Investigating the Memory Effect in Neutron Star Mergers

Abstract

This master thesis investigates the gravitational wave memory effect, a prediction of general relativity, characterized by a permanent displacement in spacetime geometry. While this effect remains undetected, next-generation detectors such as the Einstein Telescope (ET) and the Laser Interferometer Space Antenna (LISA) are poised to enable its first observation. This work focuses on modeling and estimating the nonlinear & linear memory effect generated by neutron star mergers. By assessing its detectability across both instruments, I demonstrate that a memory signal in ET would be resolvable for an event analogous to the landmark multi-messenger discovery of August 17, 2017. Furthermore, a dedicated analysis of the memory effect from gamma-ray bursts shows that detection with ET and LISA is achievable in principle, yet sensitive to the modeling and requires a combination of several extreme physical characteristics.