Inert stellar-mass black holes, which form when massive stars reach the end of their lives, are hard to spot, because they don’t interact much with their surroundings. This is because, unlike most black holes, dormant holes do not emit high levels of X-rays.
Although this type of black hole is considered a fairly common cosmic phenomenon It has not been “unequivocally detected outside our galaxy,” according to the team of American and European researchers involved in the study.
The newly discovered black hole, called VFTS 243, has a mass at least nine times the mass of our Sun. It orbits a hot blue star that weighs 25 times the mass of the Sun, making it part of a binary system.
“It’s incredible that we barely know about dormant black holes, given how much astronomers think about them,” said study co-author Pablo Marchant, an astronomer at KU Leuven, a Belgian university, in a بيان صحفي.
exclusion process
To find the black hole, which is not directly observable, astronomers examined 1,000 massive stars (each weighing at least eight times the mass of the Sun) in the Tarantula Nebula in the Large Magellanic Cloud, a galaxy near the Milky Way Lake.
The discovery was made through a process of elimination, said co-author Tomer Shenar, who worked at KU Leuven in Belgium when the study began and is now a Marie Curie fellow at the University of Amsterdam, في هولندا.
The researchers first identified stars that were part of binary systems — stars moving around a cosmic companion. Then they searched for binary systems where the companion was not visible, Careful analysis eventually showed that VFTS 243 is a dormant black hole, he explained via email.
“What we’re seeing here is a star that weighs about 25 times the mass of our sun, and it moves periodically (every 10 days or so) around something ‘invisible,’ which we can’t see in the data,” Schnarer said.
“The analysis tells us that this other ‘thing’ must be at least 9 times the mass of our sun. The main part of the analysis is disposal: what could weigh nine solar masses and not emit any light? The black hole is the only possibility we have left (this, or a large invisible alien…)”.
“There could be more out there, but only for this one we can unambiguously show the existence of a black hole,” Schnarer said.
The black hole was discovered during six years of observations by ESO’s Large Multi-Element Fiber Array (FLAMES) instrument. FLAMES allows astronomers to observe more than a hundred objects simultaneously.
black hole line
Some of the study’s 40 authors are known in astronomy circles as black hole police, according to the press release, because they debunked many other discoveries of other black holes.
The paper says that more than 10 discoveries of black hole binary systems in the past two years have been disputed. However, they were convinced that their discovery was not a “false alarm”.
“We know what the challenges are and we’ve done everything we can to rule out all other options,” Schnarer said.
The research team said they were invited to review their latest findings.
“In science, you’re always right until someone proves you wrong, and I don’t know that’s never going to happen — I just know that none of us can spot an analysis flaw,” Schnarer said.
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