Astronomers have uncovered the largest pair of black hole jets ever observed, stretching an astonishing 23 million light-years across the universe. This discovery, made using W. M. Keck Observatory on Maunakea and other telescopes around the world, was recently published in Nature and featured on the cover of the journal’s September issue.
“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,” said Martijn Oei, a Caltech postdoctoral scholar and lead author of the new study. “The Milky Way would be a little dot in these two giant eruptions.”
The jet structure, nicknamed Porphyrion after a giant from Greek mythology, dates back to when the universe was only 6.3 billion years old—less than half its current age. These powerful outflows, with an energy output equivalent to trillions of suns, are emitted from a supermassive black hole at the center of a distant galaxy.
Porphyrion now holds the record for the largest black hole jet system, surpassing the previous titleholder, Alcyoneus, which spanned about 100 Milky Way diameters.
Galaxy development
The discovery suggests that these enormous jet systems may have played a more significant role in the development of early galaxies than previously thought. Porphyrion emerged during a time when the universe’s “cosmic web”—the large-scale structure that connects galaxies—was much denser, allowing jets like these to reach further than those in today’s universe.
“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,” said co-author George Djorgovski, a Caltech professor of astronomy and data science. “This discovery shows that their effects can extend much farther out than we thought.”
