DR. MAYUKH PAHARI

The study of X-ray/optical correlated variability in the time-scale from millisecond to few tens of seconds, has been emerged as a powerful tool to probe accretion geometry in X-ray binaries. In this talk, the speaker shall discuss X-rays and optical properties of two of such systems that show rapid flaring as well as slow optical variations and how the correlated variabilities can be used to probe the nature of accretion flow around the regime where X-ray observations alone fails to provide clear understanding of the process. The speaker shall also discuss a simpler and powerful empirical method to determine the black hole spin in X-ray binaries. This method simply requires the accretion disk and coronal luminosity during thermal emission dominated accretion state to calculate the spin and it has been successfully tested for ten black hole X-ray binaries of known spin. Finally, he shall discuss some new results that he has obtained from the LAXPC detector on-board ASTROSAT satellite.