News 2023: College of Engineering adjunct faculty finds new evidence for ringing black holes

A study led by Collin Capano, adjunct faculty in the Department of Physics, has been published in Physical Review Letters.

Dr. Collin Capano, adjunct faculty member in the Department of Physics and researcher in the UMassD Center for Scientific Computing and Data Science Research, is the lead author of a study published November 28 in the Physical Review Letters. Capano led an international team of scholars from Germany, Canada, Norway, Denmark, the Netherlands, and the U.S. who found the first strong observational evidence for multiple gravitational-wave frequencies emitted by a black hole.  

The black hole was formed by the merger of two earlier black holes. After the merger, the black hole rings like a bell. Just as a ringing bell emits a spectrum of sound waves, a ringing black hole emits gravitational waves at specific tones. The frequencies of these tones are predicted by Einstein's theory of gravity (General Relativity). "Remarkably, we found that the gravitational-wave spectrum matched what Einstein's theory predicts, despite the theory being over 100 years old and created before black holes were known to exist," Capano said. 

The source of the signal was a black hole that is more than 4 billion lightyears away. An observation of two ringing tones like this was not expected for another 10 years, when more sensitive gravitational-wave detectors will become operational. "Achieving this multimode observation – in other words, the detection of two distinct vibration frequencies of a deformed black hole – has been a welcome surprise," Capano said. "It was widely assumed this would not be possible before the next generation of gravitational-wave detectors. We were able to detect it now due to the unique properties of this signal, and new data analysis methods that we developed." 

This study is the latest in a series of breakthroughs in black hole research made by UMass Dartmouth faculty and students.  

"Remarkably, we found that the gravitational-wave spectrum matched what Einstein's theory predicts, despite the theory being over 100 years old and created before black holes were known to exist."