distribution of column densities as measured from X-ray data (N{sub H,X}), for example, is closely related to the darkness of the afterglow and skewed toward low N{sub H,X} values in samples that are dominated by bursts with bright optical afterglows.« less

Kron 3: a fourth intermediate age cluster in the SMC with evidence of multiple populations

NASA Astrophysics Data System (ADS)

Hollyhead, K.; Lardo, C.; Kacharov, N.; Bastian, N.; Hilker, M.; Rejkuba, M.; Koch, A.; Grebel, E. K.; Georgiev, I.

2018-05-01

We present the results of a spectroscopic study of the intermediate age (≈6.5 Gyr) massive cluster Kron 3 in the Small Magellanic Cloud. We measure CN and CH band strengths (at ≃3839 and 4300 Å, respectively) using VLT FORS2 spectra of 16 cluster members and find a sub-population of five stars enriched in nitrogen. We conclude that this is evidence for multiple populations in Kron 3, the fourth intermediate age cluster, after Lindsay 1, NGC 416 and NGC 339 (ages 6-8 Gyr), to display this phenomenon originally thought to be a unique characteristic of old globular clusters. At ≈6.5 Gyr this is one of the youngest clusters with multiple populations, indicating that the mechanism responsible for their onset must operate until a redshift of at least 0.75, much later than the peak of globular cluster formation at redshift ˜3.

Network analysis of the COSMOS galaxy field

NASA Astrophysics Data System (ADS)

de Regt, R.; Apunevych, S.; von Ferber, C.; Holovatch, Yu; Novosyadlyj, B.

2018-07-01

The galaxy data provided by COSMOS survey for 1°×1° field of sky are analysed by methods of complex networks. Three galaxy samples (slices) with redshifts ranging within intervals 0.88÷0.91, 0.91÷0.94, and 0.94÷0.97 are studied as two-dimensional projections for the spatial distributions of galaxies. We construct networks and calculate network measures for each sample, in order to analyse the network similarity of different samples, distinguish various topological environments, and find associations between galaxy properties (colour index and stellar mass) and their topological environments. Results indicate a high level of similarity between geometry and topology for different galaxy samples and no clear evidence of evolutionary trends in network measures. The distribution of local clustering coefficient C manifests three modes which allow for discrimination between stand-alone singlets and dumbbells (0 ≤ C ≤ 0.1), intermediately packed (0.1 < C < 0.9) and clique (0.9 ≤ C ≤ 1) like galaxies. Analysing astrophysical properties of galaxies (colour index and stellar masses), we show that distributions are similar in all slices, however weak evolutionary trends can also be seen across redshift slices. To specify different topological environments, we have extracted selections of galaxies from each sample according to different modes of C distribution. We have found statistically significant associations between evolutionary parameters of galaxies and selections of C: the distribution of stellar mass for galaxies with interim C differs from the corresponding distributions for stand-alone and clique galaxies, and this difference holds for all redshift slices. The colour index realizes somewhat different behaviour.

Network analysis of the COSMOS galaxy field

NASA Astrophysics Data System (ADS)

de Regt, R.; Apunevych, S.; Ferber, C. von; Holovatch, Yu; Novosyadlyj, B.

2018-03-01

The galaxy data provided by COSMOS survey for 1° × 1° field of sky are analysed by methods of complex networks. Three galaxy samples (slices) with redshifts ranging within intervals 0.88÷0.91, 0.91÷0.94 and 0.94÷0.97 are studied as two-dimensional projections for the spatial distributions of galaxies. We construct networks and calculate network measures for each sample, in order to analyse the network similarity of different samples, distinguish various topological environments, and find associations between galaxy properties (colour index and stellar mass) and their topological environments. Results indicate a high level of similarity between geometry and topology for different galaxy samples and no clear evidence of evolutionary trends in network measures. The distribution of local clustering coefficient C manifests three modes which allow for discrimination between stand-alone singlets and dumbbells (0 ≤ C ≤ 0.1), intermediately packed (0.1 < C < 0.9) and clique (0.9 ≤ C ≤ 1) like galaxies. Analysing astrophysical properties of galaxies (colour index and stellar masses), we show that distributions are similar in all slices, however weak evolutionary trends can also be seen across redshift slices. To specify different topological environments we have extracted selections of galaxies from each sample according to different modes of C distribution. We have found statistically significant associations between evolutionary parameters of galaxies and selections of C: the distribution of stellar mass for galaxies with interim C differ from the corresponding distributions for stand-alone and clique galaxies, and this difference holds for all redshift slices. The colour index realises somewhat different behaviour.

High-redshift Luminous Red Galaxies clustering analysis in SDSS Stripe82

NASA Astrophysics Data System (ADS)

Nikoloudakis, N.

2012-01-01

We have measured the clustering of Luminous Red Galaxies in Stripe 82 using the angular correlation function. We have selected 130000 LRGs via colour cuts in R-I:I-K with the K band data coming from UKIDSS LAS. We have used the cross-correlation technique of Newman (2008) to establish the redshift distribution of the LRGs as a function of colour cut, cross-correlating the LRGs with SDSS QSOs, DEEP2 and VVDS galaxies. We also used the AUS LRG redshift survey to establish the n(z) at z<1. We then compare the w(theta) results to the results of Sawangwit et al (2010) from 3 samples of SDSS LRGs at lower redshift to measure the dependence of clustering on redshift and LRG luminosity. We have compared the results for luminosity-matched LRG samples with simple evolutionary models, such as those expected from long-lived, passive models for LRGs and for the HOD models of Wake et al (2009) and find that the long-lived model may be a poorer fit than at lower redshifts. We find some evidence for evolution in the LRG correlation function slope in that the 2-halo term appears to flatten in slope at z>1. We present arguments that this is not caused by systematics.

Multipole analysis of redshift-space distortions around cosmic voids

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

Hamaus, Nico; Weller, Jochen; Cousinou, Marie-Claude

We perform a comprehensive redshift-space distortion analysis based on cosmic voids in the large-scale distribution of galaxies observed with the Sloan Digital Sky Survey. To this end, we measure multipoles of the void-galaxy cross-correlation function and compare them with standard model predictions in cosmology. Merely considering linear-order theory allows us to accurately describe the data on the entire available range of scales and to probe void-centric distances down to about 2 h {sup −1}Mpc. Common systematics, such as the Fingers-of-God effect, scale-dependent galaxy bias, and nonlinear clustering do not seem to play a significant role in our analysis. We constrainmore » the growth rate of structure via the redshift-space distortion parameter β at two median redshifts, β( z-bar =0.32)=0.599{sup +0.134}{sub −0.124} and β( z-bar =0.54)=0.457{sup +0.056}{sub −0.054}, with a precision that is competitive with state-of-the-art galaxy-clustering results. While the high-redshift constraint perfectly agrees with model expectations, we observe a mild 2σ deviation at z-bar =0.32, which increases to 3σ when the data is restricted to the lowest available redshift range of 0.15< z <0.33.« less

The Hubble Space Telescope Cluster Supernova Survey. II. The Type la Supernova rate in high-redshift galaxy clusters

DOE PAGES

Barbary, K.; Aldering, G.; Amanullah, R.; ...

2011-12-28

Here we report a measurement of the Type Ia supernova (SN Ia) rate in galaxy clusters at 0.9 < z < 1.46 from the Hubble Space Telescope Cluster Supernova Survey. This is the first cluster SN Ia rate measurement with detected z > 0.9 SNe. Finding 8 ± 1 cluster SNe Ia, we determine an SN Ia rate of 0.50 +0.23 -0.19 (stat) +0.10 -0.09 (sys) h 2 70 SNuB (SNuB ≡ 10 -12 SNe L -1 ⊙,B yr -1). In units of stellar mass, this translates to 0.36 + 0.16 -0.13 (stat) +0.07 -0.06 (sys) h 2 70 SNuMmore » (SNuM ≡ 10 -12 SNe M –1 ⊙ yr –1). This represents a factor of ≈ 5 ± 2 increase over measurements of the cluster rate at z < 0.2. We parameterize the late-time SN Ia delay time distribution (DTD) with a power law: Ψ(t)∝t s . Under the approximation of a single-burst cluster formation redshift of zf = 3, our rate measurement in combination with lower-redshift cluster SN Ia rates constrains s = –1.41 +0.47 –0.40, consistent with measurements of the DTD in the field. This measurement is generally consistent with expectations for the "double degenerate" scenario and inconsistent with some models for the "single degenerate" scenario predicting a steeper DTD at large delay times. We check for environmental dependence and the influence of younger stellar populations by calculating the rate specifically in cluster red-sequence galaxies and in morphologically early-type galaxies, finding results similar to the full cluster rate. Finally, the upper limit of one hostless cluster SN Ia detected in the survey implies that the fraction of stars in the intra-cluster medium is less than 0.47 (95% confidence), consistent with measurements at lower redshifts.« less

Disentangling Redshift-Space Distortions and Nonlinear Bias using the 2D Power Spectrum

DOE PAGES

Jennings, Elise; Wechsler, Risa H.

2015-08-07

We present the nonlinear 2D galaxy power spectrum, P(k, µ), in redshift space, measured from the Dark Sky simulations, using galaxy catalogs constructed with both halo occupation distribution and subhalo abundance matching methods, chosen to represent an intermediate redshift sample of luminous red galaxies. We find that the information content in individual µ (cosine of the angle to the line of sight) bins is substantially richer then multipole moments, and show that this can be used to isolate the impact of nonlinear growth and redshift space distortion (RSD) effects. Using the µ < 0.2 simulation data, which we show ismore » not impacted by RSD effects, we can successfully measure the nonlinear bias to an accuracy of ~ 5% at k < 0.6hMpc-1 . This use of individual µ bins to extract the nonlinear bias successfully removes a large parameter degeneracy when constraining the linear growth rate of structure. We carry out a joint parameter estimation, using the low µ simulation data to constrain the nonlinear bias, and µ > 0.2 to constrain the growth rate and show that f can be constrained to ~ 26(22)% to a kmax < 0.4(0.6)hMpc-1 from clustering alone using a simple dispersion model, for a range of galaxy models. Our analysis of individual µ bins also reveals interesting physical effects which arise simply from different methods of populating halos with galaxies. We also find a prominent turnaround scale, at which RSD damping effects are greater then the nonlinear growth, which differs not only for each µ bin but also for each galaxy model. These features may provide unique signatures which could be used to shed light on the galaxy–dark matter connection. Furthermore, the idea of separating nonlinear growth and RSD effects making use of the full information in the 2D galaxy power spectrum yields significant improvements in constraining cosmological parameters and may be a promising probe of galaxy formation models.« less

Do Massive Galaxies at z~6 Present a Challenge for Hierarchical Merging?

NASA Astrophysics Data System (ADS)

Steinhardt, Charles L.; Capak, Peter L.; Masters, Daniel; Speagle, Josh S.; Splash

2015-01-01

The Spitzer Large Area Survey with Hyper-Suprime-Cam (SPLASH) recently released an initial view of the massive star-forming galaxy population at 4 < z < 6 over 1.8 square degrees. SPLASH found approximately 100 galaxy candidates with best-fit stellar masses over 10^11 solar. If even 10% of these are truly this massive and at such a high redshift, the corresponding number density would be inconsistent with the halo mass functions produced at these redshifts by numerical simulations. We will discuss these candidates, prospects for followup observations, and the potential implications for our understanding of the initial formation and early evolution of galaxies in the high-redshift universe.

GLACiAR: GaLAxy survey Completeness AlgoRithm

NASA Astrophysics Data System (ADS)

Carrasco, Daniela; Trenti, Michele; Mutch, Simon; Oesch, Pascal

2018-05-01

GLACiAR (GaLAxy survey Completeness AlgoRithm) estimates the completeness and selection functions in galaxy surveys. Tailored for multiband imaging surveys aimed at searching for high-redshift galaxies through the Lyman Break technique, the code can nevertheless be applied broadly. GLACiAR generates artificial galaxies that follow Sérsic profiles with different indexes and with customizable size, redshift and spectral energy distribution properties, adds them to input images, and measures the recovery rate.

The VIMOS Public Extragalactic Redshift Survey (VIPERS). The matter density and baryon fraction from the galaxy power spectrum at redshift 0.6 < z < 1.1

NASA Astrophysics Data System (ADS)

Rota, S.; Granett, B. R.; Bel, J.; Guzzo, L.; Peacock, J. A.; Wilson, M. J.; Pezzotta, A.; de la Torre, S.; Garilli, B.; Bolzonella, M.; Scodeggio, M.; Abbas, U.; Adami, C.; Bottini, D.; Cappi, A.; Cucciati, O.; Davidzon, I.; Franzetti, P.; Fritz, A.; Iovino, A.; Krywult, J.; Le Brun, V.; Le Fèvre, O.; Maccagni, D.; Małek, K.; Marulli, F.; Percival, W. J.; Polletta, M.; Pollo, A.; Tasca, L. A. M.; Tojeiro, R.; Vergani, D.; Zanichelli, A.; Arnouts, S.; Branchini, E.; Coupon, J.; De Lucia, G.; Ilbert, O.; Moscardini, L.; Moutard, T.

2017-05-01

We use the final catalogue of the VIMOS Public Extragalactic Redshift Survey (VIPERS) to measure the power spectrum of the galaxy distribution at high redshift, presenting results that extend beyond z = 1 for the first time. We apply a fast Fourier transform technique to four independent subvolumes comprising a total of 51 728 galaxies at 0.6 < z < 1.1 (out of the nearly 90 000 included in the whole survey). We concentrate here on the shape of the direction-averaged power spectrum in redshift space, explaining the level of modelling of redshift-space anisotropies and the anisotropic survey window function that are needed to deduce this in a robust fashion. We then use covariance matrices derived from a large ensemble of mock datasets in order to fit the spectral data. The results are well matched by a standard ΛCDM model, with density parameter ΩM h = 0.227+0.063-0.050 and baryon fraction fB=ΩB/ΩM=0.220+0.058-0.072. These inferences from the high-z galaxy distribution are consistent with results from local galaxy surveys, and also with the cosmic microwave background. Thus the ΛCDM model gives a good match to cosmic structure at all redshifts currently accessible to observational study. Based on observations collected at the European Southern Observatory, Cerro Paranal, Chile, using the Very Large Telescope under programmes 182.A-0886 and partly under programme 070.A-9007. Also based on observations obtained with MegaPrime/MegaCam, a joint project of CFHT and CEA/DAPNIA, at the Canada-France-Hawaii Telescope (CFHT), which is operated by the National Research Council (NRC) of Canada, the Institut National des Sciences de l'Univers of the Centre National de la Recherche Scientifique (CNRS) of France, and the University of Hawaii. This work is based in part on data products produced at TERAPIX and the Canadian Astronomy Data Centre as part of the Canada-France-Hawaii Telescope Legacy Survey, a collaborative project of NRC and CNRS. The VIPERS web site is http://www.vipers.inaf.it/

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

Goldstein, Adam; Connaughton, Valerie; Briggs, Michael S.

We present a method to estimate the jet opening angles of long duration gamma-ray bursts (GRBs) using the prompt gamma-ray energetics and an inversion of the Ghirlanda relation, which is a correlation between the time-integrated peak energy of the GRB prompt spectrum and the collimation-corrected energy in gamma-rays. The derived jet opening angles using this method and detailed assumptions match well with the corresponding inferred jet opening angles obtained when a break in the afterglow is observed. Furthermore, using a model of the predicted long GRB redshift probability distribution observable by the Fermi Gamma-ray Burst Monitor (GBM), we estimate themore » probability distributions for the jet opening angle and rest-frame energetics for a large sample of GBM GRBs for which the redshifts have not been observed. Previous studies have only used a handful of GRBs to estimate these properties due to the paucity of observed afterglow jet breaks, spectroscopic redshifts, and comprehensive prompt gamma-ray observations, and we potentially expand the number of GRBs that can be used in this analysis by more than an order of magnitude. In this analysis, we also present an inferred distribution of jet breaks which indicates that a large fraction of jet breaks are not observable with current instrumentation and observing strategies. We present simple parameterizations for the jet angle, energetics, and jet break distributions so that they may be used in future studies.« less

The kinematics of dense clusters of galaxies. II - The distribution of velocity dispersions

NASA Technical Reports Server (NTRS)

Zabludoff, Ann I.; Geller, Margaret J.; Huchra, John P.; Ramella, Massimo

1993-01-01

From the survey of 31 Abell R above 1 cluster fields within z of 0.02-0.05, we extract 25 dense clusters with velocity dispersions omicron above 300 km/s and with number densities exceeding the mean for the Great Wall of galaxies by one deviation. From the CfA Redshift Survey (in preparation), we obtain an approximately volume-limited catalog of 31 groups with velocity dispersions above 100 km/s and with the same number density limit. We combine these well-defined samples to obtain the distribution of cluster velocity dispersions. The group sample enables us to correct for incompleteness in the Abell catalog at low velocity dispersions. The clusters from the Abell cluster fields populate the high dispersion tail. For systems with velocity dispersions above 700 km/s, approximately the median for R = 1 clusters, the group and cluster abundances are consistent. The combined distribution is consistent with cluster X-ray temperature functions.

Stellar binary black holes in the LISA band: a new class of standard sirens

NASA Astrophysics Data System (ADS)

Del Pozzo, Walter; Sesana, Alberto; Klein, Antoine

2018-04-01

The recent Advanced LIGO detections of coalescing black hole binaries (BHBs) imply a large population of such systems emitting at milli-Hz frequencies, accessible to the Laser Interferometer Space Antenna (LISA). We show that these systems provide a new class of cosmological standard sirens. Direct LISA luminosity distance - Dl - measurements, combined with the inhomogeneous redshift - z - distribution of possible host galaxies provide an effective way to populate the Dl-z diagram at z < 0.1, thus allowing a precise local measurement of the Hubble expansion rate. To be effective, the method requires a sufficiently precise LISA distance determination and sky localization of a sizeable number of BHBs, which is best achieved for a six-link detector configuration. We find that, for a BHB population consistent with current fiducial LIGO rates, the Hubble constant H0 can be determined at the ˜5 per cent and ˜2 per cent level (68 per cent confidence), assuming two and five million kilometre arm-length, respectively.

The Reddening Curve below 1200 Angstroms.

NASA Astrophysics Data System (ADS)

Wofford, Aida; Leitherer, C.

2012-05-01

Thirty percent of the bolometric luminosity of star-forming galaxies is emitted in the wavelength range between 912 and 1200 Å. This wavelength range carries information about the stellar mass distribution and the star formation rate of the newly formed populations of massive (M > 8 M_sun) stars in these galaxies, and about the leakage of Lyman-continuum photons from these galaxies. This is also the wavelength range where the reddening curve peaks, and where our understanding of the reddening curve is the most fragmentary. We present preliminary results from a spectroscopic study aimed to characterize the reddening curve below 1200 Å. Our project is based on the analysis of archival HUT (830-1850 Å), FUSE (905-1187 Å), IUE (1150-3200 Å), and HST (1200-3200 Å) data of a sample of 70 low-redshift (z<0.1) star-forming galaxies, using synthetic spectra of stellar populations plus the ISM. The stellar population and nebula models were generated with STARBURST99 and CLOUDY, respectively. This work is supported by NASA J1401.

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

Sonnenfeld, Alessandro; Treu, Tommaso; Marshall, Philip J.

Here, we investigate the cosmic evolution of the internal structure of massive early-type galaxies over half of the age of the universe. We also perform a joint lensing and stellar dynamics analysis of a sample of 81 strong lenses from the Strong Lensing Legacy Survey and Sloan ACS Lens Survey and combine the results with a hierarchical Bayesian inference method to measure the distribution of dark matter mass and stellar initial mass function (IMF) across the population of massive early-type galaxies. Lensing selection effects are taken into account. Furthermore, we found that the dark matter mass projected within the innermore » 5 kpc increases for increasing redshift, decreases for increasing stellar mass density, but is roughly constant along the evolutionary tracks of early-type galaxies. The average dark matter slope is consistent with that of a Navarro-Frenk-White profile, but is not well constrained. The stellar IMF normalization is close to a Salpeter IMF at log M * = 11.5 and scales strongly with increasing stellar mass. No dependence of the IMF on redshift or stellar mass density is detected. The anti-correlation between dark matter mass and stellar mass density supports the idea of mergers being more frequent in more massive dark matter halos.« less

The Vimos VLT deep survey. Global properties of 20,000 galaxies in the IAB < 22.5 WIDE survey

NASA Astrophysics Data System (ADS)

Garilli, B.; Le Fèvre, O.; Guzzo, L.; Maccagni, D.; Le Brun, V.; de la Torre, S.; Meneux, B.; Tresse, L.; Franzetti, P.; Zamorani, G.; Zanichelli, A.; Gregorini, L.; Vergani, D.; Bottini, D.; Scaramella, R.; Scodeggio, M.; Vettolani, G.; Adami, C.; Arnouts, S.; Bardelli, S.; Bolzonella, M.; Cappi, A.; Charlot, S.; Ciliegi, P.; Contini, T.; Foucaud, S.; Gavignaud, I.; Ilbert, O.; Iovino, A.; Lamareille, F.; McCracken, H. J.; Marano, B.; Marinoni, C.; Mazure, A.; Merighi, R.; Paltani, S.; Pellò, R.; Pollo, A.; Pozzetti, L.; Radovich, M.; Zucca, E.; Blaizot, J.; Bongiorno, A.; Cucciati, O.; Mellier, Y.; Moreau, C.; Paioro, L.

2008-08-01

The VVDS-Wide survey has been designed to trace the large-scale distribution of galaxies at z ~ 1 on comoving scales reaching ~100~h-1 Mpc, while providing a good control of cosmic variance over areas as large as a few square degrees. This is achieved by measuring redshifts with VIMOS at the ESO VLT to a limiting magnitude IAB = 22.5, targeting four independent fields with sizes of up to 4 deg2 each. We discuss the survey strategy which covers 8.6 deg2 and present the general properties of the current redshift sample. This includes 32 734 spectra in the four regions, covering a total area of 6.1 deg2 with a sampling rate of 22 to 24%. This paper accompanies the public release of the first 18 143 redshifts of the VVDS-Wide survey from the 4 deg2 contiguous area of the F22 field at RA = 22^h. We have devised and tested an objective method to assess the quality of each spectrum, providing a compact figure-of-merit. This is particularly effective in the case of long-lasting spectroscopic surveys with varying observing conditions. Our figure of merit is a measure of the robustness of the redshift measurement and, most importantly, can be used to select galaxies with uniform high-quality spectra to carry out reliable measurements of spectral features. We also use the data available over the four independent regions to directly measure the variance in galaxy counts. We compare it with general predictions from the observed galaxy two-point correlation function at different redshifts and with that measured in mock galaxy surveys built from the Millennium simulation. The purely magnitude-limited VVDS Wide sample includes 19 977 galaxies, 304 type I AGNs, and 9913 stars. The redshift success rate is above 90% independent of magnitude. A cone diagram of the galaxy spatial distribution provides us with the current largest overview of large-scale structure up to z ~ 1, showing a rich texture of over- and under-dense regions. We give the mean N(z) distribution averaged over 6.1 deg2 for a sample limited in magnitude to IAB = 22.5. Comparing galaxy densities from the four fields shows that in a redshift bin Δz = 0.1 at z ~ 1 one still has factor-of-two variations over areas as large as ~ 0.25 deg2. This level of cosmic variance agrees with that obtained by integrating the galaxy two-point correlation function estimated from the F22 field alone. It is also in fairly good statistical agreement with that predicted by the Millennium simulations. The VVDS WIDE survey currently provides the largest area coverage among redshift surveys reaching z ~ 1. The variance estimated over the survey fields shows explicitly how clustering results from deep surveys of even 1 deg2 size should be interpreted with caution. The survey data represent a rich data base to select complete sub-samples of high-quality spectra and to study galaxy ensemble properties and galaxy clustering over unprecedented scales at these redshifts. The redshift catalog of the 4 deg2 F22 field is publicly available at http://cencosw.oamp.fr.

Exploring the early dust-obscured phase of galaxy formation with blind mid-/far-infrared spectroscopic surveys

NASA Astrophysics Data System (ADS)

Bonato, M.; Negrello, M.; Cai, Z.-Y.; De Zotti, G.; Bressan, A.; Lapi, A.; Gruppioni, C.; Spinoglio, L.; Danese, L.

2014-03-01

While continuum imaging data at far-infrared to submillimetre wavelengths have provided tight constraints on the population properties of dusty star-forming galaxies up to high redshifts, future space missions like the Space Infrared Telescope for Cosmology and Astrophysics (SPICA) and ground-based facilities like the Cerro Chajnantor Atacama Telescope (CCAT) will allow detailed investigations of their physical properties via their mid-/far-infrared line emission. We present updated predictions for the number counts and the redshift distributions of star-forming galaxies spectroscopically detectable by these future missions. These predictions exploit a recent upgrade of evolutionary models, that include the effect of strong gravitational lensing, in the light of the most recent Herschel and South Pole Telescope data. Moreover the relations between line and continuum infrared luminosity are re-assessed, considering also differences among source populations, with the support of extensive simulations that take into account dust obscuration. The derived line luminosity functions are found to be highly sensitive to the spread of the line to continuum luminosity ratios. Estimates of the expected numbers of detections per spectral line by SPICA/SpicA FAR-infrared Instrument (SAFARI) and by CCAT surveys for different integration times per field of view at fixed total observing time are presented. Comparing with the earlier estimates by Spinoglio et al. we find, in the case of SPICA/SAFARI, differences within a factor of 2 in most cases, but occasionally much larger. More substantial differences are found for CCAT.

THE ROLE OF QUENCHING TIME IN THE EVOLUTION OF THE MASS–SIZE RELATION OF PASSIVE GALAXIES FROM THE WISP SURVEY

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

Zanella, A.; Scarlata, C.; Rutkowski, M. J.

2016-06-20

We analyze how passive galaxies at z ∼ 1.5 populate the mass–size plane as a function of their stellar age, to understand if the observed size growth with time can be explained with the appearance of larger quenched galaxies at lower redshift. We use a sample of 32 passive galaxies extracted from the Wide Field Camera 3 Infrared Spectroscopic Parallel (WISP) survey with spectroscopic redshift 1.3 ≲ z ≲ 2.05, specific star formation rates lower than 0.01 Gyr{sup −1}, and stellar masses above 4.5 × 10{sup 10} M {sub ⊙}. All galaxies have spectrally determined stellar ages from fitting ofmore » their rest-frame optical spectra and photometry with stellar population models. When dividing our sample into young (age ≤2.1 Gyr) and old (age >2.1 Gyr) galaxies we do not find a significant trend in the distributions of the difference between the observed radius and that predicted by the mass–size relation. This result indicates that the relation between the galaxy age and its distance from the mass–size relation, if it exists, is rather shallow, with a slope α ≳ −0.6. At face value, this finding suggests that multiple dry and/or wet minor mergers, rather than the appearance of newly quenched galaxies, are mainly responsible for the observed time evolution of the mass–size relation in passive galaxies.« less

ORIGIN: Metal Creation and Evolution From The Cosmic Dawn

NASA Astrophysics Data System (ADS)

Piro, L.; den Herder, J. W.; Ohashi, T.; Hartmann, D. H.; Kouveliotou, C.

2011-08-01

ORIGIN is a mission designed to use Gamma-Ray Bursts as a unique probe to study the cosmic history of baryons and the metal enrichment from the first stars up to the present Universe. Reconstructing the cosmic history of metals, from the first population of stars to the processes involved in the formation of galaxies and clusters of galaxies, is a key observational challenge. Observing any single star in the early Universe is in fact beyond the reach of presently planned mission. By measuring GRB redshifts and abundances in the circumburst medium deep into the era of re-ionization (z>6), ORIGIN will discover when star formation started and how it evolved into the present day structures. ORIGIN will collect 400 GRBs per year covering the full redshift distribution. About twice per month a GRB from the re-ionization era will trigger the instruments. The resulting multi-element abundance patterns derived from high resolution X-ray and IR observations will map the evolving chemical composition of the early Universe, ``fingerprint'' the elusive PopIII stars, and constrain the shape of the Initial Mass Function (IMF) of the first stars. While not observing GRB afterglows, ORIGIN will map element abundances in local structures (z<2) by determining the properties of the hot IGM in clusters and groups of galaxies and the Warm-Hot Intergalactic Medium (WHIM). In this paper we focus on the use of GRB to track the earliest star populations.

Galaxy And Mass Assembly (GAMA): spectroscopic analysis

NASA Astrophysics Data System (ADS)

Hopkins, A. M.; Driver, S. P.; Brough, S.; Owers, M. S.; Bauer, A. E.; Gunawardhana, M. L. P.; Cluver, M. E.; Colless, M.; Foster, C.; Lara-López, M. A.; Roseboom, I.; Sharp, R.; Steele, O.; Thomas, D.; Baldry, I. K.; Brown, M. J. I.; Liske, J.; Norberg, P.; Robotham, A. S. G.; Bamford, S.; Bland-Hawthorn, J.; Drinkwater, M. J.; Loveday, J.; Meyer, M.; Peacock, J. A.; Tuffs, R.; Agius, N.; Alpaslan, M.; Andrae, E.; Cameron, E.; Cole, S.; Ching, J. H. Y.; Christodoulou, L.; Conselice, C.; Croom, S.; Cross, N. J. G.; De Propris, R.; Delhaize, J.; Dunne, L.; Eales, S.; Ellis, S.; Frenk, C. S.; Graham, Alister W.; Grootes, M. W.; Häußler, B.; Heymans, C.; Hill, D.; Hoyle, B.; Hudson, M.; Jarvis, M.; Johansson, J.; Jones, D. H.; van Kampen, E.; Kelvin, L.; Kuijken, K.; López-Sánchez, Á.; Maddox, S.; Madore, B.; Maraston, C.; McNaught-Roberts, T.; Nichol, R. C.; Oliver, S.; Parkinson, H.; Penny, S.; Phillipps, S.; Pimbblet, K. A.; Ponman, T.; Popescu, C. C.; Prescott, M.; Proctor, R.; Sadler, E. M.; Sansom, A. E.; Seibert, M.; Staveley-Smith, L.; Sutherland, W.; Taylor, E.; Van Waerbeke, L.; Vázquez-Mata, J. A.; Warren, S.; Wijesinghe, D. B.; Wild, V.; Wilkins, S.

2013-04-01

The Galaxy And Mass Assembly (GAMA) survey is a multiwavelength photometric and spectroscopic survey, using the AAOmega spectrograph on the Anglo-Australian Telescope to obtain spectra for up to ˜300 000 galaxies over 280 deg2, to a limiting magnitude of rpet < 19.8 mag. The target galaxies are distributed over 0 < z ≲ 0.5 with a median redshift of z ≈ 0.2, although the redshift distribution includes a small number of systems, primarily quasars, at higher redshifts, up to and beyond z = 1. The redshift accuracy ranges from σv ≈ 50 km s-1 to σv ≈ 100 km s-1 depending on the signal-to-noise ratio of the spectrum. Here we describe the GAMA spectroscopic reduction and analysis pipeline. We present the steps involved in taking the raw two-dimensional spectroscopic images through to flux-calibrated one-dimensional spectra. The resulting GAMA spectra cover an observed wavelength range of 3750 ≲ λ ≲ 8850 Å at a resolution of R ≈ 1300. The final flux calibration is typically accurate to 10-20 per cent, although the reliability is worse at the extreme wavelength ends, and poorer in the blue than the red. We present details of the measurement of emission and absorption features in the GAMA spectra. These measurements are characterized through a variety of quality control analyses detailing the robustness and reliability of the measurements. We illustrate the quality of the measurements with a brief exploration of elementary emission line properties of the galaxies in the GAMA sample. We demonstrate the luminosity dependence of the Balmer decrement, consistent with previously published results, and explore further how Balmer decrement varies with galaxy mass and redshift. We also investigate the mass and redshift dependencies of the [N II]/Hα versus [O III]/Hβ spectral diagnostic diagram, commonly used to discriminate between star forming and nuclear activity in galaxies.

Groups of galaxies in the Center for Astrophysics redshift survey

NASA Technical Reports Server (NTRS)

Ramella, Massimo; Geller, Margaret J.; Huchra, John P.

1989-01-01

By applying the Huchra and Geller (1982) objective group identification algorithm to the Center for Astrophysics' redshift survey, a catalog of 128 groups with three or more members is extracted, and 92 of these are used as a statistical sample. A comparison of the distribution of group centers with the distribution of all galaxies in the survey indicates qualitatively that groups trace the large-scale structure of the region. The physical properties of groups may be related to the details of large-scale structure, and it is concluded that differences among group catalogs may be due to the properties of large-scale structures and their location relative to the survey limits.

A redshift survey of IRAS galaxies. V - The acceleration on the Local Group

NASA Technical Reports Server (NTRS)

Strauss, Michael A.; Yahil, Amos; Davis, Marc; Huchra, John P.; Fisher, Karl

1992-01-01

The acceleration on the Local Group is calculated based on a full-sky redshift survey of 5288 galaxies detected by IRAS. A formalism is developed to compute the distribution function of the IRAS acceleration for a given power spectrum of initial perturbations. The computed acceleration on the Local Group points 18-28 deg from the direction of the Local Group peculiar velocity vector. The data suggest that the CMB dipole is indeed due to the motion of the Local Group, that this motion is gravitationally induced, and that the distribution of IRAS galaxies on large scales is related to that of dark matter by a simple linear biasing model.

THE PRISM MULTI-OBJECT SURVEY (PRIMUS). I. SURVEY OVERVIEW AND CHARACTERISTICS

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

Coil, Alison L.; Moustakas, John; Aird, James

2011-11-01

We present the PRIsm MUlti-object Survey (PRIMUS), a spectroscopic faint galaxy redshift survey to z {approx} 1. PRIMUS uses a low-dispersion prism and slitmasks to observe {approx}2500 objects at once in a 0.18 deg{sup 2} field of view, using the Inamori Magellan Areal Camera and Spectrograph camera on the Magellan I Baade 6.5 m telescope at Las Campanas Observatory. PRIMUS covers a total of 9.1 deg{sup 2} of sky to a depth of i{sub AB} {approx} 23.5 in seven different deep, multi-wavelength fields that have coverage from the Galaxy Evolution Explorer, Spitzer, and either XMM or Chandra, as well asmore » multiple-band optical and near-IR coverage. PRIMUS includes {approx}130,000 robust redshifts of unique objects with a redshift precision of {sigma}{sub z}/(1 + z) {approx} 0.005. The redshift distribution peaks at z {approx} 0.6 and extends to z = 1.2 for galaxies and z = 5 for broad-line active galactic nuclei. The motivation, observational techniques, fields, target selection, slitmask design, and observations are presented here, with a brief summary of the redshift precision; a forthcoming paper presents the data reduction, redshift fitting, redshift confidence, and survey completeness. PRIMUS is the largest faint galaxy survey undertaken to date. The high targeting fraction ({approx}80%) and large survey size will allow for precise measures of galaxy properties and large-scale structure to z {approx} 1.« less

Evolution of the degree of substructures in simulated galaxy clusters

NASA Astrophysics Data System (ADS)

De Boni, Cristiano; Böhringer, Hans; Chon, Gayoung; Dolag, Klaus

2018-05-01

We study the evolution of substructure in the mass distribution with mass, redshift and radius in a sample of simulated galaxy clusters. The sample, containing 1226 objects, spans the mass range M200 = 1014 - 1.74 × 1015 M⊙ h-1 in six redshift bins from z = 0 to z = 1.179. We consider three different diagnostics: 1) subhalos identified with SUBFIND; 2) overdense regions localized by dividing the cluster into octants; 3) offset between the potential minimum and the center of mass. The octant analysis is a new method that we introduce in this work. We find that none of the diagnostics indicate a correlation between the mass of the cluster and the fraction of substructures. On the other hand, all the diagnostics suggest an evolution of substructures with redshift. For SUBFIND halos, the mass fraction is constant with redshift at Rvir, but shows a mild evolution at R200 and R500. Also, the fraction of clusters with at least a subhalo more massive than one thirtieth of the total mass is less than 20%. Our new method based on the octants returns a mass fraction in substructures which has a strong evolution with redshift at all radii. The offsets also evolve strongly with redshift. We also find a strong correlation for individual clusters between the offset and the fraction of substructures identified with the octant analysis. Our work puts strong constraints on the amount of substructures we expect to find in galaxy clusters and on their evolution with redshift.

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

Jester, Sebastian; Schneider, Donald P.; Richards, Gordon T.

The author investigates the extent to which the Palomar-Green (PG) Bright Quasar Survey (BQS) is complete and representative of the general quasar population by comparing with imaging and spectroscopy from the Sloan Digital Sky Survey. A comparison of SDSS and PG photometry of both stars and quasars reveals the need to apply a color and magnitude recalibration to the PG data. Using the SDSS photometric catalog, they define the PG's parent sample of objects that are not main-sequence stars and simulate the selection of objects from this parent sample using the PG photometric criteria and errors. This simulation shows thatmore » the effective U-B cut in the PG survey is U-B < -0.71, implying a color-related incompleteness. As the color distribution of bright quasars peaks near U-B = -0.7 and the 2-{sigma} error in U-B is comparable to the full width of the color distribution of quasars, the color incompleteness of the BQS is approximately 50% and essentially random with respect to U-B color for z < 0.5. There is however, a bias against bright quasars at 0.5 < z < 1, which is induced by the color-redshift relation of quasars (although quasars at z > 0.5 are inherently rare in bright surveys in any case). They find no evidence for any other systematic incompleteness when comparing the distributions in color, redshift, and FIRST radio properties of the BQS and a BQS-like subsample of the SDSS quasar sample. However, the application of a bright magnitude limit biases the BQS toward the inclusion of objects which are blue in g-i, in particular compared to the full range of g-i colors found among the i-band limited SDSS quasars, and even at i-band magnitudes comparable to those of the BQS objects.« less

Galaxy And Mass Assembly: the evolution of the cosmic spectral energy distribution from z = 1 to z = 0

NASA Astrophysics Data System (ADS)

Andrews, S. K.; Driver, S. P.; Davies, L. J. M.; Kafle, P. R.; Robotham, A. S. G.; Vinsen, K.; Wright, A. H.; Bland-Hawthorn, J.; Bourne, N.; Bremer, M.; da Cunha, E.; Drinkwater, M.; Holwerda, B.; Hopkins, A. M.; Kelvin, L. S.; Loveday, J.; Phillipps, S.; Wilkins, S.

2017-09-01

We present the evolution of the cosmic spectral energy distribution (CSED) from z = 1 to 0. Our CSEDs originate from stacking individual spectral energy distribution (SED) fits based on panchromatic photometry from the Galaxy And Mass Assembly (GAMA) and COSMOS data sets in 10 redshift intervals with completeness corrections applied. Below z = 0.45, we have credible SED fits from 100 nm to 1 mm. Due to the relatively low sensitivity of the far-infrared data, our far-infrared CSEDs contain a mix of predicted and measured fluxes above z = 0.45. Our results include appropriate errors to highlight the impact of these corrections. We show that the bolometric energy output of the Universe has declined by a factor of roughly 4 - from 5.1 ± 1.0 at z ˜ 1 to 1.3 ± 0.3 × 1035 h70 W Mpc-3 at the current epoch. We show that this decrease is robust to cosmic sample variance, the SED modelling and other various types of error. Our CSEDs are also consistent with an increase in the mean age of stellar populations. We also show that dust attenuation has decreased over the same period, with the photon escape fraction at 150 nm increasing from 16 ± 3 at z ˜ 1 to 24 ± 5 per cent at the current epoch, equivalent to a decrease in AFUV of 0.4 mag. Our CSEDs account for 68 ± 12 and 61 ± 13 per cent of the cosmic optical and infrared backgrounds, respectively, as defined from integrated galaxy counts and are consistent with previous estimates of the cosmic infrared background with redshift.

Detecting First Supernovae with JWST

NASA Astrophysics Data System (ADS)

Regos, Eniko; FLARE

2018-01-01

We have applied for a JWST ERS First Transients Survey, FLARE to answer empirically how the Universe made its first stars. To quest the epoch of reionization we target what happened to these first stars by observing the most luminous events, supernovae. These transients provide direct constraints on star formation rates and the initial mass function.These very rare events can be reached by JWST at 27 mag AB in 2 micron and 4.4 micron over a field of 0.1 square degree visited multiple times each year.The survey may detect massive Pop III SNe at redshifts up to 10, pinpointing the redshift of first stars, a key scientific goal of JWST.We explore all models of star formation history (derived from UV luminosity densities and IR data), DTD, top heavy IMF of early, low metallicity stars, and normalizations to data of SN Ia, II rates (SNLS, CLASH, CANDELS, SDSS, SVISS), as well as SLSN (ROTSE, SNLS) to estimate the expected SN rates as function of redshift.Population synthesis of double degenerate and single degenerate scenarios of SN Ia shows that the shape of the DTD is rather insensitive to the assumptions (common envelope prescription and metallicities, or retention efficiency of accreted H to white dwarf core and mass transfer rate).Indeed GOODS High z SN Ia rates imply substantial delay in their progenitor model, and Hubble Higher z SN search constrains delay time distribution models as well.SLSN (I, II /H/ and extreme rare pulsational pair instability) are magnetars (ULGRB) in high local star formation rate, faint, low metallicity galaxies.

CFHTLenS: co-evolution of galaxies and their dark matter haloes

NASA Astrophysics Data System (ADS)

Hudson, Michael J.; Gillis, Bryan R.; Coupon, Jean; Hildebrandt, Hendrik; Erben, Thomas; Heymans, Catherine; Hoekstra, Henk; Kitching, Thomas D.; Mellier, Yannick; Miller, Lance; Van Waerbeke, Ludovic; Bonnett, Christopher; Fu, Liping; Kuijken, Konrad; Rowe, Barnaby; Schrabback, Tim; Semboloni, Elisabetta; van Uitert, Edo; Velander, Malin

2015-02-01

Galaxy-galaxy weak lensing is a direct probe of the mean matter distribution around galaxies. The depth and sky coverage of the Canada-France-Hawaii Telescope Legacy Survey yield statistically significant galaxy halo mass measurements over a much wider range of stellar masses (108.75 to 1011.3 M⊙) and redshifts (0.2 < z < 0.8) than previous weak lensing studies. At redshift z ˜ 0.5, the stellar-to-halo mass ratio (SHMR) reaches a maximum of 4.0 ± 0.2 per cent as a function of halo mass at ˜1012.25 M⊙. We find, for the first time from weak lensing alone, evidence for significant evolution in the SHMR: the peak ratio falls as a function of cosmic time from 4.5 ± 0.3 per cent at z ˜ 0.7 to 3.4 ± 0.2 per cent at z ˜ 0.3, and shifts to lower stellar mass haloes. These evolutionary trends are dominated by red galaxies, and are consistent with a model in which the stellar mass above which star formation is quenched `downsizes' with cosmic time. In contrast, the SHMR of blue, star-forming galaxies is well fitted by a power law that does not evolve with time. This suggests that blue galaxies form stars at a rate that is balanced with their dark matter accretion in such a way that they evolve along the SHMR locus. The redshift dependence of the SHMR can be used to constrain the evolution of the galaxy population over cosmic time.

Demographics of Star-forming Galaxies since z ∼ 2.5. I. The UVJ Diagram in CANDELS

NASA Astrophysics Data System (ADS)

Fang, Jerome J.; Faber, S. M.; Koo, David C.; Rodríguez-Puebla, Aldo; Guo, Yicheng; Barro, Guillermo; Behroozi, Peter; Brammer, Gabriel; Chen, Zhu; Dekel, Avishai; Ferguson, Henry C.; Gawiser, Eric; Giavalisco, Mauro; Kartaltepe, Jeyhan; Kocevski, Dale D.; Koekemoer, Anton M.; McGrath, Elizabeth J.; McIntosh, Daniel; Newman, Jeffrey A.; Pacifici, Camilla; Pandya, Viraj; Pérez-González, Pablo G.; Primack, Joel R.; Salmon, Brett; Trump, Jonathan R.; Weiner, Benjamin; Willner, S. P.; Acquaviva, Viviana; Dahlen, Tomas; Finkelstein, Steven L.; Finlator, Kristian; Fontana, Adriano; Galametz, Audrey; Grogin, Norman A.; Gruetzbauch, Ruth; Johnson, Seth; Mobasher, Bahram; Papovich, Casey J.; Pforr, Janine; Salvato, Mara; Santini, P.; van der Wel, Arjen; Wiklind, Tommy; Wuyts, Stijn

2018-05-01

This is the first in a series of papers examining the demographics of star-forming (SF) galaxies at 0.2 < z < 2.5 in CANDELS. We study 9100 galaxies from GOODS-S and UDS, having published values of redshifts, masses, star formation rates (SFRs), and dust attenuation (A V ) derived from UV–optical spectral energy distribution fitting. In agreement with previous works, we find that the UVJ colors of a galaxy are closely correlated with its specific star formation rate (SSFR) and A V . We define rotated UVJ coordinate axes, termed S SED and C SED, that are parallel and perpendicular to the SF sequence and derive a quantitative calibration that predicts SSFR from C SED with an accuracy of ∼0.2 dex. SFRs from UV–optical fitting and from UV+IR values based on Spitzer/MIPS 24 μm agree well overall, but systematic differences of order 0.2 dex exist at high and low redshifts. A novel plotting scheme conveys the evolution of multiple galaxy properties simultaneously, and dust growth, as well as star formation decline and quenching, exhibit “mass-accelerated evolution” (“downsizing”). A population of transition galaxies below the SF main sequence is identified. These objects are located between SF and quiescent galaxies in UVJ space, and have lower A V and smaller radii than galaxies on the main sequence. Their properties are consistent with their being in transit between the two regions. The relative numbers of quenched, transition, and SF galaxies are given as a function of mass and redshift.

OPTICAL SPECTRA OF CANDIDATE INTERNATIONAL CELESTIAL REFERENCE FRAME (ICRF) FLAT-SPECTRUM RADIO SOURCES

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

Titov, O.; Stanford, Laura M.; Johnston, Helen M.

2013-07-01

Continuing our program of spectroscopic observations of International Celestial Reference Frame (ICRF) sources, we present redshifts for 120 quasars and radio galaxies. Data were obtained with five telescopes: the 3.58 m European Southern Observatory New Technology Telescope, the two 8.2 m Gemini telescopes, the 2.5 m Nordic Optical Telescope (NOT), and the 6.0 m Big Azimuthal Telescope of the Special Astrophysical Observatory in Russia. The targets were selected from the International VLBI Service for Geodesy and Astrometry candidate International Celestial Reference Catalog which forms part of an observational very long baseline interferometry (VLBI) program to strengthen the celestial reference frame.more » We obtained spectra of the potential optical counterparts of more than 150 compact flat-spectrum radio sources, and measured redshifts of 120 emission-line objects, together with 19 BL Lac objects. These identifications add significantly to the precise radio-optical frame tie to be undertaken by Gaia, due to be launched in 2013, and to the existing data available for analyzing source proper motions over the celestial sphere. We show that the distribution of redshifts for ICRF sources is consistent with the much larger sample drawn from Faint Images of the Radio Sky at Twenty cm (FIRST) and Sloan Digital Sky Survey, implying that the ultra-compact VLBI sources are not distinguished from the overall radio-loud quasar population. In addition, we obtained NOT spectra for five radio sources from the FIRST and NRAO VLA Sky Survey catalogs, selected on the basis of their red colors, which yielded three quasars with z > 4.« less

An HST/COS Survey of the Low-redshift Intergalactic Medium. I. Survey, Methodology, and Overall Results

NASA Astrophysics Data System (ADS)

Danforth, Charles W.; Keeney, Brian A.; Tilton, Evan M.; Shull, J. Michael; Stocke, John T.; Stevans, Matthew; Pieri, Matthew M.; Savage, Blair D.; France, Kevin; Syphers, David; Smith, Britton D.; Green, James C.; Froning, Cynthia; Penton, Steven V.; Osterman, Steven N.

2016-02-01

We use high-quality, medium-resolution Hubble Space Telescope/Cosmic Origins Spectrograph (HST/COS) observations of 82 UV-bright active galactic nuclei (AGNs) at redshifts zAGN < 0.85 to construct the largest survey of the low-redshift intergalactic medium (IGM) to date: 5138 individual extragalactic absorption lines in H I and 25 different metal-ion species grouped into 2611 distinct redshift systems at zabs < 0.75 covering total redshift pathlengths ΔzH I = 21.7 and ΔzO VI = 14.5. Our semi-automated line-finding and measurement technique renders the catalog as objectively defined as possible. The cumulative column density distribution of H I systems can be parametrized d{ N }(\\gt N)/{dz} = {C}14{(N/{10}14{{cm}}-2)}-(β -1), with C14 = 25 ± 1 and β = 1.65 ± 0.02. This distribution is seen to evolve both in amplitude, {C}14\\propto {(1+z)}2.3+/- 0.1, and slope β(z) = 1.75-0.31 z for z ≤ 0.47. We observe metal lines in 418 systems, and find that the fraction of IGM absorbers detected in metals is strongly dependent on {N}{{H}{{I}}}. The distribution of O VI absorbers appears to evolve in the same sense as the Lyα forest. We calculate contributions to Ωb from different components of the low-z IGM and determine the Lyα decrement as a function of redshift. IGM absorbers are analyzed via a two-point correlation function in velocity space. We find substantial clustering of H I absorbers on scales of Δv = 50-300 km s-1 with no significant clustering at Δv ≳ 1000 km s-1. Splitting the sample into strong and weak absorbers, we see that most of the clustering occurs in strong, NH I ≳ 1013.5 cm-2, metal-bearing IGM systems. The full catalog of absorption lines and fully reduced spectra is available via the Mikulski Archive for Space Telescopes (MAST) as a high-level science product at http://archive.stsci.edu/prepds/igm/. Based on observations made with the NASA/ESA Hubble Space Telescope, obtained from the data archive at the Space Telescope Science Institute. STScI is operated by the Association of Universities for Research in Astronomy, Inc. under NASA contract NAS5-26555.

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

Okumura, Teppei; Hand, Nick; Seljak, Uros

Theoretical modeling of the redshift-space power spectrum of galaxies is crucially important to correctly extract cosmological information from galaxy redshift surveys. The task is complicated by the nonlinear biasing and redshift space distortion (RSD) effects, which change with halo mass, and by the wide distribution of halo masses and their occupations by galaxies. One of the main modeling challenges is the existence of satellite galaxies that have both radial distribution inside the halos and large virial velocities inside halos, a phenomenon known as the Finger-of-God (FoG) effect. We present a model for the redshift-space power spectrum of galaxies in whichmore » we decompose a given galaxy sample into central and satellite galaxies and relate different contributions to the power spectrum to 1-halo and 2-halo terms in a halo model. Our primary goal is to ensure that any parameters that we introduce have physically meaningful values, and are not just fitting parameters. For the lowest order 2-halo terms we use the previously developed RSD modeling of halos in the context of distribution function and perturbation theory approach. This term needs to be multiplied by the effect of radial distances and velocities of satellites inside the halo. To this one needs to add the 1-halo terms, which are nonperturbative. We show that the real space 1-halo terms can be modeled as almost constant, with the finite extent of the satellites inside the halo inducing a small k 2R 2 term over the range of scales of interest, where R is related to the size of the halo given by its halo mass. Furthermore, we adopt a similar model for FoG in redshift space, ensuring that FoG velocity dispersion is related to the halo mass. For FoG k 2 type expansions do not work over the range of scales of interest and FoG resummation must be used instead. We test several simple damping functions to model the velocity dispersion FoG effect. Applying the formalism to mock galaxies modeled after the “CMASS” sample of the BOSS survey, we find that our predictions for the redshift-space power spectra are accurate up to k ≃ 0.4 h Mpc –1 within 1% if the halo power spectrum is measured using N-body simulations and within 3% if it is modeled using perturbation theory.« less

Solving puzzles of GW150914 by primordial black holes

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

Blinnikov, S.; Dolgov, A.; Porayko, N.K.

The black hole binary properties inferred from the LIGO gravitational wave signal GW150914 posed several serious problems. The high masses and low effective spin of black hole binary can be explained if they are primordial (PBH) rather than the products of the stellar binary evolution. Such PBH properties are postulated ad hoc but not derived from fundamental theory. We show that the necessary features of PBHs naturally follow from the slightly modified Affleck-Dine (AD) mechanism of baryogenesis. The log-normal distribution of PBHs, predicted within the AD paradigm, is adjusted to provide an abundant population of low-spin stellar mass black holes.more » The same distribution gives a sufficient number of quickly growing seeds of supermassive black holes observed at high redshifts and may comprise an appreciable fraction of Dark Matter which does not contradict any existing observational limits. Testable predictions of this scenario are discussed.« less

The LAMOST Complete Spectroscopic Survey of Pointing Area (LaCoSSPAr) in the Southern Galactic Cap. I. The Spectroscopic Redshift Catalog

NASA Astrophysics Data System (ADS)

Yang, Ming; Wu, Hong; Yang, Fan; Lam, Man I.; Cao, Tian-Wen; Wu, Chao-Jian; Zhao, Pin-Song; Zhang, Tian-Meng; Zhou, Zhi-Min; Wu, Xue-Bing; Zhang, Yan-Xia; Shao, Zheng-Yi; Jing, Yi-Peng; Shen, Shi-Yin; Zhu, Yi-Nan; Du, Wei; Lei, Feng-Jie; He, Min; Jin, Jun-Jie; Shi, Jian-Rong; Zhang, Wei; Wang, Jian-Ling; Wu, Yu-Zhong; Zhang, Hao-Tong; Luo, A.-Li; Yuan, Hai-Long; Bai, Zhong-Rui; Kong, Xu; Gu, Qiu-Sheng; Zhou, Xu; Ma, Jun; Hu, Zou; Nie, Jun-Dan; Wang, Jia-Li; Zhang, Yong; Hou, Yong-Hui; Zhao, Yong-Heng

2018-01-01

We present a spectroscopic redshift catalog from the LAMOST Complete Spectroscopic Survey of Pointing Area (LaCoSSPAr) in the Southern Galactic Cap (SGC), which is designed to observe all sources (Galactic and extragalactic) by using repeating observations with a limiting magnitude of r=18.1 {mag} in two 20 {\\deg }2 fields. The project is mainly focusing on the completeness of LAMOST ExtraGAlactic Surveys (LEGAS) in the SGC, the deficiencies of source selection methods, and the basic performance parameters of the LAMOST telescope. In both fields, more than 95% of galaxies have been observed. A post-processing has been applied to the LAMOST 1D spectrum to remove the majority of remaining sky background residuals. More than 10,000 spectra have been visually inspected to measure the redshift by using combinations of different emission/absorption features with an uncertainty of {σ }z/(1+z)< 0.001. In total, 1528 redshifts (623 absorption and 905 emission line galaxies) in Field A and 1570 redshifts (569 absorption and 1001 emission line galaxies) in Field B have been measured. The results show that it is possible to derive redshift from low S/N galaxies with our post-processing and visual inspection. Our analysis also indicates that up to one-fourth of the input targets for a typical extragalactic spectroscopic survey might be unreliable. The multi-wavelength data analysis shows that the majority of mid-infrared-detected absorption (91.3%) and emission line galaxies (93.3%) can be well separated by an empirical criterion of W2-W3=2.4. Meanwhile, a fainter sequence paralleled to the main population of galaxies has been witnessed both in M r /W2-W3 and M */W2-W3 diagrams, which could be the population of luminous dwarf galaxies but contaminated by the edge-on/highly inclined galaxies (∼ 30 % ).

Probability of lensing magnification by cosmologically distributed galaxies

NASA Technical Reports Server (NTRS)

Pei, Yichuan C.

1993-01-01

We present the analytical formulae for computing the magnification probability caused by cosmologically distributed galaxies. The galaxies are assumed to be singular, truncated-isothermal spheres without both evolution and clustering in redshift. We find that, for a fixed total mass, extended galaxies produce a broader shape in the magnification probability distribution and hence are less efficient as gravitational lenses than compact galaxies. The high-magnification tail caused by large galaxies is well approximated by an A exp -3 form, while the tail by small galaxies is slightly shallower. The mean magnification as a function of redshift is, however, found to be independent of the size of the lensing galaxies. In terms of the flux conservation, our formulae for the isothermal galaxy model predict a mean magnification to within a few percent with the Dyer-Roeder model of a clumpy universe.

VIMOS Ultra-Deep Survey (VUDS): IGM transmission towards galaxies with 2.5 < z < 5.5 and the colour selection of high-redshift galaxies

NASA Astrophysics Data System (ADS)

Thomas, R.; Le Fèvre, O.; Le Brun, V.; Cassata, P.; Garilli, B.; Lemaux, B. C.; Maccagni, D.; Pentericci, L.; Tasca, L. A. M.; Zamorani, G.; Zucca, E.; Amorin, R.; Bardelli, S.; Cassarà, L.; Castellano, M.; Cimatti, A.; Cucciati, O.; Durkalec, A.; Fontana, A.; Giavalisco, M.; Grazian, A.; Hathi, N. P.; Ilbert, O.; Paltani, S.; Pforr, J.; Ribeiro, B.; Schaerer, D.; Scodeggio, M.; Sommariva, V.; Talia, M.; Tresse, L.; Vanzella, E.; Vergani, D.; Capak, P.; Charlot, S.; Contini, T.; Cuby, J. G.; de la Torre, S.; Dunlop, J.; Fotopoulou, S.; Koekemoer, A.; López-Sanjuan, C.; Mellier, Y.; Salvato, M.; Scoville, N.; Taniguchi, Y.; Wang, P. W.

2017-01-01

The observed UV rest-frame spectra of distant galaxies are the result of their intrinsic emission combined with absorption along the line of sight produced by the inter-galactic medium (IGM). Here we analyse the evolution of the mean IGM transmission Tr(Lyα) and its dispersion along the line of sight for 2127 galaxies with 2.5 < z < 5.5 in the VIMOS Ultra Deep Survey (VUDS). We fitted model spectra combined with a range of IGM transmission to the galaxy spectra using the spectral fitting algorithm GOSSIP+. We used these fits to derive the mean IGM transmission towards each galaxy for several redshift slices from z = 2.5 to z = 5.5. We found that the mean IGM transmission defined as Tr(Lyα) = e- τ (with τ as the HI optical depth) is 79%, 69%, 59%, 55%, and 46% at redshifts 2.75, 3.22, 3.70, 4.23, and 4.77, respectively. We compared these results to measurements obtained from quasar lines of sight and found that the IGM transmission towards galaxies is in excellent agreement with quasar values up to redshift z 4. We found tentative evidence for a higher IGM transmission at z ≥ 4 compared to results from QSOs, but a degeneracy between dust extinction and IGM prevents us from firmly concluding whether the internal dust extinction for star-forming galaxies at z > 4 takes a mean value significantly in excess of E(B-V) > 0.15. Most importantly, we found a large dispersion of IGM transmission along the lines of sight towards distant galaxies with 68% of the distribution within 10 to 17% of the median value in δz = 0.5 bins, similar to what is found on the lines of sight towards QSOs. We demonstrate that taking this broad range of IGM transmission into account is important when selecting high-redshift galaxies based on their colour properties (e.g. LBG or photometric redshiftselection) because failing to do so causes a significant incompleteness in selecting high-redshift galaxy populations. We finally discuss the observed IGM properties and speculate that the broad range of observed transmissions might be the result of cosmic variance and clustering along lines of sight. This clearly shows that the sources that cause this extinction need to be more completely modelled. Based on data obtained with the European Southern Observatory Very Large Telescope, Paranal, Chile, under Large Program 185.A-0791.

A Study of Nine High-Redshift Clusters of Galaxies. II. Photometry, Spectra, and Ages of Clusters 0023+0423 and 1604+4304

NASA Astrophysics Data System (ADS)

Postman, Marc; Lubin, Lori M.; Oke, J. B.

1998-08-01

We present an extensive photometric and spectroscopic study of two high-redshift clusters of galaxies based on data obtained from the Keck 10 m telescopes and the Hubble Space Telescope. The clusters Cl 0023+0423 (z = 0.84) and Cl 1604+4304 (z = 0.90) are part of a multiwavelength program of Oke, Postman & Lubin to study nine candidate clusters at z >~ 0.6. Based on these observations, we study in detail both the field and cluster populations. From the confirmed cluster members, we find that Cl 0023+0423 actually consists of two components separated by ~2900 km s^-1. A kinematic analysis indicates that the two components are a poor cluster with ~3 x 10^14 M_⊙ and a less massive group with ~10^13 M_⊙. Cl 1604+4304 is a centrally concentrated, rich cluster at z = 0.8967 with a velocity dispersion of 1226 km s^-1 and a mass of ~3 x 10^15 M_⊙. A large percentage of the cluster members show high levels of star formation activity. Approximately 57% and 50% of the galaxies are active in Cl 0023+0423 and Cl 1604+4304, respectively. These numbers are significantly larger than those found in intermediate-redshift clusters. We also observe many old, red galaxies. Found mainly in Cl 1604+4304, they have spectra consistent with passive stellar evolution, typical of the populations of early-type galaxies in low- and intermediate-redshift clusters. We have calculated their ages by comparing their spectral energy distributions to standard Bruzual & Charlot evolutionary models. We find that their colors are consistent with models having an exponentially decreasing star formation rate with a time constant of 0.6 Gyr. We also observe a significant luminosity brightening in our brightest cluster galaxies. Compared with brightest cluster galaxies at z ~ 0.1, we find a luminosity increase of ~1 mag in the rest M_B and ~0.8 mag in the rest M_V. In the field, we find that ~76% of the galaxies with z > 0.4 show emission-line activity. These numbers are consistent with previous studies. We find that an exponentially decaying star formation rate is required to produce the observed amount of star formation for the majority of the galaxies in our sample. A time constant of tau = 0.6 Gyr appears to be optimal. We also detect several interesting galaxies at z > 1. Two of these galaxies are extremely luminous, with strong Mg ii lambda2800 absorption and Fe ii resonance-line absorption. These lines are so strong that we conclude that they must be generated within the atmospheres of a large population of young, hot stars.

Large-scale clustering of galaxies in the CfA Redshift Survey

NASA Technical Reports Server (NTRS)

Vogeley, Michael S.; Park, Changbom; Geller, Margaret J.; Huchra, John P.

1992-01-01

The power spectrum of the galaxy distribution in the Center for Astrophysics Redshift Survey (de Lapparent et al., 1986; Geller and Huchra, 1989; and Huchra et al., 1992) is measured up to wavelengths of 200/h Mpc. Results are compared with several cosmological simulations with Gaussian initial conditions. It is shown that the power spectrum of the standard CDM model is inconsistent with the observed power spectrum at the 99 percent confidence level.

A critical analysis of high-redshift, massive, galaxy clusters. Part I

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

Hoyle, Ben; Jimenez, Raul; Verde, Licia

2012-02-01

We critically investigate current statistical tests applied to high redshift clusters of galaxies in order to test the standard cosmological model and describe their range of validity. We carefully compare a sample of high-redshift, massive, galaxy clusters with realistic Poisson sample simulations of the theoretical mass function, which include the effect of Eddington bias. We compare the observations and simulations using the following statistical tests: the distributions of ensemble and individual existence probabilities (in the > M, > z sense), the redshift distributions, and the 2d Kolmogorov-Smirnov test. Using seemingly rare clusters from Hoyle et al. (2011), and Jee etmore » al. (2011) and assuming the same survey geometry as in Jee et al. (2011, which is less conservative than Hoyle et al. 2011), we find that the ( > M, > z) existence probabilities of all clusters are fully consistent with ΛCDM. However assuming the same survey geometry, we use the 2d K-S test probability to show that the observed clusters are not consistent with being the least probable clusters from simulations at > 95% confidence, and are also not consistent with being a random selection of clusters, which may be caused by the non-trivial selection function and survey geometry. Tension can be removed if we examine only a X-ray selected sub sample, with simulations performed assuming a modified survey geometry.« less

Weak lensing of the Lyman α forest

NASA Astrophysics Data System (ADS)

Croft, Rupert A. C.; Romeo, Alessandro; Metcalf, R. Benton

2018-06-01

The angular positions of quasars are deflected by the gravitational lensing effect of foreground matter. The Lyman α (Lyα) forest seen in the spectra of these quasars is therefore also lensed. We propose that the signature of weak gravitational lensing of the Lyα forest could be measured using similar techniques that have been applied to the lensed cosmic microwave background (CMB), and which have also been proposed for application to spectral data from 21-cm radio telescopes. As with 21-cm data, the forest has the advantage of spectral information, potentially yielding many lensed `slices' at different redshifts. We perform an illustrative idealized test, generating a high-resolution angular grid of quasars (of order arcminute separation), and lensing the Lyα forest spectra at redshifts z = 2-3 using a foreground density field. We find that standard quadratic estimators can be used to reconstruct images of the foreground mass distribution at z ˜ 1. There currently exists a wealth of Lyα forest data from quasar and galaxy spectral surveys, with smaller sightline separations expected in the future. Lyα forest lensing is sensitive to the foreground mass distribution at redshifts intermediate between CMB lensing and galaxy shear, and avoids the difficulties of shape measurement associated with the latter. With further refinement and application of mass reconstruction techniques, weak gravitational lensing of the high-redshift Lyα forest may become a useful new cosmological probe.

KiDS-450: the tomographic weak lensing power spectrum and constraints on cosmological parameters

NASA Astrophysics Data System (ADS)

Köhlinger, F.; Viola, M.; Joachimi, B.; Hoekstra, H.; van Uitert, E.; Hildebrandt, H.; Choi, A.; Erben, T.; Heymans, C.; Joudaki, S.; Klaes, D.; Kuijken, K.; Merten, J.; Miller, L.; Schneider, P.; Valentijn, E. A.

2017-11-01

We present measurements of the weak gravitational lensing shear power spectrum based on 450 ° ^2 of imaging data from the Kilo Degree Survey. We employ a quadratic estimator in two and three redshift bins and extract band powers of redshift autocorrelation and cross-correlation spectra in the multipole range 76 ≤ ℓ ≤ 1310. The cosmological interpretation of the measured shear power spectra is performed in a Bayesian framework assuming a ΛCDM model with spatially flat geometry, while accounting for small residual uncertainties in the shear calibration and redshift distributions as well as marginalizing over intrinsic alignments, baryon feedback and an excess-noise power model. Moreover, massive neutrinos are included in the modelling. The cosmological main result is expressed in terms of the parameter combination S_8 ≡ σ _8 √{Ω_m/0.3} yielding S8 = 0.651 ± 0.058 (three z-bins), confirming the recently reported tension in this parameter with constraints from Planck at 3.2σ (three z-bins). We cross-check the results of the three z-bin analysis with the weaker constraints from the two z-bin analysis and find them to be consistent. The high-level data products of this analysis, such as the band power measurements, covariance matrices, redshift distributions and likelihood evaluation chains are available at http://kids.strw.leidenuniv.nl.

Binary Population and Spectral Synthesis Version 2.1: Construction, Observational Verification, and New Results

NASA Astrophysics Data System (ADS)

Eldridge, J. J.; Stanway, E. R.; Xiao, L.; McClelland, L. A. S.; Taylor, G.; Ng, M.; Greis, S. M. L.; Bray, J. C.

2017-11-01

The Binary Population and Spectral Synthesis suite of binary stellar evolution models and synthetic stellar populations provides a framework for the physically motivated analysis of both the integrated light from distant stellar populations and the detailed properties of those nearby. We present a new version 2.1 data release of these models, detailing the methodology by which Binary Population and Spectral Synthesis incorporates binary mass transfer and its effect on stellar evolution pathways, as well as the construction of simple stellar populations. We demonstrate key tests of the latest Binary Population and Spectral Synthesis model suite demonstrating its ability to reproduce the colours and derived properties of resolved stellar populations, including well-constrained eclipsing binaries. We consider observational constraints on the ratio of massive star types and the distribution of stellar remnant masses. We describe the identification of supernova progenitors in our models, and demonstrate a good agreement to the properties of observed progenitors. We also test our models against photometric and spectroscopic observations of unresolved stellar populations, both in the local and distant Universe, finding that binary models provide a self-consistent explanation for observed galaxy properties across a broad redshift range. Finally, we carefully describe the limitations of our models, and areas where we expect to see significant improvement in future versions.

Revisiting Abell 2744: a powerful synergy of GLASS spectroscopy and HFF photometry

NASA Astrophysics Data System (ADS)

Wang, Xin; Wang

We present new emission line identifications and improve the lensing reconstruction of the mass distribution of galaxy cluster Abell 2744 using the Grism Lens-Amplified Survey from Space (GLASS) spectroscopy and the Hubble Frontier Fields (HFF) imaging. We performed blind and targeted searches for faint line emitters on all objects, including the arc sample, within the field of view (FoV) of GLASS prime pointings. We report 55 high quality spectroscopic redshifts, 5 of which are for arc images. We also present an extensive analysis based on the HFF photometry, measuring the colors and photometric redshifts of all objects within the FoV, and comparing the spectroscopic and photometric redshift estimates. In order to improve the lens model of Abell 2744, we develop a rigorous algorithm to screen arc images, based on their colors and morphology, and selecting the most reliable ones to use. As a result, 25 systems (corresponding to 72 images) pass the screening process and are used to reconstruct the gravitational potential of the cluster pixellated on an adaptive mesh. The resulting total mass distribution is compared with a stellar mass map obtained from the Spitzer Frontier Fields data in order to study the relative distribution of stars and dark matter in the cluster.

Calibrating the Galaxy Color-Redshift Relation: A Critical Foundation for Weak Lensing Cosmology with WFIRST and Euclid

NASA Astrophysics Data System (ADS)

Stern, Daniel

2016-08-01

A primary objective of both WFIRST and Euclid is to provide a 3D map of the distribution of matter across a significant fraction of the universe from the weak lensing shear field, but to do so requires robust distances to billions of galaxies. We propose a 4-semester, 20-night Key Strategic Mission Support program, supporting both the NASA PCOS and COR science goals, to obtain the necessary galaxy spectroscopy to calibrate the color-redshift relation. Combined with a coordinated, similarly sized Caltech Keck proposal, the proposed program will achieve the photometric redshift calibration requirements for Euclid, and make significant progress towards the WFIRST requirements. [2016B is the 2nd semester of our 4-semester request.

Dark Energy Survey Year 1 Results: galaxy mock catalogues for BAO

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

Avila, S.; et al.

Mock catalogues are a crucial tool in the analysis of galaxy surveys data, both for the accurate computation of covariance matrices, and for the optimisation of analysis methodology and validation of data sets. In this paper, we present a set of 1800 galaxy mock catalogues designed to match the Dark Energy Survey Year-1 BAO sample (Crocce et al. 2017) in abundance, observational volume, redshift distribution and uncertainty, and redshift dependent clustering. The simulated samples were built upon HALOGEN (Avila et al. 2015) halo catalogues, based on a $2LPT$ density field with an exponential bias. For each of them, a lightconemore » is constructed by the superposition of snapshots in the redshift range $0.45« less

Visualizing the universe, part 2

NASA Technical Reports Server (NTRS)

Falco, Emilio E.; Kurtz, Michael J.; Bajuk, Mark

1992-01-01

It is now possible to create animated views of the universe that are realistic, physically relevant, and breathtaking. To demonstrate the point, we describe our efforts to navigate the CfA redshift survey. For our project, we selected several CCD images of spiral and elliptical galaxies, and placed them at their observed positions in redshift space. We demonstrate how, by choreographing aesthetically pleasing trajectories, we are able to develop our own and the viewer's intuition about the large-scale structures found in the CfA redshift survey. We show for instance that three-dimensional motion enhances significantly our perception of voids and sheets in the distribution of galaxies. Such sophistication happily has become possible with the 'coming of age' of observational cosmology, as data have grown to drive the field.

Stacked lensing estimators and their covariance matrices: Excess surface mass density vs. Lensing shear

NASA Astrophysics Data System (ADS)

Shirasaki, Masato; Takada, Masahiro

2018-05-01

Stacked lensing is a powerful means of measuring the average mass distribution around large-scale structure tracers. There are two stacked lensing estimators used in the literature, denoted as ΔΣ and γ+, which are related as ΔΣ = Σcrγ+, where Σcr(zl, zs) is the critical surface mass density for each lens-source pair (zl and zs are lens and source redshifts, respectively). In this paper we derive a formula for the covariance matrix of ΔΣ-estimator focusing on "weight" function to improve the signal-to-noise (S/N). We assume that the lensing fields and the distribution of lensing objects obey the Gaussian statistics. With this formula, we show that, if background galaxy shapes are weighted by an amount of Σ _cr^{-2}(z_l,z_s), the ΔΣ-estimator maximizes the S/N in the shot noise limited regime. We also show that the ΔΣ-estimator with the weight Σ _cr^{-2} gives a greater (S/N)2 than that of the γ+-estimator by about 5-25% for lensing objects at redshifts comparable with or higher than the median of source galaxy redshifts for hypothetical Subaru HSC and DES surveys. However, for low-redshift lenses such as zl ≲ 0.3, the γ+-estimator has higher (S/N)2 than ΔΣ. We also discuss that the (S/N)2 for ΔΣ at large separations in the sample variance limited regime can be boosted, by up to a factor of 1.5, if one adopts a weight of Σ _cr^{-α } with α > 2. Our formula allows one to explore how the combination of the different estimators can approach an optimal estimator in all regimes of redshifts and separation scales.

Resolving the Structure of Ionized Helium in the Intergalactic Medium with the Far Ultraviolet Spectroscopic Explorer. 2.3

NASA Technical Reports Server (NTRS)

Kriss, G. A.; Shull, J. M.; Oegerle, W.; Zheng, W.; Davidsen, A. F.; Songaila, A.; Tumlinson, J.; Cowie, L. L.; Dehavreng, J.-M.; Friedman, S. D.

2001-01-01

The neutral hydrogen and the ionized helium absorption in the spectra of high-redshift quasi-stellar objects (QSOs) are unique probes of structure in the universe at epochs intermediate between the earliest density fluctuations seen in the cosmic background radiation and the distribution of galaxies visible today. We present Far-Ultraviolet Spectroscopic Explorer (FUSE) observations of the line of sight to the QSO HE2347-4342 in the 1000-1187 angstrom band at a resolving power of 15,000. Above redshift z = 2.7, the IGM is largely opaque in He II Ly-alpha (304 angstroms). At lower redshifts, the optical depth gradually decreases to a mean value tau = 1 at z = 2.4. We resolve the He II Ly-alpha absorption as a discrete forest of absorption lines in the z = 2.3 - 2.7 redshift range. Approximately 50% of these spectral features have H I counterparts with column densities N(sub HI) > 10(exp 12.3)/sq cm visible in a Keck spectrum. These account for most of the observed opacity in He II Ly-alpha. The remainder have N(sub HI) < 10(exp 12.3)/sq cm, below the threshold for current observations. A short extrapolation of the power-law distribution of H I column densities to lower values can account for these new absorbers. The He II to H I column density ratio eta averages approximately 80, consistent with photoionization of the IGM by a hard ionizing spectrum resulting from the integrated light of quasars at high redshift, but there is considerable scatter. Values of eta > 100 in many locations indicate that there may be localized contributions from starbursts or heavily filtered QSO radiation.

Hierarchical clustering in chameleon f(R) gravity

NASA Astrophysics Data System (ADS)

Hellwing, Wojciech A.; Li, Baojiu; Frenk, Carlos S.; Cole, Shaun

2013-11-01

We use a suite of high-resolution state-of-the-art N-body dark matter simulations of chameleon f(R) gravity to study the higher order volume-averaged correlation functions overline{ξ _n} together with the hierarchical nth-order correlation amplitudes S_n=overline{ξ }_n/overline{ξ }_2^{n-1} and density distribution functions (PDF). We show that under the non-linear modifications of gravity the hierarchical scaling of the reduced cumulants is preserved. This is however characterized by significant changes in the values of both overline{ξ _n} and Sn and their scale dependence with respect to General Relativity gravity (GR). In addition, we measure a significant increase of the non-linear σ8 parameter reaching 14, 5 and 0.5 per cent in excess of the GR value for the three flavours of our f(R) models. We further note that the values of the reduced cumulants up to order n = 9 are significantly increased in f(R) gravity for all our models at small scales R ≲ 30 h-1 Mpc. In contrast, the values of the hierarchical amplitudes, Sn, are smaller in f(R) indicating that the modified gravity density distribution functions are deviating from the GR case. Furthermore, we find that the redshift evolution of relative deviations of the f(R) hierarchical correlation amplitudes is fastest at high and moderate redshifts 1 ≤ z ≤ 4. The growth of these deviations significantly slows down in the low-redshift universe. We also compute the PDFs and show that for scales below ˜20 h-1 Mpc, they are significantly shifted in f(R) gravity towards the low densities. Finally, we discuss the implications of our theoretical predictions for measurements of the hierarchical clustering in galaxy redshift surveys, including the important problems of the galaxy biasing and redshift space distortions.

Redshift distributions of galaxies in the Dark Energy Survey Science Verification shear catalogue and implications for weak lensing

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

Bonnett, C.; Troxel, M. A.; Hartley, W.

We present photometric redshift estimates for galaxies used in the weak lensing analysis of the Dark Energy Survey Science Verification (DES SV) data. Four model- or machine learning-based photometric redshift methods { annz2, bpz calibrated against BCC-U fig simulations, skynet, and tpz { are analysed. For training, calibration, and testing of these methods, we also construct a catalogue of spectroscopically confirmed galaxies matched against DES SV data. The performance of the methods is evalu-ated against the matched spectroscopic catalogue, focusing on metrics relevant for weak lensing analyses, with additional validation against COSMOS photo-zs. From the galaxies in the DES SVmore » shear catalogue, which have mean redshift 0.72 ±0.01 over the range 0:3 < z < 1:3, we construct three tomographic bins with means of z = {0.45; 0.67,1.00g}. These bins each have systematic uncertainties δ z ≲ 0.05 in the mean of the fiducial skynet photo-z n(z). We propagate the errors in the redshift distributions through to their impact on cosmological parameters estimated with cosmic shear, and find that they cause shifts in the value of σ 8 of approx. 3%. This shift is within the one sigma statistical errors on σ8 for the DES SV shear catalog. We also found that further study of the potential impact of systematic differences on the critical surface density, Σ crit, contained levels of bias safely less than the statistical power of DES SV data. We recommend a final Gaussian prior for the photo-z bias in the mean of n(z) of width 0:05 for each of the three tomographic bins, and show that this is a sufficient bias model for the corresponding cosmology analysis.« less

STRESS: an intermediate redshift SN search

NASA Astrophysics Data System (ADS)

Botticella, Maria Teresa; Riello, Marco; Cappellaro, Enrico

2007-08-01

We present STRESS (Southern intermediate redshift ESO Supernova Search) a Supernova (SN) survey successfully carried out with ESO telescopes. This SN survey distinguishes itself by other ones for its main goals that are to obtain an estimate of both type Ia and core collapse SN rate and to link them with stellar populations. We detail the observing strategy and data sets collected during our survey and describe the analysis of data. Finally, we illustrate our preliminary results and progress report.

Evolution of the Stellar Mass–Metallicity Relation. I. Galaxies in the z ∼ 0.4 Cluster Cl0024

NASA Astrophysics Data System (ADS)

Leethochawalit, Nicha; Kirby, Evan N.; Moran, Sean M.; Ellis, Richard S.; Treu, Tommaso

2018-03-01

We present the stellar mass–stellar metallicity relationship (MZR) in the galaxy cluster Cl0024+1654 at z ∼ 0.4 using full-spectrum stellar population synthesis modeling of individual quiescent galaxies. The lower limit of our stellar mass range is M * = 109.7 M ⊙, the lowest galaxy mass at which individual stellar metallicity has been measured beyond the local universe. We report a detection of an evolution of the stellar MZR with observed redshift at 0.037 ± 0.007 dex per Gyr, consistent with the predictions from hydrodynamical simulations. Additionally, we find that the evolution of the stellar MZR with observed redshift can be explained by an evolution of the stellar MZR with the formation time of galaxies, i.e., when the single stellar population (SSP)-equivalent ages of galaxies are taken into account. This behavior is consistent with stars forming out of gas that also has an MZR with a normalization that decreases with redshift. Lastly, we find that over the observed mass range, the MZR can be described by a linear function with a shallow slope ([{Fe}/{{H}}]\\propto (0.16+/- 0.03){log}{M}* ). The slope suggests that galaxy feedback, in terms of mass-loading factor, might be mass-independent over the observed mass and redshift range.

Discovery of Compact Quiescent Galaxies at Intermediate Redshifts in DEEP2

NASA Astrophysics Data System (ADS)

Blancato, Kirsten; Chilingarian, Igor; Damjanov, Ivana; Moran, Sean; Katkov, Ivan

2015-01-01

Compact quiescent galaxies in the redshift range 0.6 < z < 1.1 are the missing link needed to complete the evolutionary histories of these objects from the high redshift z ≥ 2 Universe to the local z ~ 0 Universe. We identify the first intermediate redshift compact quiescent galaxies by searching a sample of 1,089 objects in the DEEP2 Redshift Survey that have multi-band photometry, spectral fitting, and readily available structural parameters. We find 27 compact quiescent candidates between z = 0.6 and z = 1.1 where each candidate galaxy has archival Hubble Space Telescope (HST) imaging and is visually confirmed to be early-type. The candidates have half-light radii ranging from 0.83 < Re,c < 7.14 kpc (median Re,c = 1.77 kpc) and virial masses ranging from 2.2E10 < Mdyn < 5.6E11 Msun (median Mdyn = 7.7E10 Msun). Of our 27 compact quiescent candidates, 13 are truly compact with sizes at most half of the size of their z ~ 0 counterparts of the same mass. In addition to their structural properties bridging the gap between their high and low redshift counterparts, our sample of intermediate redshift quiescent galaxies span a large range of ages but is drawn from two distinct epochs of galaxy formation: formation at z > 2 which suggests these objects may be the relics of the observed high redshift compact galaxies and formation at z ≤ 2 which suggests there is an additional population of more recently formed massive compact galaxies. This work is supported in part by the NSF REU and DOD ASSURE programs under NSF grant no. 1262851 and by the Smithsonian Institution.

A redshift survey of IRAS galaxies

NASA Astrophysics Data System (ADS)

Smith, Beverly J.; Kleinmann, S. G.; Huchra, J. P.; Low, F. J.

1987-05-01

Results are presented from a redshift survey of all 72 galaxies detected by IRAS in Band 3 at flux levels equal to or greater then 2 Jy. The luminosity function at the high luminosity end is proportional to L-2, however, a flattening was observed at the low luminosity end indicating that a single power law is not a good description of the entire luminosity function. Only three galaxies in the sample have emission line spectra indicative of AGN's, suggesting that, at least in nearby galaxies, unobscured nuclear activity is not a strong contributor to the far infrared flux. Comparisons between the selected IRAS galaxies and an optically complete sample taken from the CfA redshift survey show that they are more narrowly distributed than those optically selected, in the sence that the IRAS sample includes few galaxies of low absolute blue luminosity. It was also found that the space distributions of the two samples differ: the density enhancement or IRAS galaxies is only approx. 1/3 that of the optically selected galaxies in the core of the Coma cluster.

The optical and near-infrared colors of galaxies, 1: The photometric data

NASA Technical Reports Server (NTRS)

Bershady, Matthew A.; Hereld, Mark; Kron, Richard G.; Koo, David C.; Munn, Jeffrey A.; Majewski, Steven R.

1994-01-01

We present optical and near-infrared photometry and spectroscopic redshifts of a well defined sample of 171 field galaxies selected from three high galactic latitude fields. This data set forms the basis for subsequent studies to characterize the trends, dispersion, and evolution of rest-frame colors and image structure. A subset of 143 galaxies constitutes a magnitude-limited sample to B approx. 19.9-20.75 (depending on field), with a median redshift of 0.14, and a maximum redshift of 0.54. This subset is statistically representative in its sampling of the apparent color distribution of galaxies. Thirty six galaxies were selected to have the reddest red-optical colors in two redshift intervals between 0.2 less than z less than 0.3. Photometric passbands are similar to U, B, V, I, and K, and sample galaxy spectral energy distributions between 0.37 and 2.2 micrometers in the observed frame, or down to 0.26 micrometers in the rest frame for the most distant galaxies. B and K images of the entire sample are assembled to form the first optical and near-infrared atlas of a statistically-representative sample of field galaxies. We discuss techniques for faint field-galaxy photometry, including a working definition of a total magnitude, and a method for matching magnitudes in different passbands and different seeing conditions to ensure reliable, integrated colors. Photographic saturation, which substantially affects the brightest 12% of our sample in the optical bands, is corrected with a model employing measured plate-density distributions for each galaxy, calibrated via similar measurements for stars as a function of known saturation level. Both the relative and absolute calibration of our photometry are demonstrated.

The Star Formation Rate Density of the Universe at z = 0.24 and 0.4 from Halpha

NASA Astrophysics Data System (ADS)

Pascual, S.

2005-01-01

Knowledge of both the global star formation history of the universe and the nature of individual star-forming galaxies at different look-back times is essential to our understanding of galaxy formation and evolution. Deep redshift surveys suggest star-formation activity increases by an order of magnitude from z = 0 to ~1. As a direct test of whether substantial evolution in star-formation activity has occurred, we need to measure the star formation rate (SFR) density and the properties of the corresponding star-forming galaxy populations at different redshifts, using similar techniques. The main goal of this work is to extend the Universidad Complutense de Madrid (UCM) survey of emission-line galaxies to higher redshifts. (continues)

GLACiAR, an Open-Source Python Tool for Simulations of Source Recovery and Completeness in Galaxy Surveys

NASA Astrophysics Data System (ADS)

Carrasco, D.; Trenti, M.; Mutch, S.; Oesch, P. A.

2018-06-01

The luminosity function is a fundamental observable for characterising how galaxies form and evolve throughout the cosmic history. One key ingredient to derive this measurement from the number counts in a survey is the characterisation of the completeness and redshift selection functions for the observations. In this paper, we present GLACiAR, an open python tool available on GitHub to estimate the completeness and selection functions in galaxy surveys. The code is tailored for multiband imaging surveys aimed at searching for high-redshift galaxies through the Lyman-break technique, but it can be applied broadly. The code generates artificial galaxies that follow Sérsic profiles with different indexes and with customisable size, redshift, and spectral energy distribution properties, adds them to input images, and measures the recovery rate. To illustrate this new software tool, we apply it to quantify the completeness and redshift selection functions for J-dropouts sources (redshift z 10 galaxies) in the Hubble Space Telescope Brightest of Reionizing Galaxies Survey. Our comparison with a previous completeness analysis on the same dataset shows overall agreement, but also highlights how different modelling assumptions for the artificial sources can impact completeness estimates.

Identifying High-redshift Gamma-Ray Bursts with RATIR

NASA Astrophysics Data System (ADS)

Littlejohns, O. M.; Butler, N. R.; Cucchiara, A.; Watson, A. M.; Kutyrev, A. S.; Lee, W. H.; Richer, M. G.; Klein, C. R.; Fox, O. D.; Prochaska, J. X.; Bloom, J. S.; Troja, E.; Ramirez-Ruiz, E.; de Diego, J. A.; Georgiev, L.; González, J.; Román-Zúñiga, C. G.; Gehrels, N.; Moseley, H.

2014-07-01

We present a template-fitting algorithm for determining photometric redshifts, z phot, of candidate high-redshift gamma-ray bursts (GRBs). Using afterglow photometry, obtained by the Reionization and Transients InfraRed (RATIR) camera, this algorithm accounts for the intrinsic GRB afterglow spectral energy distribution, host dust extinction, and the effect of neutral hydrogen (local and cosmological) along the line of sight. We present the results obtained by this algorithm and the RATIR photometry of GRB 130606A, finding a range of best-fit solutions, 5.6 < z phot < 6.0, for models of several host dust extinction laws (none, the Milky Way, Large Magellanic Clouds, and Small Magellanic Clouds), consistent with spectroscopic measurements of the redshift of this GRB. Using simulated RATIR photometry, we find that our algorithm provides precise measures of z phot in the ranges of 4 < z phot <~ 8 and 9 < z phot < 10 and can robustly determine when z phot > 4. Further testing highlights the required caution in cases of highly dust-extincted host galaxies. These tests also show that our algorithm does not erroneously find z phot < 4 when z sim > 4, thereby minimizing false negatives and allowing us to rapidly identify all potential high-redshift events.

The Evolution of Dusty Star formation in Galaxy Clusters to z = 1: Spitzer Infrared Observations of the First Red-Sequence Cluster Survey

NASA Astrophysics Data System (ADS)

Webb, T. M. A.; O'Donnell, D.; Yee, H. K. C.; Gilbank, David; Coppin, Kristen; Ellingson, Erica; Faloon, Ashley; Geach, James E.; Gladders, Mike; Noble, Allison; Muzzin, Adam; Wilson, Gillian; Yan, Renbin

2013-10-01

We present the results of an infrared (IR) study of high-redshift galaxy clusters with the MIPS camera on board the Spitzer Space Telescope. We have assembled a sample of 42 clusters from the Red-Sequence Cluster Survey-1 over the redshift range 0.3 < z < 1.0 and spanning an approximate range in mass of 1014-15 M ⊙. We statistically measure the number of IR-luminous galaxies in clusters above a fixed inferred IR luminosity of 2 × 1011 M ⊙, assuming a star forming galaxy template, per unit cluster mass and find it increases to higher redshift. Fitting a simple power-law we measure evolution of (1 + z)5.1 ± 1.9 over the range 0.3 < z < 1.0. These results are tied to the adoption of a single star forming galaxy template; the presence of active galactic nuclei, and an evolution in their relative contribution to the mid-IR galaxy emission, will alter the overall number counts per cluster and their rate of evolution. Under the star formation assumption we infer the approximate total star formation rate per unit cluster mass (ΣSFR/M cluster). The evolution is similar, with ΣSFR/M cluster ~ (1 + z)5.4 ± 1.9. We show that this can be accounted for by the evolution of the IR-bright field population over the same redshift range; that is, the evolution can be attributed entirely to the change in the in-falling field galaxy population. We show that the ΣSFR/M cluster (binned over all redshift) decreases with increasing cluster mass with a slope (ΣSFR/M_{cluster} \\sim M_{cluster}^{-1.5+/- 0.4}) consistent with the dependence of the stellar-to-total mass per unit cluster mass seen locally. The inferred star formation seen here could produce ~5%-10% of the total stellar mass in massive clusters at z = 0, but we cannot constrain the descendant population, nor how rapidly the star-formation must shut-down once the galaxies have entered the cluster environment. Finally, we show a clear decrease in the number of IR-bright galaxies per unit optical galaxy in the cluster cores, confirming star formation continues to avoid the highest density regions of the universe at z ~ 0.75 (the average redshift of the high-redshift clusters). While several previous studies appear to show enhanced star formation in high-redshift clusters relative to the field we note that these papers have not accounted for the overall increase in galaxy or dark matter density at the location of clusters. Once this is done, clusters at z ~ 0.75 have the same or less star formation per unit mass or galaxy as the field.

Identifying Protoclusters in the High Redshift Universe and Mapping Their Evolution

NASA Astrophysics Data System (ADS)

Franck, Jay Robert

2018-01-01

To investigate the growth and evolution of the earliest structures in the Universe, we identify more than 200 galaxy overdensities in the Candidate Cluster and Protocluster Catalog (CCPC). This compilation is produced by mining open astronomy data sets for over-densities of high redshift galaxies that are spectroscopically confirmed. At these redshifts, the Universe is only a few billion years old. This data mining approach yields a nearly 10 fold increase in the number of known protoclusters in the literature. The CCPC also includes the highest redshift, spectroscopically confirmed protocluster at z=6.56. For nearly 1500 galaxies contained in the CCPC between redshifts of 2.02, the brightest galaxies are older and more massive than anticipated by the model.

THE SWIFT BAT SURVEY DETECTS TWO OPTICAL BROAD LINE, X-RAY HEAVILY OBSCURED ACTIVE GALAXIES: NVSS 193013+341047 AND IRAS 05218-1212

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

Hogg, J. Drew; Winter, Lisa M.; Mushotzky, Richard F.

2012-06-20

The Swift Burst Alert Telescope (BAT) is discovering interesting new objects while monitoring the sky in the 14-195 keV band. Here we present the X-ray properties and spectral energy distributions (SEDs) for two unusual active galactic nucleus sources. Both NVSS 193013+341047 and IRAS 05218-1212 are absorbed, Compton-thin, but heavily obscured (N{sub H} {approx} 10{sup 23} cm{sup -2}), X-ray sources at redshifts <0.1. The SEDs reveal these galaxies to be very red, with high extinction in the optical and UV. A similar SED is seen for the extremely red objects (EROs) detected in the higher redshift universe. This suggests that thesemore » unusual BAT-detected sources are a low-redshift (z << 1) analog to EROs, which recent evidence suggests are a class of the elusive type II quasars. Studying the multi-wavelength properties of these sources may reveal the properties of their high-redshift counterparts.« less

A 14 h-3 Gpc3 study of cosmic homogeneity using BOSS DR12 quasar sample

NASA Astrophysics Data System (ADS)

Laurent, Pierre; Le Goff, Jean-Marc; Burtin, Etienne; Hamilton, Jean-Christophe; Hogg, David W.; Myers, Adam; Ntelis, Pierros; Pâris, Isabelle; Rich, James; Aubourg, Eric; Bautista, Julian; Delubac, Timothée; du Mas des Bourboux, Hélion; Eftekharzadeh, Sarah; Palanque Delabrouille, Nathalie; Petitjean, Patrick; Rossi, Graziano; Schneider, Donald P.; Yeche, Christophe

2016-11-01

The BOSS quasar sample is used to study cosmic homogeneity with a 3D survey in the redshift range 2.2 < z < 2.8. We measure the count-in-sphere, N(< r), i.e. the average number of objects around a given object, and its logarithmic derivative, the fractal correlation dimension, D2(r). For a homogeneous distribution N(< r) propto r3 and D2(r) = 3. Due to the uncertainty on tracer density evolution, 3D surveys can only probe homogeneity up to a redshift dependence, i.e. they probe so-called ``spatial isotropy". Our data demonstrate spatial isotropy of the quasar distribution in the redshift range 2.2 < z < 2.8 in a model-independent way, independent of any FLRW fiducial cosmology, resulting in 3 - langleD2rangle < 1.7 × 10-3 (2 σ) over the range 250 < r < 1200 h-1 Mpc for the quasar distribution. If we assume that quasars do not have a bias much less than unity, this implies spatial isotropy of the matter distribution on large scales. Then, combining with the Copernican principle, we finally get homogeneity of the matter distribution on large scales. Alternatively, using a flat ΛCDM fiducial cosmology with CMB-derived parameters, and measuring the quasar bias relative to this ΛCDM model, our data provide a consistency check of the model, in terms of how homogeneous the Universe is on different scales. D2(r) is found to be compatible with our ΛCDM model on the whole 10 < r < 1200 h-1 Mpc range. For the matter distribution we obtain 3 - langleD2rangle < 5 × 10-5 (2 σ) over the range 250 < r < 1200 h-1 Mpc, consistent with homogeneity on large scales.

Digging for the Truth: Photon Archeology with GLAST

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

Stecker, F. W.

2007-07-12

Stecker, Malkan and Scully, have shown how ongoing deep surveys of galaxy luminosity functions, spectral energy distributions and backwards evolution models of star formation rates can be used to calculate the past history of intergalactic photon densities for energies from 0.03 eV to the Lyman limit at 13.6 eV and for redshifts out to 6 (called here the intergalactic background light or IBL). From these calculations of the IBL at various redshifts, they predict the present and past optical depth of the universe to high energy {gamma}-rays owing to interactions with photons of the IBL and the 2.7 K CMB.more » We discuss here how this proceedure can be reversed by looking for sharp cutoffs in the spectra of extragalactic {gamma}-ray sources such as blazars at high redshifts in the multi-GeV energy range with GLAST (Gamma-Ray Large Are Space Telescope). By determining the cutoff energies of sources with known redshifts, we can refine our determination of the IBL photon densities in the past, i.e., the archeo-IBL, and therefore get a better measure of the past history of the total star formation rate. Conversely, observations of sharp high energy cutoffs in the {gamma}-ray spectra of sources at unknown redshifts can be used instead of spectral lines to give a measure of their redshifts.« less

Complete Calibration of the Color-Redshift Relation (C3R2): A Critical Foundation for Weak Lensing Cosmology with Euclid and WFIRST

NASA Astrophysics Data System (ADS)

Masters, Daniel C.; Stern, Daniel; Cohen, Judy; Capak, Peter

2018-01-01

A primary objective of both WFIRST and Euclid is to provide a 3D map of the distribution of matter across a significant fraction of the universe from the weak lensing shear field. Doing so will require accurate redshifts to the billions of galaxies that comprise the weak lensing samples of these surveys; achieving the required accuracy is a “tall pole” challenge for both missions. Here we present the ongoing Complete Calibration of the Color-Redshift Relation (C3R2) survey, designed specifically to calibrate the empirical galaxy color-redshift relation to Euclid depth. C3R2 is an ambitious Keck spectroscopy program, with a survey design based on a machine learning technique that allows us to optimally select the most important galaxies to sample the full range of galaxy colors. C3R2 is a multi-center program with time from all the primary Keck partners (Caltech, UC, Hawaii, and NASA), with a total of 34.5 Keck nights allocated to this project. Data Release 1, including 1283 high-confidence spectroscopic redshifts, is published as Masters, Stern, Cohen, Capak, et al. (2017), and we are currently completing Data Release 2, which will include >2000 additional high-confidence spectroscopic redshifts (Masters et al., in prep.). We will discuss current results and prospects for the survey going forward.

Photometric redshifts for Hyper Suprime-Cam Subaru Strategic Program Data Release 1

NASA Astrophysics Data System (ADS)

Tanaka, Masayuki; Coupon, Jean; Hsieh, Bau-Ching; Mineo, Sogo; Nishizawa, Atsushi J.; Speagle, Joshua; Furusawa, Hisanori; Miyazaki, Satoshi; Murayama, Hitoshi

2018-01-01

Photometric redshifts are a key component of many science objectives in the Hyper Suprime-Cam Subaru Strategic Program (HSC-SSP). In this paper, we describe and compare the codes used to compute photometric redshifts for HSC-SSP, how we calibrate them, and the typical accuracy we achieve with the HSC five-band photometry (grizy). We introduce a new point estimator based on an improved loss function and demonstrate that it works better than other commonly used estimators. We find that our photo-z's are most accurate at 0.2 ≲ zphot ≲ 1.5, where we can straddle the 4000 Å break. We achieve σ[Δzphot/(1 + zphot)] ˜ 0.05 and an outlier rate of about 15% for galaxies down to i = 25 within this redshift range. If we limit ourselves to a brighter sample of i < 24, we achieve σ ˜ 0.04 and ˜8% outliers. Our photo-z's should thus enable many science cases for HSC-SSP. We also characterize the accuracy of our redshift probability distribution function (PDF) and discover that some codes over-/underestimate the redshift uncertainties, which has implications for N(z) reconstruction. Our photo-z products for the entire area in Public Data Release 1 are publicly available, and both our catalog products (such as point estimates) and full PDFs can be retrieved from the data release site, "https://hsc-release.mtk.nao.ac.jp/".

Bulge growth and quenching since z = 2.5 in CANDELS/3D-HST

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

Lang, Philipp; Wuyts, Stijn; Schreiber, Natascha M. Förster

2014-06-10

Exploiting the deep high-resolution imaging of all five CANDELS fields, and accurate redshift information provided by 3D-HST, we investigate the relation between structure and stellar populations for a mass-selected sample of 6764 galaxies above 10{sup 10} M {sub ☉}, spanning the redshift range 0.5 < z < 2.5. For the first time, we fit two-dimensional models comprising a single Sérsic fit and two-component (i.e., bulge + disk) decompositions not only to the H-band light distributions, but also to the stellar mass maps reconstructed from resolved stellar population modeling. We confirm that the increased bulge prominence among quiescent galaxies, as reportedmore » previously based on rest-optical observations, remains in place when considering the distributions of stellar mass. Moreover, we observe an increase of the typical Sérsic index and bulge-to-total ratio (with median B/T reaching 40%-50%) among star-forming galaxies above 10{sup 11} M {sub ☉}. Given that quenching for these most massive systems is likely to be imminent, our findings suggest that significant bulge growth precedes a departure from the star-forming main sequence. We demonstrate that the bulge mass (and ideally knowledge of the bulge and total mass) is a more reliable predictor of the star-forming versus quiescent state of a galaxy than the total stellar mass. The same trends are predicted by the state-of-the-art, semi-analytic model by Somerville et al. In this model, bulges and black holes grow hand in hand through merging and/or disk instabilities, and feedback from active galactic nuclei shuts off star formation. Further observations will be required to pin down star formation quenching mechanisms, but our results imply that they must be internal to the galaxies and closely associated with bulge growth.« less

The Chajnantor Sub/Millimeter Survey Telescope

NASA Astrophysics Data System (ADS)

Golwala, Sunil

2018-01-01

We are developing the Chajnantor Sub/millimeter Survey Telescope, a project to build a 30-m telescope operating at wavelengths as short as 850 µm with 1 degree field of view for imaging and multi-object spectroscopic surveys. This project will provide massive new data sets for studying star formation at high redshift and in the local universe, feedback mechanisms in galaxy evolution, the structure of galaxy clusters, and the cosmological peculiar velocity field. We will highlight CSST's capabilities for studying galaxy evolution, where it will: trace the evolution of dusty, star-forming galaxies from high redshift to the z ≍ 1-3 epoch when they dominate the cosmic star formation rate; connect this population to the high-redshift rest-frame UV/optical galaxy population; use these dusty galaxies, the most biased overdensities, to guide ultra-deep followup at z > 3.5 and possibly z > 7; measure the brightness of important submm/FIR spectral lines like [CII]; search for molecular and atomic outflows; and do calorimetry of the CGM via the thermal SZ effect. We will describe the expected surveys addressing these science goals, the novel telescope design, and the planned survey instrumentation.

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.

How Well Do Submillimeter Galaxies Trace Protoclusters?

NASA Astrophysics Data System (ADS)

Hayward, Christopher C.

2017-07-01

It has been suggested that associations of (or even individual) high-redshift submillimeter galaxies (SMGs) may serve as beacons of protoclusters because SMGs are high-mass galaxies undergoing rapid assembly. Moreover, it has been claimed that the protocluster environment may lead to 'synchronized' starbursts and thus multiple SMGs within the protocluster region. We investigate this possibility using the Bolshoi cosmological N-body simulation and a model for populating the simulation with SMGs. We find that although SMG associations correspond to some of the highest overdensities at z > 2.5, they are highly incomplete tracers because of stochastic sampling effects. At lower redshift, because of 'downsizing' (i.e. the most massive galaxies have already ceased forming stars and are thus not SMGs), the highest dark matter overdensities are not well traced by SMG associations. I will close by discussing the implications of this work for observational studies of protoclusters and how the highest-redshift SMGs can be used to maximize the potential of JWST for studying very high redshift galaxies.

Técnica de Construcción de Catálogos Sintéticos

NASA Astrophysics Data System (ADS)

Díaz, M. E.; Muriel, H.; Merchán, M.

We present a mock catalogue construction technic which enable us to mimic simultaniously several observational properties, such as spectral types, angular positions, redshifts distribution, aparent and absolut magnitudes and gravitational evolution. We analyze some prescriptions for volume and flux limited samples. As an aplication, we present a mock catalogue of the 2dF redshift survey and the corresponding comparison between the observational properties of the real data and the corresponding to the mock catalogue constructed in this work.

(Sub)millimetre interferometric imaging of a sample of COSMOS/AzTEC submillimetre galaxies. I. Multiwavelength identifications and redshift distribution

NASA Astrophysics Data System (ADS)

Miettinen, O.; Smolčić, V.; Novak, M.; Aravena, M.; Karim, A.; Masters, D.; Riechers, D. A.; Bussmann, R. S.; McCracken, H. J.; Ilbert, O.; Bertoldi, F.; Capak, P.; Feruglio, C.; Halliday, C.; Kartaltepe, J. S.; Navarrete, F.; Salvato, M.; Sanders, D.; Schinnerer, E.; Sheth, K.

2015-05-01

We used the Plateau de Bure Interferometer (PdBI) to map a sample of 15 submillimetre galaxies (SMGs) in the COSMOS field at the wavelength of 1.3 mm. The target SMGs were originally discovered in the James Clerk Maxwell Telescope (JCMT)/AzTEC 1.1 mm continuum survey at S/N1.1 mm = 4-4.5. This paper presents, for the first time, interferometric millimetre-wavelength observations of these sources. The angular resolution of our observations, 1''&dotbelow;8, allowed us to accurately determine the positions of the target SMGs. Using a detection threshold of S/N1.3 mm> 4.5 regardless of multiwavelength counterpart association, and 4