The destiny of Dark Matter

TL;DR

This paper explores the potential fates of dark matter particles, proposing two gravitationally driven scenarios where they either spiral into black holes or disperse due to cosmic expansion.

Contribution

It introduces two novel gravitational pathways for dark matter evolution, expanding understanding of dark matter's ultimate fate in the universe.

Findings

Massive DM particles may spiral into black holes and evaporate.

Lighter DM particles cause central halos to merge with black holes and evaporate.

Remaining DM halos are dispersed by cosmic expansion.

Abstract

The majority of baryons, which account for $15\%$ of the matter in the Universe, will end their lives as carbon and oxygen inside cold black dwarfs. Dark matter (DM) makes up the remaining $85\%$ of the matter in the universe, however, the fate of DM is unknown. Here we show that the destiny of purely gravitationally interacting DM particles follows one of two possible routes. The first possible route, the "radiation-destiny" scenario, is that massive DM particles lose sufficient energy through gravitational radiation causing them to spiral into a supermassive black hole that ultimately disappears through Hawking radiation. The second possible route, the "drifting-alone" destiny, applies to lighter DM particles, where only the central DM halo region spirals into the central BH which is then Hawking radiated away. The rest of the DM halo is ripped apart by the accelerated expansion of the Universe.