July 6, 2022

Black hole wandering the Milky Way spied by Hubble

Black hole wandering the Milky Way spied by Hubble

When stars large enough to dwarf our sun die, they explode in a supernova and the remaining core is shattered by its own gravity, forming a black hole.

Sometimes, the explosion could push the black hole into motion, rushing through the galaxy like a pinball. By rights, there should be a lot of wandering black holes known to scientists, but they are practically invisible in space, and therefore difficult to detect.

Astronomers believe that 100 million floating black holes roam our galaxy. Now, researchers believe they have discovered such an object. The discovery was made after six years were devoted to observations – and astronomers were even able to accurately measure the mass of an extreme cosmic object.

The black hole is located 5,000 light-years away, and is located in a spiral arm of the Milky Way called Carina-Sagittarius. This observation allowed the research team to estimate that the closest isolated black hole to Earth could be only 80 light-years away.

But if black holes are fundamentally indistinguishable from the void in space, how did Hubble discover this hole?

The extremely strong gravitational field of black holes distorts the space around them, creating conditions that can deflect and amplify the starlight that lines up behind them. This phenomenon is known as gravitational lensing. Ground-based telescopes look at the millions of stars scattered in the center of the Milky Way and look for this transient brightness, which indicates that a large object has passed between us and the star.

Hubble is well positioned to follow up on these observations. Two different teams of researchers studied the observations to determine body mass. Both studies have been accepted for publication in the Astrophysical Journal.

one team, Led by astronomer Kailash Sahu, Hubble Instrument Scientist at the Space Telescope Science Institute In Baltimore, we determined that the black hole weighs seven times the mass of our sun.
second team Led by PhD student Casey Lamm and Jessica Lowe, an associate professor of astronomy, both from the University of California, Berkeley, reached a smaller mass range, between 1.6 and 4.4 times that of the Sun. According to this estimate, the object could be a black hole or a neutron star. Neutron stars are incredibly dense remnants of exploding stars.

“Whatever this object is, it is the first dark stellar remnant to be discovered wandering through the galaxy unaccompanied by another star,” Lamm said in a statement.

The starry sky shown in this Hubble image lies toward the center of the galaxy.

The black hole passed in front of a background star located 19,000 light-years from Earth toward the galactic center, amplifying starlight for 270 days. Astronomers have had a difficult time determining their measurements because there is another bright star very close to the one they observed shining behind the black hole.

“It’s like trying to measure the tiny movement of a firefly next to a bright light bulb,” Saho said in a statement. “We had to precisely subtract the light from a nearby bright star to accurately measure the deflection of the faint source.”

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Saho’s team believes the object could be traveling at up to 99,419 miles per hour (160,000 kilometers per hour), faster than most stars in that part of the galaxy, while Lou and Lam’s team came to an estimate of 67,108 miles per hour (108,000 kilometers per hour). ).

More data and observations from Hubble and more analysis could settle the debate over the object’s identity. Astronomers continue to search for more of these unseen anomalies, which could help them better understand how stars develop and die.

“Using the finer lens, we can examine and weigh these isolated, compressed objects. I think we’ve opened a new window on these dark objects, which you can’t see any other way,” Lu said.