A&A 489, 1121-1127 (2008)
DOI: 10.1051/0004-6361:200810213

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

M. Revnivtsev^{1, 2, 3}, S. Sazonov^{1, 2}, R. Krivonos^{2, 1}, H. Ritter¹, and R. Sunyaev<sup>1, 2

1</sup>  Max-Planck-Institute für Astrophysik, Karl-Schwarzschild-Str. 1, 85740 Garching bei München, Germany
    e-mail: mikej@mpa-garching.mpg.de
²  Space Research Institute, Russian Academy of Sciences, Profsoyuznaya 84/32, 117997 Moscow, Russia
³  Excellence Cluster Universe, Technische Universität München, Garching, Germany

Received 17 May 2008 / Accepted 23 July 2008

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 CVs detected by INTEGRAL are intermediate polars of luminosity in the range 10³²–10³⁴ erg s^-1. The scale height of the Galactic disk population of intermediate polars is found to be  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| > 10° as opposed to the INTEGRAL sample, which is strongly concentrated to the Galactic plane). The cumulative 17–60 keV luminosity density of CVs per unit stellar mass is found to be (1.30.3)10²⁷ erg s^-1 , which is 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.

Key words: stars: binaries: close -- stars: binaries: general -- stars: novae, cataclysmic variables -- stars: luminosity function, mass function -- stars: white dwarfs -- X-rays: binaries

© ESO 2008