Chandra Acis Survey of X-Ray Point Sources in 383 Nearby Galaxies I. the Source Catalog

TL;DR

This paper presents a comprehensive catalog of over 11,800 X-ray point sources in 380 nearby galaxies, derived from uniform analysis of 626 Chandra observations, enabling advanced studies of X-ray populations and variability.

Contribution

It provides the largest uniform catalog of X-ray point sources in nearby galaxies, with new sources identified and analyzed for variability, based on extensive Chandra data.

Findings

Detected 28,099 X-ray point sources in 626 observations.

Catalog includes 11,824 sources within galaxy isophotes, most reported for the first time.

Data enables future studies on X-ray luminosity functions and source classification.

Abstract

The Chandra data archive after eight years' accumulation is a treasure for various studies, and in this paper we exploit this valuable resource to study the X-ray point source populations in nearby galaxies. By December 14, 2007, 383 galaxies within 40 Mpc with isophotal major axis above 1 arcminute have been observed by 626 public ACIS observations, 60% of which are for the first time analyzed by this survey to study the X-ray point sources. Uniform data analysis procedures are applied to the 626 ACIS observations and lead to the detection of 28099 point sources, which belong to 17599 independent sources. These include 8700 sources observed twice or more and 1000 sources observed 10 times or more, providing us 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 8519 sources within the D25 isophotes of 351 galaxies, 3305 sources between the D25 and 2D25 isophotes of 309 galaxies, and additionally 5735 sources outside 2D25 isophotes of galaxies. This survey has produced a uniform catalog, by far the largest, of 11824 X-ray point sources within 2D25 isophotes of 380 galaxies with 71% of them reported for the first time. With a uniform dataset and good statistics, this survey enables future works on various topics, such as X-ray luminosity functions, and multiwavelength identification and classification.