XMMSDSSGCS ivo://nasa.heasarc/xmmsdssgcs NASA/GSFC HEASARC Takey et al. 2026-05-08 NASA/GSFC HEASARC help desk heasarc-vo at athena.gsfc.nasa.gov Survey Source The authors have compiled a sample of X-ray-selected galaxy groups and clusters from the XMM-Newton Serendipitous Source Catalog (2XMMi-DR3) with optical confirmation and redshift measurement from the Sloan Digital Sky Survey (SDSS). In their paper, they present an analysis of the X-ray properties of this new sample with particular emphasis on the X-ray luminosity-temperature (L<sub>X</sub> - T) relation. The X-ray cluster candidates were selected from the 2XMMi-DR3 catalog in the footprint of the SDSS-DR7. The authors developed a finding algorithm to search for overdensities of galaxies at the positions of the X-ray cluster candidates in the photometric redshift space and to measure the redshifts of the clusters from the SDSS data. For optically confirmed clusters with good quality X-ray data, they derived the X-ray flux, luminosity, and temperature from proper spectral fits, while the X-ray flux for clusters with low-quality X-ray data was obtained from the 2XMMi-DR3 catalogue. The detection algorithm provides the photometric redshift of 530 galaxy clusters. Of these, 310 clusters have a spectroscopic redshift for at least one member galaxy. About 75 percent of the optically confirmed cluster sample are newly discovered X-ray clusters. Moreover, 301 systems are known as optically selected clusters in the literature while the remainder are new discoveries in X-ray and optical bands. The optically confirmed cluster sample spans a wide redshift range 0.03 to 0.70 (median z = 0.32). In this paper, they present the catalog of X-ray-selected galaxy groups and clusters from the 2XMMi/SDSS galaxy cluster survey. The catalog has two subsamples: (i) a cluster sample comprising 345 objects with their X-ray spectroscopic temperature and flux from the spectral fitting; (these objects are identified by having values for the table_sample parameter of 1 in this HEASARC implementation of the catalog) and (ii) a cluster sample consisting of 185 systems with their X-ray flux from the 2XMMi-DR3 catalog, because their X-ray data are insufficient for spectral fitting (these objects are identified by having values for the table_sample parameter of 2 herein). For each cluster, the catalog also provides the X-ray bolometric luminosity and the cluster mass at R<sub>500</sub> based on scaling relations and the position of the likely brightest cluster galaxy (BCG). The updated L<sub>X</sub> - T relation of the current sample with X-ray spectroscopic parameters is presented in the paper. The authors found the slope of the L<sub>X</sub> - T relation to be consistent with published ones. They see no evidence for evolution in the slope and intrinsic scatter of the L<sub>X</sub> - T relation with redshift when excluding the low-luminosity groups. This catalog of X-ray selected galaxy clusters and groups supersedes and subsumes the first release of the 2XMMi/SDSS Galaxy Cluster Survey, comprising 175 clusters of galaxies, which was presented in Takey et al. (2011, A&A, 534, A120). This table was created by the HEASARC in October 2013 based on <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/A+A/558/A75">CDS catalog J/A+A/558/A75</a> files table1.dat and table2.dat. This is a service provided by NASA HEASARC . 2013A&A...558A..75T https://heasarc.gsfc.nasa.gov/W3Browse/all/xmmsdssgcs.html Catalog Research served-by HEASARC TAP https://heasarc.gsfc.nasa.gov/xamin/vo/cone?showoffsets&table=xmmsdssgcs& GET text/xml 180 99999 true 8.32687 -21.41319 0.0166666666666667 https://heasarc.gsfc.nasa.gov/xamin/vo/tap https://heasarc.gsfc.nasa.gov/cgi-bin/W3Browse/getvotable.pl?name=xmmsdssgcs GET text/xml https://heasarc.gsfc.nasa.gov/cgi-bin/W3Browse/w3query.pl?tablehead=name=heasarc_xmmsdssgcs&Action=More+Options&Action=Parameter+Search&ConeAdd=1 XMM-NEWTON 0.0166666666666667 Optical X-ray public xmmsdssgcs 2XMMi/SDSS Galaxy Cluster Survey detid X-Ray Detection Number in the 2XMMi-DR3 Catalog meta.id int nullable name X-Ray Source Designation meta.id;meta.main char nullable ra Right Ascension of the X-Ray Detection degree pos.eq.ra;meta.main double nullable dec Declination of the X-Ray Detection degree pos.eq.dec;meta.main double nullable redshift Cluster Redshift src.redshift double nullable radius_500 Estimated Radius R_500 kpc phys.size.radius double nullable lx_500 X-Ray Bolometric Luminosity within R_500 erg/s phys.luminosity;em.X-ray.soft double nullable lx_500_error Error in X-Ray Bolometric Luminosity erg/s stat.error;phys.luminosity;em.X-ray.soft double nullable kt_ap X-Ray Spectroscopic Temperature within Optimal Aperture Radius keV phys.temperature double nullable kt_ap_pos_err Positive Error in X-Ray Spectroscopic Temperature within Optimal Aperture Radius keV stat.error;phys.temperature double nullable kt_ap_neg_err Negative Error in X-Ray Spectroscopic Temperature within Optimal Aperture Radius keV stat.error;phys.temperature double nullable kt_500 X-Ray Temperature within R_500 keV phys.temperature double nullable kt_500_error Error in X-Ray Temperature within R_500 keV stat.error;phys.temperature 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 ref_alt_name Reference Code(s) for the Cluster Designation(s) meta.ref char nullable phot_redshift Cluster Photometric Redshift src.redshift.phot double nullable flux_ap Aperture X-Ray Flux in 0.5-2keV Band erg/s/cm^2 phot.flux;em.X-ray.soft double nullable sdss_dr8_bcg_ra Likely BCG Right Ascension degree pos.eq.ra double nullable cat_lx X-Ray Luminosity in 0.5-2keV Band erg/s phys.luminosity;em.X-ray.soft double nullable radius_ap Optimal Aperture Radius kpc phys.size.radius double nullable redshift_type Redshift Type (Spec-z or Photo-z) meta.code;src.redshift char nullable num_spect_members Number of Cluster Members with Spectra meta.number short nullable cat_flux_error Error in X-Ray Flux in 0.5-2.0keV Band erg/s/cm^2 stat.error;phot.flux;em.X-ray.soft double nullable obsid XMM-Newton Observation Identifier meta.id;obs char nullable lii Galactic Longitude of the X-Ray Detection degree pos.galactic.lon double nullable mass_500_error Error in Mass within R_500 Solar_Mass stat.error;phys.mass double nullable nh_gal Galactic HI Column Density cm^-2 phys.columnDensity double nullable flux_ap_neg_err Negative Error in Aperture X-Ray Flux erg/s/cm^2 stat.error;phot.flux;em.X-ray.soft double nullable table_sample Indicates Published Table from Which the Source Originates meta.ref;meta.table char nullable sdss_dr8_bcg_dec Likely BCG Declination degree pos.eq.dec double nullable lx_ap Aperture X-Ray Luminosity in 0.5-2keV Band erg/s phys.luminosity;em.X-ray.soft double nullable mass_500 Mass within R_500 Solar_Mass phys.mass double nullable spatial_offset Offset Between Optical and X-Ray Detections kpc pos.distance;em.X-ray.soft;em.opt double nullable cat_lx_error Error in X-Ray Luminosity in 0.5-2keV Band erg/s stat.error;phys.luminosity;em.X-ray.soft double nullable sdss_dr8_bcg_id Identification in the SDSS-DR8 of the Likely BCG meta.id.assoc char nullable lx_ap_neg_err Negative Error in Aperture X-Ray Luminosity erg/s stat.error;phys.luminosity;em.X-ray.soft double nullable cat_flux X-Ray Flux in 0.5-2.0keV Band erg/s/cm^2 phot.flux;em.X-ray.soft double nullable bii Galactic Latitude of the X-Ray Detection degree pos.galactic.lat double nullable linear_scale_factor Scale at the Cluster Redshift kpc/arcsec arith.factor;pos.distance double nullable flux_ap_pos_err Positive Error in Aperture X-Ray Flux erg/s/cm^2 stat.error;phot.flux;em.X-ray.soft double nullable alt_name Alternative (NED) Designation of X-Ray Cluster, If Known meta.id char nullable lx_ap_pos_err Positive Error in Aperture X-Ray Luminosity erg/s stat.error;phys.luminosity;em.X-ray.soft double nullable spect_redshift Cluster Spectroscopic Redshift src.redshift double nullable