X-ray Spectral Variations of U Gem from Quiescence to Outburst

Abstract

In this paper we report the discovery of a high energy component of the X-ray spectra of U Gem, which can be observed while the source is in outburst. We used Chandra and XMM-Newton observations to compare the quiescence and outburst X-ray spectra of the source. The additional component may be the result of the reflection of X-rays emitted from an optically thin plasma close to the white dwarf, from the optically thick boundary layer during the outburst. Another possible explanation is that some magnetically channeled accretion may occur onto the equatorial belt of the primary causing shocks similar to the ones in the intermediate polars as it was suggested by \citep{w2002}. We have also found a timing structure at about 73 mHz ($\sim$13.7 s.) in the RXTE observation, resembling dwarf novae oscillations (DNOs).

arXiv commentaccepted by MNRAS, figure 1 replaced with a newer one

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• X-ray Observations of the Boundary Layer in Dwarf Novae at Low Accretion Rates
• Dwarf Nova Oscillations and Quasi-Periodic Oscillations in Cataclysmic Variables: II. A Low Inertia Magnetic Accretor Model
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Cited by in corpus (8)

• X-ray Emissions from Accreting White Dwarfs: a Review
• The Fall and the Rise of X-rays from Dwarf Novae in Outburst: RXTE Observations of VW Hydri and WW Ceti
• SWIFT XRT Observations of the Nova-like Cataclysmic Variables MV Lyr, BZ Cam and V592 Cas
• Accretion Flows in Nonmagnetic White Dwarf Binaries as Observed in X-rays
• Superhumps linked to X-ray emission. The superoutbursts of SSS J122221.7-311525 and GW Lib
• Pre-outburst $Chandra$ Observations of the Recurrent Nova T Pyxidis
• X-ray properties of dwarf nova EY Cyg and the companion star using an XMM-Newton observation
• Broad Observational Perspectives Achieved by the Accreting White Dwarf Sciences in the XMM-Newton and Chandra Eras