This giant black hole spins at half the speed of light

This artist’s illustration shows the region around a supermassive black hole a star that wandered too close and was ripped apart. Some of the remains of the star can be drawn in a X-ray-bright disk where they circle the black hole before you get on the “event horizon”, the boundary beyond which nothing, including light, can escape. The elongated spot shows a bright region in the disk, which will cause a regular variation in the X-ray brightness of the source, so that the spin rate of the black hole to be estimated.
(Image: NASA/CXC/M. Weiss; X-ray: NASA/CXC/MIT/D. Pasham et al: Optical: HST/STScI/I. Arcavi)

The crumbs that remain of a supermassive black hole in a recent meal, have allowed scientists to calculate the sample rotation speed, and the results are mind-boggling.

The huge black hole, known as ASASSN-14li, is the spinning of at least 50 percent of the speed of light, study team members said.

“This black hole’s event horizon is about 300 times larger than the Earth,” study co-author Ron Remillard of the Massachusetts Institute of Technology (MIT), said in a statement. (The event horizon is the boundary beyond which nothing, not even light, can escape a black hole is the gravity claws.) [Images: Black Holes of the Universe]

“Yet it is the black hole rotates so fast completes one rotation in about two minutes, versus the 24 hours it takes our planet to rotate,” Remillard adds.

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ASASSN-14li is located in the heart of a galaxy 290 million kilometers from the Earth, and of the ports between 1 million and 10 million times the mass of the sun. So, it is just about as intense as the black hole in the Milky way’s core known as Sagittarius A*, which contains about 4 million solar masses. (Supermassive black holes can be much heavier; some tip the scales in the tens of billions of solar masses.)

ASASSN-14li was discovered in November 2014, after it tore apart a star that wandered too close. This dramatic event caused a flash of bright light, which was spotted by a system of optical telescopes, called the All-Sky Automated Survey for Supernovae (hence the black hole of the name).

In the new study, a team led by Dheeraj Pasham, also of MIT, observed on the X-ray light of the ASASSN-14li system. The researchers analysed the data collected by a number of instruments, including NASA’s Chandra X-ray Observatory, and Neil Gehrels Swift space telescopes, as well as the European space agency’s XMM-Newton spacecraft.

These datasets proved to be a consistent vibration: ASASSN-14li X-ray emission rise and fall every 131 seconds. This clock signal is most likely caused by a group of the torn-in addition to the star, circling around the black hole very close to the event horizon, study team members said.

“The fact that we can track the region of the bright X-ray emission around the black hole can follow us how fast the material in the disk rotates,” Pasham said in the same statement. “That gives us information about the spin rate of the supermassive black hole itself.”

That the speed of rotation is impressive, but not unprecedented. The pair of supermassive black holes whose rotation rates are clocked to date are in the same extreme near, generally whipping around between 33 percent and 84 percent the speed of light.

The new results, which Pasham presented Wednesday (Jan. 9) at the 233rd meeting of the American Astronomical Society (AAS) in Seattle, could help astronomers better understand how supermassive black holes evolve.

These giants can grow in two main ways, Pasham said — by the galaxy-scale mergers and/or by a steadily accreting smaller pieces of the surrounding material. A relatively low rotation speed would imply mergers as the primary factor, because this random smashups would probably be unable to keep up with the turning of the growing black hole in the same direction.

However, “if you have a high-spin black hole, supermassive black hole, that tells us that maybe steady accretion was dominant,” Pasham said during a press conference at AAS Wednesday.

The new study was also published online Wednesday in the journal Science. You can read a preprint of the free on

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