The Swift X-Ray Telescope Cluster Survey. III. Cluster Catalog from 2005-2012 Archival Data
Date Issued
2015
Author(s)
Liu, Teng
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Tundo, Elena
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Wang, Jun-Xian
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Giavalisco, Mauro
Description
T.L. and J.X.W. acknowledge support from National Basic Research Program of China (973 program, grant No. 2015CB857005) and the Chinese National Science Foundation (grant No. 11233002, 11421303 and 11403021). T.L., A.M., E.T., and P.T. received support from the “Exchange of Researchers” program for scientific and technological cooperation between Italy and the People's Republic of China for the years 2013–2015 (code CN13MO5). We also thank the anonymous referee for helpful comments. This research has made use of the NASA/IPAC Extragalactic Database (NED) which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration.
Abstract
We present the Swift X-ray Cluster Survey (SWXCS) catalog obtained using archival data from the X-ray telescope (XRT) on board the Swift satellite acquired from 2005 February to 2012 November, extending the first release of the SWXCS. The catalog provides positions, soft fluxes, and, when possible, optical counterparts for a flux-limited sample of X-ray group and cluster candidates. We consider the fields with Galactic latitude |b| > 20° to avoid high H I column densities. We discard all of the observations targeted at groups or clusters of galaxies, as well as particular extragalactic fields not suitable to search for faint extended sources. We finally select ~3000 useful fields covering a total solid angle of ~400 deg2. We identify extended source candidates in the soft-band (0.5-2 keV) images of these fields using the software EXSdetect, which is specifically calibrated for the XRT data. Extensive simulations are used to evaluate contamination and completeness as a function of the source signal, allowing us to minimize the number of spurious detections and to robustly assess the selection function. Our catalog includes 263 candidate galaxy clusters and groups down to a flux limit of 7 × 10-15 erg cm-2 s-1 in the soft band, and the logN-logS is in very good agreement with previous deep X-ray surveys. The final list of sources is cross-correlated with published optical, X-ray, and Sunyaev-Zeldovich catalogs of clusters. We find that 137 sources have been previously identified as clusters in the literature in independent surveys, while 126 are new detections. Currently, we have collected redshift information for 158 sources (60% of the entire sample). Once the optical follow-up and the X-ray spectral analysis of the sources are complete, the SWXCS will provide a large and well-defined catalog of groups and clusters of galaxies to perform statistical studies of cluster properties and tests of cosmological models.
Volume
216
Issue
2
Start page
28
Issn Identifier
0067-0049
Ads BibCode
2015ApJS..216...28L
Rights
open.access
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