Journal Article

The angular momentum of gas in protogalaxies — II. The impact of pre-heating

Frank C. van den Bosch, Tom Abel and Lars Hernquist

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 346, issue 1, pages 177-185
Published in print November 2003 | ISSN: 0035-8711
Published online November 2003 | e-ISSN: 1365-2966 | DOI: http://dx.doi.org/10.1046/j.1365-2966.2003.07079.x
The angular momentum of gas in protogalaxies — II. The impact of pre-heating

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Abstract

We examine the effect of pre-heating of the intergalactic medium on galaxy formation using cosmological hydrodynamical simulations. By performing simulations both with and without a simple model for pre-heating, we analyse and compare the angular momentum distributions of the dark matter and the baryons. Pre-heating unbinds baryons from their dark-matter haloes, yielding a baryonic mass fraction that declines with decreasing halo mass. In addition, the spin parameter of the gas is reduced with respect to the case without pre-heating, while the misalignment between the angular momentum directions of the gas and dark matter increases strongly. The angular momentum distributions of individual haloes reveal that pre-heating decreases (increases) the mass fraction with low (negative) specific angular momentum. We discuss the implications of these findings for the formation of disc galaxies in a pre-heated intergalactic medium, and compare our results to the predictions of Maller & Dekel, who propose an alternative interpretation for the origin of the angular momentum of (proto)galaxies.

Keywords: galaxies: formation; galaxies: haloes; galaxies: structure; dark matter

Journal Article.  7592 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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