Analyzing Relativistic Effects around Black Holes: XMM observations of Cygnus X-1

Abstract

We investigate the relativistic effects around black holes by spectral analysis of Modified Timing Mode observations of Cygnus X-1 with XMM-Newton. Simultaneous RXTE observations extend the energy to 120 keV and serve to constrain the continuum, which consists of a power law with exponential cutoff and a reflection component. As the majority of the reflected photons are emitted very close to the black hole, this component is relativistically smeared. Hence, the parameters of space time are imprinted in the spectrum, which is modeled by using the relline code. We find that Cygnus X-1 is fast spinning (a ≈ 0.9), assuming the solution with a canonical emissivity of r −3 from a thin accretion disk. These results are explained in detail in a letter submitted to A&A (Duro et al., 2011). Using a new version of the relline code, we could also show that the data is equally well described if the emission is assumed to originate from the base of a jet at 7 rg above the black hole.