Astronomers Spot The Biggest Galaxy Ever, And The Scale Will Break Your Brain - ScienceAlert

Lurking some 3 billion light-years away, Alcyoneus is a giant radio galaxy reaching 5 megaparsecs into space.

They consist of a host galaxy (that's the cluster of stars orbiting a galactic nucleus containing a supermassive black hole), as well as colossal jets and lobes that erupt forth from the galactic center.

"If there exist host galaxy characteristics that are an important cause for giant radio galaxy growth, then the hosts of the largest giant radio galaxies are likely to possess them," the researchers, led by astronomer Martijn Oei of Leiden Observatory in the Netherlands, explained in their paper, which was published in April this year.

"Similarly, if there exist particular large-scale environments that are highly conducive to giant radio galaxy growth, then the largest giant radio galaxies are likely to reside in them.".

They found that it's a fairly normal elliptical galaxy, embedded in a filament of the cosmic web, clocking in at around 240 billion times the mass of the Sun, with a supermassive black hole at its center around 400 million times the mass of the Sun.

Both of these parameters are actually at the low end for giant radio galaxies, which could provide some clues as to what drives the growth of radio lobes.

"Beyond geometry, Alcyoneus and its host are suspiciously ordinary: the total low-frequency luminosity density, stellar mass, and supermassive black hole mass are all lower than, though similar to, those of the medial giant radio galaxies," the researchers wrote.