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arXiv · 2205.02243

Cosmological simulations with rare and frequent dark matter self-interactions

Moritz S. Fischer·Marcus Brüggen·Kai Schmidt-Hoberg·Klaus Dolag·Felix Kahlhoefer·Antonio Ragagnin·Andrew Robertson
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Abstract

Dark matter (DM) with self-interactions is a promising solution for the small-scale problems of the standard cosmological model. Here we perform the first cosmological simulation of frequent DM self-interactions, corresponding to small-angle DM scatterings. The focus of our analysis lies in finding and understanding differences to the traditionally assumed rare DM (large-angle) self scatterings. For this purpose, we compute the distribution of DM densities, the matter power spectrum, the two-point correlation function and the halo and subhalo mass functions. Furthermore, we investigate the density profiles of the DM haloes and their shapes. We find that overall large-angle and small-angle scatterings behave fairly similarly with a few exceptions. In particular, the number of satellites is considerably suppressed for frequent compared to rare self-interactions with the same cross-section. Overall we observe that while differences between the two cases may be difficult to establish using a single measure, the degeneracy may be broken through a combination of multiple ones. For instance, the combination of satellite counts with halo density or shape profiles could allow discriminating between rare and frequent self-interactions. As a by-product of our analysis, we provide - for the first time - upper limits on the cross-section for frequent self-interactions.

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Moritz S. Fischer, Marcus Brüggen, Kai Schmidt-Hoberg, Klaus Dolag, Felix Kahlhoefer, Antonio Ragagnin, Andrew Robertson. 2022-09-05. Cosmological simulations with rare and frequent dark matter self-interactions. https://doi.org/10.1093/mnras%2Fstac2207

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