Abstract
Supermassive primordial stars are expected to form in a small fraction of
massive protogalaxies in the early universe, and are generally conceived of as
the progenitors of the seeds of supermassive black holes (BHs) at high
redshift. Supermassive stars with masses of \~ 55,000 M\_Sun, however, have been
found to explode and completely disrupt in a supernova (SN) with an energy of
up to \~ 10^55 erg, instead of collapsing to a BH. Such events, roughly 10,000
times more energetic than typical SNe today, would be among the biggest
explosions in the history of the universe. We carry out a simulation of such a
supermassive star SN in two stages. Using the RAGE radiation hydrodynamics code
we first evolve the explosion from the earliest stages, through the breakout of
the shock from the surface of the star until the blast wave has propagated out
to several parsecs from the explosion site, which lies deep within an atomic
cooling dark matter (DM) halo at z \~ 15. Then, using the GADGET cosmological
hydrodynamics code we evolve the explosion out to several kiloparsecs from the
explosion site, far into the low-density intergalactic medium. The host DM
halo, with a total mass of 4 x 10^7 M\_Sun, much more massive than typical
primordial star-forming halos, is completely evacuated of high density gas
after < 10 Myr, although dense metal-enriched gas recollapses into the halo,
where it will likely form second-generation stars after > 70 Myr. The \~ 20,000
M\_Sun in metals that are released in the explosion are widely distributed, and
enrich the dense recollapsing gas to an average metallicity of \~ 0.05 Z\_Sun.
Such a high level of enrichment suggests that the chemical signature of these
supermassive star explosions may have been missed in previous surveys of
metal-poor stars.
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