Abstract
We perform cosmological simulations of the intergalactic medium (IGM) at
redshift z ˜ 3 using the numerical gravity-hydrodynamics codes
GADGET-3 and ENZO for the purpose of modelling the gaseous environments
of galaxies. We identify haloes in the simulations using three different
algorithms. Different rank orderings of the haloes by mass result,
introducing a limiting factor, in identifying haloes with observed
galaxies. We also compare the physical properties of the gas between the
two codes, focusing primarily on the gas outside the virial radius,
motivated by recent H I absorption measurements of the gas around z
˜ 2-3 galaxies. The internal dispersion velocities of the gas in
the haloes have converged for a box size of 30 comoving Mpc, but the
centre-of-mass peculiar velocities of the haloes have not up to a box
size of 60 comoving Mpc. The density and temperature of the gas within
the instantaneous turn-around radii of the haloes are adequately
captured for box sizes of 30 Mpc on a side, but the results are highly
sensitive to the treatment of unresolved, rapidly cooling gas, with the
gas mass fraction within the virial radius severely depleted by star
formation in the GADGET-3 simulations. Convergence of the gas peculiar
velocity field on large scales requires a box size of at least 60 Mpc.
Outside the turn-around radius, the physical state of the gas agrees to
30 per cent or better both with box size and between simulation methods.
We conclude that generic IGM simulations make accurate predictions for
the intergalactic gas properties beyond the halo turn-around radii, but
the gas properties on smaller scales are highly dependent on star
formation and feedback implementations.
Original language | English |
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Pages (from-to) | 2462-2475 |
Number of pages | 14 |
Journal | Monthly Notices of the Royal Astronomical Society |
Volume | 445 |
Issue number | 3 |
Early online date | 20 Oct 2014 |
DOIs | |
Publication status | Published - 11 Dec 2014 |
Keywords
- methods: numerical
- galaxies: formation
- intergalactic medium
- large-scale structure of Universe