Rubens C. Reis, Jon M. Miller, Mark T. Reynolds, Andrew C. Fabian, Dominic J. Walton
We report on a Suzaku observation of the nearly discovered X-ray binary MAXI
J1836-194. The source is found to be in the hard/intermediate spectral state
and displays a clear and strong relativistically broadened iron emission line.
We fit the spectra with a variety of phenomenological, as well as physically
motivated disk reflection models, and find that the breadth and strength of the
iron line are always characteristic of emission within a few gravitational
radii around a black hole. This result is independent of the continuum used and
strongly points toward the central object in MAXI J1836-194 being a stellar
mass black hole rotating with a spin of a=0.86 \pm 0.04 (90% confidence). We
discuss this result in the context of spectral state definitions, physical
changes (or lack thereof) in the accretion disk and on the potential importance
of the accretion disk corona in state transitions.
View original:
http://arxiv.org/abs/1111.6665
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