http://arxiv.org/abs/1705.07255
Using a series of high resolution hydrodynamical simulations we show that during the rapid growth of high redshift (z > 5) galaxies, reserves of molecular gas are consumed over a timescale of 300Myr; almost independent of feedback scheme. We find there exists no such simple relation for the total gas fractions of these galaxies, with little correlation between gas fractions and specific star formation rates. The bottleneck or limiting factor in the growth of early galaxies is in converting infalling gas to cold star forming gas. Thus we find that the majority of high redshift dwarf galaxies are effectively in recession, with demand (of star formation) never rising to meet supply (of gas), irrespective of the baryonic feedback physics modelled. We conclude that the basic assumption of self-regulation in galaxies – that they can adjust total gas consumption within a Hubble time – does not apply for the dwarf galaxies thought to be responsible for providing most UV photons to reionise the high redshift Universe. We demonstrate how this rapid molecular timescale improves agreement between semi-analytic model predictions of the early Universe and observed stellar mass functions.
A. Duffy, S. Mutch, G. Poole, et. al.
Tue, 23 May 17
38/68
Comments: 17 pages, 27 figures, accepted for publication in MNRAS
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