Astronomers see a black hole swallow a neutron star for the first time ever

Talk about a heavy snack. For the first time, astronomers have witnessed a black hole swallow a neutron star, the densest object in the universe — all in a split second.

Ten days later they saw the same thing, on the other side of the universe. Either way, a neutron star—a teaspoon of it weighing a billion tons—spins closer to the final point of no return, a black hole, until they eventually collide together and the neutron star disappears.

Astronomers experienced the last 500 cycles before swallowing neutron stars, a process that took less than a minute and briefly generated the same amount of energy as all visible light in the visible universe.

“It was just a quick big dose,” said study co-author Patrick Brady, an astrophysicist at the University of Wisconsin-Milwaukee. Black hole ‘gets a cool dinner from a neutron star and makes itself a little bit bigger’.

The bursts of energy from the collisions were discovered when detectors on Earth detected the gravitational waves of mergers, energetic cosmic ripples flying through space and time as Albert Einstein first hypothesized. All of them came from over a billion light-years away. The waves were detected in January of 2020, but the study that analyzed and interpreted data by more than 100 scientists was published Tuesday in Astrophysical Journal Letters.

While astronomers have seen gravitational waves from two black holes colliding with each other and two neutron stars colliding with each other, this is the first time they have seen one of them collide together.

Neutron stars are the corpses of massive stars, what remains after the death of a large star in a supernova explosion. It’s so dense, Brady said, that its mass is 1.5 to twice the mass of our Sun, but it thickens to about 6 miles (10 kilometers) wide. Some black holes, known as stellar black holes, are created when a larger star collapses in on itself creating something with a strong gravitational pull from which not even light can escape.

Scientists believe that there must be many pairs of neutron stars and a black hole, but they have not yet found one in our galaxy.

“This is pretty cool,” said Mark Kamionkowski, an astrophysicist at Johns Hopkins University, who was not part of the research. This will help astronomers predict how abundant these pairings will be, he said.

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