Near-Infrared Counterparts to Chandra X-Ray Sources Toward the Galactic Center. I. Statistics and a Catalog of Candidates

We present a catalog of 5184 candidate infrared counterparts to X-ray sources detected toward the Galactic center. The X-ray sample contains 9017 point sources detected in this region by the Chandra X-ray Observatory during the past decade, including data from a recent deep survey of the central 2° × 0°.8 of the Galactic plane. A total of 6760 of these sources have hard X-ray colors, and the majority of them lie near the Galactic center, while most of the remaining 2257 soft X-ray sources lie in the foreground. We cross-correlated the X-ray source positions with the 2MASS and SIRIUS near-infrared catalogs, which collectively contain stars with a 10σ limiting flux of K_s ≤ 15.6 mag. In order to distinguish absorbed infrared sources near the Galactic center from those in the foreground, we defined red and blue sources as those which have H – K_s ≥ 0.9 and