Gravitational bremsstrahlung in plasmas and clusters

TL;DR

This paper investigates gravitational bremsstrahlung in plasmas and clusters, deriving an approximate Gaunt factor and cross-sections, highlighting their significance as a source of high-frequency gravitational noise in the solar system.

Contribution

It introduces a combined classical and Born approximation approach to model gravitational bremsstrahlung and derives relevant cross-sections with angular momentum considerations.

Findings

Total gravitational wave power of the Sun: 76±20 MW

Dominant source of high-frequency gravitational noise in the solar system

Development of an approximate gravitational Gaunt factor

Abstract

We study the gravitational bremsstrahlung owing to collisions mediated by a $1/r$ potential. We combine classical and first order Born approximation results in order to construct an approximate gravitational `Gaunt factor' for the total emitted energy. We also obtain the cross-section with an angular momentum cut-off, and hence the cross-section for emission via close hyperbolic encounters in a gravitating cluster. These effects are the dominant source of very high frequency gravitational noise in the solar system. The total gravitational wave power of the Sun is $76\pm 20\,$MW.