Colloquium: Galaxy-based gravitational wave observatory and its promises

Guest Presenter

A. Gopakumar
TIFR, Mumbai, India
Chair, Indian Pulsar Timing Array

Abstract

Maturing pulsar timing arrays monitor millisecond pulsars which can be converted into `Einstein clocks' to search for perturbations due to gravitational waves at nanohertz frequencies.  Very recent independent and coordinated investigations by the established Pulsar Timing Array collaborations strongly indicate that the universe is humming with gravitational radiation — a very low-frequency rumble that rhythmically stretches and compresses spacetime and the matter embedded in it. This stochastic GW signal is consistent with that expected from an ensemble of supermassive black hole binaries, but could also be attributable to more exotic sources. I will describe these efforts from the perspectives of the European and Indian Pulsar Timing Array (EPTA+InPTA) consortia. I will share the excitement of our InPTA collaboration that employs niche abilities of India's upgraded Giant Metrewave Radio Telescope (uGMRT). Possible future directions that include persistent multi-messenger nHz GW astronomy which  should be exciting to both astronomers and physicists will be discussed.