THE FORMATION OF SUPERMASSIVE BLACK HOLES FROM LOW-MASS POP III SEEDS

The existence of 10(9) M-circle dot black holes (BHs) in massive galaxies by z similar to 7 is one of the great unsolved mysteries in cosmological structure formation. One theory argues that they originate from the BHs of Pop III stars at z similar to 20 and then accrete at the Eddington limit down to the epoch of reionization, which requires that they have constant access to rich supplies of fuel. Because early numerical simulations suggested that Pop III stars were greater than or similar to 100 M-circle dot, the supermassive black hole (SMBH) seeds considered up to now were 100-300 M-circle dot. However, there is a growing numerical and observational consensus that some Pop III stars were tens of solar masses, not hundreds, and that 20-40 M-circle dot BHs may have been much more plentiful at high redshift. However, we find that natal kicks imparted to 20-40 M-circle dot Pop III BHs during formation eject them from their halos and hence their fuel supply, precluding them from Eddington-limit growth. Consequently, SMBHs are far less likely to form from low-mass Pop III stars than from very massive ones.