1. Nustar and integral observations of a low/hard state of 1E1740.7-2942
- Author
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Natalucci, L, Tomsick, JA, Bazzano, A, Smith, DM, Bachetti, M, Barret, D, Boggs, SE, Christensen, FE, Craig, WW, Fiocchi, M, Fürst, F, Grefenstette, BW, Hailey, CJ, Harrison, FA, Krivonos, R, Kuulkers, E, Miller, JM, Pottschmidt, K, Stern, D, Ubertini, P, Walton, DJ, and Zhang, WW
- Subjects
accretion ,accretion disks ,black hole physics ,X-rays: binaries ,X-rays: individual ,astro-ph.HE ,accretion ,accretion disks ,Astronomy & Astrophysics ,Astronomical and Space Sciences ,Atomic ,Molecular ,Nuclear ,Particle and Plasma Physics ,Physical Chemistry ,Atomic ,Molecular ,Nuclear ,Particle and Plasma Physics ,Physical Chemistry (incl. Structural) - Abstract
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. © 2014. The American Astronomical Society. All rights reserved.
- Published
- 2014