ROSAT All-Sky Survey and Sloan Digital Sky Survey DR7 Galaxy Clusters

ROSAT All-Sky Survey and Sloan Digital Sky Survey DR7 Galaxy Clusters RASSSDSSGC ivo://nasa.heasarc/rasssdssgc NASA/GSFC HEASARC Wang et al. 2026-06-12 NASA/GSFC HEASARC help desk heasarc-vo at athena.gsfc.nasa.gov Cluster of Galaxies The authors use ROSAT All-Sky Survey (RASS) broad-band X-ray images and the optical clusters identified from the Sloan Digital Sky Survey Data Release 7 (SDSS DR7) to estimate the X-ray luminosities around ~65,000 candidate galaxy clusters with masses >~1013 h-1 Msun based on an optical to X-ray (OTX) code that they developed. They obtain a catalog with X-ray luminosities for all 64,646 clusters. A total of 34,522 (~53%) of these clusters have a signal-to-noise ratio S/N > 0 after subtracting the background signal. According to the reference paper (but see HEASARC Caveats section below), this catalog contains 817 clusters (473 at redshift z <= 0.12) with S/N > 3 for their X-ray detections (an additional 12,629 clusters have 3 >= S/N > 1 and 21,076 clusters have 1 >= S/N > 0). The authors find about 65% of these X-ray clusters have their most massive member located near the X-ray flux peak; for the remaining 35%, the most massive galaxy is separated from the X-ray peak, with the separation following a distribution expected from a Navarro-Frenk-White profile. In the reference paper, the authors investigate a number of correlations between the optical and X-ray properties of these X-ray clusters, and find that the cluster X-ray luminosity is correlated with the stellar mass (luminosity) of the clusters, as well as with the stellar mass (luminosity) of the central galaxy and the mass of the halo, although the scatter in these correlations is large. Comparing the properties of X-ray clusters of similar halo masses but having different X-ray luminosities, they find that massive haloes with masses >~1014 h-1 Msun contain a larger fraction of red satellite galaxies when they are brighter in X-ray. An opposite trend is found in central galaxies in relative low-mass haloes with masses <~1014 h-1 Msun where X-ray brighter clusters have smaller fraction of red central galaxies. Clusters with masses >~1014 h-1 Msun that are strong X-ray emitters contain many more low-mass satellite galaxies than weak X-ray emitters. These results are also confirmed by checking X-ray clusters of similar X-ray luminosities but having different characteristic stellar masses. The cluster catalog containing the optical properties of member galaxies and the X-ray luminosity is also available at <a href="http://gax.shao.ac.cn/data/Group.html">http://gax.shao.ac.cn/data/Group.html</a>. The optical data used in this analysis are taken from the SDSS galaxy group catalogs of Yang et al. (2007, ApJ, 671, 153), constructed using the adaptive halo-based group finder of Yang et al. (2005, MNRAS, 356, 1293), here updated to DR7. The parent galaxy catalog is the New York University Value-Added Galaxy Catalog (NYU-VAGC; Blanton et al. 2005, AJ, 129, 2562) based on the SDSS DR7 (Abazajian et al. 2009, ApJS, 182, 543), which contains an independent set of significantly improved reductions. In this study, the authors adopt a Lambda cold dark matter cosmology whose parameters are consistent with the 7-year data release of the WMAP mission: Omegam = 0.275, OmegaLambda = 0.725, h = H0/(100 km s-1 Mpc-1) = 0.702, and sigma8 = 0.816. This table was created by the HEASARC in June 2017 based upon the <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/MNRAS/439/611">CDS Catalog J/MNRAS/439/611</a> file catalog.dat. This is a service provided by NASA HEASARC . 2014MNRAS.439..611W https://heasarc.gsfc.nasa.gov/W3Browse/all/rasssdssgc.html Catalog Research served-by HEASARC TAP https://heasarc.gsfc.nasa.gov/xamin/vo/cone?showoffsets&table=rasssdssgc& GET text/xml 180 99999 true 6.15256 -11.24408 0.0333333333333333 https://heasarc.gsfc.nasa.gov/xamin/vo/tap https://heasarc.gsfc.nasa.gov/cgi-bin/W3Browse/getvotable.pl?name=rasssdssgc GET text/xml https://heasarc.gsfc.nasa.gov/cgi-bin/W3Browse/w3query.pl?tablehead=name=heasarc_rasssdssgc&Action=More+Options&Action=Parameter+Search&ConeAdd=1 SDSS 0.0333333333333333 Optical X-ray public rasssdssgc ROSAT All-Sky Survey and Sloan Digital Sky Survey DR7 Galaxy Clu name Optical Group Identification meta.id;meta.main char nullable ra Right Ascension degree pos.eq.ra;meta.main double nullable dec Declination degree pos.eq.dec;meta.main double nullable count_rate X-Ray Photons Count Rate (in 0.1-2.4 keV) in Detection Radius 0.5*r200 ct/s phot.count;em.X-ray.soft double nullable count_rate_error Error for the Count Rate ct/s stat.error;phot.count;em.X-ray.soft double nullable flux X-Ray Flux erg/s/cm^2 phot.flux;em.X-ray.soft double nullable redshift Optical Spectroscopic Redshift of the Central Galaxy src.redshift double nullable lx X-Ray Luminosity of Cluster in 0.1-2.4 keV erg/s phys.luminosity;em.X-ray.soft double nullable lbol Bolometric Luminosity (Derived from LX) erg/s phys.luminosity double nullable "__x_ra_dec" System unit vector column double nullable "__y_ra_dec" System unit vector column double nullable "__z_ra_dec" System unit vector column double nullable "__row" System index column char nullable nyuvagc_name Central Galaxy Identification in NYUVAGC Catalog meta.id.assoc char nullable lii Galactic Longitude degree pos.galactic.lon double nullable exposure Average Exposure Time on the Detection s time.duration;obs.exposure double nullable multi_z_b3_flag Multiple Redshift Flag b3 meta.code short nullable off_set Offset Between the Optical Galaxy and X-Ray Cluster Center arcmin pos.angDistance;em.opt;em.X-ray.soft double nullable multi_z_b1_flag Multiple Redshift Flag b1 meta.code short nullable number_galaxies Number of Galaxies in the group meta.number short nullable beta_model_cor_fac Beta Model Correction Factor for Missing Fraction of Projected Source Emission arith.factor;phys.luminosity;em.X-ray.soft double nullable t_gas Gas Temperature of the Group Derived from the Velocity Dispersion Sigma keV phys.temperature double nullable multi_flux_fraction Flux Fraction of X-Ray Source in a Multi-Cluster Detection meta.code;phot.flux;em.X-ray.soft double nullable multi_z_b2_flag Multiple Redshift Flag b2 meta.code short nullable sigma_velocity Velocity Dispersion Derived from the Optical Halo Mass km/s phys.veloc.dispersion double nullable central_galaxy_id Central Galaxy Identification of this group meta.id.assoc int nullable mass_sequence_id Mass Sequence Identification for Central, k-th Most Massive Galaxy in Group meta.code short nullable log_nh_gal Galactic Hydrogen Column Density log(cm^-2) phys.columnDensity double nullable snr Signal-to-Noise Ratio of the X-Ray Detection stat.snr;em.X-ray.soft double nullable r500_aperture Aperture of r500 arcmin pos.angDistance double nullable angular_radius Radius of the Extended X-Ray Source, Rx = 0.5*r200 arcmin phys.angSize double nullable bii Galactic Latitude degree pos.galactic.lat double nullable