Space scientists speculate that intermediate-mass black holes exist. These are black holes with the capability to partly devour wayward stars and then flinging the remains across the galaxy.
There are different types of black holes. Some are created when supernovae collapse, stellar remnant black holes are about 3 to 10 times the mass of our sun. On the other end of the spectrum, supermassive black holes, which lurk in the centres of galaxies, are millions to billions times the mass of our Sun. Intermediate-mass black holes are thought to fit somewhere in the middle: 10 to 10,000 times more massive than stellar remnant black holes but not nearly as massive as supermassive black holes.
While astrophysicists have not yet proven the existence of phenomena called ‘intermediate-mass black holes’, new 3D computer simulations have allowed researchers to model how intermediate-mass black holes might interact with nearby stars. This assessment will aid the detection of these types of black holes.
The computer models used black holes of varying masses and assessed how they might hurl stars (about the size of our Sun). This demonstrated that when a star approaches an intermediate-mass black hole, it initially becomes caught in the black hole’s orbit.
Following this, the black hole begins the process of consuming the star. Each time the star makes a lap, the black hole takes away some of the matter. The researchers describe this as akin to cannibalizing the star with each passage.
Eventually, nothing is left but the star’s misshapen and incredibly dense core. At that point, the black hole ejects the remains. The star’s remnant is pushed away across the galaxy.
The researchers from Northwestern University have also discovered that stars would orbit the black hole as many as five times, losing mass on each orbit, and then get ejected back into the galaxy. In terms of a sign or signal, each time a star loses mass, it becomes more luminous, creating a flare signature.
Astronomers can potentially use this signature in order to search for medium black holes.
According to lead researcher Fulya Kıroğlu: “We obviously cannot observe black holes directly because they don’t emit light. So, instead, we have to look at the interactions between black holes and their environments. We found that stars undergo multiple passages before being ejected. After each passage, they lose more mass, causing a flair of light as its ripped apart. Each flare is brighter than the last, creating a signature that might help astronomers find them.”
The findings have been presented to the American Physical Society’s (APS) April 2023 meeting, with the presentation titled: “Tidal disruption events of stars by intermediate-mass black holes”.
