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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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