Multiwavelength observations of accreting binary systems

CVs are interacting binaries accreting through Roche lobe overflow. The main motivation of this thesis is to enhance our understanding of accretion disc physics, and in particular, the mechanism producing X-rays in these and in other accreting objects. This thesis comprises four case studies. Two of the studies have focused on individual CVs; a serendipitously discovered polar candidate 2XMM J131223.4 + 173659 (J1312) and a WZ Sge-type dwarf nova (DN), GW Lib, which went into an outburst in 2007. The X-ray analysis of J1312 showed that a soft component, assumed to be a typical spectral characteristic of polars, was not observed in these data. The most likely explanation is that this component probably has too low a temperature to be seen in X-rays. The multiwavelength study of the 2007 outburst of GW Lib represents a unique opportunity for understanding the disc physics of this rare type of outbursting system. A major finding of this study is that the X-rays are not suppressed during the outburst. This is in contrast to the outburst behaviour of WZ Sge, the defining member of this class. The remainder of this thesis focused on larger source samples. First, I have derived the most accurate 2–10 keV X-ray luminosity function (XLF) of DNe to date with parallax-based distance measurements. The other study consists of a survey of serendipitous X-ray point sources in the direction of the Galactic Plane. The conclusion is that a significant fraction of the source sample could be associated with CVs based on the X-ray spectral characteristics of these sources.