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1971. Candidate Cluster Members with Deep learning
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.
1972. Candidate clusters detected in six CFHTLS fields
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.
1973. Candidate clusters in 4 CFHTLS T0007 Wide fields
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.
1974. Candidate field horizontal-branch stars catalog
ID:
ivo://CDS.VizieR/J/ApJS/67/461
Title:
Candidate field horizontal-branch stars catalog
Short Name:
J/ApJS/67/461
Date:
21 Oct 2021
Publisher:
CDS
Description:
Coordinates and brightness estimates are presented for 4408 candidate field horizontal-branch stars selected using an objective-prism, interference-filter survey technique. The candidates lie primarily in the southern Galactic hemisphere, and are distributed in color over the range B-V from -0.2 to 0.40. Previous spectroscopic observation of a subset of these candidates indicates that roughly 85 percent of the catalog objects are bona fide members of the field blue horizontal branch. The remaining candidates include, in order of frequency, stars with main-sequence gravity which are likely to be a mix of metal-deficient turnoff stars and field blue stragglers, metallic line (Am) stars, A stars of near-solar metallicity, and high-luminosity or binary stars.
1975. Candidate Galaxies Behind the Milky Way
ID:
ivo://nasa.heasarc/cgmw
Title:
Candidate Galaxies Behind the Milky Way
Short Name:
CG
Date:
21 Feb 2025
Publisher:
NASA/GSFC HEASARC
Description:
This catalog gathers the searches for galaxies of apparent size greater than 0.1 mm on film (6.7&quot; in angular size) lieing behind the Milky Way from photographic surveys in the near-infrared. The four volumes (CGMW1, CGMW2, CGMW3, and CGMW4) cover the galactic longitude ranges from -7 to +43 degrees, and from 210 to 250 degrees. The two volumes, CGMW1 and CGMW2, giving about 7000 galaxies behind the Milky Way between l = 210 degrees and 250 degrees, represent a systematic search for galaxies by means of 32 film copies of the UK Schmidt Southern Infrared Atlas on the Milky Way covering about 900 square degrees. In the search galaxies with apparent sizes greater than 0.1mm on film (6.7 arcsec in size) were detected by visual inspection. The material and procedure of search are described as well as the detectability of galaxies in paper I and paper II appended before Vol. 1 and Vol. 2 of the catalog, respectively, which have been published in Publ. Astron. Soc Japan, Vol. 42 (1990) and Vol. 43 (1991). The parameters of catalogued galaxies are also explained in paper I. Cross-identifications with other catalogs are also given. The third volume CGMW3 lists about 5300 galaxy candidates having sizes larger than 0.1 arcminutes that were found in a search of Schmidt atlases covering a Milky Way region of about 800 square degrees around l = 8 to 43 degrees, and b = -17 to +17 degrees. This surveyed region is located between the northern Local void and the Ophiuchus void. The fourth volume CGMW4 lists about 7150 galaxies and galaxy candidates having sizes larger than 0.1 arcminutes that were found in a search of Schmidt atlases covering a Milky Way region of about 260 square degrees around l = -7 to +16 degrees, and b = -19 to -1 degrees, i.e., a field in Sagittarius in the Galactic Center region. This database was created by the HEASARC in October 1999 based on a machine-readable version that was obtained from the CDS Data Center. This is a service provided by NASA HEASARC .
1976. Candidate galaxy clusters in KiDS-DR2
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.
1977. Candidate Gamma-Ray Blazar Survey Source Catalog
ID:
ivo://nasa.heasarc/cgrabs
Title:
Candidate Gamma-Ray Blazar Survey Source Catalog
Short Name:
CGRABS
Date:
21 Feb 2025
Publisher:
NASA/GSFC HEASARC
Description:
The authors have constructed a uniform all-sky survey of bright blazars, selected primarily by their flat radio spectra, that is designed to provide a large catalog of likely gamma-ray active galactic nuclei (AGNs). The defined sample, the Candidate Gamma-Ray Blazar Survey (CGRaBS) source catalog, has 1625 targets with radio and X-ray properties similar to those of the EGRET blazars, spread uniformly across the |b| &gt; 10 degrees sky. They also report progress toward optical characterization of the sample; of objects with known red magnitude R &lt; 23, 85% have been classified and 81% have measured redshifts. One goal of this program is to focus attention on the most interesting (e.g., high-redshift, high-luminosity, etc.) sources for intensive multi-wavelength study during the observations by the Large Area Telescope (LAT) on the Gamma-Ray Large-Area Space Telescope (GLAST) satellite observatory. This table was created by the HEASARC in April 2008 based on an electronic version of Table 2 of the reference paper obtained from the electronic ApJS web site. This is a service provided by NASA HEASARC .
1978. Candidate globular clusters in NGC 5170
ID:
ivo://CDS.VizieR/J/MNRAS/403/429
Title:
Candidate globular clusters in NGC 5170
Short Name:
J/MNRAS/403/429
Date:
21 Oct 2021
Publisher:
CDS
Description:
Here, we present Hubble Space Telescope/Advanced Camera for Surveys (ACS) imaging, in the B and I bands, of the edge-on Sb/Sc galaxy NGC 5170. Excluding the central disc region, we detect 142 objects with colours and sizes typical of globular clusters (GCs). Our main result is the discovery of a "blue tilt" (a mass-metallicity relation), at the 3{sigma} level, in the metal-poor GC subpopulation of this Milky Way like galaxy.
1979. Candidate globular clusters in NGC 1316
ID:
ivo://CDS.VizieR/J/ApJ/750/140
Title:
Candidate globular clusters in NGC 1316
Short Name:
J/ApJ/750/140
Date:
21 Oct 2021
Publisher:
CDS
Description:
We study mass functions of globular clusters derived from Hubble Space Telescope/Advanced Camera for Surveys images of the early-type merger remnant galaxy NGC 1316, which hosts a significant population of metal-rich globular clusters of intermediate age (~3Gyr). For the old, metal-poor ("blue") clusters, the peak mass of the mass function M_p_ increases with internal half-mass density {rho}_h_ as M_p_{prop.to}{rho}_h_^0.44^, whereas it stays approximately constant with galactocentric distance R_gal_. The mass functions of these clusters are consistent with a simple scenario in which they formed with a Schechter initial mass function and evolved subsequently by internal two-body relaxation. For the intermediate-age population of metal-rich ("red") clusters, the faint end of the previously reported power-law luminosity function of the clusters with R_gal_>9kpc is due to many of those clusters having radii larger than the theoretical maximum value imposed by the tidal field of NGC 1316 at their R_gal_. This renders disruption by two-body relaxation ineffective. Only a few such diffuse clusters are found in the inner regions of NGC 1316. Completeness tests indicate that this is a physical effect. Using comparisons with star clusters in other galaxies and cluster disruption calculations using published models, we hypothesize that most red clusters in the low-{rho}_h_ tail of the initial distribution have already been destroyed in the inner regions of NGC 1316 by tidal shocking, and that several remaining low-{rho}_h_ clusters will evolve dynamically to become similar to "faint fuzzies" that exist in several lenticular galaxies. Finally, we discuss the nature of diffuse red clusters in early-type galaxies.
1980. Candidate halo dark matter
ID:
ivo://CDS.VizieR/J/other/Sci/292.698
Title:
Candidate halo dark matter
Short Name:
J/other/Sci/292.
Date:
21 Oct 2021
Publisher:
CDS
Description:
The Milky Way galaxy contains a large, spherical component which is believed to harbor a substantial amount of unseen matter. Recent observations indirectly suggest that as much as half of this "dark matter" may be in the form of old, very cool white dwarfs, the remnants of an ancient population of stars as old as the galaxy itself. We conducted a survey to find faint, cool white dwarfs with large space velocities, indicative of their membership in the galaxy's spherical halo component. The survey reveals a substantial, directly observed population of old white dwarfs, too faint to be seen in previous surveys. This newly discovered population accounts for at least 2 percent of the halo dark matter. It provides a natural explanation for the indirect observations, and represents a direct detection of galactic halo dark matter.

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