Journal Article

Hard X-ray properties of magnetic cataclysmic variables*

S. Scaringi, A. J. Bird, A. J. Norton, C. Knigge, A. B. Hill, D. J. Clark, A. J. Dean, V. A. McBride, E. J. Barlow, L. Bassani, A. Bazzano, M. Fiocchi and R. Landi

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 401, issue 4, pages 2207-2218
Published in print February 2010 | ISSN: 0035-8711
Published online January 2010 | e-ISSN: 1365-2966 | DOI: http://dx.doi.org/10.1111/j.1365-2966.2009.15826.x
Hard X-ray properties of magnetic cataclysmic variables*

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Hard X-ray surveys have proven remarkably efficient in detecting intermediate polars and asynchronous polars, two of the rarest type of cataclysmic variable (CV). Here, we present a global study of hard X-ray-selected intermediate polars and asynchronous polars, focusing particularly on the link between hard X-ray properties and spin/orbital periods. To this end, we first construct a new sample of these objects by cross-correlating candidate sources detected in INTEGRAL/IBIS observations against catalogues of known CVs. We find 23 CV matches, and also present an additional nine (of which three are definite) likely magnetic cataclysmic variables (mCVs) identified by others through optical follow-ups of IBIS detections. We also include in our analysis hard X-ray observations from the Swift/BAT and SUZAKU/HXD in order to make our study more complete. We find that most hard X-ray-detected mCVs have Pspin/Porb < 0.1 above the period gap. In this respect, we also point out the very low number of detected systems in any band between Pspin/Porb= 0.3 and Pspin/Porb= 1 and the apparent peak of the Pspin/Porb distribution at about 0.1. The observational features of the PspinPorb plane are discussed in the context of mCV evolution scenarios. We also present for the first time evidence for correlations between hard X-ray spectral hardness and Pspin, Porb and Pspin/Porb. An attempt to explain the observed correlations is made in the context of mCV evolution and accretion footprint geometries on the white dwarf surface.

Keywords: surveys; novae, cataclysmic variables; gamma-rays: observations; X-rays: binaries

Journal Article.  8667 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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