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arXiv · 1711.11085

Dark matter halos in the multicomponent model. II. Density profiles of galactic halos

Keita Todoroki·Mikhail V. Medvedev
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Abstract

The multicomponent dark matter model with self-scattering and inter-conversions of species into one another is an alternative dark matter paradigm that is capable of resolving the long-standing problems of $Λ$CDM cosmology at small scales. In this paper, we have studied in detail the properties of dark matter halos with $M \sim 4-5 \times10^{11} M_{\odot}$ obtained in $N$-body cosmological simulations with the simplest two-component (2cDM) model. A large set of velocity-dependent cross-section prescriptions for elastic scattering and mass conversions, $σ_s(v)\propto v^{a_s}$ and $σ_c(v)\propto v^{a_c}$, has been explored and the results were compared with observational data. The results demonstrate that self-interactions with the cross-section per particle mass evaluated at $v=100$ km s$^{-1}$ being in the range of $0.01\lesssim σ_0/m\lesssim 1$ cm$^2$g$^{-1}$ robustly suppress central cusps, thus resolving the core-cusp problem. The core radii are controlled by the values of $σ_0/m$ and the DM cross-section's velocity-dependent power-law indices $(a_s,a_c)$, but are largely insensitive to the species' mass degeneracy. These values are in full agreement with those resolving the substructure and too-big-to-fail problems. We have also studied the evolution of halos in the 2cDM model with cosmic time.

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Keita Todoroki, Mikhail V. Medvedev. 2017-11-29. Dark matter halos in the multicomponent model. II. Density profiles of galactic halos. https://doi.org/10.1093/mnras%2Fsty3353

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