Dissipative dark matter halos: The steady state solution II (1801.09359v3)

Abstract: Within the mirror dark matter model and dissipative dark matter models in general, halos around galaxies with active star formation (including spirals and gas rich dwarfs) are dynamical: they expand and contract in response to heating and cooling processes. Ordinary Type II supernovae (SN) can provide the dominant heat source, possible if kinetic mixing interaction exists with strength $\epsilon \sim 10^{-9} - 10^{-10}$. Dissipative dark matter halos can be modelled as a fluid governed by Euler's equations. Around sufficiently isolated and unperturbed galaxies the halo can relax to a steady state configuration, where heating and cooling rates locally balance and hydrostatic equilibrium prevails. These steady state conditions can be solved to derive the physical properties, including the halo density and temperature profiles, for model galaxies. Here, we have considered idealized spherically symmetric galaxies within the mirror dark particle model, as in the earlier paper [paper I, arXiv:1707.02528], but we have assumed that the local halo heating in the SN vicinity dominates over radiative sources. With this assumption, physically interesting steady state solutions arise which we compute for a representative range of model galaxies. The end result is a rather simple description of the dark matter halo around idealized spherically symmetric systems, characterized in principle by only one parameter, with physical properties that closely resemble the empirical properties of disk galaxies.