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SWIFT J1910.2-0546: A Possible Black Hole Binary with a Retrograde Spin or Truncated Disk

Reis, R. C. and Reynolds, M. T. and Miller, J. M. and Walton, D. J. and Maitra, D. and King, A. and Degenaar, N. (2013) SWIFT J1910.2-0546: A Possible Black Hole Binary with a Retrograde Spin or Truncated Disk. Astrophysical Journal, 778 (2). Art. No. 155. ISSN 0004-637X.

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We present the first results from a long (51 ks) XMM-Newton observation of the Galactic X-ray binary SWIFT J1910.2-0546 in an intermediate state, obtained during its 2012 outburst. A clear, asymmetric iron emission line is observed and physically motivated models are used to fully describe the emission-line profile. Unlike other sources in their intermediate spectral states, the inner accretion disk in SWIFT J1910.2-0546 appears to be truncated, with an inner radius of r_(in)=9.4^(+1.7)_(-1.3) r_g at a 90% confidence limit. Quasi-periodic oscillations are also found at approximately 4.5 and 6 Hz, which correlates well with the break frequency of the underlying broad-band noise. Assuming that the line emission traces the innermost stable circular orbit, as would generally be expected for an intermediate state, the current observation of SWIFT J1910.2-0546 may offer the best evidence for a possible retrograde stellar mass black hole with a spin parameter a < – 0.32cJ/GM^2 (90% confidence). Although this is an intriguing possibility, there are also a number of alternative scenarios which do not require a retrograde spin. For example, the inner accretion disk may be truncated at an unusually high luminosity in this case, potentially suffering frequent evaporation/condensation, or it could instead be persistently evacuated through mass loss in a relativistic jet. Further observations are required to distinguish between these different interpretations.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Walton, D. J.0000-0001-5819-3552
Additional Information:© 2013 American Astronomical Society. Received 2013 January 23; accepted 2013 October 1; published 2013 November 13. R.C.R. thanks the Michigan Society of Fellows and NASA. We further thank the XMM-Newton team, which scheduled this Target of Opportunity observation, and to the Swift team for providing prompt notice of this new source to the astronomical community at large. R.C.R. is supported by NASA through the Einstein Fellowship Program, grant No. PF1-120087, and is a member of the Michigan Society of Fellows.
Funding AgencyGrant Number
NASA Einstein Fellowship ProgramPF1-120087
Subject Keywords:accretion, accretion disks; relativistic processes; X-rays: binaries; X-rays: individual (SWIFT J1910.2-0546)
Issue or Number:2
Record Number:CaltechAUTHORS:20140106-150444775
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Official Citation: SWIFT J1910.2-0546: A Possible Black Hole Binary with a Retrograde Spin or Truncated Disk R. C. Reis et al. 2013 ApJ 778 155
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:43234
Deposited By: Ruth Sustaita
Deposited On:06 Jan 2014 23:26
Last Modified:09 Mar 2020 13:19

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