Dark matter halos in the multicomponent inelastic model. From dwarfs to galaxy clusters

A possibility of dark matter (DM) being multicomponent has a strong implication on resolving longstanding cosmological problems on small scale. The simplest two-component DM (2cDM) model with inelastic interactions has recently been shown to robustly resolve the missing satellites, core-cusp, and too-big-to-fail problems in N-body cosmological DM-only simulations tested on MW-like environments with DM halos of a virial mass ∼5×10¹¹ M_sun [1,2]. With the aim of further constraining the parameter space available for the 2cDM model, we extend our analysis to dwarf and galaxy cluster haloes with their virial mass of ∼10⁷ M_sun and ∼10¹⁵ M_sun, respectively. We find that the normalized cross-sections σ/m≥0.1 cm²/g are disfavored for both dwarfs and galaxy cluster haloes, while σ/m≤0.001 cm²/g have too little effect on DM halos making them nearly indistinguishable from their CDM counterparts. We conclude that the 2cDM model can naturally resolve the above small-scale cosmological problems of DM halos across about eight orders of magnitude in their virial mass for the cross-sections σ/m∼0.1-0.001 cm²/g.

[1,2] K. Todoroki, M.V. Medvedev, MNRAS, 483, 3983 (2019); MNRAS, 483, 4004 (2019)