Black holes and stars have been drawn together in unfortunate ways, leading to an incredible scenario.
Scientists have discovered the black hole is incredibly elusive, being somewhere between the heavyweights and light weights in terms of mass. They have measured the intensity of X-rays that were emitted as the star was torn apart by gravity.
The discovery of intermediate mass black holes (IMBHs) is a real prize, not only because it represents a unique laboratory for astroparticle physics, but also because it may shed light on how supermassive black holes grow to such unprecedented proportions.
“The fact that we were able to catch this black hole while it was devouring a star offers a remarkable opportunity to observe what otherwise would be invisible,” said astronomer Ann Zabludoff of the University of Arizona.
“Not only that, by analyzing the flare we were able to better understand this elusive category of black holes, which may well account for the majority of black holes in the centers of galaxies.”
While the distinction between intermediate-mass black holes (IMBHs) and supermassive black holes (SMBHs) is currently unclear, intermediate-mass black holes are larger than a typical collapsed star or stellar black hole (up to a hundred solar masses) but not supermassive (between a million and a billion times more mass than a typical stellar black hole).
Detections of IMBHs to date have been scarce. There have been a few observations of IMBHs so far, but modeling suggests there may be a lot more out there.
As a star gets close enough, black holes, usually invisible, are revealed. After that, the immense gravitational pull of the black hole stretches and then rips the star apart due to its tidal force.
A tidal disruption event (TDE) occurs when the debris of a star disintegrates before disappearing beyond the black hole’s event horizon.
It was spotted in 2003, in the center of a star cluster located on the outskirts of a galaxy 740 million light-years away, called J2150 (J2150 for short). The bright flare faded over the course of 10 years, allowing for a wealth of data to be collected. IMBHs were suggested by analyzing the photons.
Using sophisticated theoretical models, the new group is reanalyzing the data and testing it against astronomer Sixiang Wen’s data to measure the mass and spin of the black hole more precisely. Approximately 10,000 solar masses are responsible for the problem.
The spinning is very fast, which is fascinating. In order to study dark matter, these researchers used a fast spin. The black hole does not spin as fast as it is observed if dark matter is composed of hypothetical particles called ultralight bosons.
It offers some clues about how the black hole grew, too, with its fast spin.
“It’s possible that the black hole formed that way and hasn’t changed much since, or that two intermediate-mass black holes merged recently to form this one,” Zabludoff said.
“We do know that the spin we measured excludes scenarios where the black hole grows over a long time from steadily eating gas or from many quick gas snacks that arrive from random directions.”
In 2019, a merger led to a black hole with 142 times as much mass as the Sun. Black holes in the intermediate mass range can be created by mergers. This is how black holes can reach this size, but we don’t know how often it happens. For this to be determined, we will need to locate more information.
The center of a dwarf galaxy might be a good place to search for them. Most galaxies larger than the Milky Way host black holes at their centers, and the mass of the black hole correlates with the mass of the bulge, which is the spherical cluster of stars across the middle of the galaxy.
Since smaller galaxies have smaller black holes, one would expect them to have smaller black holes, but observing them has been difficult. It is possible, though, that we would be able to detect the dwarf galaxies based on their tidal disruption flares if most dwarf galaxies orbit IMBHs. As a first step, we will have to improve detection rate, but future instruments should make that much easier.
According to Wen, “we can estimate the black hole population of the universe by fitting the X-ray emission of these flares to theoretical models.”
The Astrophysical Journal has published the findings.