CAREER: Investigating Matter and Spacetime Using Gravitational Waves

Gravitational waves, a prediction of general relativity, are produced during the mergers of strongly gravitating objects, such as black holes and neutron stars. The NSF Laser Interferometer Gravitational-Wave Observatory (LIGO) facilities detect the waves from these mergers almost daily during operations. The North American Nanohertz Observatory for Gravitational Waves (NANOGrav), also an NSF-supported collaboration, has detected a background of gravitational waves from many supermassive black holes throughout cosmic time.

These detectors opened new windows onto the universe, provided novel insights into the nature of gravity, and impact fields beyond gravitational physics. This project will develop data analysis methods and perform new theoretical calculations to search for as-of-yet-undiscovered predictions of general relativity and identify new relativistic phenomena that could be observed through gravitational wave measurements by LIGO and NANOGrav.

The PI will carry out the work in collaboration with students, who will learn transferable quantitative skills when conducting the research. The project also has a closely related educational component that involves creating new visualizations of the warped space around colliding black holes and accompanying recorded video explanations of the visualizations.

This will help students learn about the LIGO discoveries and teachers to convey these results to their students.

The project aims to use gravitational waves from black-hole and neutron-star mergers to understand the infrared properties of the gravitational interaction in general relativity (gravitational wave memory effects) and to probe the nature of dark matter around these systems when it is present in high densities. The primary research efforts of the project can be summarized in terms of four main goals, which are (i) to determine the prospects for pulsar timing arrays to detect the memory effect from intermediate or extreme mass-ratio inspirals, which have not been systematically studied before; (ii) to compute analogs of the memory effect in electromagnetism and Yang-Mills theories, to highlight the similarities with and the unique differences from gravitational-wave memory effects; (iii) to perform simulation studies to determine the optimal method for searching for the gravitational wave memory effect in LIGO and Virgo data; and (iv) to model the gravitational waves from compact objects surrounded by dense distributions of dark matter and infer constraints that can be placed on the dark-matter cross-section, assuming there are non-gravitational interactions between nuclear matter and dark matter.

The educational goals of the project are two-fold: (a) The PI and undergraduate students will make visualizations of the curved space around black-hole mergers, which illustrate how gravitational waves are generated and help convey the project's results in simpler terms. The PI will record video explanations of the visualizations with descriptions at three different levels: for high-school level students, for advanced undergraduate or beginning graduate students, and for experts who might use the visualizations in teaching. (b) This project also involves training undergraduate and graduate students to learn analytical, data analysis and numerical techniques highly valued in quantitative fields.

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.