The discovery of a black hole with a "dormant" star mass
The circle of known black holes in the universe is expanding, with a team of astrophysicists announcing the discovery of the first "dormant" stellar-mass black hole orbiting another star in a neighboring galaxy.
And while these black holes are believed to be common in the universe, they have proven difficult to find.
The international team found a "needle in a haystack," said Tomer Schinar, an astrophysicist at the University of Amsterdam, lead author of the new study published in the journal Nature Astronomy.
The team was searching in the sky for an object that eventually turned out to be a binary black hole, in which two black holes orbit each other after swallowing their stars in a supernova explosion.
"We found a massive star that weighs 25 times the mass of our sun and orbits something we don't see," Shinar told AFP.
Researchers believe that the blue star, located in the large Magellanic Cloud galaxy that neighbors the Milky Way, is constantly associated with a black hole nine times the mass of our sun.
These types of black holes are usually discovered by X-rays they emit while collecting material from their companion star.
But this binary system, known as VFTS243, is described as "dormant" because it does not emit X-rays, as it is not close enough to absorb matter from its star.
100 million black holes
The Milky Way alone is believed to contain about 100 million stellar-mass black holes, which are much smaller than its large, super-massive siblings, said astrophysicist KU Leuven in Belgium .
But Sana, a co-author of the study, explained that only ten such black holes have been found.
This may be because many of these holes remain dormant and take a long time to eventually swallow their companion star.
Sana pointed out that observing these holes was like watching two people dancing in a dark room, one wearing white and the other wearing black. One may only be visible, but the other is also present.
"We have never discovered such systems before," Chinar told AFP. "There were a few allegations in the past years, but they were more or less refuted."
In fact, members of his team were among those who rejected previous discoveries of black holes, putting forward alternative hypotheses for what the data might indicate.
For this reason, Shinar said he and his team members expect more scrutiny of the discovery.
He pointed out that the team members dropped all other possibilities precisely, until they were convinced that "either in front of an invisible, obese alien, or a black hole." Then the researchers used the most famous black hole detector they know.
Shinar explained that Karim El-Badri of the Harvard-Smithsonian Center for Astrophysics has been "revealing black holes one by one" over the past two years, calling him "the destroyer of black holes."
"I sent him the data and said, 'Listen, we found this thing - prove me wrong.'"
"I had my doubts, but I couldn't find a plausible explanation for the data that didn't link it to black holes," said Al-Badri, who joined the team and ran its simulations.
This discovery could give a glimpse into how black holes form.
It is believed that stellar-mass black holes were born during the death of a large star, in a supernova explosion.
The force of the explosion causes black holes in a binary system to be in an elliptical rather than a circular orbit.
However, VFTS243 has a perfectly circular orbit as well.
"This means that the star immediately disappeared into the black hole," Shinar said, adding, "This has a lot of implications in terms of how these pairs of black holes are formed," so the star "VFTS 243" could eventually collapse in a similar way. .
"This is important evidence that all these stars may not end their lives in supernova explosions," said Andrew Norton, an astrophysicist at Britain's Open University, who was not involved in the study.
Chinar said he welcomed other scholars trying to refute the allegations.
"If someone comes along and debunks this as well, I'm sure they'll have a great explanation, something like a fat alien [hypothesis]," he added.
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