- ID:
- ivo://CDS.VizieR/J/A+A/643/A177
- Title:
- Candidate Cluster Members with Deep learning
- Short Name:
- J/A+A/643/A177
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The next generation of extensive and data-intensive surveys are bound to produce a vast amount of data, which can be efficiently dealt with using machine-learning and deep-learning methods to explore possible correlations within the multi-dimensional parameter space. We explore the classification capabilities of convolution neural networks (CNNs) to identify galaxy cluster members (CLMs) by using Hubble Space Telescope (HST) images of fifteen galaxy clusters at redshift 0.19<~z<~0.60, observed as part of the CLASH and Hubble Frontier Field programmes. We used extensive spectroscopic information, based on the CLASH-VLT VIMOS programme combined with MUSE observations, to define the knowledge base. We performed various tests to quantify how well CNNs can identify cluster members on ht basis of imaging information only. Furthermore, we investigated the CNN capability to predict source memberships outside the training coverage, in particular, by identifying CLMs at the faint end of the magnitude distributions. We find that the CNNs achieve a purity-completeness rate >~90%, demonstrating stable behaviour across the luminosity and colour of cluster galaxies, along with a remarkable generalisation capability with respect to cluster redshifts. We concluded that if extensive spectroscopic information is available as a training base, the proposed approach is a valid alternative to catalogue-based methods because it has the advantage of avoiding photometric measurements, which are particularly challenging and time-consuming in crowded cluster cores. As a byproduct, we identified 372 photometric cluster members, with mag(F814)<25, to complete the sample of 812 spectroscopic members in four galaxy clusters RX J2248-4431, MACS J0416-2403, MACS J1206-0847 and MACS J1149+2223. When this technique is applied to the data that are expected to become available from forthcoming surveys, it will be an efficient tool for a variety of studies requiring CLM selection, such as galaxy number densities, luminosity functions, and lensing mass reconstruction.
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/509/A81
- Title:
- Candidate clusters detected in six CFHTLS fields
- Short Name:
- J/A+A/509/A81
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Counting clusters is one of the methods to constrain cosmological parameters, but has been limited up to now both by the redshift range and by the relatively small sizes of the homogeneously surveyed areas. In order to enlarge publicly available optical cluster catalogs, in particular at high redshift, we have performed a systematic search for clusters of galaxies in the Canada France Hawaii Telescope Legacy Survey (CFHTLS). We considered the deep 2, 3 and 4 CFHTLS Deep fields (each 1x1deg^2^), as well as the wide 1, 3 and 4 CFHTLS Wide fields. We used the Le Phare photometric redshifts for the galaxies detected in these fields with magnitude limits of i'=25 and 23 for the Deep and Wide fields respectively. We then constructed galaxy density maps in photometric redshift bins of 0.1 based on an adaptive kernel technique and detected structures with SExtractor at various detection levels. In order to assess the validity of our cluster detection rates, we applied a similar procedure to galaxies in Millennium simulations. We measured the correlation function of our cluster candidates. We analyzed large scale properties and substructures, including filaments, by applying a minimal spanning tree algorithm both to our data and to the Millennium simulations.
- ID:
- ivo://CDS.VizieR/J/A+A/613/A67
- Title:
- Candidate clusters in 4 CFHTLS T0007 Wide fields
- Short Name:
- J/A+A/613/A67
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Obtaining large samples of galaxy clusters is important for cosmology: cluster counts as a function of redshift and mass can constrain the parameters of our Universe. They are also useful in order to understand the formation and evolution of clusters. We develop an improved version of the Adami & MAzure Cluster FInder (AMACFI), now the Adami, MAzure & Sarron Cluster FInder (AMASCFI), and apply it to the 154deg^2^ of the Canada-France-Hawaii Telescope Legacy Survey (CFHTLS) to obtain a large catalogue of 1371 cluster candidates with mass M_200_>10^14^M{_sun}_ and redshift z<=0.7. We derive the selection function of the algorithm from the Millennium simulation, and cluster masses from a richness-mass scaling relation built from matching our candidates with X-ray detections. We study the evolution of these clusters with mass and redshift by computing the i'-band galaxy luminosity functions (GLFs) for the early-type (ETGs) and late-type galaxies (LTGs). This sample is 90% pure and 70% complete, and therefore our results are representative of a large fraction of the cluster population in these redshift and mass ranges. We find an increase in both the ETG and LTG faint populations with decreasing redshift (with Schechter slopes {sigma}_ETG_=-0.65+/-0.03 and {sigma}_LTG_=-0.95+/-0.04 at z=0.6, and {sigma}_ETG_=-0.79+/-0.02 and {sigma}_LTG_=-1.26+/-0.03 at z=0.2) and also a decrease in the LTG (but not the ETG) bright end. Our large sample allows us to break the degeneracy between mass and redshift, finding that the redshift evolution is more pronounced in high-mass clusters, but that there is no significant dependence of the faint end on mass for a given redshift. These results show that the cluster red sequence is mainly formed at redshift z>0.7, and that faint ETGs continue to enrich the red sequence through quenching of brighter LTGs at z<=0.7. The efficiency of this quenching is higher in large-mass clusters, while the accretion rate of faint LTGs is lower as the more massive clusters have already emptied most of their environment at higher redshifts.
- ID:
- ivo://CDS.VizieR/J/A+A/598/A107
- Title:
- Candidate galaxy clusters in KiDS-DR2
- Short Name:
- J/A+A/598/A107
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In this paper, we present the tools used to search for galaxy clusters in the Kilo Degree Survey (KiDS), and our first results. The cluster detection is based on an implementation of the optimal filtering technique that enables us to identify clusters as over-densities in the distribution of galaxies using their positions on the sky, magnitudes, and photometric redshifts. The contamination and completeness of the cluster catalog are derived using mock catalogs based on the data themselves. The optimal signal to noise threshold for the cluster detection is obtained by randomizing the galaxy positions and selecting the value that produces a contamination of less than 20%. Starting from a subset of clusters detected with high significance at low redshifts, we shift them to higher redshifts to estimate the completeness as a function of redshift: the average completeness is ~85%. An estimate of the mass of the clusters is derived using the richness as a proxy.
- ID:
- ivo://CDS.VizieR/J/MNRAS/476/3336
- Title:
- Candidate high-z protoclusters among PCS
- Short Name:
- J/MNRAS/476/3336
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- By determining the nature of all the Planck compact sources within 808.4deg^2^ of large Herschel surveys, we have identified 27 candidate protoclusters of dusty star-forming galaxies (DSFGs) that are at least 3{sigma} overdense in either 250, 350, or 500um sources. We find roughly half of all the Planck compact sources are resolved by Herschel into multiple discrete objects, with the other half remaining unresolved by Herschel. We find a significant difference between versions of the Planck catalogues, with earlier releases hosting a larger fraction of candidate protoclusters and Galactic cirrus than later releases, which we ascribe to a difference in the filters used in the creation of the three catalogues. We find a surface density of DSFG candidate protoclusters of (3.3+/-0.7)x10^-2^sources/deg^2^, in good agreement with previous similar studies. We find that a Planck colour selection of S_857_/S_545_<2 works well to select candidate protoclusters, but can miss protoclusters at z<2. The Herschel colours of individual candidate protocluster members indicate our candidate protoclusters all likely all lie at z>1. Our candidate protoclusters are a factor of 5 times brighter at 353GHz than expected from simulations, even in the most conservative estimates. Further observations are needed to confirm whether these candidate protoclusters are physical clusters, multiple protoclusters along the line of sight, or chance alignments of unassociated sources.
- ID:
- ivo://CDS.VizieR/J/A+A/641/A22
- Title:
- CARLA J1103+3449 cluster datacube
- Short Name:
- J/A+A/641/A22
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Passive early-type galaxies dominate cluster cores at z<~1.5. At higher redshift, cluster core galaxies are observed to have on-going star-formation, which is fuelled by cold molecular gas.We measured the molecular gas reservoir of the central region around the radioloud active galactic nucleus (AGN) in the cluster CARLA J1103+3449 at z=1.44 using NOEMA. The AGN synchrotron emission dominates the continuum emission at 94.48GHz, and we measured its flux at the AGN position and at the position of two radio jets. Combining our measurements with published results over the range 4.71GHz-94.5GHz, and assuming S_synch_{prop.to}{nu}^-{alpha}^, we obtain a flat spectral index of = 0:14 0:03 for the AGN core emission, and a steeper index of {alpha}=1.43+/-0.04 and {alpha}=1.15+/-0.04 at positions close to the western and eastern lobes, respectively. The total spectral index is {alpha}=0.92+/-0.02 over the range 73.8MHz-94.5GHz.We detect two CO(2-1) emission lines, both blueshifted with respect to the AGN. Their emission corresponds to two regions, 17kpc southeast and 14kpc southwest of the AGN, not associated with galaxies. In these two regions, we find a total massive molecular gas reservoir of M^tot^_gas_=3.9+/-0.4x10^10^M_{sun}_, which dominates (>~60%) the central total molecular gas reservoir. These results can be explained by massive cool gas flows in the center of the cluster. The AGN early-type host is not yet quenched; its star formation rate is consistent with being on the main sequence of star-forming galaxies in the field (star formation rate ~30-140M_[sun}_/yr), and the cluster core molecular gas reservoir is expected to feed the AGN and the host star formation before quiescence. The other confirmed cluster members show star formation rates at 2 below the field main sequence at similar redshifts and do not have molecular gas masses larger than galaxies of similar stellar mass in the field.
- ID:
- ivo://CDS.VizieR/J/ApJS/148/243
- Title:
- Catalog of clusters of galaxies from SDSS
- Short Name:
- J/ApJS/148/243
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a catalog of 799 clusters of galaxies in the redshift range z_est_=0.05-0.3 selected from ~400deg^2^ of early Sloan Digital Sky Survey (SDSS) commissioning data along the celestial equator. The catalog is based on merging two independent selection methods - a color-magnitude red-sequence maxBCG technique (B), and a hybrid matched filter method (H). The BH catalog includes clusters with richness {Lambda}>=40 (matched filter) and Ngal>=13 (maxBCG), corresponding to typical velocity dispersion of {sigma}_v_>~400km/s and mass (within 0.6h^-1^Mpc radius) >~5x10^13^h^-1^M_{sun}_. This threshold is below Abell richness class 0 clusters. The average space density of these clusters is 2x10^-5^h^3^/Mpc^3^. All NORAS (<J/ApJS/129/435>) X-ray clusters and 53 of the 58 Abell clusters in the survey region are detected in the catalog; the five additional Abell clusters are detected below the BH catalog cuts. The cluster richness function is determined and found to exhibit a steeply decreasing cluster abundance with increasing richness. We derive observational scaling relations between cluster richness and observed cluster luminosity and cluster velocity dispersion; these scaling relations provide important physical calibrations for the clusters. The catalog can be used for studies of individual clusters, for comparisons with other sources such as X-ray clusters and active galactic nuclei, and, with proper correction for the relevant selection functions, also for statistical analyses of clusters.
- ID:
- ivo://CDS.VizieR/J/ApJS/97/77
- Title:
- Catalog of Coma Cluster Galaxies
- Short Name:
- J/ApJS/97/77
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A homogeneous photometry catalog is presented for 450 galaxies with B25.5 <= 16 mag located in the 9.8 x 9.8 deg region centred on the Coma Cluster. The catalog is based on photographic photometry using an automated surface photometry software for data reduction applied to B-band Schmidt plates. The catalog provides accurate positions, isophotal and total magnitudes, major and minor axes, and a few other photometric parameters including rudimentary morphology (early or late type).
- ID:
- ivo://CDS.VizieR/J/AJ/130/425
- Title:
- Catalog of distant compact groups of galaxies
- Short Name:
- J/AJ/130/425
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In this paper we present an objectively defined catalog of 459 small, high-density groups of galaxies out to z~0.2 in a region of ~6260deg^2^ in the northern sky derived from the Digitized Second Palomar Observatory Sky Survey. Our catalog extends down to r=19.0 and has a median redshift of z_med_=0.12, making it complementary to Hickson's catalog (Cat. <VII/213>) for the nearby universe (z_med_=0.03).
- ID:
- ivo://CDS.VizieR/J/ApJ/306/30
- Title:
- Catalog of distant galaxy clusters
- Short Name:
- J/ApJ/306/30
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A photographic survey for faint galaxies has been carried out with fine-grained photographic emulsions using the 1.2m Schmidt and 5m Hale telescopes, as well as the 4m Mayall telescope. A total of 418 clusters have been found with redshifts mostly in the range from 0.15 to 0.92. The survey was planned to minimize distance-dependent selection effects in the resulting catalog. In areas of sky where the deepest search was made, the sample is complete to about z=0.50; there are 11 clusters per square degree at this limit. At a redshift of 1.0 there should be 63 or 45 clusters per square degree depending on whether q_0_ is 0.0 or 0.5, provided there is no evolution.
