Dark matter and gas density profiles — a consequence of entropy bifurcation

Abstract

The radial profiles of dark matter and hot plasma density distributions of relaxed galaxies and clusters were hitherto commonly fitted by empirical functions. On the other hand, the fundamental concept of non‐extensive statistics accounts for long‐range interactions and correlations present in gravitationally coupled ensembles and plasmas. We provide a theoretical link of non‐extensive statistics to large scale astrophysical structures and show that the underlying tandem character of the entropy results in a bifurcation of the density distribution. A kinetic dark matter and thermodynamic gas branch turn out as natural consequence within the theory and is controlled by one single parameter, measuring physically the degree of correlations in the system. The theoretically derived density profiles are shown to represent accurately the characteristics of both, DM and hot plasma distributions, as observed or generated in N‐body and hydro‐simulations. The significant advantage over empirical fitting functions is...