Porphyrion, the largest black hole jet discovered

Astronomers have found the largest pair of black hole jets ever discovered. Nicknamed Porphyrion spanning 23 million light-years in total length. This makes them equivalent to 140 times the Milky Way galaxy.

“This pair is not just the size of a solar system, or a Milky Way; we are talking about 140 Milky Way diameters in total,” says Martijn Oei, a Caltech postdoctoral scholar and lead author of a new Nature paper reporting the findings. “The Milky Way would be a little dot in these two giant eruptions.”

The jet megastructure, nicknamed Porphyrion after a giant in Greek mythology, have been dated to when the universe was 6.3 billion years old, under half of its current age of 13.8 billion years. These “fierce overflows” have a total power output of a trillion times that of the sun and shoot out from above as well as below a supermassive blackhole at the centre of a remote galaxy.

Before the discovery of Porphyrion, the largest confirmed jet system was Alcyoneus, also named for a Greek mythology giant. Discovered in 2022 by the same team that found Porphyrion, it was the equivalent of 100 Milky Way galaxies. Our nearest major jet system, Centaurus A jets, span just ten Milky Ways.

The newest findings suggest that these giant jet systems could have more of an influence on the formation of galaxies in the early life of the universe than was previously thought. Porphyrion existed in a time when the ‘cosmic web’ that connect and feed new galaxies were closer together than they are today. That meant that enormous jets reached a greater portion of the ‘cosmic web.’

“Astronomers believe that galaxies and their central black holes co-evolve, and one key aspect of this is that jets can spread huge amounts of energy that affect the growth of their host galaxies and other galaxies near them,” says co-author George Djorgovski, professor of astronomy and data science at Caltech. “This discovery shows that their effects can extend much farther out than we thought.”