SALT LAKE CITY — In a galaxy that stretches across many light years and is more than 13 billion years old, it’s understandable that major astronomical discoveries are few and far between — and that would be putting it mildly.
The galaxy contains Omega Centauri, a cosmic cluster of millions of stars – so dense toward the center that individual stars are impossible to distinguish – visible only as a tiny speck in the night sky from southern latitudes.
But there’s something within that cluster that astronomers have been looking for and debating for nearly a decade, and a new study from researchers at the University of Utah and the Mac Planck Institute for Astronomy has confirmed it: Omega Centauri has a central black hole.
“This is a once-in-a-career discovery. I’ve been excited about it for nine months straight. Whenever I think about it, I have a hard time sleeping,” said Anil Seth, associate professor of astronomy at the U.S. and co-principal investigator of the study.
‘On the level of Bigfoot’
StudyThe study, published in the journal “Nature” on Wednesday, states that black holes come in different mass ranges.
Common black holes include stellar black holes, with masses ranging from one to a few dozen solar masses, and supermassive black holes, with masses equivalent to billions of suns.
Even more infamous are the intermediate-mass black holes that have not yet been definitively identified, the ones discovered by the research team.
“These intermediate-mass black holes are Bigfoot-level. Finding them is like finding the first evidence for Bigfoot — people will freak out,” said Matthew Whittaker, a graduate student at the University of California and co-author of the study.
‘needle in a haystack’
Omega Centauri appears to be the center of a small, isolated galaxy whose growth stopped when it was swallowed up by the Milky Way, the paper says. The current state of galaxy evolution suggests that these early galaxies should have had moderately sized central black holes that would have grown over time.
But how do you find it?
Seth and Nadine Neumayr, group leaders at the Max Planck Institute and principal investigators of the study, first began researching how to better understand the formation history of Omega Centauri in 2019.
They realized that if they could find stars rotating rapidly around its center, they could finally settle the question surrounding the cluster’s central black hole by measuring the black hole’s mass.
The discovery of these stars fell into the hands of Maximilian Haberle, a doctoral student at the Max Planck Institute. Haberle went on to develop a massive catalog of the motions of stars in Omega Centauri, studying more than 500 Hubble images of the cluster and measuring the velocities of 1.4 million stars.
The challenge was that most of the images available to Haberle were taken to test Hubble’s instruments, not to aid in any revolutionary scientific discovery.
Still, with over 500 images, this unadulterated dataset served its purpose.
“Looking for fast-moving stars and documenting their motions was like finding a needle in a haystack,” Haberle said. In the end, Haberle not only had the most complete catalog of the motions of stars in Omega Centauri to date, but he also found seven needles in his archival haystack — seven fast-moving stars in a small region at the center of Omega Centauri.
Search
However, the work didn’t end with finding these seven stars. With all seven stars having different velocities and motion directions, researchers were able to separate the different effects and determine that Omega Centauri does in fact have a central mass, with a mass equivalent to at least 8,200 Suns.
Furthermore, the images do not indicate any visible object at the location of the central mass, as would be expected for a black hole.
Further analysis revealed even more good news for the team. As the paper explains, a single high-speed star in the image may not belong to Omega Centauri. It could be a star from outside the cluster that coincidentally passes right behind or in front of the centre of Omega Centauri. On the other hand, the observation of seven such stars cannot be a coincidence and leaves no room for any other explanation than the presence of a black hole.
Checkmate.
Going forward
The team now plans to build on their important findings by further probing the centre of Omega Centauri. Seth is leading a project that has been approved to measure the speed of high-speed stars moving towards or away from Earth using the James Webb Space Telescope.
As Devices of the future roll out what could be Accurately locating the position of stars With even greater precision than Hubble, the goal is to determine how stars speed up and how their orbits curve – however, this project will fall into the hands of future generations of researchers.
Still, the discovery makes the case for Omega Centauri, a galaxy that engulfed the Milky Way billions of years ago.
For those interested in hearing directly from the researchers, Seth will be presenting the team’s findings at the Clark Planetarium IMAX Theater in Salt Lake City on August 8 at 7 p.m. In the meantime, the full study can be found here Online.
“I think extraordinary claims require extraordinary evidence. This is truly extraordinary evidence,” Seth said.
Disclaimer : The content in this article is for educational and informational purposes only.
