|Physical Research Laboratory
|Conference ID :
|AstroSat CZTI as a sub-MeV spectrometer: hard X-ray spectral states in Cygnus X-1
|Abhay kumar, Santosh vadawale, Tanmoy chattopadhyay, A.R. Rao , CZTI team
|Abstract Category :
|Instrumentation and Techniques
|We explore the utility of the AstroSat CZTI instrument for spectroscopy above 100 keV using the Compton scattered double events in the pixelated CZT detectors. The background selection and subtraction techniques are refined and we get consistent hard X-ray flux and spectral index for Crab. We extend this method to investigate the different hard X-ray spectral states in the Galactic black hole source Cygnus X-1. For this we measure the flux and spectral index in two energy bands (30 - 100 keV and 100 - 380 keV), variability in hard X-rays and short term spectral and flux correlation index. We could identify distinct accretion modes in the source based on the hard X-ray data, consistent with the recent INTEGRAL results. We investigate the implications of these results to understand the accretion disk and coronal geometry in this source.