Hard X-ray spectra of some X-ray binaries from balloon-borne observations.
Abstract
The authors have studied X-ray binaries 4U 1907+09, GX 1+4 and Cygnus X-1 in the energy range 20 - 100 keV, using balloon-borne xenon-filled multi-layer proportional counters flown from Hyderabad, India. X-ray binary 4U 1907+09 was observed in 1985 and 1991. During 1985 the source was detected above 20 keV at a significance level of 13 σ and was only marginally detected in 1991, indicating that the flux was four times lower than that on the first occasion. GX 1+4 was observed in December 1991 and April 1992. The source showed a factor of two decrease in flux during the two observations. Hard X-ray spectra obtained on two occasions are found to be consistent with spectrum obtained from HEXE experiment on board Kvant module. Cygnus X-1 was observed on several occasions from 1984 to 1992. There is an indication of QPO in April 1992 Cyg X-1 observations.
- Publication:
-
Bulletin of the Astronomical Society of India
- Pub Date:
- September 1993
- Bibcode:
- 1993BASI...21..555C
- Keywords:
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- Balloon-Borne Instruments;
- Cyclotron Radiation;
- Energy Spectra;
- X Ray Astronomy;
- X Ray Binaries;
- X Ray Spectra;
- Data Correlation;
- Data Reduction;
- Light Curve;
- Spectrum Analysis;
- Astronomy