Formation of the first supermassive black holes

We consider the physical conditions under which supermassive black holes could have formed inside the first galaxies. Our smoothed particle hydrodynamics simulations indicate that metal-free galaxies with a virial temperature of similar to10(4) K and suppressed H-2 formation (due to an intergalactic UV background) tend to form a binary black hole system that contains a substantial fraction (greater than or similar to10%) of the total baryonic mass of the host galaxy. Fragmentation into stars is suppressed without substantial H-2 cooling. Our simulations follow the condensation of similar to5 x 10(6) M-circle dot around the two centers of the binary down to a scale of less than or similar to0.1 pc. Low-spin galaxies form a single black hole instead. These early black holes lead to quasar activity before the epoch of reionization. Primordial black hole binaries lead to gravitational radiation emission at redshifts z greater than or similar to 10 that would be detectable by Laser Interferometer Space Antenna.