In 2014, a supermassive black hole was detected in a galaxy 290 million light-years from Earth — after astronomers picked up a strong X-ray signal coming from this far-off object. Spotted by the All-Sky Automated Survey for Supernovae (ASASSN) on November 22, the signal turned out to be produced not by a supernova, but by a black hole that was emitting a tremendous amount of energy while gobbling up a nearby star, notes Physics World.
Dubbed ASASSN-14li, after the network of telescopes that aided in its discovery, the supermassive black hole was found to be between 1 million and 10 million times as massive as the sun. That’s in the same ballpark as the black hole at the center of the Milky Way galaxy, known as Sagittarius A* — a black hole which boasts a mass 4 million times larger than that of the sun, as previously reported by the Inquisitr.
The monster black hole was recently studied with NASA’s Chandra and Neil Gehrels Swift X-ray observatories, as well as with the XMM-Newton space observatory of the European Space Agency (ESA). The effort led to an incredibly rare find, unveiling the spin rate of ASASSN-14li.
“Astronomers can estimate a black hole’s mass relatively easily from a relationship between it and the properties of the host galaxy. Getting good estimates of black hole spin, on the other hand, have been notoriously difficult,” explains the Chandra X-Ray Observatory.
The results of this latest research on ASASSN-14li were published yesterday in the journal Science — and are absolutely “mind-boggling,” according to Space. As it turns out, the mammoth black hole is spinning at a very fast velocity, one that was calculated to be half the speed of light.
This incredible revelation came after the team picked up a very intense X-ray signal coming from ASASSN-14li, which was most likely produced by leftover material from the dying star.
Known as a tidal disruption flare — an emission coming from a tidal disruption event, which is the violent process in which a massive back hole consumes a star — the signal is believed to have originated from a clump of gas belonging to the torn-apart star — stuck in the innermost stable circular orbit around the black hole. This is the closest spot where objects can orbit a black hole without being devoured by it, Astronomy magazine explains.
The latest telescope observations revealed that this signal — representing the “final cries” of the shredded star, as poetically described by the ESA — oscillated in brightness every 131 seconds, appearing as X-ray bursts near the black hole’s event horizon — the point where the object starts swallowing material, and where its gravity is so strong that even light can’t escape. What’s more, the bright emissions remained constant for more than 450 days, detailed the space agency.
The data, combined with previous information on the black hole’s size and mass, revealed that ASASSN-14li was spinning very rapidly, at more than 50 percent of the speed of light.
“It’s an exceptional finding: such a bright signal that is stable for so long has never been seen before in the vicinity of any black hole,” said study co-author Alessia Franchini, an astronomer at the University of Milan, Italy.
Commenting on the discovery, team member Ron Remillard of the Massachusetts Institute of Technology offered more details on the fast spin of ASASSN-14li.
“This black hole’s event horizon is about 300 times bigger than the Earth. Yet the black hole is spinning so fast it completes one rotation in about two minutes, compared to the 24 hours it takes our planet to rotate.”
However, study lead author Dheeraj Pasham, also from MIT, revealed that the spin rate of ASASSN-14li is actually “not super-fast.”
“There are other black holes with spins estimated to be near 99 percent the speed of light. But this is the first time we’re able to use tidal disruption flares to constrain the spins of supermassive black holes.”