NEW CONSTRAINTS ON THE BLACK HOLE LOW/HARD STATE INNER ACCRETION FLOW WITH NuSTAR
- Department of Astronomy, University of Michigan, 500 Church Street, Ann Arbor, MI 48109-1042 (United States)
- Space Sciences Laboratory, University of California, Berkeley, CA 94720 (United States)
- Universite de Toulouse, UPS-OMP, IRAP, F-31100 Toulouse (France)
- Department of Astronomy and Physics, Saint Mary's University, Halifax, NS. B3H 3C3 (Canada)
- Danish Technical University, DK-2800, Lyngby (Denmark)
- Lawrence Livermore National Laboratory, Livermore CA (United States)
- Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 OHA (United Kingdom)
- Cahill Center for Astronomy and Astrophysics, California Institute of Technology, Pasadena, CA 91125 (United States)
- Columbia University, New York, NY 10027 (United States)
- Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109 (United States)
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{sub −2}{sup +7} GM/c{sup 2} and h = 18 ± 4 GM/c {sup 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{sub in}=5{sub −4}{sup +3} GM/c{sup 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.
- OSTI ID:
- 22364439
- Journal Information:
- Astrophysical Journal Letters, Vol. 799, Issue 1; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 2041-8205
- Country of Publication:
- United States
- Language:
- English
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