XMM-Newton observations of OY Car III: OM light curve modelling, X-ray timing and spectral studies

Abstract

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.

arXiv comment10 pages, 12 figures, accepted for publication in A&A

References in corpus (9)

• The XMM-Newton Optical/UV Monitor Telescope
• Imaging Performance of the XMM-Newton X-ray telescopes
• Dwarf Nova Oscillations and Quasi-Periodic Oscillations in Cataclysmic Variables: III. A New Kind of Dwarf Nova Oscillation, and Further Examples of the Similarities to X-Ray Binaries
• First XMM-Newton observations of a Cataclysmic Variable I: Timing studies of OY Car
• The X-ray eclipse of OY Car resolved with XMM-Newton: X-ray emission from the polar regions of the white dwarf
• A double-frequency dwarf nova oscillation
• First XMM-Newton observations of a cataclysmic variable II: the X-ray spectrum of OY Car
• Optical and ROSAT X-ray observations of the dwarf nova OY Carinae in superoutburst and quiescence
• 3D eclipse mapping in AM Herculis systems - `Genetically modified fireflies'

Cited by in corpus (3)

• XMM-Newton observations of the dwarf nova YZ Cnc in quiescence
• QPOs in compact binaries from small scale eruptions in an inner magnetized disk
• Dwarf nova oscillations and quasi-periodic oscillations in cataclysmic variables - VII. OY Carinae and oscillations in dwarf novae in quiescence