A West Virginia University theoretical astrophysicist will be instrumental in the creation of a unique space probe designed to identify and precisely quantify gravitational waves, which are rippling effects in space and time.
WVU astrophysicist Sean McWilliams was on the team that first detected gravitational waves in 2015. Now, he will play a key role in the development of a first-of-its-kind space probe that will detect and accurately measure gravitational waves with support from NASA funding. Image Credit: WVU
Sean McWilliams, an associate professor of physics and astronomy at WVU Eberly College of Arts and Sciences, was a member of the team that discovered those imperceptible ripples in 2015, confirming Albert Einstein’s general theory of relativity.
Now that McWilliams has received $750,000 in funding from NASA’s Established Program to Stimulate Competitive Research, he will take the lead in creating models that will make it easier for the planned space probe to make observations.
The probe, which will be known as the Laser Interferometer Space Antenna, or LISA, will be the first specifically designed space-based gravitational wave observatory capable of measuring binaries throughout a broad mass range.
Gravitational waves, as predicted by Einstein in 1916, arise from monumental events such as the merging of black holes and neutron stars, supernovae, and even the remnants of radiation from the Big Bang.
McWilliams' team is set to explore the inspirals of stellar-mass binaries poised to merge, as well as the massive binaries within the centers of colliding galaxies. The LISA mission will enhance scientific knowledge of the universe, allowing researchers to study phenomena that are invisible in traditional optical wavelengths.
LISA signals will be much louder relative to the detector noise than LIGO’s were, so the models have to be much more accurate to make sure the models don’t limit the science we can do. This project will attempt to make the necessary dramatic improvements in modeling accuracy that will be required.
Sean McWilliams, Associate Professor, West Virginia University
LIGO, the Laser Interferometer Gravitational-Wave Observatory, operates in Washington and Louisiana. This large-scale facility detects gravitational waves and played a crucial role in the 2015 discovery by the team that included McWilliams.
McWilliams added, “For supermassive black-hole binaries, their spin and eccentricity distributions are sensitive to their environments just prior to entering the LISA band. In addition, LISA can observe stellar-mass binaries earlier than ground-based detectors, and the measurement of their spins and eccentricities can provide insights into their formation and evolutionary history that cannot be obtained otherwise.”
The launch of LISA is scheduled for 2035.
Additionally, researchers will build on McWilliams’ innovative “backward one-body method” model. This model simplifies the analysis of gravitational waves by providing a precise mathematical formula for the signal generated by the merger of two black holes.
Before McWilliams developed this approach, researchers had to use a mathematical transformation to deduce the exact waveform from a black hole merger, a process that often required numerous numerical simulations and was highly labor-intensive.
McWilliams enhanced the accuracy of these analyses by applying principles of general relativity to calculate how a small test mass spirals into and disturbs the final black hole.
We will first improve the efficiency of the best models for inspirals that are currently available, and we will replace the merger signals with BOB (backward one-body). From there, we will be able to rapidly assess new ideas for improving accuracy throughout the waveform. Ultimately, we plan to have a model that builds on all known physics throughout the signal and then add tunability to the model.
Sean McWilliams, Associate Professor, West Virginia University
McWilliams’ team includes Zach Etienne, an adjunct associate professor.
It is very gratifying to receive this support for the work my group has been doing for quite a few years now. It is also humbling since it means we are now responsible for helping LISA fulfill its science mission. The challenge is honestly a bit daunting since the current models are not nearly at the level of accuracy that will be needed and the next decade will pass quickly. The instrument is really being built and, barring catastrophe, will launch in decade from now.
Sean McWilliams, Associate Professor, West Virginia University