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EINGALCLUS - Einstein Observatory Clusters of Galaxies Catalog

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Overview

The Einstein Observatory Clusters of Galaxies Catalog presents the X-ray characteristics of a sample of 368 clusters of galaxies with redshifts less than 0.2 which were observed with the Einstein Imaging Proportional Counter (IPC). For each cluster, the authors measured the 0.5 - 4.5 keV counting rate and computed the 0.5 - 4.5 keV source luminosity, as well as the bolometric luminosity within fixed metric radii. They detected 85% of Abell clusters with z < 0.1, demonstrating that the large majority of these optically selected clusters are not the results of chance superpositions. For 163 clusters, they measured their X-ray surface brightness profiles and determined their core radii. For about 230 clusters, they then used either their measured core radii and beta values, or mean values derived for this sample, to measure central gas densities and gas masses. They used estimated or measured cluster gas temperatures, along with the derived gas-density profiles, to estimate total cluster masses, under the assumptions that the gas is isothermal and in hydrostatic equilibrium.

Catalog Bibcode

1999ApJ...511...65J

References

Einstein Observatory Images of Clusters of Galaxies
       Jones C., and Forman W.
      <Astrophys. J. 511, 65 (1999)>
      =1999ApJ...511...65J

Provenance

This table was created by the HEASARC in June 2005 based on the merger of CDS tables J/ApJ/511/65/table3.dat and table4.dat.

Parameters

Name
The name of the cluster of galaxies, where the designation of 'A' stands for an "Abell" cluster, the recommended prefix for which is 'ACO'. In a number of cases where clusters have multiple, spatially resolved subclusters, there are multiple entries for individual clusters, and suffixes such as 'N', 'S', or 'SS' or used to differentate the subclusters.

Position_Flag
This flag is set to 'L' to indicate less accurate values (RA values given to 0.1 minutes of time and Dec values to 1 arcminute), for the positional coordinates (typically given to 0.1 seconds of time and 1 arcsecond).

RA
The Right Ascension of the cluster of galaxies, in the selected equinox. The position given is generally the peak of the X-ray surface brightness, except for a few clusters in which the peak is offset from the cluster centroid, as in, for example, SC 0559-40 or A754, or in which, even in the central region, the cluster has multiple surface brightness peaks, as in the case of Coma. For these clusters, the position is that of the X-ray centroid. The RA was given in 1950 coordinates in the originating table, and to a precision of 0.1 seconds of time, except for cases for which position_flag has a value of 'L' which were given only to a precision of 0.1 minutes of time.

Dec
The Declination of the cluster of galaxies, in the selected equinox. The position given is generally the peak of the X-ray surface brightness, except for a few clusters in which the peak is offset from the cluster centroid, as in, for example, SC 0559-40 or A754, or in which, even in the central region, the cluster has multiple surface brightness peaks, as in the case of Coma. For these clusters, the position is that of the X-ray centroid. The Dec was given in 1950 coordinates in the originating table, and to a precision of 1 arcsecond, except for cases for which position_flag has a value of 'L' which were given only to a precision of 1 arcminute.

LII
The Galactic Longitude of the cluster of galaxies.

BII
The Galactic Latitude of the cluster of galaxies.

Redshift
The redshift of the cluster of galaxies.

Ref_Redshift
The reference code for the cluster redshift as follows:

  ACO    1989ApJS...70....1A   Abell+ 1989
  B      1995A&AS..109..147B   Brinkmann et al. 1995 (added at CDS,
                               missing in the paper)
  BB     1985AJ.....90.1413B   Batuski & Burns 1985
  BD     1994A&A...283..407B   Braine & Dupraz 1994
  BG     1982AJ.....87.1245B   Burns & Gregory 1982
  BJ     1994ApJ...424...59B   Breen+ 1994
  BP     1994ApJ...423...94B   Burns+ 1994
  C      1995MNRAS.274.1071C   Collins+ 1995
  D      1980ApJS...42..565D   Dressler 1980
  deV    ...................   de Vaucouleurs, G., de Vaucouleurs, A., Corwin,
                               H., Buta, R., Paturel, G., & Fouque, P. 1991,
             Third Reference Catalogue of Bright Galaxies (New York: Springer)
  DGF    1994AJ....107..427D   Dell'Antonio, Geller, & Fabricant 1994
  DS     1994MNRAS.269..151D   Dalton+ 1994
  GMT    1993A&AS..100...33G   Garilli, Maccagni, & Tarenghi 1993
  H      1990ApJ...365...66H   Huchra+ 1990
  HMS    1956AJ.....61...97H   Humason, Mayall, & Sandage 1956
  JFN    1987MNRAS.224...75J   Johnstone, Fabian, & Nulsen 1987
  KL     1994A&A...228..122K   Kim+ 1994
  LO     1995AJ....109..853L   Ledlow & Owen 1995
  LvdB   1977ApJS...34..381L   Leir & van den Berg 1977
  MMM    1963ApJ...137..153M   Maltby, Mathews, & Moffet 1963
  M10    ...................   redshift based on magnitude of the
                               tenth-brightest galaxy
  M10P   1992ApJ...384..404P   Postman, Huchra, & Geller 1992
  N      1981ApJS...45..613N   Noonan 1982
  OSC    1988A&AS...73..125O   Olowin, de Souza & Chincarini
  P      1992ApJ...384..404P   Postman, Huchra, & Geller 1992
  PL     1995ApJ...440...28P   Postman & Lauer 1995
  QR     1995ApJS...96..343Q   Quintana & Ramirez 1995
  RK     1988A&AS...72..243R   Rhee & Katgert 1988
  S      1982A&A...108...L7S   Sarazin, Rood, & Struble 1982
  Sp     1985PASP...97..932S   Spinrad+ 1985
  SR     1987ApJS...63..543S   Struble & Rood 1987
  SR 2   1991ApJS...77..363S   Struble & Rood 1991
  SW     1991ApJS...76..813S   Stocke+ 1991
  TCG    1990ApJS...72..715T   Teague, Carter, & Gray 1990
  Z      1993AJ....106.1273Z   Zabludoff+ 1993
  

Count_Rate
The IPC count rate, in counts/s, in the 0.5-4.5keV energy band (IPC PI channels 4-11) within a fixed linear aperture selected, if possible, to be a 1 Mpc radius (with an assumed Hubble Constant of 50 km/s/Mpc). This count rate value has been background subtracted and vignetting corrected. If the source count rate exceeded at least 3 times the count rate uncertainty in the region, this is considered to be a positive detection.

Count_Rate_Error
The uncertainty in the IPC count rate, in counts/s.

Region_Radius
The radius of the region inside which the IPC count rate was measured, in Mpc. This was chosen, if possible, to be 1 Mpc (with an assumed Hubble Constant of 50 km/s/Mpc). It was not always possible to determine the count rate within 1 Mpc of the cluster center, however. For clusters with redshifts less than 0.035, the 1 Mpc radius region is partially obscured by the IPC window support structure. For redshifts less than 0.02, part of the 1 Mpc region lies outside the IPC field of view (FOV). For those clusters which were not centered in the detector FOV, the rib obscuration occurred at a variety of radii depending on the cluster redshift and its location on the detector. For all such cases, the authors used the largest possible radial region to determine the count rate and extrapolated the measured count rate to that expected within a 1 Mpc radius.

Lx_Limit
An upper limit flag for the cluster X-Ray luminosity.

Lx
The X-Ray (0.5 - 4.5 keV) cluster luminosity, in ergs/s, given for the 1 Mpc radius and extrapolated, if necessary, from that measured, based on the surface brightness parameters. If the source was not detected at a 3-sigma level, lx_limit is set to '<' and the quoted value is a 3-sigma upper limit to the X-ray luminosity. The luminosity reported has had an X-ray K-correction applied, so that the value is in the 0.5 - 4.5 keV band at the source.

Lx_Error
The uncertainty in the cluster X-Ray luminosity, in erg/s (not given if the quoted X-ray luminosity is an upper limit).

Tx
The measured cluster gas temperature, in keV.

NH_Gal
The Galactic Hydrogen column density, in H atoms per cm^2.

L_Bol
The cluster bolometric luminosity, in ergs/s, calculated using either the measured (given by the tx parameter) or estimated (see Section 3.1 of the published paper) gas temperature, within 1 Mpc radius.

Cluster_Radius
The derived or assumed cluster core radius, in Mpc. This is one of the parameters used to characterize the radial surface brightness distribution of the cluster: see equation (1) of the published paper.

Cluster_Radius_Error
The uncertainty in the cluster core radius, in Mpc.

Beta
The derived or assumed beta parameter. This is one of the parameters used to characterize the cluster radial surface brightness distribution: see equation (1) of the published paper).

Beta_Error
The uncertainty in the beta parameter.

Fit_Method
The method used to fit the cluster surface brightness distribution. As discussed in Section 2.3 of the published paper, four different methods were used, which are flagged as follows:

      m = Central cluster region excluded from fit
      d = beta fixed at 0.6
      r = cluster size determined by ratio of cluster counts calculated
          at different cluster radii
      D = clusters with unconstrained structural parameters
  

Rad_Cooling_Time
The radiative cooling time of the gas at the cluster center, in units of 10^10 years (10 Gyr).

Gas_Density
The gas density at the cluster center, in units of 10^-3 cm^-3, determined using the cluster X-ray luminosity and the measured gas-density profile parameters (core radii and beta values), as discussed in Section 3.3 of the published paper. This was done for detected clusters with a single component or at least a dominant subcluster.

Gas_Mass_1mpc
The gas mass within 1 Mpc, in units of 10^14 solar masses, determined using the cluster X-ray luminosity and the measured gas-density profile parameters (core radii and beta values), as discussed in Section 3.3 of the published paper. This was done for detected clusters with a single component or at least a dominant subcluster.

Gas_Mass_5rc
The gas mass within 5 core radii, in units of 10^14 solar masses.

Total_Mass_1mpc
The total virial mass of the cluster within 1 Mpc radius, in units of 10^14 solar masses (see Section 3.4 of the published paper).

Total_Mass_5rc
The total virial mass of the cluster within 5 core radii, in units of 10^14 solar masses.

Bm_Class
The Bautz-Morgan classification of the cluster.

Richness
The richness class of the cluster.

Number_Galaxies
The number of galaxies in the cluster.

Xray_Morphology
A flag indicating the X-Ray morphological classification of the cluster, as follows:

      s = single symmetric peak
      o = offset center
      e = elliptical
      c = complex, multiple structures
      d = double, roughly equal components
      p = primary with small secondary
      g = primarily galaxy emission
  

Contact Person

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

Page Author: Browse Software Development Team
Last Modified: 24-Jun-2005