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Title: NuSTAR and integral observations of a low/hard state of 1E1740.7-2942

The microquasar 1E1740.7-2942, also known as the 'Great Annihilator,' was observed by NuSTAR in the summer of 2012. We have analyzed in detail two observations taken ∼2 weeks apart, for which we measure hard and smooth spectra typical of the low/hard state. A few weeks later the source flux declined significantly. Nearly simultaneous coverage by INTEGRAL is available from its Galactic Center monitoring campaign lasting ∼2.5 months. These data probe the hard state spectrum from 1E1740.7-2942 before the flux decline. We find good agreement between the spectra taken with IBIS/ISGRI and NuSTAR, with the measurements being compatible with a change in flux with no spectral variability. We present a detailed analysis of the NuSTAR spectral and timing data and upper limits for reflection of the high energy emission. We show that the high energy spectrum of this X-ray binary is well described by thermal Comptonization.
Authors:
; ; ;  [1] ; ; ; ;  [2] ;  [3] ; ;  [4] ;  [5] ; ; ;  [6] ;  [7] ;  [8] ;  [9] ;  [10] ;  [11] more »; « less
  1. Istituto di Astrofisica e Planetologia Spaziali, INAF, via del Fosso del Cavaliere, I-00133 Roma (Italy)
  2. Space Sciences Laboratory, 7 Gauss Way, University of California, Berkeley, CA 94720-7450 (United States)
  3. Physics Department and Santa Cruz Institute for Particle Physics, University of California, Santa Cruz, CA 95064 (United States)
  4. Université de Toulouse, UPS-OMP, IRAP, Toulouse (France)
  5. DTU Space, National Space Institute, Technical University of Denmark, Elektrovej 327, DK-2800 Lyngby (Denmark)
  6. Cahill Center for Astronomy and Astrophysics, California Institute of Technology, Pasadena, CA 91125 (United States)
  7. Columbia Astrophysics Laboratory, Columbia University, New York, NY 10027 (United States)
  8. European Space Astronomy Centre (ESA/ESAC), Science Operations Department, E-28691 Villanueva de la Cañada (Madrid) (Spain)
  9. Department of Astronomy, University of Michigan, 500 Church Street, Ann Arbor, MI 48109 (United States)
  10. CRESST and NASA Goddard Space Flight Center, Astrophysics Science Division, Code 661, Greenbelt, MD 20771 (United States)
  11. Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 (United States)
Publication Date:
OSTI Identifier:
22348317
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; ACCRETION DISKS; BINARY STARS; BLACK HOLES; COSMIC X-RAY SOURCES; EMISSION; ENERGY SPECTRA; QUASARS; REFLECTION; X RADIATION