Core formation from self-heating dark matter

Abstract

Cosmological simulations of the $\Lambda$CDM model suggest that the dark matter halos of dwarf galaxies are denser in their center than what observational data of such galaxies imply. In this letter, we propose a novel solution to this problem by invoking a certain class of dark matter self-heating processes. As we will argue, such processes lead to the formation of dark matter cores at late times by considerably reducing the inner mass density of dwarf-sized halos. For deriving concrete results, we focus on semi-annihilating dark matter scenarios and model the inner region of dark matter halos as a gravothermal fluid. An important aspect of this new solution is that the semi-annihilation effects are much more prominent in dwarf-sized halos than in the more massive halos that host galaxies and clusters, even if the corresponding cross sections are the same. Furthermore, the preferred parameter space for solving the small-scale problem suggests a thermal dark matter candidate with a mass below the GeV scale, which can be probed in dark matter direct and indirect detection experiments.

Published version. 9 pages, 7 figures

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• Linear Sigma Dark Matter
• Self-heating of Strongly Interacting Massive Particles
• Dark matter freeze-in from semi-production
• Escalating core formation with dark matter self-heating
• Manifesting hidden dynamics of a sub-component dark matter
• Semi-annihilating dark matter coupled with Majorons
• Late-Time Dark Matter Oscillations and the Core-Cusp Problem
• Constraints on dark matter models from the stellar cores observed in ultra-faint dwarf galaxies: Self-interacting dark matter
• The Forward Physics Facility at the High-Luminosity LHC
• Pseudo-Nambu-Goldstone-boson Dark Matter from Three Complex Scalars