Gravitational Waves from Coalescing Binary Sources

TL;DR

This paper discusses the theoretical aspects of gravitational waves emitted by coalescing binary systems, highlighting the role of the BMS group and the news function in understanding wave detection.

Contribution

It introduces the application of the BMS-covariant wave equation to better understand gravitational wave signals from binary sources.

Findings

Existence of a non-vanishing news function implies gravitational radiation.

The BMS group symmetry depends on the source orbit periodicity.

Breaks the isotropy of Poincaré translations at null infinity.

Abstract

Coalescing binary systems (eg pulsars, neutron stars and black holes) are the most likely sources of gravitational radiation, yet to be detected on or near Earth, where the local gravitational field is negligible and the Poincar\'e symmetry rules. On the other hand, the general theory of gravitational waves emitted by axially symmetric rotating sources predicts the existence of a non-vanishing news function. The existence of such function implies that, for a distant observer, the asymptotic group of isometries, the BMS group, has a translational symmetry that depends on the orbit periodicity of the source, thus breaking the isotropy o the Poincar\'e translations. These results suggest the application of the asymptotic BMS-covariant wave equation to obtain a proper theoretical basis for the gravitational waves observations.