Examination of a simple example of gravitational wave memory

TL;DR

This paper analyzes a simplified model of gravitational wave memory caused by particle decay, distinguishing between null and ordinary memory types and their behaviors under different decay scenarios.

Contribution

It provides a clear example illustrating how gravitational wave memory can originate from particle decay, highlighting the conditions under which null and ordinary memory occur.

Findings

Null memory arises when decay produces a null particle.

Ordinary memory occurs with timelike decay products.

Large velocity limits can make ordinary memory mimic null memory.

Abstract

We examine a simple example of gravitational wave memory due to the decay of a point particle into two point particles. In the case where one of the decay products is null, there are two types of memory: a null memory due to the null particle and an ordinary memory due to the recoiling timelike particle. In the case where both decay products are timelike, there is only ordinary memory. However, this ordinary memory can mimic the null memory in the limit where one of the decay products has a large velocity.