A New Spin: The Next Generation of Gravitational-Wave Searches for Merging Black Holes

University Of Massachusetts, Dartmouth, North Dartmouth MA

Investigators

Abstract

Current gravitational-wave searches for signals from merging black holes and neutron stars have been extraordinarily successful, allowing us to probe new astrophysics and test strong-field gravity. However, these searches have not yet begun to access the full, rich discovery space of gravitational-wave signals. In particular, if binary black holes have large, misaligned spins and asymmetric masses, then the binary’s orbit will precess. The resulting gravitational waves can have significant amplitude and phase modulations, causing the signals to be missed entirely by current searches. However, measurement of these modulations would allow us to disentangle various binary parameters, enabling more accurate probes of fundamental physics in the strong-gravity regime than are possible with current detections. This award supports the development of tools needed to search for and potentially detect this important class of precessing signals. Additionally, this work will provide data-analysis skill training for undergraduates participating in this research with the PI, particularly through the ACCOMPLISH program at the University of Massachusetts Dartmouth which seeks to increase STEM degree completion of low-income, high achieving undergraduates. The work supported by this award will access the interesting class of precessing binary black holes using a two-pronged approach. The PI and a PhD student will design and perform a gravitational-wave search for moderately-precessing binary systems using a two-harmonic approximation to the precessing waveform, enabling the exploitation of the well-behaved morphology of the separate harmonics. Additionally, the group will design and perform a gravitational-wave search for highly-precessing binary systems using a generalization of the matched-filter statistic over a constrained region of parameter space. These searches will be deployed over archival gravitational-wave data, potentially making a detection of a precessing gravitational-wave signal or setting meaningful upper limits on the rates of mergers of such systems. The development work enabled by this award will inform future directions for more complex searches in general, particularly as we move to the third generation of gravitational-wave detectors. 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.