Phenomenology of Vector Dark Matter produced by a First Order Phase Transition

TL;DR

This paper explores how first order phase transitions in the dark sector can produce vector and scalar dark matter, affecting their abundance and generating gravitational wave signals.

Contribution

It identifies parameter regions where phase transitions significantly alter dark matter relic densities and predicts associated gravitational wave signals.

Findings

Phase transitions around 1 GeV impact scalar dark matter.

Transitions near 10 MeV affect vector dark matter.

Gravitational wave signals are expected from these phase transitions.

Abstract

Both scalar and vector dark matter can be produced during a cosmological first order phase transition if the dark matter is coupled to the field undergoing the transition. Both kinds of particle are also produced by the plasma through the normal freeze out scenario. For different dark matter masses, we identify the regions of parameter space where there are significant deviations from the normal freeze out scenario and discover there are some rather general predictions. For dark matter particles in the traditional thermal relic GeV-TeV window, dark sector phase transitions around a GeV affect scalar dark matter and dark sector phase transitions around 10 MeV affect vector dark matter abundances (and therefore should take place in a dark sector). When the phase transitions are in the interesting temperature range, the normal range of dark matter masses are different to those predicted by thermal freeze out. We calculate the expected gravitational wave signal of these phase transitions.