It was the cosmic equivalent of a high-speed collision between a Ford-F550 and a Harley Sportster.
Last year, on August 14, a black hole 23 times more massive than our sun smashed into a smaller object, one only 2.6 times more massive than the sun.
The collision set off ripples in spacetime that were detected by two observatories, one known as Virgo and the other as LIGO, or the Laser Interferometer Gravitational-Wave Observatory. After studying those ripples, physicists believe the smaller object is either a neutron star or another black hole.
But no matter what the object is, it’s the mass of the object that has physicists excited.
There’s little doubt that the smaller object is either a neutron star or a black hole. Thus, it would be either the largest neutron star or the smallest black hole yet discovered.
Jolien Creighton, a physics professor at the University of Wisconsin-Milwaukee said this mass is “unusual” for either a neutron star or a black hole. Creighton leads a team that helped detect this collision and is one of the approximately 1,300 team members involved with the study,released Tuesday in The Astrophysical Journal Letters.
Neutron stars are small, super-dense stars formed from the death and collapse of larger stars. If the smaller object detected in this study was a neutron star, it could change theories about how massive a neutron star can possibly get before collapsing into a black hole.
“That would be quite a surprise because we don’t think that mass could hold up a neutron star at the mass that we observed,” said Creighton.
If the smaller object was a black hole, then it would be the smallest black hole ever observed.
According to John Friedman, an emeritus professor of physics at UWM who was not involved with this study, this result and a past LIGO observation suggest that black holes of this size could form from these cosmic collisions more frequently than expected.
“This is going to change how scientists talk about neutron stars and black holes,” said Patrick Brady, a physics professor at UWM, in a news release. Brady was involved with the study.
LIGO was the first observatory to detect gravitational waves, ripples in the fabric of spacetime. Gravitational waves previously detected by LIGO came from violent collisions of objects with relatively similar masses.
Not enough data was collected during the Aug. 14 collision to determine if the smaller object is a neutron star or a black hole. Physicists are hoping to observe similar collisions in the future in order to puzzle out what the smaller object actually is.
“LIGO and Virgo have given us many wonderful surprises since they began to take data, and this is the latest one,” said Eric Poisson, a professor of physics at the University of Guelph who was not involved with the study. “Astrophysicists will be busy trying to understand what this mysterious object is.”
Jordan Nutting is a AAAS Mass Media Fellow writing about science at the Milwaukee Journal Sentinel this summer. She’s working on a Ph.D. in organic chemistry at the University of Wisconsin-Madison.
Read or Share this story: https://www.jsonline.com/story/news/2020/06/25/black-hole-impact-detected-ligo-raises-massive-questions/3249257001/