THE BIGGEST EXPLOSIONS IN THE UNIVERSE. II.
One of the leading contenders for the origin of supermassive black holes (SMBHs) at z ≳ 7 is catastrophic baryon collapse in atomically cooled halos at z ∼ 15. In this scenario, a few protogalaxies form in the presence of strong Lyman–Werner UV backgrounds that quench H2 formation in their constituent halos, preventing them from forming stars or blowing heavy elements into the intergalactic medium prior to formation. At masses of 108 M☉ and virial temperatures of 104 K, gas in these halos rapidly cools by H lines, in some cases forming 104–106 M☉ Population III stars and, a short time later, the seeds of SMBHs. Instead of collapsing directly to black holes (BHs), some of these stars died in the most energetic thermonuclear explosions in the universe. We have modeled the explosions of such stars in the dense cores of line-cooled protogalaxies in the presence of cosmological flows. In stark contrast to the explosions in diffuse regions in previous simulations, these supernovae briefly engulf the protogalaxy, but then collapse back into its dark matter potential. Fallback drives turbulence that efficiently distributes metals throughout the interior of the halo and fuels the rapid growth of nascent BHs at its center. The accompanying starburst and X-ray emission from these line-cooled galaxies easily distinguish them from more slowly evolving neighbors and might reveal the birthplaces of SMBHs on the sky.