First XMM-Newton observations of strongly magnetic cataclysmic variables I: spectral studies of DP Leo and WW Hor

Abstract

We present an analysis of the X-ray spectra of two strongly magnetic cataclysmic variables, DP Leo and WW Hor, made using XMM-Newton. Both systems were in intermediate levels of accretion. Hard optically thin X-ray emission from the shocked accreting gas was detected from both systems, while a soft blackbody X-ray component from the heated surface was detected only in DP Leo. We suggest that the lack of a soft X-ray component in WW Hor is due to the fact that the accretion area is larger than in previous observations with a resulting lower temperature for the re-processed hard X-rays. Using a multi-temperature model of the post-shock flow, we estimate that the white dwarf in both systems has a mass greater than 1 Msun. The implications of this result are discussed. We demonstrate that the `soft X-ray excess' observed in many magnetic cataclysmic variables can be partially attributed to using an inappropriate model for the hard X-ray emission.

arXiv commentAccepted by MNRAS as a letter, 5 pages, 2 figures

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• Determining the mass of the accreting white dwarf in magnetic CVs using data
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• First XMM-Newton observations of strongly magnetic cataclysmic variables - II. Timing studies of DP Leo and WW Hor
• Discovery of a Significant Magnetic CV Population in the Limiting Window
• XMM-Newton observations of the polars EV UMa, RX J1002-19 and RX J1007-20
• XMM-Newton observations of the asynchronous polar BY Cam
• A burst from the direction of UZ Fornacis with XMM-Newton
• First X-ray observations of the polar CE Gru
• Phase-Resolved Infrared Spectroscopy and Photometry of V1500 Cygni, and a Search for Similar Old Classical Novae
• Fluorescent Fe K line emission of gamma Cas stars II. Predictions for magnetic interactions and white-dwarf accretion scenarios