Gravitional radiation from first-order phase transitions in the presence of a fluid

TL;DR

This paper presents high-resolution simulations of gravitational wave production during first-order phase transitions, analyzing the contributions from scalar fields and fluids across various models.

Contribution

It provides a detailed parameterization of the gravitational wave spectrum based on energy ratios and coupling, advancing the understanding of sources during phase transitions.

Findings

Scalar field is usually the dominant gravitational wave source.

Fluid contributions can dominate in specific scenarios.

The spectrum depends on energy ratios and coupling parameters.

Abstract

First-order phase transitions are a source of stochastic gravitational radiation. Precision calculations of the gravitational waves emitted during these processes, sourced by both the degrees of freedom undergoing the transition and anisotropic stress of the coupled, ambient constituents, have reached an age of maturity. Here we present high-resolution numerical simulations of a scalar field coupled to a fluid and parameterize the final gravitational wave spectrum as a function of the ratio of the energies of the two sectors and the coupling between the two sectors for a set of models that represent different types of first-order phase transitions. In most cases, the field sector is the dominant source of gravitational radiation, but it is possible in certain scenarios for the fluid to have the most important contribution.