Bibcode
Crain, Robert A.; Theuns, Tom; Dalla Vecchia, C.; Eke, Vincent R.; Frenk, Carlos S.; Jenkins, Adrian; Kay, Scott T.; Peacock, John A.; Pearce, Frazer R.; Schaye, Joop; Springel, Volker; Thomas, Peter A.; White, Simon D. M.; Wiersma, Robert P. C.
Bibliographical reference
Monthly Notices of the Royal Astronomical Society, Volume 399, Issue 4, pp. 1773-1794.
Advertised on:
11
2009
Citations
242
Refereed citations
225
Description
We present the first results of hydrodynamical simulations that follow
the formation of galaxies to the present day in nearly spherical regions
of radius ~20h-1Mpc drawn from the Millennium Simulation
(Springel et al.). The regions have mean overdensities that deviate by
(-2, -1, 0, +1, +2)σ from the cosmic mean, where σ is the
rms mass fluctuation on a scale of ~20h-1Mpc at z = 1.5. The
simulations have mass resolution of up to
~106h-1Msolar, cover the entire range
of large-scale cosmological environments, including rare objects such as
massive clusters and sparse voids, and allow extrapolation of statistics
to the (500h-1Mpc)3 Millennium Simulation volume
as a whole. They include gas cooling, photoheating from an imposed
ionizing background, supernova feedback and galactic winds, but no AGN.
In this paper, we focus on the star formation properties of the model.
We find that the specific star formation rate density at z <~ 10
varies systematically from region to region by up to an order of
magnitude, but the global value, averaged over all volumes, closely
reproduces observational data. Massive, compact galaxies, similar to
those observed in the GOODS fields (Wiklind et al.), form in the
overdense regions as early as z = 6, but do not appear in the underdense
regions until z ~ 3. These environmental variations are not caused by a
dependence of the star formation properties on environment, but rather
by a strong variation of the halo mass function from one environment to
another, with more massive haloes forming preferentially in the denser
regions. At all epochs, stars form most efficiently in haloes of
circular velocity vc ~ 250kms-1. However, the star
formation history exhibits a form of `downsizing' (even in the absence
of AGN feedback): the stars comprising massive galaxies at z = 0 have
mostly formed by z = 1-2, whilst those comprising smaller galaxies
typically form at later times. However, additional feedback is required
to limit star formation in massive galaxies at late times.