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NuSTAR Spectroscopy of GRS 1915+105: Disk Reflection, Spin, and Connections to Jets

Miller, J. M. and Parker, M. L. and Fuerst, F. and Bachetti, M. and Harrison, F. A. and Barret, D. and Boggs, S. E. and Chakrabarty, D. and Christensen, F. E. and Craig, W. W. and Fabian, A. C. and Grefenstette, B. W. and Hailey, C. J. and King, A. L. and Stern, D. K. and Tomsick, J. A. and Walton, D. J. and Zhang, W. W. (2013) NuSTAR Spectroscopy of GRS 1915+105: Disk Reflection, Spin, and Connections to Jets. Astrophysical Journal Letters, 775 (2). Art. No. L45. ISSN 2041-8205. http://resolver.caltech.edu/CaltechAUTHORS:20131017-133805051

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Abstract

We report on the results of spectral fits made to a NuSTAR observation of the black hole GRS 1915+105 in a "plateau" state. This state is of special interest because it is similar to the "low/hard" state seen in other black holes, especially in that compact, steady jets are launched in this phase. The 3–79 keV bandpass of NuSTAR, and its ability to obtain moderate-resolution spectra free from distortions such as photon pile-up, are extremely well suited to studies of disk reflection in X-ray binaries. In only 15 ks of net exposure, an extraordinarily sensitive spectrum of GRS 1915+105 was measured across the full bandpass. Ionized reflection from a disk around a rapidly spinning black hole is clearly required to fit the spectra; even hybrid Comptonization models including ionized reflection from a disk around a Schwarzschild black hole proved inadequate. A spin parameter of a = 0.98 ± 0.01 (1σ statistical error) is measured via the best-fit model; low spins are ruled out at a high level of confidence. This result suggests that jets can be launched from a disk extending to the innermost stable circular orbit. A very steep inner disk emissivity profile is also measured, consistent with models of compact coronae above Kerr black holes. These results support an emerging association between the hard X-ray corona and the base of the relativistic jet.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1088/2041-8205/775/2/L45DOIArticle
http://iopscience.iop.org/2041-8205/775/2/L45/PublisherArticle
http://arxiv.org/abs/1308.4669arXivDiscussion Paper
ORCID:
AuthorORCID
Bachetti, M.0000-0002-4576-9337
Harrison, F. A.0000-0003-2992-8024
Boggs, S. E.0000-0001-9567-4224
Stern, D. K.0000-0003-2686-9241
Additional Information:© 2013 American Astronomical Society. Received 2013 July 26; accepted 2013 August 16; published 2013 September 18. This work was supported under NASA contract No. NNG08FD60C, and made use of data from the NuSTAR mission, a project led by the California Institute of Technology, managed by the Jet Propulsion Laboratory, and funded by NASA. J.M.M. thanks Sergei Trushkin for communicating radio results.
Group:NuSTAR, Space Radiation Laboratory
Funders:
Funding AgencyGrant Number
NASANNG08FD60C
NASA/JPL/CaltechUNSPECIFIED
Subject Keywords:accretion, accretion disks; black hole physics; gravitation; relativistic processes; X-rays: binaries
Record Number:CaltechAUTHORS:20131017-133805051
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:20131017-133805051
Official Citation:NuSTAR Spectroscopy of GRS 1915+105: Disk Reflection, Spin, and Connections to Jets J. M. Miller et al. 2013 ApJ 775 L45
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:41975
Collection:CaltechAUTHORS
Deposited By: Jason Perez
Deposited On:21 Oct 2013 18:10
Last Modified:02 Oct 2017 20:13

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