Monstrous Black Hole Spews Largest Jet Ever Seen Spanning 23M Light Years

Astronomers have detected the largest pair of black hole jets ever seen. The pair spans 23-million light-years, or the equivalent to lining up 140 Milky Way galaxies back to back.

According to NASA, supermassive black holes are millions to tens of billions times the mass of the Sun. A census using the Hubble Space Telescope showed that a black hole’s mass is dependent on the mass of its host galaxy’s central bulge of stars: the larger the galaxy, the larger the black hole. So, the new finding by a group of astronomers of such massive black hole jets was astounding.

“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,” explained 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.”

Nicknamed Porphyrion after a giant in Greek mythology, the jet megastructure dates to a time when the universe was 6.3 billion years old, or less than half its present age of 13.8 billion years. According to the research, the outflows have a mind blowing total output equivalent to trillions of suns, and shoot out from above and below a supermassive black hole at the center of a remote galaxy.

The previous largest confirmed jet system, named Alcyoneus (also after a giant in Greek mythology), was discovered in 2022 by the same team. Alcyoneus is believed to span the equivalent of 100 Milky Ways. To add a bit of perspective to the size of the two behemoths is the well-known Centaurus A major jet system, which is the closest to Earth, and spans only 10 Milky Ways.

Researchers believe the findings may suggest these giant jet systems had a larger influence on the formation of galaxies in the young universe than previously thought.

“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,” remarked 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.”

The Porphyrion jet system is the largest found to date during a sky survey that has revealed over 10,000 faint megastructures. The massive population of huge jets was found using Europe’s LOFAR (LOw Frequency ARay) radio telescope. LOFAR is operated by the Astron Netherlands Institute for Radio Astronomy, and consists of 51 antenna stations from Sweden to Ireland and Poland. It is tasked with studying some of the lowest frequencies that can be observed from Earth, probing the primordial era before stars and galaxies were formed.

“Giant jets were known before we started the campaign, but we had no idea that there would turn out to be so many,” explained Martin Hardcastle, second author of the study and a professor of astrophysics at the University of Hertfordshire in England. “Usually when we get a new observational capability, such as LOFAR’s combination of wide field of view and very high sensitivity to extended structures, we find something new, but it was still very exciting to see so many of these objects emerging.”

The team systematically searched for more hidden jets by inspecting the radio images by eye, using machine-learning tools to scan the images for signs of looming jets, and enlisted the help of citizen scientists around the globe to inspect the images further. A paper describing the most recent batch of giant outflows, containing over 8,000 jet pairs, has been accepted for publication in the journal Astronomy & Astrophysics.

As to what comes next, the team wants to better understand how these giant jet outflows influence their surroundings. One specific area of interest is finding out the extent to which giant jets spread magnetism. “The magnetism on our planet allows life to thrive, so we want to understand how it came to be,” remarked Oei. “We know magnetism pervades the cosmic web, then makes its way into galaxies and stars, and eventually to planets, but the question is: Where does it start? Have these jets spread magnetism through the cosmos?”