Astronomy and Astrophysics – Astronomy
Scientific paper
Dec 1991
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1991apj...383..263u&link_type=abstract
Astrophysical Journal, Part 1 (ISSN 0004-637X), vol. 383, Dec. 10, 1991, p. 263-268. Research supported by CNR.
Astronomy and Astrophysics
Astronomy
11
Black Holes (Astronomy), Crab Nebula, Gamma Rays, Pulsars, Stellar Spectra, X Ray Binaries, Gamma Ray Spectrometers, Radiant Flux Density, X Ray Astronomy, X Ray Spectra, X Ray Telescopes
Scientific paper
Results are reported of observations of the black hole candidate Cygnus X-1 at a low flux level on August 5, 1985, with the POKER experiment in the hard X-ray range (15-120 keV). During the same flight the Crab Nebula was also observed as an in-flight calibration source, and the spectral results are reported. The measurement shows a low flux from Cygnus X-1, at a level between the ones reported as gamma-1 and gamma-2 during 1979 observations. The photon spectrum is well described by a single power law, with a photon index of 1.87 and an intensity of 0.00257 photons/sq cm s keV at 50 keV, corresponding to 1.11 Crab. The low hard X-ray flux of the POKER observations is well matched at lower energies with Exosat data collected on August 12, 1985. Applying the model of Sunyaev and Titarchuk (1980) to an accretion disk surrounding a black hole, the emission from a few keV up to the MeV region is consistent with a single temperature Comptonized spectrum.
Bazzano Angela
Kendziorra Eckhard
La Padula C.
Manchanda Ravi K.
Perotti Federico
No associations
LandOfFree
Low-flux hard X-ray observation of Cygnus X-1 does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Low-flux hard X-ray observation of Cygnus X-1, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Low-flux hard X-ray observation of Cygnus X-1 will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-1536726