We revisit the XMM-Newton observations of the dwarf nova OY Car taken in July
2000 which occured shortly after an outburst. Ramsay et al (2001a) found a
prominent energy dependent modulation at a period of 2240 sec: this modulation
was only seen for app. 1/3 of the observation duration. In our new analysis, we
examine this time interval in greater detail. In addition to the 2240 sec
period we find evidence for other periods, the most prominent being near 3500
sec. Both these modulations are most likely due to changes in photoelectric
absorption over this period: this is supported by phase-resolved spectroscopy.
This may indicate the presence of matter above the accretion disc or a presence
of a magnetic accretion curtain. In this case the 2240 sec period could
represent a spin period of the white dwarf and the 3500 sec period a beat
period between the spin and orbital periods. We also model the B band and UV
eclipse profiles and light curves using a new technique to map the spatial
extent of the accretion disc. As a result we find that whilst the optical
emission is dominated by both the emission close to the accretion disc boundary
layer and the hot spot where the accretion stream hits the disc, the UV
emission is mainly dominated by the inner disc/boundary layer only.Comment: 10 pages, 12 figures, accepted for publication in A&
