Physical properties of dark matter in galaxy U11454

Abstract

In this paper physical characteristics of dark matter distribution in the spiral galaxy U11454 is explored
using only well-known cored density profiles in the literature such as the pseudo-isothermal, Burkert,
Einasto, exponential sphere, Beta and Brownstein profiles. It is presumed that the distribution of dark
matter in the considered galaxy is spherically symmetric without taking into account its complex
structural components. It is assumed that dark matter possesses non-vanishing pressure which allows
theoretically analyzing the state parameter. The model free parameters of each profile are inferred from
the rotation curve data of the galaxy by means of non-linear model fit procedure. Using the Bayesian
Information Criterion the best fit profile among the considered ones is selected. Furthermore, the
hydrostatic equilibrium equation is solved and the pressure profiles for each above mentioned density
profile are constructed in the weak gravitational field regime. Combining the pressure and corresponding
density profiles one gains equations of state for the dark matter in the galaxy U11454. The mass and
gravitational potential are evaluated and constructed as a function of the radial distance for each profile.
The total dark matter mass is assessed and our results are confronted and contrasted with the previous
outcomes. In addition, the speed of sound is estimated in the dark matter distribution and it is shown that
its behavior is quite unusual especially for the Brownstein profile. Finally, the refracting index is
calculated in order to assess gravitational lensing effects produced