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Title: Why do some intermediate polars show soft X-ray emission? A survey of XMM-Newton spectra
Authors: Evans, P. A.
Hellier, C.
First Published: 10-Jul-2007
Publisher: American Astronomical Society (IOP Publishing)
Citation: Astrophysical Journal, 2007, 663 (2), pp. 1277-1284
Abstract: We make a systematic analysis of the XMM-Newton X-ray spectra of intermediate polars (IPs) and find that, contrary to the traditional picture, most show a soft blackbody component. We compare the results with those from AM Her stars and deduce that the blackbody emission arises from reprocessing of hard X-rays, rather than from the blobby accretion sometimes seen in AM Hers. Whether an IP shows a blackbody component appears to depend primarily on geometric factors: a blackbody is not seen in those that have accretion footprints that are always obscured by accretion curtains or are only visible when foreshortened on the white-dwarf limb. Thus we argue against previous suggestions that the blackbody emission characterizes a separate subgroup of IPs that are more akin to AM Hers, and develop a unified picture of the blackbody emission in these stars.
DOI Link: 10.1086/518552
ISSN: 0004-637X
eISSN: 1538-4357
Version: Publisher Version
Type: Journal Article
Rights: Copyright © 2007. The American Astronomical Society. All rights reserved.. Deposited with reference to the publisher’s archiving policy available on the SHERPA/RoMEO website.
Appears in Collections:Published Articles, Dept. of Physics and Astronomy

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