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The properties of warm dark matter haloes

Lovell, Mark R.; Frenk, Carlos S.; Eke, Vince R.; Jenkins, Adrian; Gao, Liang; Theuns, Tom

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Authors

Liang Gao



Abstract

Well-motivated elementary particle candidates for the dark matter, such as the sterile neutrino, behave as warm dark matter (WDM). For particle masses of the order of a keV, free streaming produces a cutoff in the linear fluctuation power spectrum at a scale corresponding to dwarf galaxies. We investigate the abundance and structure of WDM haloes and subhaloes on these scales using high resolution cosmological N-body simulations of galactic haloes of mass similar to the Milky Way's. On scales larger than the free-streaming cutoff, the initial conditions have the same power spectrum and phases as one of the cold dark matter (CDM) haloes previously simulated by Springel et al. as part of the Virgo consortium Aquarius project. We have simulated four haloes with WDM particle masses in the range 1.5–2.3 keV and, for one case, we have carried out further simulations at varying resolution. N-body simulations in which the power spectrum cutoff is resolved are known to undergo artificial fragmentation in filaments producing spurious clumps which, for small masses (<107 M⊙ in our case) outnumber genuine haloes. We have developed a robust algorithm to identify these spurious objects and remove them from our halo catalogues. We find that the WDM subhalo mass function is suppressed by well over an order magnitude relative to the CDM case for masses <109 M⊙. Requiring that there should be at least as many subhaloes as there are observed satellites in the Milky Way leads to a conservative lower limit to the (thermal equivalent) WDM particle mass of ∼ 1.5 keV. WDM haloes and subhaloes have cuspy density distributions that are well described by Navarro–Frenk–White or Einasto profiles. Their central densities are lower for lower WDM particle masses and none of the models we have considered suffering from the ‘too big to fail’ problem recently highlighted by Boylan-Kolchin et al.

Citation

Lovell, M. R., Frenk, C. S., Eke, V. R., Jenkins, A., Gao, L., & Theuns, T. (2014). The properties of warm dark matter haloes. Monthly Notices of the Royal Astronomical Society, 439(1), 300-317. https://doi.org/10.1093/mnras/stt2431

Journal Article Type Article
Acceptance Date Dec 13, 2013
Online Publication Date Feb 5, 2014
Publication Date Mar 21, 2014
Deposit Date Apr 4, 2014
Publicly Available Date Apr 8, 2014
Journal Monthly Notices of the Royal Astronomical Society
Print ISSN 0035-8711
Electronic ISSN 1365-2966
Publisher Royal Astronomical Society
Peer Reviewed Peer Reviewed
Volume 439
Issue 1
Pages 300-317
DOI https://doi.org/10.1093/mnras/stt2431
Keywords Galaxies, Dwarf, Dark matter.
Public URL https://durham-repository.worktribe.com/output/1434957

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Copyright Statement
This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society © 2014 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.






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