Gravitational wave memory and its tail in cosmology

Understand

We study gravitational wave memory effect in the FRW cosmological model with matter and cosmological constant.

• Since the background is curved, gravitational radiation develops a tail part arriving after the main signal that travels along the past light cone of the observer.
• First we discuss first order gravitational wave sourced by a binary system, and find that the tail only gives a negligible memory, in accord with previous results.
• Then we study the nonlinear memory effect coming from induced gravitational radiation sourced by first order gravitational radiation propagating over cosmological distances.