Some of the largest objects in the universe are so large that our minds have trouble conceiving of them. This collection of giants has just been joined by a jet of energy projected by a black hole, detected by an international team of scientists, and which extends over 23 million light-years, the largest recorded to date. This reference being a bit abstract, the authors preferred to formulate it thus: the length of this colossal jet is equivalent to that which would result from the alignment of 140 galaxies like the Milky Way one after the other.
The discovery, published this Wednesday in the magazine Naturewas made from radio images from the international LOFAR telescope, which is used to study the energy flows of black holes on a megaparsec scale. Through this process, Martijn Oei and his team identified these two large jet planes, which they called Porphyrionin honor of a giant from Greek mythology. “The Milky Way would be just a small dot in these two giant eruptions,” Oei explains.
The Milky Way would be just a small point in these two giant eruptions
Martin Oei
— Caltech postdoctoral researcher and lead author of the study
These jets of matter shoot out from above and below a supermassive black hole at the heart of a distant galaxy and date back to a time when our universe was 6.3 billion years old, less than half its current age of 13.8 billion years. “Until now, these giant jet systems seemed to be a phenomenon of the recent universe,” Oei says. “If distant jets like these can reach the scale of the cosmic web, then every place in the universe could have been affected by black hole activity at some point in cosmic time.”
Giants for eternity
Supermassive black holes can emit powerful jets of radiation and particles that, when sustained for millions of years, can affect the flow of matter through the intergalactic medium by hurling electrons, atomic nuclei, and magnetic fields through space. Before the discovery of PorphyrionThe largest confirmed jet system was Alcyoneawhich spans the equivalent of about 100 Milky Ways and was discovered in 2022 by the same team. For comparison, the well-known jets of Centaurus A, the closest major jet system to Earth, span 10 Milky Ways.
The authors of the book argue that the existence of Porphyrion There is evidence that jets from supermassive black holes can avoid being destroyed by fluid instabilities over large cosmic distances. However, they stress that to understand the mechanisms that have allowed them to be maintained Porphyrion further research is needed.
“Astronomers think that galaxies and their central black holes co-evolve, and a key aspect of this is that jets can scatter enormous amounts of energy that affect the growth of their host galaxies and other nearby galaxies,” says George Djorgovski, professor of astronomy and data science at Caltech and co-author of the paper. “This discovery shows that its effects can extend much further than we thought.”
A population of colossi
Previous studies have revealed a surprising number of such megastructures, although they are not that large: more than 10,000. This huge population of gigantic jets was also discovered using the LOFAR radio telescope. Although hundreds of large jet systems were known before these observations, they were thought to be rare and, on average, smaller than the thousands of systems discovered by the radio telescope.
“The giant jets were already known before the campaign started, but we didn’t know there would be so many of them,” says Martin Hardcastle, second author of the study and professor of astrophysics at the University of Hertfordshire in England. “It was very exciting to see so many of these objects emerge.” “When we discovered the giant jets, we were quite surprised. We didn’t know there were so many of them,” adds Oei.
When we discovered the giant jets, we were quite surprised. We didn’t know there were so many of them.
Martin Oei
— Caltech postdoctoral researcher and lead author of the study
As Porphyrion is located in the distant universe where black holes are radiatively abundant, the discovery implies that there may be many more colossal jets yet to be discovered. “We may be seeing just the tip of the iceberg,” Oei says. “Our LOFAR survey only covered 15 percent of the sky. And most of these giant jets are probably hard to detect, so we think there are many more of these behemoths out there.”
Plasma in the intergalactic medium
José Luis Gómez, head of the EHT group at the Institute of Astrophysics of Andalusia (IAA-CSIC), considers this to be a very interesting study and a spectacular discovery. “The jet they have discovered is enormous,” he points out. “It is as big as the distance between the nearest galaxies; if it were close to us, it would dominate the sky, it would be beastly.” The jet is made up of very light fundamental particles, such as electrons and protons. “It is a state of matter that we call plasma and that propagates in the intergalactic medium, which is denser,” he explains to elDiario.es. “To imagine it, it is as if you put a high-pressure air hose under the sea, in front of the beach of Motril, and saw the flow of bubbles reach New York.”
To imagine it, it’s like placing a high-pressure air hose in front of Motril beach and seeing the jet reach New York.
Jose Luis Gomez
— Head of the EHT group at the Institute of Astrophysics of Andalusia (IAA-CSIC)
According to the Spanish specialist, the most important thing about the study is not only the size of the jet, but the importance that these jets have in estimating the evolution of the universe, on cosmic scales that affect the intergalactic medium. “They are objects that emit a lot of radiation and particles into the intergalactic medium,” he says. “This one in particular has been active since the universe was very young, only 6.3 billion years old, perhaps it was born at the same time as the galaxies. Knowing how they combined and formed is one of the great unknowns that we would like to solve.
“This jet is so huge that it exceeds the computing power we currently have to simulate this type of phenomenon,” the astrophysicist emphasizes. Hector Vivesresearcher at CEFCA (Center for the Study of Cosmos Physics of Aragon). “This object was detected at the limits of current observations, and several factors would make its detection even more difficult if it were larger, less powerful or at a greater distance, so they are probably quite common. “This implies that supermassive black holes have a significant influence on the transport of energy in the entire cosmic network, and not just in galaxy clusters.”
