Massive Clouds of Gas Hurtle Around Our Galaxy's Black Hole at One-third the Speed of Light

Astronomers have spotted huge swaths of gas spinning around the supermassive black hole thought to sit at the heart of the Milky Way.

The rambunctious clouds—observed moving at almost one-third of the speed of light—are a "resounding confirmation" of scientists' long-standing belief in the galactic behemoth known as Sagittarius A*, researchers said in a statement released by the European Southern Observatory (ESO).

Black holes are regions of space where gravity is so intense it gulps up everything from matter to light that strays too close. As a result, the holes themselves are completely dark and incredibly cold. But nearby orbiting matter gets fiercely hot and bright as it races around the massive objects.

Astronomers using the ESO's GRAVITY instrument on the Very Large Telescope in Chile spied some of the material charging around Sagittarius A*. Flares of infrared radiation alerted scientists to the gas swirling near the black hole's event horizon.

10_30_Black hole simulation
This visualization uses data from simulations of orbital motions of gas swirling around at about 30 percent of the speed of light on a circular orbit around the black hole. ESO/Gravity Consortium/L Calçada

The infrared signals flashed from the innermost stable orbit of the spinning mass—giving scientists the best glimpse yet of matter moving so close to a black hole. Get any closer, and the black hole would gobble the gas right up. But in this stable region, it can orbit safely if it spins fast enough—hence the incredible speed of the careening gas clumps.

"It's mind-boggling to actually witness material orbiting a massive black hole at 30 percent of the speed of light," Oliver Pfuhl, a scientist at the Max Planck Institute for Extraterrestrial Physics, said in the ESO statement. "GRAVITY's tremendous sensitivity has allowed us to observe the accretion processes in real time in unprecedented detail."

Researchers spotted the flares by chance while measuring a star called S2 travel through a gravitational field near the black hole, Pfuhl explained.

The striking observations offer "a resounding confirmation of the massive black hole paradigm," Reinhard Genzel, also of the Max Planck Institute for Extraterrestrial Physics, said in the statement. Genzel led the study, which was published Wednesday in the journal Astronomy & Astrophysics.

Harvard University theoretical physicist Avi Loeb told Newsweek he was "excited" by the discovery. His own previous work had predicted what Sagittarius A*'s hotspot might look like. "Only 12 years later, this new data confirms our theoretical expectations and opens a new experimental testbed for General Relativity," he said. "This testbed is as significant as —but complementary to—gravitational waves."

In 2016, scientists announced they had detected gravitational waves for the very first time, confirming the spacetime ripples predicted by legendary physicist Albert Einstein's general theory of relativity. "These are exciting times for the interplay between theory and observations regarding Einstein's gravity in the vicinity of black holes," Loeb added.

In other black hole news, legendary cosmologist Stephen Hawking's final research paper was recently published online. The last offering from the late scientist—who passed away in March after a five-decade battle with ALS—concerns hairy black holes.

This article has been updated to include comment from Avi Loeb.

Massive Clouds of Gas Hurtle Around Our Galaxy's Black Hole at One-third the Speed of Light | Tech & Science