Publication date: Jul 2018
Abstract:
We discuss in the framework of general relativity the role of the dark energy represented by the cosmological constant, restricted due to cosmological tests, in the polytropic models of dark matter halos. The internal spacetime of the polytropic spheres governs circular geodesic orbits that can be compared with the velocity curves observed in large galaxies, indicating the possibility to use for the halo model both non-relativistic very extended and diluted polytropes, or relativistic polytropes with nearly critical value of the relativistic parameter sigma = p_mathrm{c}/varrho_mathrm{c} enabling extremely large polytrope extension, limited efficiently by the influence of the dark energy to agree with extension of dark matter halos of large galaxies. We also show that the so-called trapping relativistic polytropes with extremely large extension allow for gravitational instability of their central parts leading to the creation of a supermassive black hole inside of such an extremely extended polytrope representing galactic halo.
Authors:
Stuchlik, Zdenek; Novotn, Jan; Hladík, Jan;