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

Sawala, T and Frenk, CS and Fattahi, A and Navarro, JF and Bower, RG and Crain, RA and Dalla Vecchia, C and Furlong, M and Jenkins, A and McCarthy, IG and Qu, Y and Schaller, M and 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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Abstract

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.

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

Item Type: Article
Additional Information: This is a pre-copyedited, author-produced PDF of an article accepted for publication in Monthly Notices of the Royal Astronomical Society following peer review. The version of record MNRAS (April 11, 2015) 448 (3): 2941-2947. is available online at: http://dx.doi.org/10.1093/mnras/stu2753
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: 02 Jun 2015 12:36
Last Modified: 07 Sep 2017 15:12
DOI or Identification number: 10.1093/mnras/stu2753
URI: http://researchonline.ljmu.ac.uk/id/eprint/697

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