Properties of the Galactic population of cataclysmic variables in hard X-rays

Abstract

We measure the spatial distribution and hard X-ray luminosity function of cataclysmic variables (CVs) using the INTEGRAL all-sky survey in the 17-60 keV energy band. The vast majority of the INTEGRAL detected CVs are intermediate polars with luminosities in the range 10^{32}-10^{34} erg/sec. The scale height of the Galactic disk population of CVs is found to be 130{+90}{-50} pc. The CV luminosity function measured with INTEGRAL in hard X-rays is compatible with that previously determined at lower energies (3--20 keV) using a largely independent sample of sources detected by RXTE (located at |b|>10deg as opposed to the INTEGRAL sample, strongly concentrated to the Galactic plane). The cumulative 17-60 keV luminosity density of CVs per unit stellar mass is found to be (1.3+/-0.3)x10^{27} erg/sec/Msun and is thus comparable to that of low-mass X-ray binaries in this energy band. Therefore, faint but numerous CVs are expected to provide an important contribution to the cumulative hard X-ray emission of galaxies.

8 pages, 8 figures. Submitted to A&A

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• Time-resolved optical observations of five cataclysmic variables detected by INTEGRAL
• Low-luminosity X-ray sources and the Galactic ridge X-ray emission
• High-Energy Properties of the Enigmatic Be Star gamma Cassiopeiae
• The Norma Arm Region Chandra Survey: X-ray Populations in the Spiral Arms
• Discovery of the new X-ray transient MAXI J1807+132: a Candidate of a Neutron Star Low-mass X-ray binary
• Galactic Sources Detected in the NuSTAR Serendipitous Survey
• Sample of Cataclysmic Variables from 400d X-ray Survey
• Relation between the X-ray and Optical Luminosities in Binary Systems with Accreting Nonmagnetic White Dwarfs
• Probing the Mysteries of the X-Ray Binary 4U 1210-64 with ASM, PCA, MAXI, BAT and Suzaku
• First hard X-ray detection and broad band X-ray study of the unidentified transient AX J1949.8+2534