Researchers from Stony Brook University have contributed to a global scientific effort marking the tenth anniversary of the first direct detection of gravitational waves. Associate Professor Will Farr and graduate student Nicole Khusid, both from the Department of Physics and Astronomy at Stony Brook, participated in a study that analyzed data from what is described as the loudest black hole merger detected so far.
The research team, working within the LIGO-Virgo-KAGRA (LVK) collaboration, used advanced technology and techniques developed over the past decade to gather new insights into black holes. The findings were published in Physical Review Letters on September 10.
Will Farr, who is also affiliated with the Flatiron Institute’s Center for Computational Astrophysics, collaborated with Columbia University astrophysicist Maximiliano Isi on analyzing data collected by LIGO. Nicole Khusid contributed by developing computer codes for early analysis, which played a role in identifying the significance of this black hole event.
According to the research, gravitational waves from this event showed that a 34 solar mass black hole merged with a 32 solar mass black hole. The result was a 63 solar mass black hole spinning at 100 revolutions per second—approximately comparable in size to Long Island.
By examining all stages of the collision—from initial contact through final stabilization—the researchers measured changes in horizon areas before and after merging. Their observations support Stephen Hawking’s theoretical prediction that the area of a resulting black hole’s event horizon should be greater than or equal to the combined areas of its progenitors.
“Observing the gravitational waves emitted by these black holes is our best hope for learning about the properties of the extreme spacetimes they produce,” said 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—a Nobel laureate recognized for his leadership role in building LIGO—commented on recent advances: “The improvements in sensitivity of LIGO have truly opened up a new way to see the universe,” he said. “We now observe new events weekly, and with precision, enabling such exciting, detailed studies of black holes.”
Barish played an instrumental part as principal investigator and director during LIGO's development phase beginning in 1994. His work helped lead to LIGO's historic first detection in 2015 alongside colleagues Rainer Weiss and Kip Thorne; together they received https://www.nobelprize.org/prizes/physics/2017/barish/facts/ for their contributions related to gravitational wave observation.
With ongoing upgrades expected over coming years—projected to increase detector sensitivity tenfold—scientists anticipate further discoveries about black holes through continued observation efforts worldwide.