You are cordially invited to attend a Colloquium by Dr Deb Debabrata.
Abstract:
The discovery of gravitational waves has transformed astronomy and opened an entirely new way of exploring the Universe. While observatories such as LIGO have detected gravitational waves from merging stellar mass black holes and neutron stars, these signals represent only a small part of the gravitational wave spectrum. The slowest gravitational waves are produced by pairs of supermassive black holes in merging galaxies and have wavelengths spanning many light years, making them inaccessible to conventional interferometers. Instead, astronomers use our Galaxy itself as a detector by observing millisecond pulsars, which are among the most precise natural clocks known. By measuring the arrival times of radio pulses from an ensemble of pulsars over many years, Pulsar Timing Arrays search for tiny correlated signatures produced by passing gravitational waves. In this colloquium, I will introduce the basic principles of pulsar timing and Pulsar Timing Arrays, explain how they provide a unique window into the nanohertz gravitational wave Universe, discuss the recent evidence for a gravitational wave background, and highlight the exciting scientific opportunities that this new observational window offers for understanding the evolution of galaxies, supermassive black holes, and the Universe. The talk is intended for a broad audience and assumes no prior knowledge of pulsars, gravitational waves, or radio astronomy.