Stellar polytropes and Navarro–Frenk–White halo models: comparison with observations

Abstract

Motivated by the possible conflict between the Navarro–Frenk–White (NFW) modelpredictions for the dark matter contents of galactic systems and its correlation withbaryonic surface density, we will explore an alternative paradigm for the description of darkmatter halos. Such an alternative emerges from Tsallis’ non-extensive thermodynamicsapplied to self-gravitating systems and leads to the so-called ‘stellar polytrope’ (SP) model.We consider that this could be a better approach to real structures rather than theisothermal model, given the fact that the first one takes into account the non-extensivity ofenergy and entropy present in these type of systems characterized by long-rangeinteractions. We compare a halo based on the Navarro–Frenk–White (NFW) modeland one which follows the SP description. Analysing the dark matter contentsestimated by means of global physical parameters of galactic discs, obtained from asample of actual galaxies, with the ones of the unobserved dark matter halos, weconclude that the SP model is favoured over the NFW model in such a comparison.