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Two Types of X-ray Spectra in Cataclysmic Variables

Published online by Cambridge University Press:  12 April 2016

K. Mukai ,
A. Kinkhabwala ,
J. R. Peterson ,
S. M. Kahn  and
F. Paerels
K. Mukai
Affiliation:
NASA/GSFC and USRA, Code 662, NASA/Goddard Space Flight Center, Greenbelt, MD 20771, USA
A. Kinkhabwala
Affiliation:
Columbia Astrophysics Laboratory, Columbia University, 550 West 120th Street, New York, New York 10027, USA
J. R. Peterson
Affiliation:
Columbia Astrophysics Laboratory, Columbia University, 550 West 120th Street, New York, New York 10027, USA
S. M. Kahn
Affiliation:
Columbia Astrophysics Laboratory, Columbia University, 550 West 120th Street, New York, New York 10027, USA
F. Paerels
Affiliation:
Columbia Astrophysics Laboratory, Columbia University, 550 West 120th Street, New York, New York 10027, USA

Abstract

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We present Chandra HETG spectra of seven cataclysmic variables, including four intermediate polars. We find that they divide unambiguously into two distinct types. Spectra of the first type (nonmagnetic systems and EX Hya) are remarkably well fit by a simple cooling flow model, which assumes only steady-state isobaric radiative cooling. The maximum temperature, kTmax, and the normalization, which provides a highly precise measurement of the accretion rate, are the only free parameters of this model. Spectra of the second type (the three other IPs) are grossly inconsistent with a cooling flow model. They instead exhibit a hard continuum, and show strong H-like and He-like ion emission but little Fe L-shell emission, which is consistent with expectations for line emission from a photoionized plasma. Using a simple photoionization model, we argue that the observed line emission for these sources can be driven entirely by the hard continuum. The physical significance of these two distinct types of X-ray spectra is also explored.

Type
Part 3. A. Accretion Plasma diagnostics - Observations
Information
International Astronomical Union Colloquium , Volume 190: Magnetic Cataclysmic Variables , 2004 , pp. 113 - 119
Copyright
Copyright © Astronomical Society of the Pacific 2004

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