The DCU Relativity Group is part of the DCU Centre for Astrophysics and Relativity (CfAR). Research in the group addresses a range of topics in gravitational physics including questions of relevance to the LISA mission on the two body problem (and the problem of motion generally) and on wave propagation in curved spacetimes. Also within CfAR, researchers working on Astrophysics address relevant questions in the area of high energy astrophysics. In particular, they are actively involved in the study of high energy and very high energy emission from binary systems, and also multimessenger observations with LISA and Cherenkov telescopes.
One major theme of this work is the theory of motion: How do the details of an object’s internal structure affect its bulk movement or spin? Part of this is in essence the “self-force problem.” There is no self-force at all in Newtonian gravity, although that changes in relativistic settings where Newton’s third law fails and fields propagate at finite speeds. Our research seeks to develop a deeper understanding of this problem in General Relativity, incorporating a fully nonlinear approach, and thereby leading to a more effective perturbation theory.
The gravitational waves that LISA will detect – and accompanying electromagnetic waves – travel through strongly curved regions of spacetime: the environments of tightly bound binary systems including EMRIs. It is therefore essential to have a full understanding of curved spacetime effects on wave propagation. This is another central theme of work of the DCU group, where there is a focus on understanding global aspects of wave propagation in black hole backgrounds.
Both these strands of research will complement existing approaches to the study of the two body problem in GR and of the accompanying gravitational waves, and, it is hoped, will lead to insights into how best to calculate waveforms for LISA.