January 13, 2018
Astronomers Spot Supermassive Black Hole 'Burping' Twice After 'Feasting' On Gas

It's not unusual when a supermassive black hole "burps," or releases energy from the gas it consumes. But new findings from a team led by astronomers from the University of Colorado adds to the evidence that it is possible for such objects to release a "double burp," as observed in a distant black hole located some 800 million light-years away from our planet.

According to University of Colorado Boulder assistant professor and study lead author Julie Comerford, the supermassive black hole in question looks to have "burped" twice over a span of approximately 100,000 years, an eternity by human standards, but a brief period of time in a relation to the history of the universe. Phys.org noted that this is the latest in a handful of examples of black holes "belching," or expelling streams of bright light from the hot gas it had previously sucked in.

"We are seeing this object feast, burp, and nap, and then feast, burp and nap once again, which theory had predicted," said Comerford.

"Fortunately, we happened to observe this galaxy in a moment where we could clearly see both events."
The researchers, who documented their findings earlier this month in the Astrophysical Journal, made use of data from the Hubble Space Telescope, the Chandra X-ray Observatory, the W.M. Keck Observatory in Hawaii, and the Apache Point Observatory in New Mexico to gather proof of the supermassive black hole's "double burp." As noted by BBC News, it was the Chandra telescope in specific that picked up X-ray emissions from the galaxy codenamed SDSS J1354+1327, which then helped the researchers determine where exactly its central black hole was located.

Thanks to Hubble, the researchers spotted a blue-green cloud of gas that had stretched about 30,000 light-years away from the supermassive black hole, representing the initial belch in the so-called "double burp." In this case, gas was likely expelled from the black hole due to a nearby burst of radiation. As for the second burp, this was inferred from a "little loop" found in the team's images; Comerford compared this new belch to a "shockwave that is coming out very fast" from the supermassive black hole it originated from.

"Imagine someone eating dinner at their kitchen table and they're eating and burping, eating and burping," Comerford explained.
"You walk in the room and you notice there's an old burp still hanging in the air from the appetizer course. Meanwhile, they're eating the main course and they let out a new burp that's rocking the kitchen table."
Comerford and her team believe that the burps came from two distinct "meals," with the abundance of gas possibly having originated from the time the black hole's host galaxy collided with a neighboring system.

According to Comerford, the supermassive black hole's double burp represents a process of "feasting, burping, and napping," then repeating the same cycle all over again. This backs up previous research that suggested black holes go through such cycles, shining brightly while feasting and burping, then going dark when it's time to take a "nap."

Although it's not often that supermassive black holes emit dual burps, Phys.org pointed out that our home galaxy, the Milky Way, has burped at least once in its long history. Based on observations from the Fermi Gamma-ray Observatory, a separate team of astronomers discovered a similar burp from the Milky Way in 2010, as gas jets known as "Fermi bubbles" were found shining in the electromagnetic spectrum's gamma-ray and X-ray portions. Comerford explained that this is consistent with the bubbles that are usually seen after a black hole feeds on gas.