- ID:
- ivo://CDS.VizieR/J/ApJS/183/197
- Title:
- Galaxy clusters identified from the SDSS-DR6
- Short Name:
- J/ApJS/183/197
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Clusters of galaxies in most of the previous catalogs have redshifts z<=0.3. Using the photometric redshifts of galaxies from the Sloan Digital Sky Survey Data Release 6 (SDSS DR6), we identify 39716 clusters in the redshift range 0.05<z<0.6 with more than eight luminous (M_r_<=-21) member galaxies. Cluster redshifts are estimated accurately with an uncertainty of less than 0.022. The contamination rate of member galaxies is found to be roughly 20%, and the completeness of member galaxy detection reaches ~90%. Monte Carlo simulations show that the cluster detection rate is more than 90% for massive (M_200_>2x10^14^M_{sun}_) clusters of z<=0.42. The false detection rate is ~5%. We obtain the richness, the summed luminosity, and the gross galaxy number within the determined radius for identified clusters. They are tightly related to the X-ray luminosity and temperature of clusters. Cluster mass is related to the richness and summed luminosity with M_200_{prop.to}R^1.90+/-0.04^ and M_200_{prop.to}L^1.64+/-0.03^_r_, respectively. In addition, 790 new candidates of X-ray clusters are found by cross-identification of our clusters with the source list of the ROSAT X-ray survey.
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/ApJ/679/1144
- Title:
- Galaxy clusters in LOS to background QSOs. I.
- Short Name:
- J/ApJ/679/1144
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We describe the first optical survey of absorption systems associated with cluster galaxies at z=0.3-0.9. We have cross-correlated quasars from the third data release of the SDSS (Cat. VII/243) with high-redshift cluster/group candidates from the Red-Sequence Cluster Survey (Cat. J/ApJS/157/1). We have found 442 quasar-cluster pairs for which the MgII{lambda}2796, 2803 doublet might be detected at a transverse (physical) distance d<2h^-1^_71_Mpc from the cluster centers. To investigate the incidence dN/dz and equivalent width distribution n(W) of MgII systems at cluster redshifts, two statistical samples were drawn out of these pairs: one made of high-resolution spectroscopic quasar observations (46 pairs), and one made of quasars used in MgII searches found in the literature (375 pairs).
- ID:
- ivo://CDS.VizieR/J/MNRAS/413/3059
- Title:
- 4098 galaxy clusters in SDSS Stripe 82
- Short Name:
- J/MNRAS/413/3059
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a catalogue of 4098 photometrically selected galaxy clusters with a median redshift <z>=0.32 in the 270deg^2^ "Stripe 82" region of the Sloan Digital Sky Survey (SDSS), covering the celestial equator in the Southern Galactic Cap (-50{deg}<RA<59{deg}, |DE|<=1.25). Owing to the multi-epoch SDSS coverage of this region, the ugriz photometry is ~2mag deeper than single scans within the main SDSS footprint. We exploit this to detect clusters of galaxies using an algorithm that searches for statistically significant overdensities of galaxies in a Voronoi tessellation of the projected sky.
- ID:
- ivo://CDS.VizieR/J/A+A/578/A79
- Title:
- Galaxy clusters in SDSS Stripe 82
- Short Name:
- J/A+A/578/A79
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The discovery of new galaxy clusters is important for two reasons. First, clusters are interesting per se, since their detailed analysis allows us to understand how galaxies form and evolve in various environments and second, they play an important part in cosmology because their number as a function of redshift gives constraints on cosmological parameters. We have searched for galaxy clusters in the Stripe 82 region of the Sloan Digital Sky Survey, and analysed various properties of the cluster galaxies. Based on a recent photometric redshift (hereafter photo-z) galaxy catalogue, we built a cluster catalogue by applying the Adami & MAzure Cluster FInder (AMACFI). Extensive tests were made to fine-tune the AMACFI parameters and make the cluster detection as reliable as possible. The same method was applied to the Millennium simulation to estimate our detection efficiency and the approximate masses of the detected clusters. Considering all the cluster galaxies (i.e. within a 1Mpc radius of the cluster to which they belong and with a photo-z differing by less than +/-0.05 from that of the cluster), we stacked clusters in various redshift bins to derive colour-magnitude diagrams and galaxy luminosity functions (GLFs). For each galaxy brighter than Mr<-19.0, we computed the disk and spheroid components by applying SExtractor, and by stacking clusters we determined how the disk-to-spheroid flux ratio varies with cluster redshift and mass.
- ID:
- ivo://CDS.VizieR/J/A+A/494/845
- Title:
- Galaxy clusters in the CFHTLS
- Short Name:
- J/A+A/494/845
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We investigate the gain of added leverage and completeness of the constructed cluster catalogue, of applying the matched-filter detection algorithm to multiple passbands. In particular, we investigate the gain from having both i'- and z'-band data available when searching for galaxy clusters at z>~1. We applied a matched filter detection method to the CFHTLS r'- and z'-band data of the four Deep fields and compared the cluster catalogues with the one extracted from the i'-band data presented in a previous paper. We also applied the matched filter to the Deep fields but with the limiting magnitudes appropriate for the much larger Wide survey in order to understand the best combination of i'- and z'-band depth for the most efficient cluster searches based on this algorithm.
- ID:
- ivo://CDS.VizieR/J/A+A/461/81
- Title:
- Galaxy clusters in the CFHTLS
- Short Name:
- J/A+A/461/81
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We apply a matched-filter cluster detection algorithm to the Canada-France-Hawaii Telescope Legacy Survey (CFHTLS) i-band data for the Deep-1, Deep-2, Deep-3 and Deep-4 fields covering a total of 4 square degrees. To test the implemented procedure we carry out simulations for assessing the frequency of noise peaks as well as estimate the recovery efficiency. We estimate that up to z~0.7 the catalogue is essentially complete for clusters of richness class R>~1. The recovered redshifts are in general overestimated by dz=0.1 with a scatter of sigma_dz_~0.1, except at redshifts z>~1 where the estimated redshifts are systematically underestimated. The constructed cluster candidate catalogue contains 162 detections over an effective area of 3.112 square degrees corresponding to a density of ~52.1 per square degree. The median estimated redshift of the candidates is z=0.6. The estimated noise frequency is 16.9+/-5.4 detections per square degree. From visual inspection we identify systems that show a clear concentration of galaxies with similar colour. These systems have a density of ~20 per square degree.
- ID:
- ivo://CDS.VizieR/J/A+A/535/A65
- Title:
- Galaxy clusters in the 4 CFHTLS Wide fields
- Short Name:
- J/A+A/535/A65
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have developed a method for detecting clusters in large imaging surveys, based on the detection of structures in galaxy density maps made in slices of photometric redshifts. This method was first applied to the Canada France Hawaii Telescope Legacy Survey (CFHTLS) Deep 1 field by Mazure et al. (2007A&A...467...49M), then to all the Deep and Wide CFHTLS fields available in the T0004 data release by Adami et al. (2010, Cat. J/A+A/509/81). The validity of the cluster detection rate was estimated by applying the same procedure to galaxies from the Millennium simulation. Here we analyse with the same method the full CFHTLS Wide survey, based on the T0006 data release. In a total area of 154deg^2^, we have detected 4061 candidate clusters at 3sigma or above (6802 at 2sigma and above), in the redshift range 0.1<=z<=1.15, with estimated mean masses between 1.3x10^14^ and 12.6x10^14^M_{sun}_. We compare our detections with those made in various CFHTLS analyses with other methods. By stacking a subsample of clusters, we show that this subsample has typical cluster characteristics (colour-magnitude relation, galaxy luminosity function). We also confirm that the cluster-cluster correlation function is comparable to that obtained for other cluster surveys and analyze large scale filamentary galaxy distributions. We have increased the number of known optical high redshift cluster candidates by a large factor, an important step towards obtaining reliable cluster counts to measure cosmological parameters. The clusters that we detect behave as expected for a sample of clusters fed by filaments at the intersection of which they are located.
- ID:
- ivo://CDS.VizieR/J/MNRAS/413/1145
- Title:
- Galaxy clusters in the COSMOS field
- Short Name:
- J/MNRAS/413/1145
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Galaxy clusters are usually detected in blind optical surveys via suitable filtering methods. We present an optimal matched filter which maximizes their signal-to-noise ratio by taking advantage of the knowledge we have of their intrinsic physical properties and of the data noise properties. In this paper we restrict our application to galaxy magnitudes, positions and photometric redshifts if available, and we also apply the filter separately to weak lensing data. The method is suitable to be naturally extended to a multi-band approach which could include not only additional optical bands but also observables with different nature such as X-rays. For each detection, the filter provides its significance, an estimate for the richness and for the redshift even if photo-z are not given. The provided analytical error estimate is tested against numerical simulations. We finally apply our method to the COSMOS field and compare the results with previous cluster detections obtained with different methods. Our catalogue contains 27 galaxy clusters with minimal threshold at 3{sigma} level including both optical and weak-lensing information.
- ID:
- ivo://CDS.VizieR/J/ApJS/176/414
- Title:
- Galaxy clusters in the SDSS-DR5
- Short Name:
- J/ApJS/176/414
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Recent large-scale galaxy spectroscopic surveys, such as the Sloan Digital Sky Survey (SDSS), enable us to execute a systematic, relatively unbiased search for galaxy clusters. Such surveys make it possible to measure the 3D distribution of galaxies but are hampered by the incompleteness problem due to fiber collisions. In this study we aim to develop a density-measuring technique that alleviates the problem and derives densities more accurately by adding additional cluster member galaxies that follow optical color-magnitude relations for the given redshift. The new density measured with both spectroscopic and photometric data shows a good agreement with apparent information on cluster images and is supported by follow-up observations. By adopting this new method, a total of 924 robust galaxy clusters are found from the SDSS DR5 database in the redshift range 0.05<z<0.1, of which 212 are new. Local maximum-density galaxies successfully represent cluster centers. We provide the cluster catalog including a number of cluster parameters.
- ID:
- ivo://CDS.VizieR/J/A+A/551/A8
- Title:
- Galaxy clusters in XMM field within CFHT-LS D4
- Short Name:
- J/A+A/551/A8
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The XMM-Newton Distant Cluster Project (XDCP) aims at the identification of a well defined sample of X-ray selected clusters of galaxies at redshifts z>0.8. As part of this project, we analyse the deep XMM-Newton exposure covering one of the CFHTLS deep fields to quantify the cluster content. We validate the optical follow-up strategy as well as the X-ray selection function. We search for extended X-ray sources in archival XMM-Newton EPIC observations. Multi-band optical imaging is performed to select high redshift cluster candidates among the extended X-ray sources. Here we present a catalogue of the extended sources in one the deepest LBQS ~250ks XMM-Newton fields targeting LBQS J2212-1759 covering ~0.2 square degrees. The cluster identification is based, among others, on deep imaging with the ESO VLT and from the CFHT legacy survey. The confirmation of cluster candidates is done by VLT/FORS2 multi-object spectroscopy. Photometric redshifts from the CFHTLS D4 are utilized to confirm the effectiveness of the X-ray cluster selection method. The survey sensitivity is computed with extensive Monte-Carlo simulations. At a flux limit of S(0.5-2.0keV)~2.5e-15erg/s/cm2 we achieve a completeness level higher than 50% in an area of ~0.13 square degrees. We detect six galaxy clusters above this limit with optical counterparts, of which 5 are new spectroscopic discoveries. Two newly discovered X-ray luminous galaxy clusters are at z>1.0, another two at z=0.41 and one at z=0.34. For the most distant X-ray selected cluster in this field at z=1.45 we find additional (active) member galaxies from both X-ray and spectroscopic data. Additionally, we find evidence of large scale structures at moderate redshifts of z=0.41 and z=0.34. The quest for distant clusters in archival XMM-Newton data has led to the detection of six clusters in a single field, making XMM-Newton an outstanding tool for cluster surveys. Three of these clusters are at z>1, which emphasises the valuable contribution of small, yet deep surveys to cosmology. Beta-models are appropriate descriptions for the cluster surface brightness to perform cluster detection simulations in order to compute the X-ray selection function. The constructed log N-log S tends to favour a scenario where no evolution in the cluster X-ray luminosity function (XLF) takes place.
