Gravitational Waves From a Dark (Twin) Phase Transition

TL;DR

This paper explores how certain dark sector models with strong first order phase transitions in the early universe could produce detectable gravitational waves, offering a new way to test dark matter theories.

Contribution

It calculates the gravitational wave spectrum from SU(N) dark sectors and discusses detection prospects with eLISA and pulsar timing arrays, linking dark sector physics with observable signals.

Findings

Strong first order phase transitions in dark sectors can produce detectable gravitational waves.

Detection prospects depend on the dark confinement scale and model specifics.

The work connects gravitational wave signals with dark matter models like Twin Higgs and SIMP.

Abstract

In this work, we show that a large class of models with a composite dark sector undergo a strong first order phase transition in the early universe, which could lead to a detectable gravitational wave signal. We summarise the basic conditions for a strong first order phase transition for SU(N) dark sectors with n_f flavours, calculate the gravitational wave spectrum and show that, depending on the dark confinement scale, it can be detected at eLISA or in pulsar timing array experiments. The gravitational wave signal provides a unique test of the gravitational interactions of a dark sector, and we discuss the complementarity with conventional searches for new dark sectors. The discussion includes Twin Higgs and SIMP models as well as symmetric and asymmetric composite dark matter scenarios.