Intermediate polar X-ray power spectra

Norton, A. J.; Beardmore, A. P. and Taylor, P. (1996). Intermediate polar X-ray power spectra. In: International Conference on X-ray Astronomy and Astrophysics: Röntgenstrahlung from the Universe, 25-29 Sep 1995, Wurzburg, Germany.



The authors discuss the various emission and attenuation components that contribute to the overall X-ray signal produced by an intermediate polar. This description is then used to construct an algebraic expression that represents the complex modulation of the X-ray lightcurve in terms of a number of parameters that describe the emission and attenuation properties of the system. The authors expand this expression in terms of its individual frequency components and so determine the amplitudes and phases that would be observed at a range of spin and orbital harmonic and sideband frequencies in the X-ray power spectrum of a given source. It is concluded that a vast range of frequency components are to be expected in the X-ray lightcurve of an intermediate polar that accretes via a combination of an accretion disc and an accretion stream onto two asymmetric regions in the vicinity of the magnetic poles. For systems in which the accretion process is less complex, the power spectra are correspondingly simpler.

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