Cygnus X-1: shedding light on the spectral variability of a black hole

Grinberg, V.
Hell, N.
Wilms, J.
Rodriguez, J.
Pottschmidt, K.
Nowak, M. A.
Böck, M.
Bodaghee, A.
Cadolle Bel, M.
Fürst, F.
Hanke, M.
Kühnel, M.
Laurent, P.
Markoff, S. B.
Markowitz, A.
Marcu, D. M.
Pooley, G. G.
Popp, A.
Rothschild, R. E.
Tomsick, J. A.

Publication date

October 2012

Publisher

Sissa Medialab

Abstract

The knowledge of the spectral state of a black hole is essential for the interpretation of data from black holes in terms of their emission models. Based on pointed observations of Cyg X-1 with the Rossi X-ray timing Explorer (RXTE) that are used to classify simultaneous RXTE-ASM observations, we develop a scheme based on RXTE-ASM colors and count rates that can be used to classify all observations of this canonical black hole that were performed between 1996 and 2011. We show that a simple count rate criterion, as used previously, leads to a significantly higher fraction of misclassified observations. This scheme enables us to classify single INTEGRAL-IBIS science windows and to obtain summed spectra for the soft, intermediate and hard sta...