Investigating the Nature of X-Ray Sources in the Andromeda Galaxy Using Chandra and Hubble Data

Abstract Using data from the Panchromatic Hubble Andromeda Treasury (PHAT) program and the Chandra X-ray Observatory, we analyzed X-ray sources in the Andromeda Galaxy (M31). From this we identified 799 X-ray sources within the PHAT region. Our analysis suggests that the X-ray sources consist mainly of high-mass X-ray binaries (HMXBs) with a few low-mass X-ray binaries. These sources show a cumulative X-ray luminosity function consistent with other star-forming galaxies dominated by HMXBs. The population of evolved stars within M31, as identified by color–magnitude diagrams, further supports the hypothesis that these X-ray sources are predominantly X-ray binaries.