In a stunning astronomical breakthrough, researchers have identified the largest pair of black hole jets ever recorded, stretching an astonishing 23 million light-years in total length. This enormous scale is equivalent to lining up 140 Milky Way galaxies back to back, dwarfing our familiar cosmic neighbourhood.
Martijn Oei, a postdoctoral scholar at Caltech and lead author of a new paper published in Nature, stated, “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.” The newly discovered jet system, dubbed Porphyrion after a giant from Greek mythology, dates back to a time when the universe was just 6.3 billion years old, less than half its current age of 13.8 billion years. These powerful jets are expelled from a supermassive black hole at the centre of a distant galaxy, with an energy output equivalent to trillions of suns.
Previous Findings and Comparisons
Before the discovery of Porphyrion, the largest known jet system was Alcyoneus, identified in 2022 by the same research team. Alcyoneus measures approximately 100 Milky Ways in length, while the well-known Centaurus A jets extend over 10 Milky Ways. This new discovery suggests that these colossal jet systems may have played a more significant role in galaxy formation during the early universe than previously understood.
Oei explained, “Astronomers believe that galaxies and their central black holes co-evolve. Jets can spread enormous amounts of energy that influence the growth of their host galaxies and their neighbours.” This research highlights the far-reaching effects of such jets, indicating they could extend across a larger portion of the cosmic web than those in the local universe.
Unveiling a Vast Population of Jets
The Porphyrion jet system is part of a newfound population of gigantic jets revealed during a sky survey that identified over 10,000 of these faint megastructures using Europe’s LOFAR (LOw-Frequency ARray) radio telescope. Martin Hardcastle, a co-author and professor of astrophysics at the University of Hertfordshire, noted, “Giant jets were known before we started the campaign, but we had no idea there would turn out to be so many.”
The discovery process involved inspecting radio images for long jet systems, utilizing both machine-learning tools and citizen scientists' help to identify these extraordinary objects.
Uncovering Cosmic Mysteries
The research team utilized the Giant Metrewave Radio Telescope (GMRT) in India and data from the Dark Energy Spectroscopic Instrument (DESI) to locate the galaxy from which Porphyrion originated. They identified it as a massive galaxy approximately 10 times more massive than the Milky Way, situated 7.5 billion light-years from Earth.
Interestingly, Porphyrion emerged from what is termed a radiative-mode active black hole, surprising astronomers since they previously did not believe this mode could produce such extensive jets. Oei remarked, “If distant jets like these can reach the scale of the cosmic web, then every place in the universe may have been affected by black hole activity at some point in cosmic time.”
Future Directions
Understanding how these jets can extend far beyond their host galaxies without destabilizing remains an ongoing mystery. The researchers propose that a stable and prolonged accretion event around the central black hole may allow for these massive jets to exist for extended periods.
As they continue their research, Oei is particularly interested in how these giant jets spread cosmic rays, heat, and magnetism throughout the space between galaxies. “We want to understand how magnetism, which allows life to thrive on our planet, came to be,” he concluded.
This discovery opens new avenues for understanding the universe's complex dynamics and the influence of black hole jets on cosmic evolution. Stay tuned for more updates as astronomers explore these colossal structures and their implications for our understanding of the universe.
References:
Oei, M. S. S. L., Hardcastle, M. J., Timmerman, R., Gast, A. R. D. J. G. I. B., Botteon, A., Rodriguez, A. C., Stern, D., Calistro Rivera, G., van Weeren, R. J., Röttgering, H. J. A., Intema, H. T., de Gasperin, F., & Djorgovski, S. G. (2024). Black hole jets on the scale of the cosmic web. Nature, 633(8030), 537. https://doi.org/10.1038/s41586-024-07879-y