A decade after the first direct detection of gravitational waves, researchers from Stony Brook University have contributed to new findings that confirm theoretical predictions about black holes. Associate Professor Will Farr and graduate student Nicole Khusid, both from the Department of Physics and Astronomy in the College of Arts and Sciences, are part of an international collaboration studying data from what is described as the loudest black hole merger detected so far.
Farr and Khusid worked with colleagues in 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). Their research was published September 10 in Physical Review Letters.
The team analyzed data collected by LIGO to observe a merger between two black holes—one with 34 times the mass of the sun and another with 32 solar masses. The resulting black hole has a mass equivalent to 63 suns and spins at a rate of 100 revolutions per second. This event provided some of the clearest measurements yet taken by LIGO.
By examining both early and late phases of the collision, researchers measured changes in the areas of black hole horizons. These results support Stephen Hawking’s theory that states the area of a merged black hole must be larger than that of its progenitors combined.
“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.”
Khusid noted her involvement in sharing early analyses: “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. 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 who played a key role in building LIGO’s interferometers leading up to their historic detection in 2015, commented on technological progress: “The improvements in sensitivity of LIGO have truly opened up a new way to see the universe. We now observe new events weekly, and with precision, enabling such exciting, detailed studies of black holes.”
Barish received part of https://www.nobelprize.org/prizes/physics/2017/summary/ for his contributions alongside Rainer Weiss and Kip Thorne.
Looking ahead, researchers expect even greater sensitivity from future detectors over https://www.ligo.caltech.edu/page/detection-timeline#next-decade/, which could provide more rigorous tests regarding black hole characteristics.
