Analysis of dark matter profiles in the halos of spiral galaxies

The distribution of dark matter in the low surface brightness spiral galaxies U5750, U11454, U11819, and U11648 is analyzed by utilizing well-established density profiles from existing literature. These profiles include the Beta, Brownstein, Burkert, exponential sphere, pseudo-isothermal, and Persic profiles. For simplicity, we assume spherically symmetric distribution of dark matter in the considered galaxies, without accounting for their intricate structural complexities. For each density profile, we fit the rotation curve data to the aforementioned galaxies. Employing Markov Chain Monte Carlo statistical analyses, we infer model-free parameters from the rotation curves, namely the characteristic (central) density and scale radius. This enables us to estimate the total dark matter mass within the galactic halos. To identify the best-fit profile, we employ the Bayesian Information Criterion. Additionally, we adopt the Levenberg-Marquardt nonlinear least squares approach for the purpose of comparison and completeness. Through our statistical analysis, we offer a physical interpretation behind the selection of specific profiles. This interpretation is based on the insights obtained from the analyses

Propagation of X-ray and gamma ray emissions in strong magnetic and gravitational fields

We consider the propagation of X-ray and gamma ray emissions in strong magnetic and gravitational fields of the pulsar in nonlinear vacuum electrodynamics. We show that the radiation has birefrigence. We have calculated the delay between the two modes, as they propagate from the pulsar to the detecting device. gamma ray astrophysics, pulsar, magnetar, quantum electrodynamics, gravity. We estimate the numerical value of the delay in the case where the magnetic field source is a neutron star with field on a surface B~1016 G (magnetar). Due to the our condition, which must be satisfied for all points of considered beams, our calculation will be applicable only to the beams, for which the pericenter rp exceeds ten radii of the neutron sta

Stationar spherical-symmetric configuration of dark matter

The article is devoted to the consideration of a model problem, where mass flow of dark matter which take as only gravitational interacting spherical continuous medium without pressure and with radial opposite motion with equilibrium ascending and descending components, starting free fall from boundary of the sphere and passing through the center, stopping and fall back at the boundary of the spherical mass distribution, which give us stationary spherical-symmetric configuration of dark matter. The presence of an opposite motion makes the configuration we are considering stationary. Limited mass and dimensions of the dark matter distribution gives us possibility to modelling galaxy galo and dark stars. This configuration is considered in the classical gravity. As a result of the study, we obtained a singular density distribution in the center and in the shell of sphere and corresponding velocity field with singular center. The resulting profile can be used to construct arbitrary distributions, corresponding to the observed profiles