Hidden black hole discovered in our neighboring galaxy
By Ashley Strickland, CNN
A newly discovered black hole has been hiding in a cluster containing thousands of stars in our neighboring Large Magellanic Cloud galaxy. The black hole is 160,000 light-years away from Earth, and it’s 11 times the mass of our sun.
Astronomers found it by using the European Southern Observatory’s Very Large Telescope in Chile and observing how the black hole’s gravity influenced the motion of a nearby star, which is about five times the mass of our sun.
It’s the first time this way of detecting a black hole has been used, and it could help researchers uncover other hidden black holes in our Milky Way galaxy and other galaxies.
The more astronomers learn about black holes, the better they can understand how these cosmic objects form and change over time. A paper describing this discovery has been accepted for publication in the Monthly Notices of the Royal Astronomical Society.
“Similar to Sherlock Holmes tracking down a criminal gang from their missteps, we are looking at every single star in this cluster with a magnifying glass in one hand trying to find some evidence for the presence of black holes but without seeing them directly,” said Sara Saracino, research lead and a member of the faculty of engineering and technology from the Astrophysics Research Institute of Liverpool John Moores University, in a statement.
“The result shown here represents just one of the wanted criminals, but when you have found one, you are well on your way to discovering many others, in different clusters,” Saracino said.
While black holes are tricky to spot, they tend to give away their otherwise invisible presence by their actions. Black holes emit X-rays when they gobble up surrounding matter or create gravitational waves when they crash into one another or collide with dense neutron stars.
But all black holes are not created equal, and this one is smaller than some of the others astronomers have detected. It was only noticeable to the researchers once they saw a star with peculiar motion among so many other stars that weren’t behaving the same way.
“The vast majority (of black holes) can only be unveiled dynamically,” said Stefan Dreizler, study coauthor and professor at the University of Göttingen in Germany, in a statement.
“When they form a system with a star, they will affect its motion in a subtle but detectable way, so we can find them with sophisticated instruments.”
It’s the first time astronomers have found a young black hole in a cluster of stars that are also this young — about 100 million years old, which is infancy when compared with the rest of the universe.
Going forward, astronomers could use this method to find other young black holes to understand their evolution and compare them with larger black holes in older star clusters to see how black holes grow over time.
“Every single detection we make will be important for our future understanding of stellar clusters and the black holes in them,” said Mark Gieles, study coauthor and research professor at the University of Barcelona, Spain, in a statement.
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