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Description
The Chandra data archive is a treasure trove for various studies, and in this study the author exploits this valuable resource to study the X-ray point source populations in nearby galaxies. By 2007 December 14, 383 galaxies within 40 Mpc with isophotal major axes above 1 arcminute had been observed by 626 public ACIS observations, most of which were for the first time analyzed by this survey to study the X-ray point sources. Uniform data analysis procedures were applied to the 626 ACIS observations and led to the detection of 28,099 point sources, which belong to 17,559 independent sources. These include 8700 sources observed twice or more and 1000 sources observed 10 times or more, providing a wealth of data to study the long-term variability of these X-ray sources. Cross-correlation of these sources with galaxy isophotes led to 8,519 sources within the D<sub>25</sub> isophotes of 351 galaxies, 3,305 sources between the D<sub>25</sub> and 2 * D<sub>25</sub> isophotes of 309 galaxies, and an additional 5,735 sources outside the 2 * D<sub>25</sub> isophotes of galaxies. This survey has produced a uniform catalog, by far the largest, of 11,824 X-ray point sources within 2 * D<sub>25</sub> isophotes of 380 galaxies. Contamination analysis using the log N-log S relation shows that 74% of the sources within the 2 * D<sub>25</sub> isophotes above 10<sup>39</sup> erg s<sup>-1</sup>, 71% of the sources above 10<sup>38</sup> erg s<sup>-1</sup>, 63% of the sources above 10<sup>37</sup> erg s<sup>-1</sup>, and 56% of all sources are truly associated with the galaxies. Meticulous efforts have identified 234 X-ray sources with galactic nuclei of nearby galaxies. This archival survey leads to 300 ultraluminous X-ray sources (ULXs) with L<sub>X</sub> in the 0.3-8 keV band >= 2 x 10<sup>39</sup> erg s<sup>-1</sup> within the D<sub>25</sub> isophotes, 179 ULXs between the D<sub>25</sub> and the 2 * D<sub>25</sub> isophotes, and a total of 479 ULXs within 188 host galaxies, with about 324 ULXs truly associated with the host galaxies based on the contamination analysis. About 4% of the sources exhibited at least one supersoft phase, and 70 sources are classified as ultraluminous supersoft sources with L<sub>X</sub> (0.3-8 keV) >= 2 x 10<sup>38</sup> erg s<sup>-1</sup>. With a uniform data set and good statistics, this survey enables future works on various topics, such as X-ray luminosity functions for the ordinary X-ray binary populations in different types of galaxies, and X-ray properties of galactic nuclei. This table contains the list of 17,559 'independent' X-ray point sources that was contained in table 4 of the reference paper. As the author notes in Section 5 of this paper, there are 341 sources projected within 2 galaxies with overlapping domains which are listed for both galaxies. The 5,735 sources lieing outside the 2* D<sub>25</sub> isophotes of the galaxies are also included in this table. For these sources, the X-ray luminosities are computed as if they were in a galaxy of that group, which may or may not be the case; thus, they may not be their 'true' luminosities, but are listed for the purposes of comparison. This table was created by the HEASARC in March 2011 based on the electronic version of Table 4 of the reference paper which was obtained from the Astrophysical Journal web site. Some of the values for the name parameter in the HEASARC's implementation of this table were corrected in April 2018. This is a service provided by NASA HEASARC .
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