Columbia Scientists Say They Found Thousands of Black Holes at the Galactic Center of the Milky Way

Wednesday, 04 April 2018 - 1:29PM
Science News
Space
Wednesday, 04 April 2018 - 1:29PM
Columbia Scientists Say They Found Thousands of Black Holes at the Galactic Center of the Milky Way
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Image credit: YouTube/Outer Places

There is a theory, which claims that deep at the heart of our galaxy, there exist tens of thousands of small black holes, which all congregate around the larger, more noteworthy Sagittarius A*, like tiny soap bubbles stuck onto the side of a much larger bubble as everything swirls down the plug hole.

This theory makes sense based on our understanding of black holes and the formation of galaxies—according to everything we understand about the Milky Way, there's a lot of energetic, bright activity at the center of the galaxy, as stars are born, grow, and then die and rend themselves apart as they transform into black holes. Based on the sheer number of stars forming at the Milky Way's core, there should logically be a lot of black holes in a relatively tightly packed area of space.

The problem with this theory is that, until now, it's been exceptionally hard to prove. Black holes have earned their name for a reason—they're incredibly hard to spot because they don't give off any energy readings unless they're actively chowing down on matter or information that can be recorded. A black hole that isn't eating appears as a single dark dot against an equally dark background, and as such, is almost totally invisible.


Finally, though, researchers at Columbia University have come up with a way to measure these distant black holes and to prove their existence.

Thus far, efforts to locate black holes have centered around watching out for bursts of X-rays that are given off periodically as matter falls into their gaping maws. This isn't a hugely effective way to spot black holes, because the distance between the Earth and the center of the galaxy mean that for smaller black holes, these X-rays are too small and weak to be discernible.

Instead, the researchers looked for slow-burn signals that would also indicate the presence of smaller black holes, in order to spot all of the signals that otherwise can't be observed.

According to the study's lead author Chuck Hailey:

Opening quote
"Isolated, unmated black holes are just black—they don't do anything. So looking for isolated black holes is not a smart way to find them either. But when black holes mate with a low mass star, the marriage emits X-ray bursts that are weaker, but consistent and detectable. If we could find black holes that are coupled with low mass stars and we know what fraction of black holes will mate with low mass stars, we could scientifically infer the population of isolated black holes out there."
Closing quote


Using this method, the team identified 12 newly discovered black holes within three light years of Sagittarius A*. Extrapolating this data out to account for the full size of the Milky Way's core, there are likely between 300 and 500 black hole pairs in circulation around each other, and 10,000 isolated black holes that are spinning around by themselves.

Finally, definitive proof for a long-held belief about black holes has been found. This bodes well for future research. "Everything you'd ever want to learn about the way big black holes interact with little black holes, you can learn by studying this distribution," said Haley. 

It'll be very interesting to see what happens next with this research, and what more can be learned both about black holes and about the center of our galaxy, from this exciting study.

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