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arXiv · 1009.1154

Multi-state observations of the Galactic Black Hole XTE J1752-223: Evidence for an intermediate black hole spin

R. C. Reis·J. M. Miller·A. C. Fabian·E. M. Cackett·D. Maitra·C. S. Reynolds·M. Rupen·D. T. H. Steeghs·R. Wijnands
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Abstract

The Galactic Black hole candidate XTE J1752-223 was observed during the decay of its 2009 outburst with the Suzaku and XMM-Newton observatories. The observed spectra are consistent with the source being in the ''intermediate`` and ''low-hard state`` respectively. The presence of a strong, relativistic iron emission line is clearly detected in both observations and the line profiles are found to be remarkably consistent and robust to a variety of continuum models. This strongly points to the compact object in \j\ being a stellar-mass black hole accretor and not a neutron star. Physically-motivated and self-consistent reflection models for the Fe-\ka\ emission-line profile and disk reflection spectrum rule out either a non-rotating, Schwarzchild black hole or a maximally rotating, Kerr black hole at greater than 3sigma level of confidence. Using a fully relativistic line function in which the black hole spin parameter is a variable, we have formally constrained the spin parameter to be $0.52\pm0.11 (1σ)$. Furthermore, we show that the source in the low--hard state still requires an optically--thick disk component having a luminosity which is consistent with the $L\propto T^4$ relation expected for a thin disk extending down to the inner--most stable circular orbit. Our result is in contrast to the prevailing paradigm that the disk is truncated in the low-hard state.

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R. C. Reis, J. M. Miller, A. C. Fabian, E. M. Cackett, D. Maitra, C. S. Reynolds, M. Rupen, D. T. H. Steeghs, R. Wijnands. 2010-09-06. Multi-state observations of the Galactic Black Hole XTE J1752-223: Evidence for an intermediate black hole spin. https://doi.org/10.1111/j.1365-2966.2010.17628.x

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