Theoretical aspects of gravitational radiation

TL;DR

This paper reviews analytical methods for relating gravitational wave signals to their sources, focusing on matching post-Newtonian and multipolar expansions to improve predictions for binary inspiral waveforms.

Contribution

It introduces recent analytical approaches that combine post-Newtonian and multipolar expansions to better understand gravitational wave generation from astrophysical sources.

Findings

Enhanced accuracy in theoretical gravitational waveform predictions.

Improved understanding of the source-structure relationship in gravitational wave emission.

Analytical techniques applicable to binary neutron star and black hole inspirals.

Abstract

A central problem in gravitational wave research is the {\it generation problem}, i.e., the problem of relating the outgoing gravitational wave field to the structure and motion of the material source. This problem has become, in recent years, of increased interest in view of the development of a worldwide network of gravitational wave detectors. We review recent progress in {\it analytical} methods of tackling the gravitational wave generation problem. In particular, we describe recent work in an approach which consists of matching a post-Newtonian expansion of the metric near the material source with a multipolar-post-Minkowskian expansion of the external metric. The results of such analytical methods are important notably for providing accurate theoretical predictions for the most promising targets of the LIGO/VIRGO interferometric network: the ``chirp'' gravitational waveforms emitted during the radiation-reaction-driven inspiral of binary systems of compact objects (neutron stars or black holes).