Supermassive black hole formation at high redshifts

Observations of quasars at z>6 suggest the presence of supermassive black holes (SMBHs) of a few billion solar masses. The formation of such objects within a few hundred million years after the Big Bang presents a challenge for our understanding of early structure formation. I will discuss various black hole formation mechanisms and particularly focus on the direct collapse model which is emerged as the most promising way to assemble high redshift quasars. In this talk, I will discuss what are the typical masses of direct collapse black holes (DCBHs)? How abundant are they? I will show how realistic conditions influence the number density of DCBHs at z=6 and make their sites rare. I will also present ideas both from semi-analytical models and numerical simulations which may help in boosting the abundance of massive black hole seeds. Finally, I will discuss how to observationally constrain the BH seed formation models with present and future missions.