Browse
this table...

XMMSDSSGCS - 2XMMi/SDSS Galaxy Cluster Survey

 HEASARC
Archive

Overview

This catalog of X-ray selected galaxy clusters and groups, the first release of the 2XMMi/SDSS Galaxy Cluster Survey, comprises 175 clusters of galaxies. Among them, 139 objects are new X-ray discoveries, while the others were previously known as X-ray sources. This survey is a search for galaxy clusters detected serendipitously in observations with XMM-Newton in the footprint of the Sloan Digital Sky Survey (SDSS). The main aims of the survey are to identify new X-ray galaxy clusters, investigate their X-ray scaling relations, identify distant cluster candidates, and study the correlation of the X-ray and optical properties. In their paper, the authors describe the basic strategy to identify and characterize the X-ray cluster candidates that currently comprise 1180 objects selected from the second XMM-Newton serendipitous source catalog (2XMMi-DR3). Cross-correlation of the initial catalog with recently published optically selected SDSS galaxy cluster catalogs yields photometric redshifts for 275 objects. Of these, 182 clusters have at least one member with a spectroscopic redshift from existing public data (SDSS-DR8). The authors developed an automated method to reprocess the XMM-Newton X-ray observations, determine the optimum source extraction radius, generate source and background spectra, and derive the temperatures and luminosities of the optically confirmed clusters. Here the X-ray properties of the first cluster sample comprising 175 clusters are presented. For each cluster, the catalog provides: two identifiers, coordinates, temperature, flux [0.5-2keV, luminosity [0.5-2] keV extracted from an optimum aperture, bolometric luminosity L500, total mass M500, radius R500, and the optical properties of the counterpart. The first cluster sample from the survey covers a wide range of redshifts from 0.09 to 0.61, bolometric luminosities L500 = 1.9 x 1042 - 1.2 x 1045 erg/s, and masses M500 = 2.3 x 1013 - 4.9 x 1014Msun. The authors extend the relation between the X-ray bolometric luminosity L500 and the X-ray temperature towards significantly lower T and L and still find that the slope of the linear L-T relation is consistent with values published for high luminosities.

The cluster catalog with the X-ray/optical overlay and fitted spectra for each cluster is also available at the authors' web site: http://www.aip.de/groups/xray/XMM_SDSS_CLUSTERS.html.

Catalog Bibcode

2011A&A...534A.120T

References

The 2XMMi/SDSS Galaxy Cluster Survey
I. The first cluster sample and X-ray luminosity-temperature relation.
    Takey A., Schwope A., Lamer G.
    <Astron. Astrophys. 534, A120 (2011)>
    =2011A&A...534A.120T        (SIMBAD/NED BibCode)

Provenance

This table was created by the HEASARC in October 2011 based on CDS catalog J/A+A/534/A120 file table2.dat.

Parameters

Detid
A consecutive number which identifies each entry (detection) in the 2XMMi-DR3 Catalog.

Name
The 2XMMi-DR3 Catalog name. This IAU-style designation was assigned to each unique SRCID in the catalog based upon the IAU registered classifications 2XMM and 2XMMi: a source that is included in the 2XMM catalog has kept its 2XMM IAU identification; a source that appeared for the first time in 2XMMi retains its 2XMMi IAU identification; all new sources in 2XMMi-DR3 are also assigned an IAU name with a 2XMMi prefix. The form of the IAU names is "2XMM Jhhmmss.sSddmmss" or "2XMMi Jhhmmss.sSddmmss" where hhmmss.s is taken from the averaged and eposcorr-corrected right ascension coordinate given in the column RA and Sddmmss is the averaged and eposcorr-corrected declination taken from the column DEC of the respective catalog. Note that the averaged coordinates may have changed with respect to 2XMM but the IAU name with the 2XMM prefix will be the same as in the 2XMM catalog. The situation is similar for sources in the 2XMMi catalog where the 2XMMi-prefixed IAU name is maintained.

RA
The Right Ascension of the X-ray source detection in the selected equinox. This was taken from the 2XMMi-DR3 Catalog (q.v. for more details), and was given in J2000.0 decimal degrees in the CDS version of this table with a precision of 10-5 degrees.

Dec
The Declination of the X-ray source detection in the selected equinox. This was taken from the 2XMMi-DR3 Catalog (q.v. for more details), and was given in J2000.0 decimal degrees in the CDS version of this table with a precision of 10-5 degrees.

LII
The Galactic Longitude of the X-ray source detection.

BII
The Galactic Latitude of the X-ray source detection.

ObsID
The XMM-Newton obsid identifier for the observation in which the source was detected.

Redshift
The optical redshift z of the cluster of galaxies, being either the spectroscopic (spect_redshift) or photometric (phot_redshift).

Linear_Scale_Factor
The linear scale in kpc corresponding to 1 arcsecond at the cluster redshift.

Radius_Ap
The optimum aperture radius Rap, in kpc, for the cluster: this is the extraction radius for which the highest integrated signal-to-noise was obtained, and is discussed in Section 3.2.1 of the reference paper.

Radius_500
The estimated radius R500 at which the mean mass density of the cluster is 500 times the critical density rhoc of the Universe at the cluster redshift, R500, in kpc. Thus R500 = cube root of [(3 * M500)/(4 * pi * 500 * rhoc(z)]. See Section 4 of the reference paper for more details.

kT_Ap
The average X-ray spectroscopic temperature kTap of the hot intra-cluster medium of the cluster within the optimal aperture radius, Rap, in keV. The cluster spectra were fitted with absorbed thin thermal plasma emission models with pre-determined redshift and interstellar column density to determine the aperture X-ray temperature (kTap), flux (Fap) [0.5-2 keV band], luminosity (Lap) [0.5-2 keV band], and their errors. The authors accepted the measurements of Tap and Lap if the fractional errors were smaller than 0.5. About 80% of the confirmed clusters passed this fractional error filter. For these clusters, another visual screening of the spectral fits and the X-ray images was done. When the spectral extraction of a given cluster was strongly affected by the exclusion of field sources within the extraction radius or a poor determination of the background spectrum, it was also excluded from this final sample, which comprises 175 clusters. For a fraction of 80%, this is the first X-ray detection and the first temperature measurement.

kT_AP_Pos_Err
The positive error in the average X-ray spectroscopic temperature kTap of the hot intra-cluster medium of the cluster within the optimal aperture radius, Rap, in keV

kT_AP_Neg_Err
The negative error in the average X-ray spectroscopic temperature kTap of the hot intra-cluster medium of the cluster within the optimal aperture radius, Rap, in keV

Flux_Ap
The X-ray flux of the cluster fap within the optimal aperture radius, in the 0.5 - 2 keV band, in erg cm-2 s-1.

Flux_AP_Pos_Err
The positive error in the X-ray flux of the cluster within the optimal aperture radius, in the 0.5 - 2 keV band, in erg cm-2 s-1.

Flux_AP_Neg_Err
The negative error in the X-ray flux of the cluster within the optimal aperture radius, in the 0.5 - 2 keV band, in erg cm-2 s-1.

Lx_Ap
The X-ray luminosity of the cluster Lap within the optimal aperture radius,in the 0.5 - 2 keV band, in erg s-1.

Lx_AP_Pos_Err
The positive error in the X-ray luminosity of the cluster within the optimal aperture radius,in the 0.5 - 2 keV band, in erg s-1.

Lx_AP_Neg_Err
The negative error in the X-ray luminosity of the cluster within the optimal aperture radius,in the 0.5 - 2 keV band, in erg s-1.

Lx_500
The X-ray bolometric luminosity of the cluster within the R500 radius, L500, in erg s-1.

Lx_500_Error
The error in the X-ray bolometric luminosity of the cluster within the R500 radius, in erg s-1.

Mass_500
The mass of the cluster within the R_500 radius, M500, in solar masses.

Mass_500_Error
The error in the mass of the cluster within the R_500 radius, in solar masses.

NH_Gal
The Galactic HI column density towards the cluster of glaxies, in H atoms cm-2. This was derived from the HI map in the Leiden/Argentine/Bonn Survey of Kalberla et al. (2005, A&A, 440, 775).

Opt_Cluster_ID
The identification number of the cluster as given in the first optical catalog listed in the opt_cat_names parameter field for the given cluster.

RA_Optical
The Right Ascension of the brightest cluster galaxy (BCG) in the optical catalog, in the selected equinox, except for clusters in the Adaptive Matched Filter (AMF) Catalog of Szabo et al.(2011, ApJ, 736, 21) where the position represents the cluster stellar mass center. The optical RA was given in J2000.0 decimal degrees to a precision of 10-5 degrees in the CDS version of this table. This was taken from the first optical catalog listed in the opt_cat_names parameter field for the given cluster.

Dec_Optical
The Declination of the brightest cluster galaxy (BCG) in the optical catalog, in the selected equinox, except for clusters in the Adaptive Matched Filter (AMF) Catalog of Szabo et al.(2011, ApJ, 736, 21) where the position represents the cluster stellar mass center. The optical RA was given in J2000.0 decimal degrees to a precision of 10-5 degrees in the CDS version of this table. This was taken from the first optical catalog listed in the opt_cat_names parameter field for the given cluster.

Phot_Redshift
The photometric redshift zp of the cluster. This was taken from the first optical catalog listed in the opt_cat_names parameter field for the given cluster.

Spect_Redshift
The average spectroscopic redshift zs of the cluster galaxies having available spectroscopic redshifts. These were extracted from the SDSS-DR8 database.

Num_Spect_Members
The number of cluster members with spectroscopic redshift data. These were extracted from the SDSS-DR8 database.

Spatial_Offset
The linear offset, in kpc, between the cluster optical and X-ray positions.

Opt_Cat_Names
The names of the optical catalogs in which the cluster was identified. (Note that the optical parameters were derived from the first one listed). The abbreviations used for these catalogs are as follows: 

      GMBCG: The Gaussian Mixture Brightest Cluster Galaxy catalog (Hao et al.
  2010, ApJS, 191, 254) consists of more than 55000 rich clusters across the
  redshift range 0.1 < zp < 0.55 identified in SDSS-DR7. The galaxy clusters
  were detected by identifying the cluster red-sequence plus a brightest cluster
  galaxy (BCG). The cross-identification of X-ray cluster candidates with the
  GMBCG within a radius of 1 arcmin yields 136 confirmed clusters.

      WHL: The catalog of Wen et al. (2009, ApJS, 183, 197) consists of 39668
  clusters of galaxies drawn from SDSS-DR6 and covers the redshift range
  0.05 < zp < 0.6. A cluster was identified if more than eight member galaxies
  of Mr <= 21 were found within a radius of 0.5 Mpc and within a photometric
  redshift interval zp +/- 0.04(1 + zp). The present authors confirm 150
  X-ray clusters by cross-matching within 1 arcmin.

      MaxBCG: The Max Brightest Cluster Galaxy catalog (Koester et al. 2007,
  ApJ, 660, 239) lists 13823 clusters in the redshift range 0.1 < zp < 0.3
  from SDSS-DR5. The clusters were identified using the maxBCG red-sequence
  technique, which uses the clustering of galaxies on the sky, in both magnitude
  and color, to identify groups and clusters of bright E/S0 red-sequence
  galaxies. The cross-match with the present X-ray cluster candidate list
  reveals 54 clusters in common within a radius of one arcmin.

      AMF: The Adaptive Matched Filter catalog of Szabo et al. (2011, ApJ, 736,
  21) lists 69173 likely galaxy clusters in the redshift range 0.045 < zp <
  0.78 extracted from SDSS-DR6 using an adaptive matched filter (AMF) cluster
  finder. The cross-match yields 127 confirmed X-ray galaxy clusters.

Alt_Name
An alternative designation for the x-ray cluster, if it had been previously identified using ROSAT, Chandra, or XMM-Newton taken from NED or SIMBAD. The referencea for these alternative names are given in the ref_alt_name parameter field.

Ref_Alt_Name
The coded reference for the alternative X-ray cluster name, as follows: 

  Value  Prefix       Reference

  0       ---         None
  1     [PBG2005]     Plionis et al., 2005ApJ...622L..17P
  2     [VMF98]       Vikhlinin et al., 1998ApJ...502..558V, Cat. J/ApJ/502/558
  3                   Cavagnolo et al., 2008ApJ...682..821C, Cat. J/ApJ/682/821
  4     [FGH2007]     Finoguenov et al., 2007ApJS..172..182F, Cat. J/ApJS/172/182
  5      WARP         Horner et al., 2008ApJS..176..374H, Cat. J/ApJS/176/374
  6      BLOX         Dietrich et al., 2007A&A...470..821D, Cat. J/A+A/470/821
  7      400d         Burenin et al., 2007ApJS..172..561B, Cat. J/ApJS/172/561
  8                   Romer et al., 2000ApJS..126..209R, Cat. J/ApJS/126/209
  9     [BPG2004]     Basilakos et al., 2004MNRAS.351..989B
  10    [SBV2004]     Schuecker et al., 2004A&A...420...61S, Cat. J/A+A/420/61
  11                  Sehgal et al., 2008ApJ...673..163S

Contact Person

Questions regarding the XMMSDSSGCS database table can be addressed to the HEASARC User Hotline.

A service of the Astrophysics Science Division at NASA/GSFC and the High Energy Astrophysics Division of the Smithsonian Astrophysics Observatory (SAO)

Page Author: Browse Software Development Team
Last Modified: 28-Aug-2012