Analyzing short-term X-ray variability of Cygnus X-1 with Linear State Space Models
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.
Keywords
Cite
@article{arxiv.astro-ph/9802339,
title = {Analyzing short-term X-ray variability of Cygnus X-1 with Linear State Space Models},
author = {K. Pottschmidt and M. Koenig and J. Wilms and R. Staubert},
journal= {arXiv preprint arXiv:astro-ph/9802339},
year = {2007}
}
Comments
9 pages, 7 figures, accepted for publication in Astronomy & Astrophysics, also available at http://astro.uni-tuebingen.de/publications/