Evidence for a Gravitational-Wave Background

Evidence for a Gravitational-Wave Background
Michael Lam, SETI Institute
Photo of Michael Lam
Date and time: Wed, Sep 27, 2023 - 4:00pm
Refreshments at 3:45pm
Location: Hasbrouck 134
Category: Departmental Colloquium

The North American Nanohertz Observatory for Gravitational Waves (NANOGrav) collaboration has recently reported evidence for the background of low-frequency gravitational waves using an array of rapidly rotating, highly stable radio pulsars distributed across the galaxy. Each pulsar emits a radio beam that passes our line of sight and is observed as regular, pulsed emission. We measure the times of arrival of pulses and compare with a model that includes: the rotational motion of the pulsar, orbital motions, and interstellar propagation delays; random timing noise from pulsars themselves and from the interstellar medium; and finally a correlated gravitational-wave signal recently reported on in a suite of papers. I will highlight our recent results, including implications for the dynamics of supermassive black hole binary at the centers of merging galaxies, searches for individual supermassive black hole binary systems, and searches of gravitational wave signals from new physics. I will end by highlighting future prospects for radio facilities that will advance our look into this newly opened window to the Universe.