Effects of non-vanishing dark matter pressure in the Milky Way Galaxy

We consider the possibility that the Milky Way's dark matter halo possesses a non-vanishing equation of state. Consequently, we evaluate the contribution due to the speed of sound, assuming that the dark matter content of the galaxy behaves like a fluid with pressure. In particular, we model the dark matter distribution via an exponential sphere profile in the galactic core, and inner parts of the galaxy whereas we compare the exponential sphere with three widely used profiles for the halo, i.e. the Einasto, Burkert and Isothermal profile. For the galactic core, we also compare the effects due to a dark matter distribution without black hole with the case of a supermassive black hole in vacuum and show that present observations are unable to distinguish them. Finally we investigate the expected experimental signature provided by gravitational lensing due to the presence of dark matter in the core.

Automated summary

The researchers consider the possibility of the Milky Way's dark matter halo having a non-zero equation of state and evaluate the contributions from the speed of sound produced by the dark matter behaving like a fluid with pressure. Different profiles, including exponential sphere, Einasto, Burkert, and Isothermal, were compared to model the distribution of dark matter in the galactic core. They also investigated the expected experimental signature of gravitational lensing due to the presence of dark matter in the core, showing that current observations cannot distinguish certain scenarios.