Long Term Variability of Cyg X-1, II. The rms-Flux Relation
Abstract
We study the long term evolution of the relationship between the root mean square (rms) variability and flux (the ``rms-flux relation'') for the black hole Cygnus X-1 as monitored from 1996 to 2003 with the Rossi X-ray Timing Explorer (RXTE). We confirm earlier results by Uttley & McHardy (2001) of a linear relationship between rms and flux in the hard state on time scales > 5 s reflecting in its slope the fractional rms variability. We demonstrate the perpetuation of the linear rms-flux relation in the soft and the intermediate state. The existence of a non-zero intercept in the linear rms-flux relation argues for two lightcurve components, for example, one variable and one non-variable component, or a possible constant rms component. The relationship between these two hypothesized components can be described by a fundamental dependence of slope and intercept at time scales ~< 10 ksec with long term averages of the flux.
Keywords
Cite
@article{arxiv.astro-ph/0311039,
title = {Long Term Variability of Cyg X-1, II. The rms-Flux Relation},
author = {T. Gleissner and J. Wilms and K. Pottschmidt and P. Uttley and M. A. Nowak and R. Staubert},
journal= {arXiv preprint arXiv:astro-ph/0311039},
year = {2014}
}
Comments
14 pages, 1 table, 15 figures, accepted for publication in A&A, corrected layout