Abstract
We examine the global H I properties of galaxies in quarter billion
particle cosmological simulations using GADGET-2, focusing on how
galactic outflows impact H I content. We consider four outflow models,
including a new one (ezw) motivated by recent interstellar medium
simulations in which the wind speed and mass loading factor scale as
expected for momentum-driven outflows for larger galaxies and
energy-driven outflows for dwarfs (σ <75 km s-1).
To obtain predicted H I masses, we employ a simple but effective local
correction for particle self-shielding and an observationally
constrained transition from neutral to molecular hydrogen. Our ezw
simulation produces an H I mass function whose faint-end slope of -1.3
agrees well with observations from the Arecibo Fast Legacy ALFA survey;
other models agree less well. Satellite galaxies have a bimodal
distribution in H I fraction versus halo mass, with smaller satellites
and/or those in larger haloes more often being H I deficient. At a given
stellar mass, H I content correlates with the star formation rate and
inversely correlates with metallicity, as expected if driven by
stochasticity in the accretion rate. To higher redshifts, massive H I
galaxies disappear and the mass function steepens. The global cosmic H I
density conspires to remain fairly constant from z ˜ 5 → 0,
but the relative contribution from smaller galaxies increases with
redshift.
Original language | English |
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Pages (from-to) | 2645-2663 |
Journal | Monthly Notices of the Royal Astronomical Society |
Volume | 434 |
Issue number | 3 |
DOIs | |
Publication status | Published - 1 Aug 2013 |
Keywords / Materials (for Non-textual outputs)
- ISM: atoms
- galaxies: abundances
- galaxies: evolution
- galaxies: formation
- galaxies: ISM