Cygnus X-1 - an interpretation of the spectrum and its variability

Abstract

X-ray observations of Cygnus X-1 are compared with the 'standard' model (accretion disk surrounding a rotating black hole). Attention focuses on the shape of the X-ray spectrum, the fluctuations in X-ray intensity, and the 1971 transition in the spectrum. There are several encouraging agreements of model and data, but a detailed comparison awaits further theoretical and observational studies. Several predictions of the standard model are listed as suggestive guides for future work.