Abstract

Galactic black hole binaries (GBHB) are among the most extreme astrophysical systems in the universe. Detailed studies of GBHBs promises insights into some of the most intriguing questions of modern era such as how far the general theory of relativity is valid in strong gravity regime and how does a black hole influence the evolution of its surrounding. Vast amount of observational data from various international observatories have provided wealth of information on black hole binaries. However, there are still many uncertainties regarding the radiation processes and the exact accretion geometry in the region close to the black hole during various spectral states. With many new observatories being launched in next couple of years, this is likely to be a new golden era for X-ray astronomy. Particularly, Astrosat, the upcoming Indian multi-wavelength astronomy mission, is likely to significantly enhance the understanding of black hole binaries. However, I will try to argue here that the additional data will qualitatively be the same as existing data; and that the measurement of X-ray polarization properties is one avenue which can provide completely new observational inputs necessary to get fundamentally new insights into the physics of black hole binaries.