An artistic rendering shows a pair of black holes on a collision course, similar to one recently discovered by astronomers. Photo by Mark Myers/ARC Center of Excellence for Gravitational Wave Discovery
Sept. 2 (UPI) -- Signatures recorded by the LIGO and Virgo observatories have revealed the most massive gravitational wave source yet detected, a ripple in space-time created by a merger between two rapidly spinning, mammoth black holes.
The size of the merger isn't all that's special about GW190521. One of the two giant black holes features a mass 85 times that of the sun, making it an "impossible" black hole, according to a study published Wednesday in the journal Physical Review Letters.
Based on the best astronomical simulations of star death, any star big enough to create such a massive black hole should destroy itself upon collapse -- via a process called "pair instability."
In other words, the larger of the two black holes is too big to have been born from the collapse of an equally massive star.
"We think of black holes as the vacuum cleaners of the Universe. They suck in everything in their paths, including gas clouds and stars," study co-author Susan Scott said in a news release.
"They also suck in other black holes and it is possible to produce bigger and bigger black holes by the ongoing collisions of earlier generations of black holes," said Scott, a professor of astrophysics at the Australia National University. "The heavier 'impossible' black hole in our detected collision may have been produced in this way."
Analysis of the gravitational wave signal detected by LIGO and Virgo suggests the two black holes merged when the universe was seven billion years old, about half its current age. The blip of a signal, which lasted just one-tenth of a second, is the most distant gravitational wave signal yet detected.
Though the signal was brief, it wasn't subtle.
"This doesn't look much like a chirp, which is what we typically detect," Virgo astronomer Nelson Christensen, a researcher at the French National Center for Scientific Research, told MIT News. "This is more like something that goes 'bang,' and it's the most massive signal LIGO and Virgo have seen."
The merger responsible for generating the record signal produced a black hole with a mass of 142 stellar masses, making GW190521 an intermediate mass black hole, or IMBH -- bigger than a stellar mass black hole but not a supermassive black hole.
"We are very excited to have achieved the first direct observation of an IMBH in this mass range," said Scott. "We also saw how it formed, confirming that IMBHs can be produced through the merger of two smaller black holes."
Models of the universe suggest there should be a lot more black holes than scientists have been able to find. The latest research can help cosmologists better understand the variety of ways black holes can form.
"Every observation we make of two black holes colliding gives us new and surprising information about the lives of black holes throughout the universe," said ANU researcher Vaishali Adya. "We are beginning to populate the black hole mass gaps previously thought to exist, with 'impossible' black holes that have been revealed through our detections."
