WARPS - Wide Angle ROSAT Pointed Survey, First Phase (WARPS-I)

Overview

The Wide Angle ROSAT Pointed Survey, First Phase (WARPS-I) table is a catalog which contains optical identifications for objects found in a serendipitous survey of relatively deep, pointed ROSAT observations for clusters of galaxies. The X-ray source detection algorithm used by WARPS is Voronoi Tessellation and Percolation (VTP), a technique which is equally sensitive to point sources and to extended sources of low surface brightness. WARPS-I is based on the central regions of 86 ROSAT PSPC fields, covering an area of 16.2 square degrees. The X-ray source screening and optical identification process for WARPS-I yielded 34 clusters at 0.06<z<0.75. Twenty-two of these clusters form a complete, statistically well-defined sample drawn from 75 of these 86 fields, covering an area of 14.1 square degrees, with a flux limit of F(0.5-2.0keV) = 6.5x10^-14 erg/cm²/s. This sample can be used to study the properties and evolution of the gas, galaxy and dark matter content of clusters and to constrain cosmological parameters.

Catalog Bibcode

2002ApJS..140..265P

References

The WARPS survey. VI. Galaxy cluster and source identifications from phase I.
    Perlman E.S., Horner D.J., Jones L.R., Scharf C.A., Ebeling H., Wegner G.,
    Malkan M.
   <Astrophys. J. Suppl. Ser. 140, 265 (2002)>
   =2002ApJS..140..265P

Provenance

This online catalog was created by the HEASARC in May 2003 based on machine-readable versions of tables 2, 3, 4 and 5 of Perlman et al. (2002) that were obtained from the CDS.

HEASARC Implementation

The HEASARC has combined data from 4 separate tables from Perlman et al. (2002) into this database table. There are some changes in this HEASARC tabular version and some additional parameters that have been added compared to the published version: (i) The prefix used for the names of sources is WARPS rather than WARP as in the published version: the former version is the one recommended by the Dictionary of Astronomical Nomenclature; (ii) The HEASARC has added a new parameter, table_id, which indicates from which table a particular entry originates (2, 3 or 5); (iii) The HEASARC has added a new parameter, flux_limited_sample, which indicates whether or not a given source is part of the statistically complete, flux-limited sample, i.e., is listed in Table 4 of the published paper; and (iv) the HEASARC has set values of the parameter spectra_flag which were "..." in the original Tables 2 and 3 to "N" in this present table; for sources which were in Table 5 of the published paper but were not listed in either Tables 2 or 3, the HEASARC has left spectra_flag blank.

Parameters

Name
The assigned source name. The prefix used for the names of sources is WARPS (rather than WARP as in the published version), as recommended by the Dictionary of Astronomical Nomenclature.

ROSAT_Field
The ROSAT pointing which contains the source.

RA
The Right Ascension of the X-ray source in the selected equinox. The typical positional error is 15 arcseconds. The RA was listed in J2000 coordinates and to a precision of 0.1 seconds of time in the original published tables.

Dec
The Declination of the X-ray source in the selected equinox. The typical positional error is 15 arcseconds. The Declination was listed in J2000 coordinates and to a precision of 1 arcsecond in the original published tables.

LII
The Galactic Longitude of the X-ray source.

BII
The Galactic Latitude of the X-ray source.

Raw_Count_Rate
The raw count rate obtained from the Voronoi Tessellation and Percolation (VTP) detection algorithm, in counts per second.

Count_Rate
The corrected (i.e., total) count rate as obtained from the Voronoi Tessellation and Percolation (VTP) detection algorithm, in counts per second.

NH_Galactic
The Galactic Hydrogen column density from Dickey & Lockman (1990, ARAA, 28, 215), in units of H atoms cm^-2.

Flux
The unabsorbed X-ray flux in the 0.5 - 2.0 keV band, in units of erg/cm²/s. For clusters of galaxies, the flux was calculated using the same iterative method which was used by Ebeling et al. (1998, MNRAS, 301, 881). For some clusters, this flux may include a component from contaminating sources (e.g., AGNs): see Section 4.4 of the published paper for details for each cluster. The authors assumed a Raymond-Smith spectrum with a redshift appropriate for each cluster and a metal abundance of 0.3 solar. The temperature of the model was derived iteratively by constraining the cluster to obey the observed L-T relation (White, Jones, & Forman 1997, MNRAS, 292, 419). Fluxes were obtained for AGNs and unidentified sources assuming a power-law spectrum with F_nu ~ nu^-1, where nu is frequency. The fluxes for sources identified as stars were calculated assuming a Raymond-Smith model with a temperature of 2 x 10⁶ K and with no correction for Galactic hydrogen column density.

Log_Lx
The logarithm of the rest-frame source luminosity in the 0.5-2.0 keV band, in units of erg/s, derived in the same manner as the flux. Values of q₀ = 0.5 and H₀ = 50 km s^-1 Mpc^-1 were assumed.

Core_Radius
The core radius of the cluster, in arcseconds. Note that this is very crude as it is based on ROSAT data which in most cases barely resolve the cluster.

Extent_Parameter
The source extent parameter, defined as the ratio S_King/S_point as discussed in Section 2.1 of the published paper.

Imaging_Passband
The imaging status of the source. The letters indicates the band of the optical image(s) obtained, B, I or R.

Spectra_Flag
The status of the spectroscopic follow-up, where a "Y" indicates that spectra were taken for this source. Note that the HEASARC has set values of this parameter which were "..." in the original published Tables 2 and 3 to "N"; also that for sources which were in Table 5 of the published paper but which were not listed in either Tables 2 or 3, the HEASARC has left the value blank.

Source_Type
The identification of the source (e.g., cluster, AGN, star). Identifications in lower case were identified based on the literature (primarily using NED and SIMBAD), while upper case IDs are based on WARPS optical follow-up observations. Sources listed as blends are briefly discussed in the notes parameter.

Redshift
The redshift of the source, if known,

Redshift_Flag
This parameter is a flag which is set to ":" to indicate that the redshift value is uncertain or to "]" if the redshift was estimated photometrically. Such individual cases are discussed in Section 4.4 of the published paper.

Num_Redshifts
The number of galaxy redshifts used to derive the cluster redshift.

Spect_Type
The spectral type, given for sources that have been identified as stars.

Flags
This parameter contains some additional flags, as follows: a "c" indicates that the cluster is contaminated or possibly contaminated by other sources; a "<" indicates that the cluster flux falls below the limit for inclusion in the statistically complete, flux-limited sample; a "?" indicates a possible cluster or group for which optical follow-up was not completed, usually because it was below the flux limit; an "8" indicates that the cluster was found in a field targeted at another cluster; a "b" indicates that this field was dropped due to high background. See the notes in Section 4.4 of the published paper for more details on the flagged sources.

Notes
This parameter contains alternate names and other notes. Sources listed as SHARC appear in the SHARC Bright Survey catalog (Romer et al. 2000, ApJS, 126, 209). Sources listed as VMF correspond to sources in the CfA 160 square degree survey of Vikhlinin et al. (1998, ApJ, 498, 21). Sources listed as RIXOS correspond to sources in the RIXOS survey catalog (Mason et al. 2000, MNRAS, 311, 456). NVSS (Condon et al. 1998, AJ, 115, 1693) and FIRST (e.g., White et al. 1997, ApJ, 475, 479) radio sources are also indicated.

Table_ID
The HEASARC created this new parameter in order to indicate from which table a particular entry originates: it is set to 2 for sources listed in Table 2 of the published paper, the WARPS-I Source Catalog, to 3 for sources listed in Table 3 of the published paper, the "Other Sources", and to 5 for sources listed in Table 5 of the published paper, the WARPS-I Additional Clusters and Candidates, which were not present in either Tables 2 or 3.

Flux_Limited_Sample
The HEASARC created this new parameter in order to indicate whether or not a source is part of the WARPS-I statistically complete, flux-limited sample, i.e., is listed in Table 4 of the published paper.

Class
The HEASARC Browse object classification, based on the source_type and spect_type parameter values, if available.

Contact Person

Questions regarding the WARPS database table can be addressed to the HEASARC Help Desk.

Page Author: Browse Software Development Team
Last Modified: Monday, 16-Sep-2024 17:36:37 EDT