Dr. Swetha Bhagwat

Since the advent of gravitational wave astronomy, marked by the groundbreaking GW150914 event in 2015, we have made significant strides in understanding both the astrophysics of black holes—such as their population characteristics—and the nature of gravity in their vicinity. Gravitational waves provide an unprecedented tool to probe black holes and test our understanding of fundamental theoretical physics. I will begin by introducing the kinds of fundamental physics we can test using gravitational wave observations, focussing primarily on the signals from binary black hole mergers. Black holes lie at the heart of many fascinating phenomena and pose some of the greatest challenges in theoretical physics such as enclosing a singularity and the information paradox. When two black holes spiral around each other and merge, they form a highly distorted black hole that subsequently settles down by emitting characteristic gravitational waves —a process known as the ringdown. This part of the gravitational wave emission is fascinating because, despite its simple morphology, it is a very powerful window into probing the nature of black holes. A significant portion of my talk will focus on this. I will summarise the lessons we have learnt from the three gravitational wave transient catalogues produced by the LIGO-Virgo–Kagra detector network and assess our current understanding. I will also discuss what the future holds for gravitational wave astronomy in probing fundamental physics as we bring new detectors online.