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Start Over Subject galaxy clusters Publisher CDS
61. A2256 galaxies redshifts and 1.4GHz fluxes
ID:
ivo://CDS.VizieR/J/AJ/125/2393
Title:
A2256 galaxies redshifts and 1.4GHz fluxes
Short Name:
J/AJ/125/2393
Date:
21 Oct 2021
Publisher:
CDS
Description:
Abell 2256 is a nearby (z~0.06), rich cluster of galaxies with fascinating observed properties across a range of wavelengths. Long believed to represent a cluster merger, recent X-ray and optical results have suggested that in addition to the primary cluster and subcluster there is evidence for a third, poorer system. We present wide-field high-sensitivity 1.4GHz VLA radio observations of Abell 2256 in conjunction with optical imaging and additional spectroscopy. Over 40 cluster radio galaxies are identified, with optical spectroscopy indicating the emission source (star formation or active galactic nucleus) for most of them. While the overall fraction of galaxies exhibiting radio emission is consistent with a large sample of other nearby clusters, we find an increase in the activity level of galaxies belonging to the third system (hereafter "the Group"). Specifically, the Group has relatively more star formation than both the primary cluster and main subcluster. The position of the Group is also coincident with the observed cluster radio relic. We suggest that the Group recently (0.3Gyr) merged with the primary cluster and that this merger, not the ongoing merger of the primary and the main subcluster, might be responsible for many of the unusual radio properties of Abell 2256. Furthermore, the greater star formation activity of the Group suggests that the infall of groups is an important driver of galaxy evolution in clusters.
62. A959 galaxies r' magnitude and radial velocities
ID:
ivo://CDS.VizieR/J/A+A/495/15
Title:
A959 galaxies r' magnitude and radial velocities
Short Name:
J/A+A/495/15
Date:
21 Oct 2021
Publisher:
CDS
Description:
The connection of cluster mergers with the presence of extended, diffuse radio sources in galaxy clusters is still being debated. We aim to obtain new insights into the internal dynamics of Abell 959, showing evidence of a diffuse radio source, analyzing velocities and positions of member galaxies. Our analysis is based on redshift data for 107 galaxies in the cluster field acquired at the Telescopio Nazionale Galileo. We also use photometric data from the Sloan Digital Sky Survey (Data Release 6). We combine galaxy velocities and positions to select 81 galaxies recognized as cluster members and determine global dynamical properties. We analyze the cluster searching for substructures by using the weighted gap analysis, the KMM method and the Dressler-Shectman statistics. We also study the 2D galaxy distribution in the field of the cluster. We compare our results with those from X-ray and gravitational lensing analyses.
63. AGES HI sources in NGC 7448
ID:
ivo://CDS.VizieR/J/MNRAS/415/1883
Title:
AGES HI sources in NGC 7448
Short Name:
J/MNRAS/415/1883
Date:
21 Oct 2021
Publisher:
CDS
Description:
In this paper we describe results from the Arecibo Galaxy Environments Survey (AGES). The survey reaches column densities of ~3x10^18^cm^-2^ and masses of ~10^7^M_{sun}_, over individual regions of order 10deg^2^ in size, out to a maximum velocity of 18000km/s. Each surveyed region is centred on a nearby galaxy, group or cluster, in this instance the NGC 7448 group. Galaxy interactions in the NGC 7448 group reveal themselves through the identification of tidal tails and bridges. We find ~2.5 times more atomic gas in the intergalactic medium than in the group galaxies. We identify five new dwarf galaxies, two of which appear to be members of the NGC 7448 group. This is too small, by roughly an order of magnitude, a number of dwarf galaxies to reconcile observation with theoretical predictions of galaxy formation models. If they had observed this region of the sky in previous wide-area blind HI surveys, HIPASS and ALFALFA, they would have detected only 5 and 43 per cent, respectively, of the galaxies we have detected, missing a large fraction of the atomic gas in this volume.
64. AGES sources in Virgo cluster
ID:
ivo://CDS.VizieR/J/MNRAS/423/787
Title:
AGES sources in Virgo cluster
Short Name:
J/MNRAS/423/787
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present 21-cm observations of a 10x2deg^2^ region in the Virgo cluster, obtained as part of the Arecibo Galaxy Environment Survey. 289 sources are detected over the full redshift range (-2000<Vhel<+20000km/s) with 95 belonging to the cluster (Vhel<3000km/s). We combine our observations with data from the optically selected Virgo Cluster Catalogue (VCC) and the Sloan Digital Sky Survey. Most of our detections can be clearly associated with a unique optical counterpart, and 30 per cent of the cluster detections are new objects fainter than the VCC optical completeness limit. Seven detections may have no optical counterpart and we discuss the possible origins of these objects. Seven detections appear associated with early-type galaxies. We perform HI stacking on the HI-undetected galaxies listed in the VCC in this region and show that they must have significantly less gas than those actually detected in HI. Galaxies undetected in HI in the cluster appear to be really devoid of gas, in contrast to a sample of field galaxies from the Arecibo Legacy Fast ALFA (ALFALFA).
65. AGN emission line properties
ID:
ivo://CDS.VizieR/J/ApJS/143/257
Title:
AGN emission line properties
Short Name:
J/ApJS/143/257
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present measurements of the UV/optical emission line parameters in a sample of 158 active galactic nuclei observed with the Faint Object Spectrograph on the Hubble Space Telescope (HST), prior to the installation of COSTAR. We use an automated technique that accounts for galactic reddening, includes iron emission blends, galactic and intrinsic absorption lines, and performs multicomponent fits to the emission line profiles. We present measured line parameters (equivalent width and FWHM) for a large number (28) of different UV/optical lines, including upper limits for undetected lines.
66. AGN in supercluster A901/2
ID:
ivo://CDS.VizieR/J/MNRAS/380/1467
Title:
AGN in supercluster A901/2
Short Name:
J/MNRAS/380/1467
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present XMM data for the supercluster A901/2, at z~0.17, which is combined with deep imaging and 17-band photometric redshifts (from the COMBO-17 survey), two degree field (2dF) spectra and Spitzer 24um data, to identify active galactic nuclei (AGN) in the supercluster. The 90ks XMM image contains 139 point sources, of which 11 are identified as supercluster AGN with LX(0.5-7.5keV)>1.7x10^41^erg/cm^2^/s. The host galaxies have M_R_<-20 and only two of eight sources with spectra could have been identified as AGN by the detected optical emission lines. Using a large sample of 795 supercluster galaxies, we define control samples of massive galaxies with no detected AGN. The local environments of the AGN and control samples differ at >~98 per cent significance. The AGN host galaxies lie predominantly in areas of moderate projected galaxy density and with more local blue galaxies than the control sample, with the exception of one very bright type I AGN very near the centre of a cluster. These environments are similar to, but not limited to, cluster outskirts and blue groups. Despite the large number of potential host galaxies, no AGN are found in regions with the highest galaxy density (excluding some cluster cores where emission from the intra-cluster medium obscures moderate luminosity AGN). AGN are also absent from the areas with lowest galaxy density. We conclude that the prevalence of cluster AGN is linked to their environment.
67. A 1689 HAWK-I J-band image
ID:
ivo://CDS.VizieR/J/A+A/594/A54
Title:
A 1689 HAWK-I J-band image
Short Name:
J/A+A/594/A54
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present a ground-based, near-infrared search for lensed supernovae behind the massive cluster Abell 1689 at z=0.18, which is one of the most powerful gravitational telescopes that nature provides. Our survey was based on multi-epoch J-band observations with the HAWK-I instrument on VLT, with supporting optical data from the Nordic Optical Telescope. Our search resulted in the discovery of five photometrically classified, core-collapse supernovae with high redshifts of 0.671<z<1.703 and magnifications in the range {DELTA}m=-0.31 to -1.58mag, as calculated from lensing models in the literature. Owing to the power of the lensing cluster, the survey had the sensitivity to detect supernovae up to very high redshifts, z~3, albeit for a limited region of space. We present a study of the core-collapse supernova rates for 0.4<=z<2.9, and find good agreement with previous estimates and predictions from star formation history. During our survey, we also discovered two Type Ia supernovae in A 1689 cluster members, which allowed us to determine the cluster Ia rate to be 0.14+0.19-0.09+/-0.01SNuB*h^2^ (SNuB=10^-12^SNeL_{sun},B_^-1^yr^-1^), where the error bars indicate 1{sigma} confidence intervals, statistical and systematic, respectively. The cluster rate normalized by the stellar mass is 0.10+0.13-0.096+/-0.02 in SNuM*h^2^ (SNuM=10^-12^SNeM_{sun}_^-1^yr^-1^). Furthermore, we explore the optimal future survey for improving the core-collapse supernova rate measurements at z>~2 using gravitational telescopes, and for detections with multiply lensed images, and we find that the planned WFIRST space mission has excellent prospects.
68. A1763 infrared and optical photometry
ID:
ivo://CDS.VizieR/J/AJ/139/434
Title:
A1763 infrared and optical photometry
Short Name:
J/AJ/139/434
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present a photometric analysis of the galaxy cluster Abell 1763 at visible and infrared wavelengths. Included are fully reduced images in r', J, H, and Ks obtained using the Palomar 200in telescope, as well as the IRAC and MIPS images from Spitzer. The cluster is covered out to approximately 3 virial radii with deep 24um imaging (a 5{sigma} depth of 0.2mJy). This same field of ~40'x40' is covered in all four IRAC bands as well as the longer wavelength MIPS bands (70 and 160um). The r' imaging covers ~0.8deg^2^ down to 25.5mag, and overlaps with most of the MIPS field of view. The J, H, and Ks images cover the cluster core and roughly half of the filament galaxies, which extend toward the neighboring cluster, Abell 1770. This first, in a series of papers on Abell 1763, discusses the data reduction methods and source extraction techniques used for each data set. We present catalogs of infrared sources (with 24 and/or 70um emission) and their corresponding emission in the optical (u', g', r', i', z'), and near- to far-IR (J, H, Ks, IRAC, and MIPS 160um). We provide the catalogs and reduced images to the community through the NASA/IPAC Infrared Science Archive.
69. A2125 in X-ray
ID:
ivo://CDS.VizieR/J/ApJ/611/821
Title:
A2125 in X-ray
Short Name:
J/ApJ/611/821
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present an 82ks Chandra ACIS-I observation of a large-scale hierarchical complex, which consists of various clusters/groups of galaxies and low surface brightness X-ray emission at z=0.247. This high-resolution Chandra observation allows us for the first time to separate unambiguously the X-ray contributions from discrete sources and large-scale diffuse hot gas. We detect 99 X-ray sources in a 17{arcmin}x17{arcmin} field.
70. ALHAMBRA survey galaxy clusters and groups
ID:
ivo://CDS.VizieR/J/MNRAS/452/549
Title:
ALHAMBRA survey galaxy clusters and groups
Short Name:
J/MNRAS/452/549
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present a catalogue of 348 galaxy clusters and groups with 0.2<z<1.2 selected in the 2.78deg^2^ Advanced Large, Homogeneous Area Medium Band Redshift Astronomical (ALHAMBRA) survey. The high precision of our photometric redshifts, close to 1 percent, and the wide spread of the seven ALHAMBRA pointings ensure that this catalogue has better mass sensitivity and is less affected by cosmic variance than comparable samples. The detection has been carried out with the Bayesian Cluster Finder, whose performance has been checked in ALHAMBRA-like light-cone mock catalogues. Great care has been taken to ensure that the observable properties of the mocks photometry accurately correspond to those of real catalogues. From our simulations, we expect to detect galaxy clusters and groups with both 70 percent completeness and purity down to dark matter halo masses of M_h_~3x10^13^M_{sun}_ for z<0.85. Cluster redshifts are expected to be recovered with ~0.6 percent precision for z<1. We also expect to measure cluster masses with sigma_Mh_|M*CL_~0.25-0.35dex precision down to ~3x10^13^M_{sun}_, masses which are 50 percent smaller than those reached by similar work. We have compared these detections with previous optical, spectroscopic and X-rays work, finding an excellent agreement with the rates reported from the simulations. We have also explored the overall properties of these detections such as the presence of a colour-magnitude relation, the evolution of the photometric blue fraction and the clustering of these sources in the different ALHAMBRA fields. Despite the small numbers, we observe tentative evidence that, for a fixed stellar mass, the environment is playing a crucial role at lower redshifts (z<0.5).

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