  The first primitive galaxies formed from accretion and mergers by z ~ 15, and
were primarily responsible for cosmological reionization and the chemical
enrichment of the early cosmos. But a few of these galaxies may have formed in
the presence of strong Lyman-Werner UV fluxes that sterilized them of H_2,
preventing them from forming stars or expelling heavy elements into the IGM
prior to assembly. At masses of 10^8 Ms and virial temperatures of 10^4 K,
these halos began to rapidly cool by atomic lines, perhaps forming 10^4 - 10^6
Ms Pop III stars and, later, the seeds of supermassive black holes. We have
modeled the explosion of a supermassive Pop III star in the dense core of a
line-cooled protogalaxy with the ZEUS-MP code. We find that the supernova (SN)
expands to a radius of ~ 1 kpc, briefly engulfing the entire galaxy, but then
collapses back into the potential well of the dark matter. Fallback fully mixes
the interior of the protogalaxy with metals, igniting a violent starburst and
fueling the rapid growth of a massive black hole at its center. The starburst
would populate the protogalaxy with stars in greater numbers and at higher
metallicities than in more slowly-evolving, nearby halos. The SN remnant
becomes a strong synchrotron source that can be observed with eVLA and eMERLIN
and has a unique signature that easily distinguishes it from less energetic SN
remnants. Such explosions, and their attendant starbursts, may well have marked
the birthplaces of supermassive black holes on the sky.
