A Black Hole Met a Neutron Star and Swallowed It 'Pac-Man' Style

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This battle of the ultra-dense behemoths probably didn't last long, but its aftermath was felt across the universe. Dotted Yeti/Shutterstock

About 900 million years ago, in a galaxy far away, a black hole and a neutron star crossed paths. It didn't go well for the star.

Black holes may be the Homer Simpsons of the cosmos — and not much interrupts their timeless routine of eating, burping and napping.

You might think a neutron star wouldn't go down that easily. After all, these are the ultra dense remains of stars that, as NASA puts it, can squish the mass of two-and-a-half suns into a ball that's about the size of a city.

But down the hatch went this neutron star.

And all that remained was the belch. Or, in less Homeresque terms, the gravitational waves.

At least that's the story a newly logged event dubbed S190814bv tells us.

Those gravitational waves — essentially ripples in the fabric of space caused by major cosmic events — are only now reaching us, according to scientists at Australian National University who logged it.

In fact, they claim it's the first time a collision between these cosmic heavyweights has ever been recorded. Although it probably wasn't much of a tussle — lead researcher Susan Scott compares the black hole to Pac-man "snuffing out the star instantly" — the real story is in the ripples that took hundreds of million years to get here.

Illustration of a magnetized neutron star
A neutron star packs several solar masses into a very small form factor. Jurik Peter/Shutterstock

Researchers relied on data collected by the Advanced Laser Interferometer Gravitational-wave Observatory (LIGO) in the U.S. and the European Gravitational Observatory known as Virgo.

Both are highly sensitive to gravitational waves, collecting mountains of data on the event that the worldwide scientific community is still poring over.

"It's like the night before Christmas," Ryan Foley, an astronomer at the University of California, Santa Cruz tells ScienceAlert. "I'm just waiting to see what's under the tree."

If this is Christmas for astronomers, it only took 900 million years for Santa's sleigh to get here. At least, that's what those gravitational waves suggest so far. But there's so much more to come.

"Based on this experience, we're very confident that we've just detected a black hole gobbling up a neutron star," Scott says.

"However, there is the slight but intriguing possibility that the swallowed object was a very light black hole — much lighter than any other black hole we know about in the Universe. That would be a truly awesome consolation prize."