Rapid X-Ray variability of CYG X-1

Abstract

The black hole binary Cygnus X-1 was observed with the Indian X-ray Astronomy Experiment (IXAE) aboard the Indian Satellite IRS-P3 launched on 1996, March 21. The observations were made in 2-18 keV band with three pointed mode proportional counters with a total effective area of 1200 sq cm and field of view of 2.3 by 2.3 degree. Cyg X-1 was observed in the pointed mode first during 1996, May 2-9 period and detected at a count rate of about 500 counts per sec. To study intensity variations on different time scales, observations were made with time resolution ranging from 0.4 ms to 1 second. Pronounced intensity variation and flaring were detected onsecond and longer time scales. A search for quasi-periodic oscillations (QPO) was also made. Details of the results on variability on different time scales, flaring characteristics, etc. will be presented and discussed in terms of the current models of Cyg X-1.