Gamma-ray spectral variability of Cygnus X-1
作者:
M. L. McConnell,
K. Bennett,
H. Bloemen,
W. Collmar,
W. Hermsen,
L. Kuiper,
W. Paciesas,
B. Phlips,
J. Poutanen,
J. M. Ryan,
V. Scho¨nfelder,
H. Steinle,
A. W. Strong,
A. A. Zdziarski,
期刊:
AIP Conference Proceedings
(AIP Available online 1901)
卷期:
Volume 587,
issue 1
页码: 96-100
ISSN:0094-243X
年代: 1901
DOI:10.1063/1.1419379
出版商: AIP
数据来源: AIP
摘要:
We have used observations from CGRO to study the variation in the MeV emission of Cygnus X-1 between its low and high X-ray states. These data provide a measurement of the spectral variability above 1 MeV. The high state MeV spectrum is found to be much harder than that of the low state MeV spectrum. In particular, the power-law emission seen at hard X-ray energies in the high state spectrum (with a photon spectral index of 2.6) is found to extend out to at least 5 MeV, with no evidence for any cutoff. Here we present the data and describe our efforts to model both the low state and high state spectra using a hybrid thermal/nonthermal model in which the emission results from the Comptonization of an electron population that consists of both a thermal and nonthermal component. ©2001 American Institute of Physics.
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