Gravitational waves from bubble walls

TL;DR

This paper develops a general computational method for gravitational waves produced by bubble walls during cosmological phase transitions, analyzing various wall motions and deformations to predict their gravitational wave spectra.

Contribution

It introduces a unified approach to calculate gravitational radiation from bubble walls, including new expressions for different kinematic scenarios and deformation effects.

Findings

Derived general formulas for bubble collision and bulk flow mechanisms

Calculated gravitational wave spectra for specific deformation models

Identified peak features in the spectrum related to bubble deformations

Abstract

We present a general method for computing the gravitational radiation arising from the motion of bubble walls or thin fluid shells in cosmological phase transitions. We discuss the application of this method to different wall kinematics. In particular, we derive general expressions for the bubble collision mechanism in the envelope approximation and the so-called bulk flow model, and we also consider deformations from the spherical bubble shape. We calculate the gravitational wave spectrum for a specific model of deformations on a definite size scale, which gives a peak away from that of the bubble collision mechanism.