What keeps University of Utah researcher Anil Seth up at night and brimming with enthusiasm?

The discovery of what he and other scientists say is the best solid evidence so far indicating a black hole in the star cluster Omega Centauri.

“This is a once-in-a-career kind of finding,” he said. “Every time I think about it, I have a hard time sleeping. I think that extraordinary claims require extraordinary evidence. This is really, truly extraordinary evidence.”

Seth is associate professor of astronomy at the University of Utah and co-principal investigator of a study published Wednesday in the journal Nature detailing the closest known example of a black hole — about 18,000 light years way. The study found:

  • Newly identified fast-moving stars in the star cluster Omega Centauri provide solid evidence for a central black hole in the cluster.
  • With at least 8,200 solar masses, that black hole is the best candidate for a class of black holes astronomers have long believed to exist: intermediate-mass black holes, formed in the early stages of galaxy evolution.
  • The discovery bolsters the case for Omega Centauri as the core region of a galaxy that was swallowed by the Milky Way billions of years ago. Stripped of its outer stars, that galaxy nucleus has remained “frozen in time” since then.

According to the university media release, Omega Centauri is a spectacular collection of 10 million stars, visible as a smudge in the night sky from southern latitudes. Through a small telescope, it looks no different from other so-called globular clusters; a spherical stellar collection so dense towards the center that it becomes impossible to distinguish individual stars.

But this study, which also involved the Max Planck Institute for Astronomy, confirms what astronomers had argued about for over a decade: Omega Centauri contains a central black hole. The black hole appears to be the missing link between its stellar and supermassive kin — stuck in an intermediate stage of evolution. It seems that that Omega Centauri seems to be the core of a small, separate galaxy whose evolution was cut short when it was swallowed by the Milky Way.

Science News reported on the reaction and explained the significance.

“It’s like a missing link that is needed to explain the existence of the supermassive black holes,” says Texas-based astronomer and data scientist Eva Noyola, who was not involved in the new work. “If it’s proven that (intermediate-mass black holes) happen in dense stellar clusters, you have a solution there that’s pretty elegant and simple.”

“Astronomers have been hunting for midsize black holes for decades, and searching Omega Centauri specifically since at least 2008. As the most massive cluster of stars in the Milky Way, it’s a relatively easy spot to search, and it may be the remnant core of another galaxy that merged with the Milky Way about 10 billion years ago.

“It’s basically a galactic nucleus frozen in time,” says study coauthor Nadine Neumayer, also of the Max Planck Institute for Astronomy. Its black hole could be representative of all small galaxies’ black holes 10 billion years ago. “It tells us immediately something about the seed mass for black holes.” With that, researchers are optimistic the data could provide invaluable ‘galactic’ clues for moving forward toward additional findings that shape knowledge about space.

Black holes and Big Foot

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You would not think something that is in a star cluster about 8,200 times the size of the sun would be hard to spot, but that’s the challenge.

These “medium-sized” black holes are difficult to find. The university said that while there are promising candidates, there has been no definite detection of such an intermediate-mass black hole — that is until now.

“There are black holes a little heavier than our sun that are like ants or spiders—they’re hard to spot, but kind of everywhere throughout the universe. Then you’ve got supermassive black holes that are like Godzilla in the centers of galaxies tearing things up, and we can see them easily,” said Matthew Whittaker, an undergraduate student at the University of Utah and co-author of the study. “Then these intermediate-mass black holes are kind of on the level of Bigfoot. Spotting them is like finding the first evidence for Bigfoot — people are going to freak out.”

People can do more than just read about this but actually watch the research come to life on Aug. 8 at 7 p.m. when Seth will present these once-in-a-lifetime findings at the Clarke Planetarium IMAX theater in Salt Lake City.

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