X-Ray Emission of Cataclysmic Variables Observed by Integral

Abstract

Magnetic cataclysmic variables represent a significant fraction of all INTEGRAL detections in hard X-rays and soft gamma rays. Our deep survey of all known intermediate polars revealed five new sources, previously undetected by this mission. Our analysis, based on all available observational data from the IBIS and JEM-X instruments, has shown that the fluxes of some intermediate polars are long-term variable. Moreover, this hard X-ray and soft gamma-ray variability is correlated with changes in the optical. The broad-band spectra (3--100 keV) of surveyed intermediate polars can be fitted well by a thermal bremsstrahlung model, in some cases with the reflection from an optically thick cold medium (the surface of the white dwarf).