Space is a realm of cosmic titans, from planet-altering asteroids to colossal galaxies. Now, scientists have uncovered some of the largest known structures in the universe: immense jets of material propelled from a black hole at near light speed.
These black hole jets, stretching an astounding 23 million light-years, are the biggest ever observed. To put that into perspective, this distance is equivalent to 140 Milky Way galaxies lined up end-to-end. The research detailing this colossal structure, nicknamed Porphyrion after a giant from Greek mythology, was recently published in Nature.
“Our findings suggest that supermassive black holes influence not only their host galaxies, but also the vast cosmic web,” explained Martijn Oei, lead author of the study and researcher at the California Institute of Technology. Previous understanding suggested that these jets remained confined within or near their galaxy, but Porphyrion demonstrates their capacity to reach the scale of larger cosmic structures.
Porphyrion is an ancient structure, originating when the universe was just 6.3 billion years old, compared to its current age of nearly 14 billion years. Oei illustrated the scale by comparing the black hole powering these jets to an amoeba if the jets themselves were as wide as Earth.
An illustration and digital image showing how these jet systems extend through the cosmic web.Illustration of Porphyrion’s jets extending through the cosmic web.
Discovering a Cosmic Giant
The jets were detected using data from the LOw Frequency ARray (LOFAR) sky survey in Europe. This survey, covering roughly 15% of the sky, has revealed over 10,000 similar faint jet megastructures. The team pinpointed Porphyrion’s source galaxy by analyzing data from the Giant Metrewave Radio Telescope (GMRT) in India and the Dark Energy Spectroscopic Instrument (DESI) in Arizona. Observations from the Keck Observatory in Hawai’i then determined the structure’s distance from Earth: approximately 7.5 billion light-years.
The Enigma of Porphyrion’s Formation
While the precise conditions leading to a system like Porphyrion remain unclear, the researchers observed the black hole emitting radiation while simultaneously drawing in surrounding material with its immense gravity.
“The creation of a system like Porphyrion requires a powerful accretion event, possibly a merger with another galaxy, providing a substantial influx of gas to fuel the black hole,” explained Martin Hardcastle, astrophysicist at the University of Hertfordshire and co-author of the study.
“Astronomers believe that galaxies and their central black holes evolve together. Jets play a crucial role by distributing vast amounts of energy, impacting the growth of their host galaxy and neighboring galaxies,” added co-author George Djorgovski, an astronomer at Caltech. “This discovery reveals that their influence extends much farther than previously imagined.”
Cosmic Implications and Future Research
This same team also discovered the previous record-holder, Alcyoneus, another giant jet system spanning roughly 100 Milky Ways. Beyond magnetizing the universe, jets like Porphyrion and Alcyoneus release so much energy that they can locally heat the intergalactic medium by a million degrees. They also potentially generate and disperse magnetic fields throughout cosmic voids—the vast empty spaces between the filaments of the cosmic web.
“Observations indicate the universe is magnetized on various scales, from entire galaxies to the filaments of the cosmic web and the voids between them,” Oei stated. “This large-scale magnetism could offer insights into the universe’s origins.” He added, “Magnetic fields within these voids might reflect early universe processes, potentially hinting at new physics.”
Instruments like the Square Kilometer Array will enable surveys of the southern sky, complementing the team’s northern sky scan. Furthermore, automated image analysis techniques, such as computer vision and AI, could accelerate the discovery of more black hole jet megastructures. The team currently has identified around 10,000, but they believe this represents only a small fraction of the total, estimating anywhere from 100,000 to 1 million such structures could exist.
Rewriting Cosmic Scales
The discovery of Porphyrion underscores the immense scale of cosmic phenomena and challenges our understanding of black hole influence. These giant jets, stretching across unimaginable distances, offer a glimpse into the dynamic processes shaping the universe and raise intriguing questions about the origins of cosmic magnetism and the interplay between galaxies and their central black holes.
