Catastrophic Dark Matter Capture

TL;DR

This paper introduces a model for dark matter capture during galaxy formation, showing that mass increase thresholds can lead to rapid dark matter accumulation, influenced by intergalactic density and cosmic expansion.

Contribution

It proposes a novel nonlinear model for dark matter capture based on catastrophe theory, linking galaxy mass growth to dark matter density thresholds and dynamic infall processes.

Findings

Dark matter capture depends on galaxy mass increase and velocity thresholds.

A critical dark matter density threshold triggers rapid dark matter accumulation.

Capture rates decline as intergalactic dark matter density decreases over cosmic time.

Abstract

In this paper we describe a new idea which may be relevant to the formation of galaxies via the infall of baryonic matter (BM) and dark matter (DM) onto a pre-existing over density. Unlike BM, DM particles can fly through a static over density without being captured. We propose a simple model for DM capture: if during the passage through it, the mass of the over density increases, then slow DM particles are captured by it, further increasing its mass, while faster particles slow down, transferring part of their energy to the galaxy. We estimate the minimum initial velocity of a particle required for a passage without capture through the center of the galaxy and derive a nonlinear equation describing the rate of galaxy mass increase. An analysis carried out using the ideas of catastrophes theory shows that if the increase in the mass of baryonic matter exceeds a certain threshold value, this can lead to a very intensive capture of dark matter. We speculate that this process may be associated with the accretion of matter or with the merger of galaxies. Additionally, for the studied process to take place, the density of intergalactic DM must exceed some threshold value. Then the rate of increase in the mass of DM can be much higher than the one of baryonic matter. The capture sharply decreases after the DM density drops below the threshold value, e.g., due to the expansion of the Universe.