Stony Brook University researchers have played a significant role in an international team’s latest findings on black hole mergers, marking the 10th anniversary of the first direct detection of gravitational waves. Associate Professor Will Farr and graduate student Nicole Khusid from Stony Brook’s Department of Physics and Astronomy contributed to a global effort using data from the loudest black hole merger observed to date. Their work confirms theoretical predictions about black hole spacetimes made by Albert Einstein, Stephen Hawking, and Roy Kerr.
The research is part of the LIGO-Virgo-KAGRA (LVK) collaboration, which includes scientists associated with the Laser Interferometer Gravitational-Wave Observatory (LIGO), Virgo Interferometer, and Kamioka Gravitational Wave Detector (KAGRA). The findings will be published in Physical Review Letters.
Professor Farr and Columbia University Assistant Professor Maximiliano Isi, both also affiliated with the Flatiron Institute’s Center for Computational Astrophysics, analyzed LIGO data for this study. Nicole Khusid helped develop computer codes for early analysis that aided in identifying key features of the event. The research provides new insights into black holes and tests how quantum physics aligns with Einstein’s general relativity theory. It also confirms theories developed by Stephen Hawking regarding black hole event horizons.
According to the researchers, this observation offers precise measurements from a collision between two black holes—one 34 times the mass of the sun and another 32 times—resulting in a single 63-solar-mass black hole spinning at 100 revolutions per second. This event allowed scientists to observe all stages of the merger within milliseconds after contact. They measured areas of each progenitor's horizon before merging and compared them to that of the remnant. As predicted by Hawking’s theory, they found that “the remnant’s area must be larger than the sum of the progenitors’ areas,” which matched their observations at high statistical significance.
“Observing the gravitational waves emitted by these black holes is our best hope for learning about the properties of the extreme spacetimes they produce,” says Farr. “As we build more and better gravitational wave detectors, the precision will continue to improve; but it is amazing to think that only ten years after the very first observations of a merger like this, we are already making precision measurements of the spacetime generated by these extreme objects, and able to observationally confirm precise mathematical predictions about black holes.”
“Back in March, I had the opportunity to share my preliminary analyses of this 10-year-anniversary event with members of the LVK at a collaboration-wide meeting,” said Khusid. “The results, namely the precise measurement of multiple tones at late times in the post-merger gravitational wave signal, quickly generated interest–it felt exciting and rewarding to hear the community respond to the science potential of this merger. With this event alone, we’ve performed some of the strongest tests of our understanding of gravity and black holes!”
Barry Barish, Nobel laureate and President’s Distinguished Endowed Chair in Physics at Stony Brook University College of Arts and Sciences’ Department of Physics and Astronomy, commented on advances since LIGO's first detection: “The improvements in sensitivity of LIGO have truly opened up a new way to see the universe,” said Barish. “We now observe new events weekly, and with precision, enabling such exciting, detailed studies of black holes.”
Barish led construction efforts for LIGO beginning in 1994; his leadership culminated in its first historic detection in 2015—a breakthrough that earned him along with Rainer Weiss and Kip Thorne the Nobel Prize in Physics in 2017.
Looking ahead, researchers expect future detectors will become even more sensitive over time—by as much as tenfold within a decade—which could further advance understanding through additional discoveries about these cosmic phenomena.
Stony Brook University is recognized as New York’s flagship public university within the State University System (SUNY), enrolling over 26,000 students and participating actively in academic research initiatives across disciplines—including co-management responsibilities for Brookhaven National Laboratory for the U.S. Department of Energy—and was recently named anchor institution for The New York Climate Exchange on Governors Island.