Capture of dark matter particles by a galaxy in the case of a bimodal distribution of their velocities

TL;DR

This paper investigates how a bimodal velocity distribution of dark matter particles affects their capture rate by a galaxy, revealing complex multi-stage capture scenarios beyond previous unimodal models.

Contribution

It introduces a model considering bimodal velocity distributions of dark matter, showing more complex capture dynamics than prior unimodal assumptions.

Findings

Capture rate can exhibit two-stage transitions.

Complex scenarios depend on velocity distribution parameters.

Results extend previous unimodal capture models.

Abstract

We have analyzed the rate of capture of dark matter (DM) particles by the galaxy in the case of the existence of two different types of DM or a bimodal velocity distribution function for DM. It is shown that, in addition to the scenario considered in our previous work which is based on the assumption of an unimodal distribution, more complex scenarios are possible in which the transition to the state of intense capture and/or exit from it can occur in two stages. A detailed description is given of the change in the curve describing the rate of capture of dark matter particles as a function of the rate of increase in the baryon mass of the galaxy for various values of the rate of decrease of the DM density.