- ID:
- ivo://CDS.VizieR/J/ApJS/167/1
- Title:
- Galaxy groups and clusters from SDSS
- Short Name:
- J/ApJS/167/1
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We identify galaxy groups and clusters in volume-limited samples of the Sloan Digital Sky Survey (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 with 10 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 ~1%; a halo completeness of more than 97%; the correct projected size distribution as a function of multiplicity; and a velocity dispersion distribution that is ~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 3495.1deg^2^ on the sky, go out to redshifts of 0.1, 0.068, and 0.045, and contain 57138, 37820, and 18895 galaxies, respectively. 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.
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Search Results
- ID:
- ivo://CDS.VizieR/J/ApJ/625/6
- Title:
- Galaxy groups in the DEEP2 Galaxy Redshift Survey
- Short Name:
- J/ApJ/625/6
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We use the first 25% of the DEEP2 Galaxy Redshift Survey spectroscopic data to identify groups and clusters of galaxies in redshift space. The data set contains 8370 galaxies with confirmed redshifts in the range 0.7<=z<=1.4, over 1{deg}^2^ on the sky. Groups are identified using an algorithm (the Voronoi-Delaunay method) that has been shown to accurately reproduce the statistics of groups in simulated DEEP2-like samples. We optimize this algorithm for the DEEP2 survey by applying it to realistic mock galaxy catalogs and assessing the results using a stringent set of criteria for measuring group-finding success, which we develop and describe in detail here. We present the first DEEP2 group catalog, which assigns 32% of the galaxies to 899 distinct groups with two or more members, 153 of which have velocity dispersions above 350km/s. We provide locations, redshifts and properties for this high-dispersion subsample. This catalog represents the largest sample to date of spectroscopically detected groups at z~1.
- ID:
- ivo://CDS.VizieR/J/A+A/578/A61
- Title:
- Galaxy groups in the 2M++
- Short Name:
- J/A+A/578/A61
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We provide the galaxy group sample used as tracers of the large scale structure in the work to study the compact group environment.
- ID:
- ivo://CDS.VizieR/J/A+A/520/A42
- Title:
- Galaxy groups in the VIMOS-VLT Deep Survey
- Short Name:
- J/A+A/520/A42
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a homogeneous and complete catalogue of optical galaxy groups identified in the VIMOS-VLT Deep Survey (VVDS). We use mock catalogues extracted from the Millennium Simulation to study the potential systematics that might affect the overall distribution of the identified systems, and also to asses how well galaxy redshifts trace the line-of-sight velocity dispersion of the underlying mass overdensity. We train on these mock catalogues the adopted group-finding technique (the Voronoi-Delaunay Method, VDM), to recover in a robust and unbiased way the redshift and velocity dispersion distributions of groups and maximize the level of completeness (C) and purity (P) of the group catalogue. We identify 318(/144) VVDS groups with at least 2(/3) members within 0.2<=z<=1.0, globally with C=60% and P=50%. We use the group sample to study the redshift evolution of the fraction f_b_ of blue galaxies (U-B<=1) within 0.2<=z<=1 in both groups and in the whole ensemble of galaxies irrespectively of their environment.
- ID:
- ivo://CDS.VizieR/J/MNRAS/337/256
- Title:
- Galaxy in low X-ray luminosity clusters
- Short Name:
- J/MNRAS/337/256
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the first spectroscopic survey of intrinsically low X-ray luminosity clusters at z>>0, with Hubble Space Telescope (HST) WFPC2 imaging and spectroscopy from Calar Alto and WHT-LDSS2. We study 172 confirmed cluster members in a sample of ten clusters at 0.23<z<0.3, with LX<~4x10^43^h^-2^erg/s[0.1-2.4keV]. The core of each cluster is imaged with WFPC2 in the F702W filter, and the spectroscopic sample is statistically complete to Mr~-19.0+5logh, within an 11' (~1.8h^-1^Mpc) field. The clusters are dynamically well-separated from the surrounding field and most have velocity distributions consistent with Gaussians. The velocity dispersions range from 350-850km/s, consistent with the local L_X_-{sigma} correlation. All 10 clusters host a bright, giant elliptical galaxy without emission lines, near the centre of the X-ray emission. We measure the equivalent width of two nebular emission lines, [O II] and H{alpha}, and the H{delta} absorption line to classify the cluster members spectrally. Galaxy morphologies are measured from the HST images, using the two-dimensional surface-brightness fitting software GIM2D.
- ID:
- ivo://CDS.VizieR/J/ApJ/539/577
- Title:
- Galaxy morphologies in Cl 1358+62
- Short Name:
- J/ApJ/539/577
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We describe the morphological composition of a sample of 518 galaxies in the field of Cl 1358+62 at z=0.33, drawn from a large Hubble Space Telescope mosaic covering 53 square arcminutes. The sample is complete to I=22, corresponding to M_V_=-18.5 in the rest frame. The galaxy morphologies have been independently classified by the authors of this paper and by Alan Dressler. Dressler's classifications place our work in context with the previous MORPHS study and allow us to estimate the scatter between different sets of visual classifications. We restrict most of our analysis to the brighter part of the sample, I<21 (M_V_<-19.5), where the scatter between the two sets of classifications is 1 in morphological type.
- ID:
- ivo://CDS.VizieR/J/A+A/506/1071
- Title:
- Galaxy morphology in 5 medium redshift clusters
- Short Name:
- J/A+A/506/1071
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Following the study presented in our previous paper, based on the Nordic Optical Telescope (NOT) sample, which consists of five clusters of galaxies within the redshift range 0.18<=z<=0.25 imaged in the central 0.5-2Mpc in very good seeing conditions, we have studied the quantitative morphology of their bright galaxy population. We analyzed the surface brightness profiles of the galaxy population in those clusters, after performing simulations in order to check the reliability of the fits. We also derived a quantitative morphological classification.
- ID:
- ivo://CDS.VizieR/J/MNRAS/388/1537
- Title:
- Galaxy pairs from SDSS-DR2
- Short Name:
- J/MNRAS/388/1537
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We investigate the incidence of major mergers creating massive (M_star_>10^11^M_{sun}_) galaxies in present-day (z<=0.12) groups and clusters. Using a volume-limited sample of 845 groups with dark matter halo masses above 2.5x10^13^M_{sun}_, we isolate 221 galaxy pairs with <=1.5 r-band magnitude differences, <=30kpc projected separations and combined masses above 10^11^M_{sun}_. We fit the r-band images of each pair as the line-of-sight projection of symmetric models and identify 38 mergers by the presence of residual asymmetric structure associated with both progenitors, such as non-concentric isophotes, broad and diffuse tidal tails and dynamical friction wakes.
- ID:
- ivo://CDS.VizieR/J/A+A/527/A101
- Title:
- Galaxy population of Abell 1367
- Short Name:
- J/A+A/527/A101
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Spectroscopic and photometric data of the galaxy population of the galaxy cluster Abell 1367, over a field of 34'x90', covering the cluster centre out to a radius of ~2.2Mpc, are presented as the first stage of a study of their stellar population and star formation properties. Spectroscopic catalogue contains new detection data of emission and/or absorption lines for 84 galaxies in our survey regions. Photometric data give optical and near-infrared isophotal magnitudes for 303 galaxies, determined within R_24_ isophotal diameters. H{alpha} emission catalogue reports equivalent widths and fluxes of 72 galaxies, confirmed as cluster members of Abell 1367.
- ID:
- ivo://CDS.VizieR/J/A+A/504/347
- Title:
- Galaxy properties in clusters
- Short Name:
- J/A+A/504/347
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We investigate the dependence of several galaxy properties on the environment and cluster identification techniques.
