This Huge Black Hole Is Spinning at Half the Speed of Light!

James Marshall
January 11, 2019

Studying distant black holes in any great detail is very hard due to the fact that nothing, including light, can escape their grasp once its gets too close.

Measurements taken through multiple telescopes show brief blips of X-ray energy being released, apparently just as debris from a disintegrating star circles the black hole's event horizon - the point just before complete oblivion.

However, the boundary of a black hole-the event horizon, which is the point of no return-offers some opportunity for study.

Because MAXI had caught the black hole's initial outburst, the team began studying the X-rays emitted from the black hole over a month, measuring how they bounced off the accretion disk.

Black holes are mysterious cosmic destroyers, but we just got one step closer to figuring out one of the key characteristics of how they work: how fast they're spinning.

By observing the X-rays blasting from a star torn apart by a black hole, a team of researchers were able to calculate how fast the black hole spins - clocking it at almost 50 percent the speed of light. The findings, published in Science, focus on a supermassive black hole located nearly 290 million light years away. These X-rays can be seen every time the star orbits the black hole, which is once every 131 seconds. That data, along with the black hole's mass, suggests the supermassive black hole at the centre of the event labelled ASASSN-14li is spinning at 50 percent the speed of light.

Scientists used NASA's Chandra and Hubble space telescopes, as well as other instruments, to study the supermassive black hole system ASASSN-14li and determine the spin rate of the black hole, a fundamental property that has been hard for astronomers to measure.

But now astronomers think the streams of electromagnetic energy emitted by stars as they get sucked into nothingness might help. That black hole had captured a passing star and was ripping it apart.

The findings, reported today in the journal Science, are the first demonstration of a tidal disruption flare being used to estimate a black hole's spin. The event, known as a tidal disruption flare, for the black hole's massive tidal pull that tears a star apart, created a burst of X-ray activity near the center of the galaxy. "Estimating spins of several black holes from the beginning of time to now would be valuable in terms of estimating whether there is a relationship between the spin and the age of black holes".

Researchers from the US and the Netherlands were looking at a "tidal disruption event" or TDE (the name for a star being destroyed by a black hole) that was detected in 2014. This pulse allows scientists to try to define certain properties of the black hole in question, such as its mass and spin. The event, he said, appears to match theoretical predictions. This marks the first time that astronomers used X-rays, which orbit the black hole every 131 seconds, to calculate its incredible speed.

Such a white dwarf may have been circling the supermassive black hole, at ISCO - the innermost stable circular orbit - for some time.

As the second star disappeared, the remnants that astronomers have now identified would have been dragged into the white dwarf's wake, allowing us to see it for the first time - essentially lighting it up so it could be detected by telescopes.

The scientists admit that such a scenario would be incredibly rare and would only last for several hundred years at most - a blink of an eye in cosmic scales. The chances of detecting such a scenario would be exceedingly slim. "That gives us information about the spin rate of the supermassive black hole itself". A black hole is a collapsed star with a core so dense that it has near-unimaginable gravitational power.

"In the next decade, we hope to detect more of these events", Pasham says.

This research was supported, in part, by NASA.

Other reports by Click Lancashire

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