- ID:
- ivo://CDS.VizieR/J/MNRAS/418/2054
- Title:
- Recession velocities for fossil galaxy groups
- Short Name:
- J/MNRAS/418/2054
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Defined as X-ray bright galaxy groups with large differences between the luminosities of their brightest and second brightest galaxies, "fossil groups" are believed to be some of the oldest galaxy systems in the Universe. They have therefore been the subject of much recent research. In this work we present a study of 10 fossil group candidates with an average of 33 spectroscopically confirmed members per group, making this the deepest study of its type to date. We also use these data to perform an analysis of the luminosity function of our sample of fossil groups.
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/503/357
- Title:
- Redhift catalog of A1237+A1240 galaxies
- Short Name:
- J/A+A/503/357
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The mechanisms giving rise to diffuse radio emission in galaxy clusters, and in particular their connection with cluster mergers, are still debated. We aim to obtain new insights into the internal dynamics of the cluster Abell 1240, which appears to contain two roughly symmetric radio relics, separated by ~2h_70_^-1^Mpc.
- ID:
- ivo://CDS.VizieR/J/ApJS/224/1
- Title:
- redMaPPer cluster catalog from DES data
- Short Name:
- J/ApJS/224/1
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We describe updates to the redMaPPer algorithm, a photometric red-sequence cluster finder specifically designed for large photometric surveys. The updated algorithm is applied to 150deg^2^ of Science Verification (SV) data from the Dark Energy Survey (DES), and to the Sloan Digital Sky Survey (SDSS) DR8 photometric data set. The DES SV catalog is locally volume limited and contains 786 clusters with richness {lambda}>20 (roughly equivalent to M_500c_>~10^14^h_70_^-1^M_{sun}_) and 0.2<z<0.9. The DR8 catalog consists of 26311 clusters with 0.08<z<0.6, with a sharply increasing richness threshold as a function of redshift for z>~0.35. The photometric redshift performance of both catalogs is shown to be excellent, with photometric redshift uncertainties controlled at the {sigma}_z_/(1+z)~0.01 level for z<~0.7 , rising to ~0.02 at z~0.9 in DES SV. We make use of Chandra and XMM X-ray and South Pole Telescope Sunyaev-Zeldovich data to show that the centering performance and mass-richness scatter are consistent with expectations based on prior runs of redMaPPer on SDSS data. We also show how the redMaPPer photo-z and richness estimates are relatively insensitive to imperfect star/galaxy separation and small-scale star masks.
- ID:
- ivo://CDS.VizieR/J/ApJ/785/104
- Title:
- redMaPPer. I. Algorithm applied to SDSS DR8
- Short Name:
- J/ApJ/785/104
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We describe redMaPPer, a new red sequence cluster finder specifically designed to make optimal use of ongoing and near-future large photometric surveys. The algorithm has multiple attractive features: (1) it can iteratively self-train the red sequence model based on a minimal spectroscopic training sample, an important feature for high-redshift surveys. (2) It can handle complex masks with varying depth. (3) It produces cluster-appropriate random points to enable large-scale structure studies. (4) All clusters are assigned a full redshift probability distribution P(z). (5) Similarly, clusters can have multiple candidate central galaxies, each with corresponding centering probabilities. (6) The algorithm is parallel and numerically efficient: it can run a Dark Energy Survey-like catalog in ~500 CPU hours. (7) The algorithm exhibits excellent photometric redshift performance, the richness estimates are tightly correlated with external mass proxies, and the completeness and purity of the corresponding catalogs are superb. We apply the redMaPPer algorithm to ~10000deg^2^ of SDSS DR8 data and present the resulting catalog of ~25000 clusters over the redshift range z{isin}[0.08,0.55]. The redMaPPer photometric redshifts are nearly Gaussian, with a scatter {sigma}_z_~0.006 at z~0.1, increasing to {sigma}_z_~0.02 at z~0.5 due to increased photometric noise near the survey limit. The median value for |{Delta}z|/(1+z) for the full sample is 0.006. The incidence of projection effects is low (<= 5%). Detailed performance comparisons of the redMaPPer DR8 cluster catalog to X-ray and Sunyaev-Zel'dovich catalogs are presented in a companion paper.
- ID:
- ivo://CDS.VizieR/J/ApJS/157/1
- Title:
- Red-Sequence Cluster Survey
- Short Name:
- J/ApJS/157/1
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Red-Sequence Cluster Survey (RCS) is a ~100{deg}^2^, two-filter imaging survey in the R_C_ and z' filters, designed primarily to locate and characterize galaxy clusters to redshifts as high as z=1.4. This paper provides a detailed description of the survey strategy and execution, including a thorough discussion of the photometric and astrometric calibration of the survey data. These catalogs, representing about 10% of the total survey and comprising a total of 429 candidate clusters and groups, contain a total of 67 cluster candidates at a photometric redshift of 0.9<z<1.4, down to the chosen significance threshold of 3.29{sigma}.
- ID:
- ivo://CDS.VizieR/J/A+A/640/A34
- Title:
- Red-sequence early-type galaxies in clusters
- Short Name:
- J/A+A/640/A34
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- It is not well understood whether the growth of early-type cluster galaxies proceeds inside-out, outside-in, or at the same pace at all radii. In this work we measured the galaxy size, defined by the radius including 80% of the galaxy light, non-parametrically. We also determined a non-parametric estimate of galaxy light concentration, which measures the curvature of the surface brightness profile in the galaxy outskirts. We used an almost random sampling of a mass-limited sample formed by 128 morphologically early-type galaxies in clusters with logM/M_{sun}_>10.7 spanning the wide range 0.17<z<1.81. From these data we derived the size-mass and concentration-mass relations, as well as their evolution. At 80% light radius, early-type galaxies in clusters are about 2.7 times larger than at 50% radius at all redshifts, and close to de Vaucouleurs profiles in the last 10Gyr. While between z=2 and z=0 both half-light and 80% light sizes increase by a factor of 1.7, concentration stays constant within 2%, that is to say the size growth of early-type galaxies in cluster environments proceeds at the same pace at both radii. Existing physical explanations proposed in the literature are inconsistent with our results, demonstrating the need for dedicated numerical simulations to identify the physical mechanism affecting the galaxy structure.
- ID:
- ivo://CDS.VizieR/J/A+A/593/A2
- Title:
- Red-sequence early-type galaxies in clusters
- Short Name:
- J/A+A/593/A2
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We carried out a photometric and structural analysis in the rest-frame V band of a mass-selected (logM/M_{sun}_>10.7) sample of red sequence galaxies in 14 galaxy clusters, six of which are at z>1.45, namely JKCS041, IDCS J1426.5+3508, SpARCS104922.6+564032.5, SpARCSJ022426-032330, XDCPJ0044.0-2033, and SPT-CLJ2040-4451. To this aim, we reduced/analysed about 300 orbits of multicolor images taken with the Advanced Camera for Survey and the Wide Field Camera 3 on Hubble Space Telescope. We uniformly morphologically classified galaxies from z=0.023 to z=1.803, and we homogeneously derived sizes (effective radii) for the entire sample. Furthermore, our size derivation allows, and therefore is not biased by, the presence of the usual variety of morphological structures seen in early-type galaxies, such as bulges, bars, disks, isophote twists, and ellipticity gradients. By such a mass-selected sample, composed of 244 red-sequence early-type galaxies, we find that the log of the galaxy size at a fixed stellar mass, logM/M_{sun}_=11 increases with time with a rate of 0.023+/-0.002dex per Gyr in the last 10Gyr, in marked contrast with the threefold increase found in literature for galaxies in the general field over the same period. This suggests, at face value, to exclude that secular processes are the primary drivers of size evolution, because we observed and environmental environmental dependent size growth. Using spectroscopic ages of Coma early-type galaxies we also find that recently quenched early-type galaxies are a numerically minor population not different in size enough to alter the mean size at a given mass, which implies that the progenitor bias is minor, i.e. that the evolution measured by selecting galaxies at the redshift of observation is indistinguishable from the one that compares ancestors and descendents.
- ID:
- ivo://CDS.VizieR/J/A+A/490/945
- Title:
- Redshifs of galaxies in 23 EIS fields
- Short Name:
- J/A+A/490/945
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have carried out a spectroscopic survey of low-redshift galaxy systems identified by the matched-filter technique in a moderately deep I-band survey. We present new redshifts for 747 galaxies in 23 ESO Imaging Survey (EIS) cluster fields. We use the "gap"-technique to search for significant overdensities in redshift space for identifying groups/clusters of galaxies corresponding to the original EIS matched-filter cluster candidates. In this way we spectroscopically confirm systems in 10 of the 23 cluster candidate fields with a matched-filter estimated redshift z_MF_=0.3-0.4 and with spectroscopic redshifts in the range from z=0.158 to z=0.534, with the observations favouring the confirmation of systems at the lower redshift end. After careful analysis of the redshift distribution, one system was split into two very close clumps in redshift space. We find that the systems identified in the present paper span a broad range of velocity dispersion and richness. The measured one-dimensional velocity dispersion range from 175km/s to 497km/s, consistent with the values obtained in previous papers using much larger samples for systems over the same redshift range. Both undersampling and contamination by substructures contribute to the uncertainty of these measurements. The richness range corresponds to clusters with an estimated total luminosity in the range 12L^*^-65L^*^, but these estimates are very uncertain as are their relation to the velocity dispersion (mass) of the systems. From the analysis of the colours of the galaxy populations we find that ~60% of the spectroscopically confirmed systems have a "significant" red sequence. We find that the colour of the red sequence galaxies matches passive stellar evolution predictions. With this paper we complete our spectroscopic survey of the fields of 58 EIS cluster candidates with estimated redshifts z<=0.4 (see also Hansen et al., 2002, Cat. <J/A+A/388/1>; Olsen et al., 2003, Cat. <J/A+A/409/439>, Olsen et al., 2005, Cat. <J/A+A/435/781>). We have measured a total of 1954 galaxy redshifts in the range z=0.0065 to z=0.6706. Of the 58 systems we confirm 42 (~75%) with redshifts between z=0.095 and z=0.534.
- ID:
- ivo://CDS.VizieR/J/A+A/635/A98
- Title:
- Redshift catalogs of the Abell 2163 core
- Short Name:
- J/A+A/635/A98
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Abell 2163 at z~=0.201 is one of the most massive galaxy clusters known, very likely in a post-merging phase. Data from several observational windows suggest a complex mass structure with interacting subsystems, which makes the reconstruction of a realistic merging scenario very difficult. A missing key element in this sense is unveiling the cluster mass distribution at high resolution. We perform such a reconstruction of the cluster inner total mass through a strong lensing model based on new spectroscopic redshift measurements. We use data from the Multi Unit Spectroscopic Explorer on the Very Large Telescope to confirm 12 multiple images of four sources with redshift values from 1.16 to 2.72. We also discover four new multiple images and identify 29 cluster members and 35 foreground and background sources. The resulting galaxy member and image catalogs are used to build five cluster total mass models. The fiducial model consists of 111 small-scale subhalos, plus a diffuse component, which is centered ~2" away from the BCG belonging to the east Abell 2163 subcluster. We confirm that the latter is well represented by a single, large-scale mass component. Its strong elongation towards a second (west) subcluster confirms the existence of a preferential axis, corresponding to the merging direction. From the fiducial model, we extrapolate the cumulative projected total mass profile and measure a value of M(<300kpc)=1.43_-0.06_^+0.07^x10^14^M_{sun}_, which has a significantly reduced statistical error compared with previous estimates, thanks to the inclusion of the spectroscopic redshifts. Our strong lensing results are very accurate: the model-predicted positions of the multiple images are, on average, only 0.15" away from the observed ones.
- ID:
- ivo://CDS.VizieR/J/A+A/638/A27
- Title:
- Redshift database towards Shapley Supercluster
- Short Name:
- J/A+A/638/A27
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a database and velocity catalogue towards the region of the Shapley Supercluster based on 18,129 measured velocities for 10,702 galaxies in the approximately 300 square degree area between 12:42:13.219<RA<14:16:59.210 and -38:29:35.70<Dec<-23:28:34.90. The data catalogue contains velocities from the literature found until 2015. It also includes 5,084 velocities, corresponding to 4617 galaxies, observed by us at Las Campanas and CTIO observatories and not reported individually until now. Of these, 2585 correspond to galaxies with no other previously published velocity measurement before 2015. Every galaxy in the velocity database has been identified with a galaxy extracted from the SuperCOSMOS photometric catalogues. We also provide a combined average velocity catalogue for all 10702 galaxies with measured velocities, adopting the SuperCOSMOS positions as a homogeneous base. A general magnitude cut-off at R2=18.0mag was adopted (with exceptions only for some of the new reported velocities). In general terms, we confirm the overall structure of the Shapley Supercluster, as found on earlier papers. However, the more extensive velocity data show finer structure, to be discussed in a future publication.
