Title: <i>SWIFT</i>-BAT SURVEY OF GALACTIC SOURCES: CATALOG AND PROPERTIES OF THE POPULATIONS
Abstract: We study the populations of X-ray sources in the Milky Way in the 15–55 keV band using a deep survey with the BAT instrument aboard the Swift observatory. We present the log N–log S distributions of the various source types and we analyze their variability and spectra. For the low-mass X-ray binaries (LMXBs) and the high-mass X-ray binaries (HMXBs), we derive the luminosity functions to a limiting luminosity of LX ∼ 7 × 1034 erg s−1. Our results confirm the previously found flattening of the LMXB luminosity function below a luminosity of LX ∼ 1037 erg s−1. The luminosity function of the HMXBs is found to be significantly flatter in the 15–55 keV band than in the 2–10 keV band. From the luminosity functions we estimate the ratios of the hard X-ray luminosity from HMXBs to the star formation rate, and the LMXB luminosity to the stellar mass. We use these to estimate the X-ray emissivity in the local universe from X-ray binaries and show that it constitutes only a small fraction of the hard X-ray background.