The largest collection of potential black holes ever found outside of our own galaxy have been discovered by astronomers in the neighboring Andromeda Galaxy. Scientists found at least 26 possible new black holes in the galaxy.
A black hole is a region of space having a gravitational field so intense that no matter or radiation can escape. They emit no light, hence the name, and can only be seen by light emitted by materials falling into them.
Usually, a galaxy has massive black holes in the center of it, so they are easy to spot because of the surrounding brightness. Smaller holes are much harder to find against the black outer space.
The new 26 black holes plus an additional nine previously discovered in Andromeda bring the grand total found in that galaxy to 35.
The report says that these new black holes have a mass of about five to 10 times greater than that of our sun and came to be as a result of the death of giant stars.
Robin Barnard, an astronomer at the Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts, said in a statement:
“While we are excited to find so many black holes in Andromeda, we think it’s just the tip of the iceberg. Most black holes won’t have close companions and will be invisible to us.”
Astronomers’ suspicions that Andromeda would have many more black holes than the Milky Way does, was confirmed with this discovery. This theory was based in the fact that Andromeda’s bulge, the group of stars in the middle, is much larger than ours.
“We are particularly excited to see so many black hole candidates this close to the center, because we expected to see them and have been searching for years,” Barnard said.
“When it comes to finding black holes in the central region of a galaxy, it is indeed the case where bigger is better,” co-author Stephen Murray of Johns Hopkins University and the Center for Astrophysics said in a statement. “In the case of Andromeda, we have a bigger bulge and a bigger super massive black hole than in the Milky Way, so we expect more smaller black holes are made there as well.”
The discovery was made using NASA’s Chandra X-Ray Observatory, which took 13 years to make the findings. Researchers observed the X-ray light given off by the objects to determine whether they were likely to be black holes rather than other dense objects called neutron stars.
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