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The spatial distribution of Milky Way satellites, gaps in streams, and the nature of dark matter

Lovell, MR, Cautun, M, Frenk, CS, Hellwing, WA and Newton, O (2021) The spatial distribution of Milky Way satellites, gaps in streams, and the nature of dark matter. Monthly Notices of the Royal Astronomical Society, 507 (4). pp. 4826-4839. ISSN 0035-8711

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The spatial distribution of Milky Way (MW) subhaloes provides an important set of observables for testing cosmological models. These include the radial distribution of luminous satellites, planar configurations, and the abundance of dark subhaloes whose existence or absence is key to distinguishing among dark matter models. We use the COCON-body simulations of cold dark matter (CDM) and 3.3 keV thermal relic warm dark matter (WDM) to predict the satellite spatial distribution in the limit that the impact of baryonic physics is minimal. We demonstrate that the radial distributions of CDM and 3.3 keV-WDM luminous satellites are identical if the minimum pre-infall halo mass to form a galaxy is >108.5 M⊙M⊙⁠. The distribution of dark subhaloes is significantly more concentrated in WDM due to the absence of low mass, recently accreted substructures that typically inhabit the outer parts of a MW halo in CDM. We show that subhaloes of mass [107, 108] M⊙M⊙ and within 30 kpc of the centre are the stripped remnants of larger haloes in both models. Therefore, their abundance in WDM is 3× higher than one would anticipate from the overall WDM subhalo population. We estimate that differences between CDM and WDM concentration–mass relations can be probed for subhalo–stream impact parameters <2 kpc. Finally, we find that the impact of WDM on planes of satellites is likely negligible. Comprehensive comparisons with observations will require further work with high resolution, self-consistent hydrodynamical simulations.

Item Type: Article
Additional Information: This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society ©: 2021 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
Q Science > QC Physics
Divisions: Astrophysics Research Institute
Publisher: Oxford University Press
Related URLs:
Date Deposited: 01 Apr 2022 09:14
Last Modified: 01 Apr 2022 09:15
DOI or Identification number: 10.1093/mnras/stab2452
URI: https://researchonline.ljmu.ac.uk/id/eprint/16571

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