Physics and Astrophysics of Compact Binaries

The principal motivation of this project is to exploit gravitational-wave observations to gain a deeper understanding of gravity and to test the nature of black holes via "black hole spectroscopy." The spinning, deformed black hole formed when two black holes merge rings down like a bell. The idea of black hole spectroscopy is that such a deformed black hole can be treated as a "gravitational atom" (in analogy with atomic spectra), because its damped oscillation frequencies (the "quasinormal modes") carry unique fingerprints of spacetime dynamics. With the expected increase in volume coverage of LIGO-Virgo-KAGRA (LVK) in their fourth and fifth observational runs O4 and O5, and with the ramping up of activity on Cosmic Explorer in the US and the Einstein Telescope in Europe, this work is timely, geared at enhancing the scope of the physics and astrophysics enabled by ground-based interferometers. The project will train students and postdocs in a highly interdisciplinary field that requires expertise in general relativity, astrophysics, data analysis, and high-energy physics. The students and postdocs will benefit from interactions with a large international network of world-leading experts in gravitational physics.

Large financial resources have been invested in advanced detector design on the experimental side, and in a community effort to build compact binary detection templates on the theoretical/data analysis side. The first gravitational-wave detections by the LVK collaboration were a major milestone, but for gravitational-wave science to make even more groundbreaking contributions, we must be able to go beyond detections, extracting fundamental physics from the strong-gravity dynamics of the sources. This project on black hole spectroscopy has four main objectives: (1) to build models for the amplitudes of linear and nonlinear quasinormal modes; (2) to understand and alleviate ringdown modeling systematics in real data; (3) to clarify the connection between ringdown and light-ring physics; (4) to search for deviations from general relativity using parametrized ringdown tests. The reduced budget and duration of the award will allow us to complete only about half of the projects listed in the original proposal.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

Award Number: 2513337
Principal Investigator: Emanuele Berti
Funds Obligated: $400,000
State: MD