This is what it looks like when a black hole snacks on a star

This illustration shows a glowing stream from a star that was torn into pieces by a supermassive dark hole. A ring of dust surrounds the feeding black hole, similar to how a toddler's plate is covered in crumbs after eating. Credit: NASA/JPL-Caltech
Although black holes and toddlers may not have much in common but they share one thing in common: They are both messy eaters. This is a strong indicator that there has been a meal.

While one may leave behind a few drops of pasta or yogurt, the other leaves behind a trail of staggering proportions. A "tidal disruption" is a phenomenon that occurs when a black hole swallows up a star. The star's destruction is followed by a burst of radiation that can exceed the combined light from all the stars in the host galaxy for many months or even years.

A team of astronomers led By Sixiang Wen (a postdoctoral researcher at the University of Arizona Steward Observatory), use the Xrays from a tidal disturbance event called J2150 to measure the mass and spin of the black hole in a paper published by The Astrophysical Journal. This particular black hole is an intermediate-mass blackhole, which has been difficult to observe.

Ann Zabludoff (UArizona professor in astronomy, co-author of the paper) said that "the fact that we were able t catch this black hole as it was devouring a Star offers a remarkable opportunity for observation what otherwise would have been invisible." "Analyzing the flare allowed us to gain a better understanding of this mysterious category of black hole, which could be responsible for most black holes found in the centers galaxies.

The authors reanalyzed the X-ray data that was used to observe J2150's flare and compared it with advanced theoretical models. They found that the flare was indeed the result of an encounter between an unlucky Star and an intermediate-mass Black hole. The intermediate black hole is a very small black hole for a black hole. It weighs in at approximately 10,000 times that of the sun.

Wen stated that the X-ray emission from the inner disk, which was formed by the debris and the dead star, made it possible to infer the mass spin of the black hole and classify the black hole as an intermediate one.

Numerous tidal disturbance events have been observed in the center of large galaxies with supermassive black hole centers. A few others have also been observed in small galaxies with intermediate black hole centers. Past data is not sufficient to prove that a single tidal disturbance flare was caused by an intermediate blackhole.

"We know from modern astronomical observations that most galaxies larger than the Milky Way's center host central supermassive dark holes," Nicholas Stone, senior lecturer at Hebrew University, Jerusalem, said. These behemoths can range in size from 1,000,000 to 10,000,000 times the mass our sun and become powerful sources for electromagnetic radiation when interstellar gases fall into their vicinity.

These black holes have a mass that is closely related to the total mass of the host galaxies. The largest galaxies are home to the most massive supermassive black hole.

Peter Jonker, co-author of the paper from Radboud University and SRON Netherlands Institute for Space Research in the Netherlands said that "we still don't know much about the existence black holes in the centres of galaxies smaller then the Milky Way." It is difficult to find central black holes smaller than 1,000,000 solar masses due to limitations in observational data.

A star that is too close to a dark hole will experience intense gravitational waves, which break it apart into a stream gas. This is known as a "tidal disruption". A tidal disturbance can cause a galaxy to shine brighter when it releases enormous amounts of energy. Credit: NASA's Goddard Space Flight Center/Chris Smith. (USRA/GESTAR).

Jonker says that supermassive black hole origins are unknown despite their apparent abundance. Many theories exist to explain them. The seeds of supermassive black hole growth could come from intermediate-mass blackholes.

He said, "Therefore, we can get a better grasp of how many bona-fide intermediate black holes there are, it can help us determine which theories about supermassive hole formation are correct."

Zabludoff says that even more interesting is the measurement of J2150 spin that the group was capable to make. The spin measurement provides clues about how black holes grow and may even lead to particle physics.

The black hole spins fast, but not at the fastest speed, Zabludoff explained. This raises the question: how does it end up with such a spin?

She said that it was possible that the blackhole formed in this way, and that it hasn't changed since. Or that two intermediate mass black holes merged to create this one. We know that the spin measurements exclude scenarios in which the black hole is fueled by steady gas intake or random gas snacking.

The spin measurement also allows astrophysicists test hypotheses regarding the nature of dark matter. This is believed to be the majority of the matter in our universe. Dark matter could be composed of unknown elementary particles that have not been seen in laboratory experiments. Stone explained that among the candidates are ultralight bosons, a hypothetical class of particles.

He said that if these particles are present and have masses within a specific range, they will stop an intermediate-mass blackhole from spinning fast. But J2150's black holes are spinning very fast. Our spin measurement rules out many ultralight boson theories. This highlights the importance of black holes as extraterrestrial laboratories in particle physics.

The authors believe that future observations of tidal disturbance flares could allow astronomers to fill in the gaps in black hole mass distribution.

Stone stated, "If it turns out most dwarf galaxies have intermediate-mass black holes, then they will dominate stellar tidal disruption rate." Wen said, "By fitting X-ray emission from these flares with theoretical models, it is possible to conduct a census on the intermediate-mass Black hole population in the universe."

However, it is necessary to observe more tidal disturbance events in order to do this. Astronomers have high hopes that new telescopes will soon be available on Earth and in space. This includes the Vera C. Rubin Observatory (also known as Legacy Survey of Space and Time or LSST), which is expected discover thousands of tidal disturbance events each year.

Further Black hole seeds are key to galaxies behemoths.

Information: Sixiang Wen and colleagues, Mass, Spin and Ultralight Boson Constraints From the Intermediate-mass Black Hole In the Tidal Disruption event 3XMM J215022.4055108. The Astrophysical Journal (2021). Journal information: Astrophysical Journal Sixiang Wen et al, Mass, Spin, and Ultralight Boson Constraints from the Intermediate-mass Black Hole in the Tidal Disruption Event 3XMM J215022.4055108,(2021). DOI: 10.3847/1538-4357/ac00b5

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