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Swift observations of MAXI J1659-152: A compact binary with a black hole accretor

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journal contribution
posted on 24.10.2012, 09:06 by J. A. Kennea, P. Romano, V. Mangano, A. P. Beardmore, P. A. Evans, P. A. Curran, H. A. Krimm, C. B. Markwardt, K. Yamaoka
We report on the detection and follow-up high-cadence monitoring observations of MAXI J1659–152, a bright Galactic X-ray binary transient with a likely black hole accretor, by Swift over a 27 day period after its initial outburst detection. MAXI J1659–152 was discovered almost simultaneously by Swift and the Monitor of All-sky X-ray Image on 2010 September 25, and was monitored intensively from the early stages of the outburst through the rise to a brightness of ~0.5 Crab by the Swift X-ray, UV/Optical, and the hard X-ray Burst Alert Telescopes. We present temporal and spectral analysis of the Swift observations. The broadband light curves show variability characteristic of black hole candidate transients. We present the evolution of thermal and non-thermal components of the 0.5-150 keV combined X-ray spectra during the outburst. MAXI J1659–152 displays accretion state changes typically associated with black hole binaries, transitioning from its initial detection in the hard state, to the steep power-law state, followed by a slow evolution toward the thermal state, signified by an increasingly dominant thermal component associated with the accretion disk, although this state change did not complete before Swift observations ended. We observe an anti-correlation between the increasing temperature and decreasing radius of the inner edge of the accretion disk, suggesting that the inner edge of the accretion disk infalls toward the black hole as the disk temperature increases. We observed significant evolution in the absorption column during the initial rise of the outburst, with the absorption almost doubling, suggestive of the presence of an evolving wind from the accretion disk. We detect quasi-periodic oscillations that evolve with the outburst, as well as irregular shaped dips that recur with a period of 2.42 ± 0.09 hr, strongly suggesting an orbital period that would make MAXI J1659–152 the shortest period black hole binary yet known.

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Citation

Astrophysical Journal, 2011, 736 (1), 22

Version

VoR (Version of Record)

Published in

Astrophysical Journal

Publisher

American Astronomical Society (IOP Publishing)

issn

0004-637X

eissn

1538-4357

Copyright date

2011

Available date

24/10/2012

Publisher version

http://iopscience.iop.org/0004-637X/736/1/22/

Language

en

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