About 7,800 light-years away – in our galactic environment – is globular cluster NGC 6397, basically a wad of stars held together by gravity. It used to be thought that that set of stars had a medium-sized black hole in the center. But upon closer inspection, a team from the Paris Institute of Astrophysics has determined that the cluster actually houses a group of smaller black holes, holding things together in a more diffuse system.
Previous research had suggested that the cluster’s core could be populated with such a conglomeration of black holes the size of a star, but this article takes it a step further by also measuring the mass and size of those objects. The team’s investigation was published this week in the journal Astronomy and Astrophysics.
To identify the mystery at the center of the cluster, the researchers looked at how stars moved near the center using data from two space telescopes, the Hubble Space Telescope and the European Space Agency’s Gaia Observatory.
“We found very strong evidence for an invisible mass in the dense core of the globular cluster, but we were surprised to find that this extra mass is not ‘pointy’,” said Eduardo Vitral of the Paris Institute of Astrophysics, in a statement. NASA press release. If only one black hole were responsible, the mysterious mass would be more densely concentrated. “Our study is the first to provide both the mass and magnitude of what appears to be a collection of mostly black holes at the center of an the core collapsed globular cluster. “
Intermediate black holes have long been considered a missing link in the evolution of black holes. Perhaps less in the public eye than supermassive black holes (which have been proven to exist) or tiny primal black holes (which remain theoretical), intermediate black holes, as their name suggests, would help astronomers understand how these enigmatic structures evolve.
“Our analysis indicated that the orbits of the stars throughout the cluster are almost random, rather than systematically circular or very elongated,” explains Gary Mamon, also at the Paris Institute of Astrophysics, in the same release. If the orbits of the stars were coordinated, this would indicate one massive object. Instead, the stars seemed to be invested in their own ad hoc movements. Mamon and Vitral believe this is because dense stellar remnants such as white dwarfs, neutron stars and black holes – formed when stars reach the end of their lifetimes and collapse on their own – have sunk to the center of the cluster, in a sort of three. dimensional Plinko. Conversely, stars with a lower mass found their way to the periphery of the cluster.
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“The authors have conducted a thorough analysis and the conclusions of this work represent an unexpected development in the hunt [intermediate black holes] in spherical clusters, ”said Misty Bentz, an astrophysicist at Georgia State University who has no affiliation with the recent paper, in an email. “However, there are many assumptions needed in conducting these types of studies, and the results still leave room for the possibility of a [intermediate black hole] in this globular cluster.
Artistic illustrations of the globular star cluster, shown in the video above, look like someone perforated spacetime with a stellar-scale shotgun. Abysses of immense gravity loom from the cluster; the remains of dead stars that hold their living brothers together in a gravitational grid (or entangle them, depending on your view). It is no surprise that there would be so many white dwarfs, neutron stars and black holes in such an area; NGC 6397 is a very old cluster, clocks in at 12.6 billion years old, give or take half a billion, giving stars enough time to complete their life cycle.
Bentz said the new study does not fully show that the cluster contains many small black holes instead of one larger, “but if so, it makes the origins of supermassive black holes even more mysterious than they already are! That’s because, she explained, “we expect supermassive black holes to have grown from smaller seeds. But the result of this study would suggest that it is actually difficult to merge many small black holes into a globular cluster, because the globular cluster is old and yet the little black holes still hang around separately, not merged. “
It’s an intriguing findingAlthough it was predicted by Albert Einstein in 1916 that the existence of black holes was, it was only two years ago, in April 2019, that scientists actual image of a. We clearly have a lot more to learn about these mysterious objects.