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Bent by baryons: the low-mass galaxy-halo relation

Sawala, T, Frenk, CS, Fattahi, A, Navarro, JF, Bower, RG, Crain, RA, Dalla Vecchia, C, Furlong, M, Jenkins, A, McCarthy, IG, Qu, Y, Schaller, M, Schaye, J and Theuns, T (2015) Bent by baryons: the low-mass galaxy-halo relation. Monthly Notices of the Royal Astronomical Society, 448 (3). pp. 2941-2947. ISSN 0035-8711

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The relation between galaxies and dark matter halos is of vital importance for evaluating theoretical predictions of structure formation and galaxy formation physics. We show that the widely used method of abundance matching based on dark matter only simulations fails at the low mass end because two of its underlying assumptions are broken: only a small fraction of low mass (< 109:5M�) halos host a visible galaxy, and halos grow at a lower rate due to the effect of baryons. In this regime, reliance on dark matter only simulations for abundance matching is neither accurate nor self-consistent. We find that the reported discrepancy between observational estimates of the halo masses of dwarf galaxies and the values predicted by abundance matching does not point to a failure of �CDM, but simply to a failure to account for baryonic effects. Our results also imply that the Local Group contains only a few hundred observable galaxies in contrast with the thousands of faint dwarfs that abundance matching would suggest. We show how relations derived from abundance matching can be corrected, so that they can be used self-consistently to calibrate models of galaxy formation.

Keywords: cosmology: theory, galaxies: formation, galaxies: evolution, galaxies: mass functions, methods: N-body simulations

Item Type: Article
Additional Information: This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society ©: 2015 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved
Uncontrolled Keywords: 0201 Astronomical And Space Sciences
Subjects: Q Science > QB Astronomy
Divisions: Astrophysics Research Institute
Publisher: Oxford University Press
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Date Deposited: 28 Oct 2015 14:16
Last Modified: 04 Sep 2021 14:16
DOI or ID number: 10.1093/mnras/stu2753
URI: https://researchonline.ljmu.ac.uk/id/eprint/1459

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