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CSUF Scientists Contribute to Mysterious Gravitational-Wave Signal From Neutron Star-Black Hole Cosmic Collision

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Cal State Fullerton physicists are on the forefront of a new discovery of gravitational waves from two compact cosmic objects not seen by scientists before. 

The discovery — on May 29, 2023 —  is the first gravitational-wave detection of a mass-gap object paired with a neutron star, detected during the latest observing run by LIGO, European Virgo Collaboration and Japan’s KAGRA

The international collaboration announced the new observation today at the American Physical Society meeting in Sacramento. Physicists and students from around the world, including CSUF faculty and student researchers, are attending and presenting at the meeting. 

Jocelyn Read, CSUF professor of physics and a co-author of the latest discovery, said one of the two compact objects that make up this mysterious merger with a neutron star is a small black hole — less massive than any black hole observed in the galaxy.

“It turns out this event is quite interesting because it’s a merger of a neutron star mass object — between one and just above two times the mass of the sun — with another object between 2.5 to 4.5 times the mass of our sun,” said Read, an astrophysicist. “The most massive neutron star possible is between two and three times the sun’s mass.”

The black hole is smaller because of how light it is compared to other black holes detectors have observed since the first gravitational-wave discovery in 2015. The discovery of gravitational waves from a pair of colliding black holes some 1.3 billion light-years away marked the dawn of a new era for astronomy.

“This new merger is interesting because it tells us that there are black holes out there that are much smaller than we anticipated,” said Sunny Ng, a physics graduate student and a co-author of the research.

“The fact that we’ve detected a merger with a black hole in a lower mass gap range better informs us on merger rates between compact objects and how our current model of the stellar population might look and why.”

In addition to Read and Ng, the other Cal State Fullerton co-authors of the global research effort are postdoctoral research associates Lami Suleiman and Marcie Bonilla; physics professor Geoffrey Lovelace; and Joshua Smith, professor of physics and Dan Black Director of the Nicholas and Lee Begovich Center for Gravitational-Wave Physics and Astronomy (GWPAC).

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