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| Paper: |
Fragmentation of Accretion Streams into the First Galaxies |
| Volume: |
432, New Horizons in Astronomy: Frank N. Bash Symposium 2009 |
| Page: |
249 |
| Authors: |
Safranek-Shrader, C.; Bromm, V.; Milosavljević |
| Abstract: |
Motivated by recent simulations of galaxy formation in which protogalaxies
acquire their baryonic content through filamentary accretion streams,
we study the gravitational fragmentation of gas flowing into a typical first galaxy.
Our idealized one-zone model computes the post-shock thermal evolution of accretion
streams flowing into a 108M DM halo at z = 10. We find there to be a
sharp drop in the fragmentation mass scale from roughly 105M to 1M when
the accreting gas rises above a metallicity of 10-4.5 Z due to the increased cooling
metals provide, assuming there is a Lyman-Werner background of sufficient
strength to disassociate molecular species (H2 and HD). If molecules are able
to form they will dominate the cooling and degree of metallicity does not affect
the fate of the gas. This simplified model identifies the key physical processes
and sets the stage for more complex simulations on this important epoch of star
formation. |
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