Enhancing the Discovery Potential of Merging Black Holes with Robust Extraction of Spin-Precession and Eccentricity

California Institute Of Technology, Pasadena CA

Investigators

Abstract

This award supports research in relativity and relativistic astrophysics, and it addresses the priority areas of NSF's "Windows on the Universe" Big Idea. Since the first detection of gravitational waves from the coalescence of two black holes in 2015, the nascent field of gravitational wave astrophysics is on an accelerating trajectory with dozens more detections, including black hole, neutron star, and mixed neutron star-black hole binaries. This spectacular progress is driven by the improving sensitivity of the LIGO/Virgo detectors and advances in analysis techniques. The fourth observing campaign will more than quadruple the number of detections and offer a wealth of information about the most powerful astronomical events. This wealth of information will answer key questions about black holes, but also bring new challenges: such precise measurements must be accompanied by a careful assessment of potential sources of systematic errors. This award focuses on systematic uncertainties originating by issues with the quality of data, known as glitches. The main goal is to provide robust constraints on some of the most elusive properties of black holes in binaries: their spins and the eccentricity of their orbit. This project focuses on gravitational wave signal from black holes and neutron stars that overlap with instrumental artifacts in the detectors, known as glitches. Past experience indicates that the increased rate of detection expected during the fourth observing run will result in more instances of such overlaps that jeopardize astrophysical parameter estimation. Existing mitigation techniques based on modeling and subtracting the glitch result in robust inference of black hole masses and spins aligned with the orbit. The goal in this award is to extend glitch-mitigation techniques to robustly measure more subtle physical effects such as spins in the orbital plane (spin-precession) and orbital eccentricity, effects that can provide invaluable information about the astrophysical formation environment of compact binaries. This award tackles eccentricity and spin-precession inference in the presence of data quality issues along two fronts. The first relates to the observed signals where the group will use traditional inference to study the phenomenology and measurability of spin-precession and eccentricity from merger-dominated signals in the next observing run and beyond. The second turns to the detector noise where the group will construct a novel approach that is inspired by astrophysical population inference: they use detector data to infer the population properties of various glitch families and then obtain source inference that marginalizes over data quality issues by using the glitch population distributions as priors. This work increases the likelihood of a measurement of eccentricity or spin-precession during the fourth observing run that is robust against data quality issues. 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.