The brightest of known galaxies engulfs its neighbors – Astronomy Now

Observations from the brightest known galaxy show that it engulfs three smaller neighbors, sucking enormous streams of dusty debris that contribute to its record brilliance.

The galaxy, discovered in 2015 by the Wide-Field Infrared Survey Explorer (WISE), is powered by a black hole of 4 billion solar mass in its core. The enormous gravity of the black hole accelerates the fall of current matter, heating it to millions of degrees. The result is a powerful quasar 350,000 times brighter than the Sun.

Although not being the largest or most massive galaxy of the known universe, WISE J224607.55-052634.9 would easily be the brightest if all other galaxies were at the same distance from Earth. W2246-0526 is about 12 billion light years away, which means it is visible as it was when the Universe was one tenth of its current age.

Recent observations made by Atacama's large millimeter / submillimeter (ALMA) network show distinct streaks of dust removed from three nearby galaxies. The researchers explain that the traces contain almost as many materials as the galaxies themselves and that it is difficult to know if any of them would survive the encounter or if they could be totally consumed by their bright neighbor.

"It is possible that this binge eating has already been going on for some time, and we expect the galactic feast to continue for at least a few hundred million years," said Tanio Diaz-Santos of the Universidad Diego Portales in Santiago, Chile. author of an article in the newspaper Science.

This type of galactic cannibalism is not unusual, but W2246-0526 is the farthest galaxies from which it has been discovered to draw materials from multiple sources.

"We knew from previous data that there were three galaxies companions, but there was no evidence of interactions between these neighbors and the central source," Diaz-Santos said. "We were not looking for cannibalistic behavior and we were not expecting it, but this deep dive with the ALMA observatory shows it very clearly."

W2246-0526 is classified as hot galaxy, hidden by dust or Hot DOG. Most quasars are thought to draw at least some of their fuel from external sources, perhaps gas in an intergalactic space or in a food binge consuming other nearby galaxies. W2246-0526 may be representative of other masked quasars or it may belong to a class of its own.

"This galaxy is perhaps unique because it is almost twice as bright as any other galaxy found with WISE and formed very early in the history of the universe," said Peter Eisenhardt, researcher and co-author. of WISE in the newspaper Science.

"But we have discovered many other galaxies with WISE similar to this one: far away, dusty and thousands of times brighter than typical galaxies nowadays. So with W2246-0526, we can see what happens during a key step in the evolution of darkened galaxies and quasars. "