Rick Robinson

Jun 26th 2020

Black Hole Eruption Is a Pretty Big Bang


Astronomers using a combination of space-based and Earth-based telescopes have spotted the aftermath of the largest known cosmic outburst since the original Big Bang that formed the universe as we know it some 14 billion years ago.

The blast, reports NASA, is due to a black hole eruption in a galaxy cluster some 390 million light-years from Earth, in the direction of the far-northern constellation Ophiuchus.

How big was this eruption? Big enough to punch though the sheet of hot gas that stretches across the Ophiuchus cluster — leaving a gap more than a million light-years across. The blast, says EarthSky, was five times more powerful than the previous cosmic record holder, another black hole eruption designated MS 0735+74.

Astronomy magazine adds that the eruption was “hundreds and thousands” of times more powerful than the typical output of galaxy clusters. These, like the Ophiuchus cluster where the eruption took place, are the largest gravitational objects in the universe, and shine with the light of many trillions of stars.

Call it a pretty big bang.

A Cosmic Mount St. Helens

Researchers got their first hint of this cosmic explosion in 2016, reports Astronomy, when NASA’s Chandra X-ray Observatory spacecraft detected a peculiar curved edge to the glowing gas nebula in the Ophiuchus cluster. The observations resembled the rim of a crater blasted through the gas, but astronomers couldn’t confirm the cause, and were initially taken aback by the sheer scale of blast required to produce such a cosmic crater.

Another research team set to work combining the Chandra results with observations from several Earth-based radio telescopes. Their work confirmed that a crater or void had been punched through the Ophiuchus gas cloud.

According to EarthSky, the team report’s lead author, Simona Giacintucci, compared the eruption to the 1980 blast that blew the top off of Mount St. Helens in Washington State. “The difference,” she added, “is that you could fit 15 Milky Way galaxies in a row into the crater this eruption punched into the cluster’s hot gas.”

How Black Holes Erupt

Once you get past the sheer mind-numbing scale of this explosion, it might seem odd that a black hole could erupt. Of all space discoveries, black holes may be the strangest: objects with such powerful gravity that not even light can escape from them — hence the name black hole. But if nothing can escape them, how can they erupt?

The answer, explains EarthSky, is that the powerful gravity field of a black hole can pull in everything around it, including entire stars. As streams of matter fall toward the black hole, they collide with each other, and some of the infalling material is deflected away, in turn slamming into surrounding material and heating it up.

Eruption and Aftermath

Thus, while no light (or any other radiation) comes directly out of a black hole, the region around it can be extremely bright. And if enough surrounding material is falling toward the black hole, the resulting collisions can build up into a full-blown eruption.

Sci-News quotes another team member, Melanie Johnston-Hollitt, who describes the eruption as “like an explosion in slow motion that took place over hundreds of millions of years.”

According to NASA, the black hole eruption has ended, since the researchers found no hints of the high-energy jets of gas that would be seen in an ongoing eruption. The black hole must have consumed all the gas in its immediate vicinity, while the “sloshing” of gas through the space around a galaxy cluster has shifted the remaining gas away from the black hole.

But as astronomers continue to investigate the site of this distant cosmic eruption, who can say what other space discoveries they will encounter.