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Self-interacting dark matter scattering rates through cosmic time.

Robertson, A. and Massey, R. and Eke, V. and Bower, R. (2015) 'Self-interacting dark matter scattering rates through cosmic time.', Monthly notices of the Royal Astronomical Society., 453 (3). pp. 2267-2276.


We estimate the rate of dark matter scattering in collapsed structures throughout the history of the Universe. If the scattering cross-section is velocity independent, then the canonical picture is correct that scatterings occur mainly at late times. The scattering rate peaks slightly at redshift z ∼ 6, and remains significant today. Half the scatterings occur after z ∼ 1, in structures more massive than 1012 M⊙. Within a factor of 2, these numbers are robust to changes in the assumed astrophysics, and the scatterings would be captured in cosmological simulations. However, for particle physics models with a velocity-dependent cross-section (as for Yukawa potential interactions via a massive mediator), the scattering rate peaks before z ∼ 20, in objects with mass ≲104 M⊙. These precise values are sensitive to the redshift-dependent mass–concentration relation and the small-scale cut-off in the matter power spectrum. In extreme cases, the qualitative effect of early interactions may be reminiscent of warm dark matter and strongly affect the subsequent growth of structure. However, these scatterings are being missed in existing cosmological simulations with limited mass resolution.

Item Type:Article
Keywords:Astroparticle physics, Galaxies: haloes, Dark matter.
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Publisher statement: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.
Date accepted:No date available
Date deposited:16 February 2016
Date of first online publication:November 2015
Date first made open access:No date available

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