Resolving different sources of fast X-ray variability of the dwarf nova RU Peg in quiescence

Abstract

We analysed an X-ray light curve of the dwarf nova RU Peg taken by XMM-Newton with a duration of 46300 s. The power density spectrum has a complicated shape with two red noise and two white noise components, indicating the presence of two turbulent regions. We developed a statistical "toy model" to study light curves with variability produced by an unstable turbulent accretion flow from the inner disc. Our results are consistent with a disc truncation radius maximally 0.8 x 10^9 cm. We found that any fluctuation of the viscous mass accretion at the inner disc are visible as UV and X-ray variations with the same break frequency in the power density spectrum. This process is generating low frequency variability. A second break suggests the presence of a faster X-ray variability component which must be generated by another process likely localised between the inner disc and the white dwarf.

accepted for publication in MNRAS, 12 pages, 8 figures, 1 table

References in corpus (2)

• Modelling the behaviour of accretion flows in X-ray binaries
• A two-armed pattern in flickering maps of the nova-like variable UU Aquarii

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