The largest pair of black hole jets ever recorded spans 23 million light-years

Could giant black hole jets have formed the early universe?

Saima S. Iqbal

In a galaxy 7.5 billion light-years away, a supermassive black hole spews out a stream of magnetized plasma that spans 140 galaxies in length. Nicknamed Porphyrion, after the giant from Greek mythology, this incredible structure contains the largest black hole jet that physicists have ever seen. reported to nature transmission. And their existence suggests that black hole jets may have played a more important role in shaping the universe than previously thought.

Black holes sometimes produce jets when they overeat. This is because material builds up around the mouth and faces extreme astrophysical forces. Any matter that approaches a black hole takes the form of a spiral disk. This disk rotates at such a fast speed that the material within it glows white-hot and ionizes, turning into a dense plasma that churns with magnetic fields. A spinning black hole can twist these magnetic fields into a tight cone at each rotating pole. Most of the material coming out of the disk will speed straight to the black hole entrance. But instead, a small section slingshots outward into a field of twists, creating two straight beams that some astrophysicists liken to a Jedi lightsaber.

These jets initially caught the attention of scientists because they served as visual indicators of black holes, bottomless pits invisible to most telescopes. Over time, researchers learned that the jets were important in their own right. The intense heat given off by the jets sometimes prevented the surrounding gas from collapsing and forming new stars. However, such effects appeared to be limited because the jets were not thought to extend too far beyond their own galaxy. Sky surveys underpinning the new study complicate that picture by identifying more than 10,000 massive black hole jet systems, the most important of which is Porphyrion.

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Martijn Oei, an astronomer at the California Institute of Technology and lead study author, says that a stream as old and massive as Porphyrion may have contributed to some features of the early universe.

In 2022, Oei and his fellow researchers discovered a jet system spewing out another black hole spanning 16 million light-years, or 100 galaxies. Porphyrion surpasses the previous record holder, Alcyoneus, not only in absolute size but also in relative influence on the cosmic environment. Porphyrion, which was born when the universe was less than half its current age and therefore much smaller and denser than it is today, can reach and touch more than Alcyoneus.

Porphyrion’s jets contain the combined power of trillions of suns and are estimated to raise the temperature of the surrounding gas by about a million degrees Celsius. This means they may have suppressed the formation of not only stars but entire galaxies in the early universe. High-velocity sprays of magnetized emissions may also have penetrated and filled voids in the cosmic web, a network of material-rich filaments and material-poor cavities that form the large-scale structure of the universe.

Oei is most intrigued by the possibility that jet systems like Porphyrion helped set the stage for life on Earth. Our planet’s magnetic field protects Earth’s biosphere and atmosphere from high-energy cosmic rays and dangerous bursts of solar particles and radiation. But Earth’s magnetic field is itself embedded in and interconnected with our star’s magnetic field, which in turn lies within other magnetic fields that stretch across the Milky Way and perhaps beyond. This scalar trail, though long and weak, can be traced back through time and space to our own place in a strand of the cosmic web, and even to potential disturbances in structures such as porphyrion.

To better assess the impact such jets may have had on the early universe, researchers need to compile a more comprehensive catalog of the structures. The new study only covers 15% of the sky, so it’s possible there are still more jets to be discovered. It is difficult to estimate how many of these massive structures exist because the conditions that create and maintain powerful rivers are still poorly understood, Oei notes.

That scientists can identify such large jets is a testament to the sensitivity of modern telescopes. Because the jets are so large, they are difficult to detect in the small field of view available to most powerful telescopes. In the new study, Oei and his team used a network of European radio telescopes called the Low Frequency Array (LOFAR) to search images of the sky for radio light with a wavelength of about 2 meters. These “human-sized waves,” he says, provided signs of “a place where something violent and dramatic was happening.” When Porphyrion appeared, they used two different facilities – the Giant Metrewave Radio Telescope in India and the WM Keck Observatory in Hawaii – to discover and study the source of the signal, the galaxy. Oei, who initially set out to study cosmic webs, discovered that Porphyrion’s jet pairs were twice as surprising. As the team continues to study Porphyrion and other giant jet systems, he expects countless more jets.