The UCD Relativity Group has a broad range of interests in the study of motion in general relativity, especially in the treatment of the two-body problem. In particular, the group has expertise in perturbative methods including the gravitational self-force approach, black hole perturbation theory, post-Newtonian, and post-Minkowskian methods. Using a range of analytic and numerical techniques, these approaches are applied to develop gravitational waveform templates for data analysis with the LISA and LIGO-Virgo-KAGRA interferometers.
A particular focus of the group is the construction of fast and faithful waveform models for extreme mass ratio inspirals (EMRIs). These are a key class of LISA sources in which a much smaller compact object gradually spirals into a supermassive black hole. Such black holes are usually found at the centres of galaxies. Modelling EMRIs is a challenging task, not least because of the complicated orbital motion of the compact object around the massive black hole — see the figure below. The slow, multi-year-long inspiral enables the detailed probing of the spacetime around the black hole. Detection and measurement of such systems’ parameters will also inform us about the environments in galactic centres, the multipole nature of the black hole spacetime, and offer new means to test Einstein’s theory of General Relativity.
The UCD group are also a co-leads (with the University of Southampton) in second-order self-force calculations. These models unlock the full potential of EMRI science for LISA and also provide a path to model elusive intermediate mass-ratio inspirals (IMRIs).