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New Constraints on the Black Hole Low/Hard State Inner Accretion Flow with NuSTAR

Miller, J. M. and Tomsick, J. A. and Bachetti, M. and Wilkins, D. and Boggs, S. E. and Christensen, F. E. and Craig, W. W. and Fabian, A. C. and Grefenstette, B. W. and Hailey, C. J. and Harrison, F. A. and Kara, E. and King, A. L. and Stern, D. K. and Zhang, W. W. (2015) New Constraints on the Black Hole Low/Hard State Inner Accretion Flow with NuSTAR. Astrophysical Journal Letters, 799 (1). Art. No. L6. ISSN 2041-8205. doi:10.1088/2041-8205/799/1/L6.

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We report on an observation of the Galactic black hole candidate GRS 1739–278 during its 2014 outburst, obtained with NuSTAR. The source was captured at the peak of a rising "low/hard" state, at a flux of ~0.3 Crab. A broad, skewed iron line and disk reflection spectrum are revealed. Fits to the sensitive NuSTAR spectra with a number of relativistically blurred disk reflection models yield strong geometrical constraints on the disk and hard X-ray "corona." Two models that explicitly assume a "lamp post" corona find its base to have a vertical height above the black hole of h = 5^(+7)_(-2) (GM)/c^(2) and h = 18 ± 4 GM/c ^2(90% confidence errors); models that do not assume a "lamp post" return emissivity profiles that are broadly consistent with coronae of this size. Given that X-ray microlensing studies of quasars and reverberation lags in Seyferts find similarly compact coronae, observations may now signal that compact coronae are fundamental across the black hole mass scale. All of the models fit to GRS 1739–278 find that the accretion disk extends very close to the black hole—the least stringent constraint is r_(in) = 5^(+3)_(-4) GM/c^(2). Only two of the models deliver meaningful spin constraints, but a = 0.8 ± 0.2 is consistent with all of the fits. Overall, the data provide especially compelling evidence of an association between compact hard X-ray coronae and the base of relativistic radio jets in black holes.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Tomsick, J. A.0000-0001-5506-9855
Bachetti, M.0000-0002-4576-9337
Boggs, S. E.0000-0001-9567-4224
Christensen, F. E.0000-0001-5679-1946
Fabian, A. C.0000-0002-9378-4072
Grefenstette, B. W.0000-0002-1984-2932
Harrison, F. A.0000-0003-2992-8024
Kara, E.0000-0003-0172-0854
Stern, D. K.0000-0003-2686-9241
Zhang, W. W.0000-0002-1426-9698
Additional Information:© 2015 American Astronomical Society. Received 2014 September 2; accepted 2014 November 5; published 2015 January 19. J.M.M. thanks Javier Garcia and Thomas Dauser for helpful conversations. 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.
Group:NuSTAR, Space Radiation Laboratory
Funding AgencyGrant Number
Subject Keywords:accretion, accretion disks; black hole physics
Other Numbering System:
Other Numbering System NameOther Numbering System ID
Space Radiation Laboratory2015-87
Issue or Number:1
Record Number:CaltechAUTHORS:20150219-092157983
Persistent URL:
Official Citation:New Constraints on the Black Hole Low/Hard State Inner Accretion Flow with NuSTAR J. M. Miller et al. 2015 ApJ 799 L6
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:54996
Deposited By: Ruth Sustaita
Deposited On:19 Feb 2015 18:03
Last Modified:10 Nov 2021 20:40

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