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Title

Galaxies-intergalactic medium interaction calculation I: galaxy formation as a function of large-scale environment

Author(s)

Crain, Robert A.;  Theuns, Tom;  Dalla Vecchia, Claudio;  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.

Abstract

We present the first results of hydrodynamical simulations that follow the formation of galaxies to the present day in nearly spherical regions of radius ~ 20 h^-1 Mpc/h 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 ~ 20 h^-1 Mpc/h at z = 1.5. The simulations have mass resolution of up to ~ 10^6 M sun/h, 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 (500 h^-1 Mpc)^3 Millennium Simulation volume as a whole. They include gas cooling, photoheating from an imposed ionising 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 ~ 250 km s^-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.

Publication type

Journal article

Research centre

Swinburne University of Technology. Faculty of Information and Communication Technologies. Centre for Astrophysics and Supercomputing

Source

Monthly Notices of the Royal Astronomical Society, Vol. 399, no. 4, pp. 1773-1794

Publication year

2009

FOR Code(s)

0201 Astronomical and Space Sciences;  020103 Cosmology and Extragalactic Astronomy

Keyword(s)

Abundances;  Cosmology;  Galaxy clusters;  Galaxy formation;  GOODS;  Intergalactic medium;  Millennium Simulation;  N-body simulation methods

Publisher

Wiley-Blackwell

ISSN

0035-8711

Publisher URL

http://dx.doi.org/10.1111/j.1365-2966.2009.15402.x

Copyright

Copyright © 2009 The Authors. Journal compilation copyright © 2009 Royal Astronomical Society. Author version of the paper reproduced here in accordance with the copyright policy of the publisher. The definitive version is available at www.interscience.wiley.com.

Full text

Peer reviewed