Gravitational Waves Reveal Most Massive Black Hole Merger Ever Detected

An international collaboration of scientists that includes Astronomy Professor Maximiliano Isi and recent Columbia Physics alumnus Harrison Siegel has detected the largest merger of two black holes ever measured. The merger resulted in a monstrous black hole 225 times our sun’s mass. 

While the combined black hole’s mass sets records, that’s not the only surprising aspect of the finding. The two original black holes seemingly had masses near or in a range largely forbidden by current astrophysical models. The results, therefore, challenge assumptions scientists have made about how black holes can form.

The researchers behind the discovery reported their initial findings in a new preprint posted to arXiv.org.

“Merging black holes that are this heavy and fast-spinning present huge challenges to our understanding of the lives and deaths of massive stars, and their interactions with their surroundings: how do such black-hole binaries form? It is fair to say that no one knows for certain yet,” Isi said. “Irrespective of how this binary came to be, pairs of black holes in this configuration display unique behaviors that reveal some of the most interesting aspects of the dynamics of space and time, as predicted by Einstein's theory of general relativity.”

Another mystery comes from the new black hole’s motion: it’s spinning rapidly around its axis at a rate 4 million times that of Earth. The scientists suspect that this could also be a factor in why the black holes merged the way they did.

“There are signs that these black holes may have been rotating extremely fast in directions opposite to each other, leading them to precess as they came together like a pair of spinning tops,” Isi said. “This potentially created a very distorted new black hole in the process, that then wobbled as it settled down into a stable state.”

The detection was made by a collaboration of researchers from three experiments that measure ripples in the fabric of space-time created by events such as black hole mergers: LIGO, Virgo and KAGRA (LVK). 

The data analysis was unusually challenging, and pushed the detectors to their limits in many ways, the scientists said. "We are still learning how to extract every ounce of power out of the LIGO instrument, and hopefully results like this will get the broader public excited about continuing to fund this extraordinary scientific machine so that we can keep sharing fascinating discoveries with the world for years to come," said Siegel.

Gravitational waves are a key component of Albert Einstein's theory of general relativity and can provide critical insights into extreme cosmic events like exploding stars or merging black holes. 

“To me, this discovery highlights that gravitational wave astronomy is a discovery-driven field that is full of surprises, interesting puzzles and open questions,” Isi added. “We are at the frontier of the unknown.”

Isi has a joint appointment at Columbia and the Simons Foundation.

This news story was adapted from a press release by the Simons Foundation.