Black Hole Collision May Have Exploded with Light June 25, 2020 Caltech

Pablo Tucker
June 28, 2020

Graham and his team used Italy's Virgo antenna and the Laser Interferometer Gravitational-Wave Observatory (LIGO), which has antennas located both in Hanford, Washington, and Livingston, Louisiana, to make the discovery. This size falls into what scientists call the mass gap: an object significantly smaller than any black hole studied to date (about 5 times the mass of the sun), but also probably larger than any known neutron star (about 2.5 times the mass of the sun). GW190814 is highlighted in the middle of the graphic as the merger of a black hole and a mystery object around 2.6 times the mass of the sun. Now, for the first time, astronomers believe they have detected the first light from a black hole merger.

Charlie Hoy, who took part in the study, said the discovery would transform our understanding of astronomy. "What is really exciting is that this is just the start".

LIGO and Virgo can detect titanic collisions involving black holes or neutron stars by measuring the slight spatial distortions created by the gravitational waves that are thrown off. Physicist Albert Einstein predicted that such waves should exist, based on his general theory of relativity, but they weren't directly observed until 2015 (which led to a Nobel Prize for LIGO's leaders).

Originally published June 23, 2020 by the global LIGO-Virgo collaboration. Future observations with LIGO, Virgo, and possibly other telescopes may catch similar events that would help reveal whether additional objects exist in the mass gap. When stars that are a bit less massive than this die, they explode in a supernova and leave behind dense, dead remnants of stars called neutron stars. As the two black holes tumbled into each other, they tore into and kicked up material in the disk, generating a piercing flare that lasted for roughly a month.

"But due to the very unequal masses of the colliding objects and because this event was so far away, the absence of any visual clues is consistent with either a binary black hole merger or the merger of a black hole with a neutron star".

Gravitational waves form when massive objects distort spacetime surrounding them and send ripples out across the universe.

"It's a challenge for current theoretical models to form merging pairs of compact objects with such a large mass ratio in which the low-mass partner resides in the mass gap".

If both of the objects were black holes, it's not likely there'd ever be any light to see.

"We don't know a lot about the nuclear physics of neutron stars".

But the other object was a mere 2.6 times the mass of our star - as yet unidentified by science.

The S190521g event happened near the supermassive black hole at the centre of our galaxy.

Either way, if GW190814 is an ultra-heavy neutron star "perhaps even new physics would be required to explain it", Rory Smith, an astrophysicist at Monash University in Australia, told CNET. "They can briefly find gravitational partners and pair up but usually lose their partners quickly to the mad dance", explained K. E. Saavik Ford, an astronomer at the City University of New York (CUNY) and a co-author of the new paper, in a press release. At the same time in the Universe was discovered a new kind of black hole. But there were plenty of gravitational waves: Some of the mass of the two combined objects - amounting to about a fifth of the mass of our sun - was converted directly into energy, in accordance with Einstein's E=mc equation. "So, every single current theory we now have of what goes on inside of one has some uncertainty".

"More cosmic observations and research will need to be undertaken to establish whether this new object is indeed something that has never been observed before or whether it may instead be the lightest black hole ever detected".

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