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Title: The reflection component from Cygnus X-1 in the soft state measured by NuSTAR and Suzaku

The black hole binary Cygnus X-1 was observed in late 2012 with the Nuclear Spectroscopic Telescope Array (NuSTAR) and Suzaku, providing spectral coverage over the ∼1-300 keV range. The source was in the soft state with a multi-temperature blackbody, power law, and reflection components along with absorption from highly ionized material in the system. The high throughput of NuSTAR allows for a very high quality measurement of the complex iron line region as well as the rest of the reflection component. The iron line is clearly broadened and is well described by a relativistic blurring model, providing an opportunity to constrain the black hole spin. Although the spin constraint depends somewhat on which continuum model is used, we obtain a {sub *} > 0.83 for all models that provide a good description of the spectrum. However, none of our spectral fits give a disk inclination that is consistent with the most recently reported binary values for Cyg X-1. This may indicate that there is a >13° misalignment between the orbital plane and the inner accretion disk (i.e., a warped accretion disk) or that there is missing physics in the spectral models.
Authors:
; ;  [1] ;  [2] ; ;  [3] ; ;  [4] ; ; ; ; ;  [5] ; ;  [6] ;  [7] ;  [8] ;  [9] ;  [10] ;  [11] more »; « less
  1. Space Sciences Laboratory, 7 Gauss Way, University of California, Berkeley, CA 94720-7450 (United States)
  2. Massachusetts Institute of Technology, Kavli Institute for Astrophysics, Cambridge, MA 02139 (United States)
  3. Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA (United Kingdom)
  4. Department of Astronomy, University of Michigan, 500 Church Street, Ann Arbor, MI 48109 (United States)
  5. Cahill Center for Astronomy and Astrophysics, California Institute of Technology, Pasadena, CA 91125 (United States)
  6. Université de Toulouse, UPS-OMP, IRAP, F-31400 Toulouse (France)
  7. DTU Space, National Space Institute, Technical University of Denmark, Elektrovej 327, DK-2800 Lyngby (Denmark)
  8. Columbia Astrophysics Laboratory, Columbia University, New York, NY 10027 (United States)
  9. Istituto Nazionale di Astrofisica, INAF-IAPS, via del Fosso del Cavaliere, I-00133 Roma (Italy)
  10. CRESST and NASA Goddard Space Flight Center, Astrophysics Science Division, Code 661, Greenbelt, MD 20771 (United States)
  11. Physics Department, College of the Holy Cross, Worcester, MA 01610 (United States)
Publication Date:
OSTI Identifier:
22348293
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 780; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ABSORPTION; ACCRETION DISKS; BLACK HOLES; INCLINATION; IRON; KEV RANGE; LIMITING VALUES; REFLECTION; RELATIVISTIC RANGE; SPECTRA; SPIN; STARS; TELESCOPES; X RADIATION