Formation of the First Supermassive Black Holes

We consider the physical conditions under which supermassive black holescould have formed inside the first galaxies. Our SPH simulations indicate thatmetal-free galaxies with a virial temperature ~10^4 K and with suppressed H2formation (due to an intergalactic UV background) tend to form a binary blackhole system which contains a substantial fraction (>10%) of the total baryonicmass of the host galaxy. Fragmentation into stars is suppressed withoutsubstantial H2 cooling. Our simulations follow the condensation of ~5x10^6M_sun around the two centers of the binary down to a scale of < 0.1pc. Low-spingalaxies form a single black hole instead. These early black holes lead toquasar activity before the epoch of reionization. Primordial black holebinaries lead to the emission of gravitational radiation at redshifts z>10 thatwould be detectable by LISA.Comment: 11 pages, 9 figures, revised version, ApJ in press (October 10, 2003