Geodesic congruences, impulsive gravitational waves and gravitational memory

TL;DR

This paper presents a covariant, detector-independent method to analyze how impulsive gravitational waves affect geodesic congruences, revealing a discontinuity in the B-tensor that characterizes gravitational memory.

Contribution

It introduces a novel covariant approach to study the effects of impulsive waves on geodesic congruences, highlighting a discontinuity in the B-tensor as a signature of gravitational memory.

Findings

Discontinuity in the B-tensor caused by impulsive waves

Covariant, detector-independent characterization of gravitational memory

Effect of mixed material sources and gravitational waves on geodesic congruences

Abstract

In this paper we introduce a new approach to the study of the effects that an impulsive wave, containing a mixture of material sources and gravitational waves, has on a geodesic congruence that traverses it. We find that the effect of the wave on the congruence is a discontinuity in the B-tensor of the congruence. Our results thus provide a detector independent and covariant characterization of gravitational memory.