Analyzing short-term X-ray variability of Cygnus X-1 with Linear State Space Models

K. Pottschmidt; M. Koenig; J. Wilms; R. Staubert

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arXiv · astro-ph/9802339

Analyzing short-term X-ray variability of Cygnus X-1 with Linear State Space Models

K. Pottschmidt·M. Koenig·J. Wilms·R. Staubert

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Abstract

Cyg X-1 exhibits irregular X-ray variability on all measured timescales. The usually applied shot noise models describe the typical short-term behavior of this source by superposition of randomly occuring shots with a distribution of shot durations. We have reanalyzed EXOSAT ME observations of Cyg X-1 using the more general Linear State Space Models (LSSMs). These models, which explicitly take the observation-noise into account, model the intrinsic system variability with an autoregressive (AR) process. Our fits show that an AR process of first order can reproduce the system variability of Cyg X-1. A possible interpretation is again the superposition of individual shots, but with a single relaxation timescale tau. This parameter was found to be 0.19s.

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K. Pottschmidt, M. Koenig, J. Wilms, R. Staubert. 1998-02-26. Analyzing short-term X-ray variability of Cygnus X-1 with Linear State Space Models. https://arxiv.org/abs/astro-ph/9802339

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