Astronomers have made a staggering discovery of colossal black hole jets, the largest ever observed, extending a whopping 23 million light-years across the universe. The observation, which has challenged existing notions of what's possible, comes from a supermassive black hole located a staggering 7.5 billion light-years from Earth.

Black holes, often referred to as the universe's garbage disposals, are known to consume nearly everything that comes near them. However, a small fraction of material is ejected, forming jets on either side of the black hole before it falls in, as explained by Martijn Oei, a postdoctoral scholar at the California Institute of Technology and lead author of the study published in Nature.

These black hole jets can accelerate radiation and particles to near-light speeds, causing them to glow in wavelengths visible to radio telescopes. It was this glow that caught the attention of the astronomers who discovered the jets while using Europe's LOFAR (LOw Frequency ARray) radio telescope in 2018.

Dubbed "Porphyrion" after a giant from Greek mythology, the newly described jets have a power output equivalent to that of trillions of suns. The discovery is prompting astronomers to rethink their understanding of the scale of massive black hole jets and their impact on the universe's structure.

"The Milky Way would be a little dot in these two giant eruptions," Oei remarked, emphasizing the sheer size of the phenomenon. Initially, the researchers were searching for the cosmic web's filaments using LOFAR, but instead, they stumbled upon these massive jets.

The team's observations have revealed that an increasing number of galaxies have black hole jets reaching far beyond their borders. This discovery has led to the spotting of 10,000 new black hole jet pairs, with a paper describing the pairs accepted for publication in Astronomy & Astrophysics.

The most massive pair of jets was first spotted by Aivin Gast, a researcher from a different field who was assisting with visual inspections of the radio images. The discovery has opened up new possibilities for understanding how these giant features can affect their surroundings and the structure of the universe.

Before Porphyrion, the largest confirmed black hole jet system was Alcyoneus, also named for a mythical Greek giant, found by the same team in 2022. The Milky Way galaxy, estimated to be 100,000 light-years in diameter, pales in comparison to the colossal scale of Porphyrion, which is equivalent to 140 Milky Way diameters.

The study authors believe that with improving radio telescope technology, it's possible to find even larger jets in the future. Follow-up observations using the Giant Metrewave Radio Telescope in India and the W. M. Keck Observatory in Hawaii pointed to a distant galaxy about 10 times more massive than the Milky Way as the origin of the jets.

The data also revealed that the structures came from a radiative-mode active black hole, surprising the researchers. This mode is more common in the distant universe, while jet-mode black holes are more common closer to home.

"Our study suggests that radiative-mode active black holes might be as capable of generating giant jets as jet-mode active black holes are in the nearby universe," Oei said. The discovery could help answer big questions about how the universe became magnetized and how the cosmic web's large-scale structures came to be.

The team's research shows that Porphyrion was able to heat its surroundings in intergalactic space by about 1 million degrees. This heating could have slowed down the formation of galaxies, which require relatively cold intergalactic plasma or gas to collapse and form.

The discovery of Porphyrion has not only provided a "fossil record" of supermassive black hole activity but also offers insights into how these jets and black holes have evolved over time. The team continues to investigate how the black hole jets can extend so far beyond their host galaxy without becoming unstable.

"The remarkable longevity of the jets can also help us to test the physical models of jets, in particular their stability," said Sasha Tchekhovskoy, an associate professor not involved in the study.

The origin of magnetism is key to understanding how life-sustaining atmospheres are protected and shielded. "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?" Oei pondered. "Have these giant jets spread magnetism through the cosmos?"