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Two Types of X-ray Spectra in Cataclysmic Variables
Published online by Cambridge University Press: 12 April 2016
Abstract
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