An enormous pair of black hole jets has been discovered by an international team of astronomers. Given the nickname Porphyrion after a mythological Greek giant, the jets are the biggest ever observed, spanning 23 million light years across and having a total power output equivalent to trillions of Suns.
The jets are powerful streams of energy and particles that shoot out from a black hole. As dust and gas surrounding a black hole are pulled towards it some of it becomes superheated. Instead of falling into the black hole, this superhot material is blasted out across the Cosmos at lightning-fast speeds.
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"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," said Dr Martijn Oei, one of the study authors from the California Institute of Technology. “The Milky Way would be a little dot in these two giant eruptions."
Porphyrion is much larger than the previous largest megajet structure observed. Alcyoneus, which spans 100 Milky Way galaxies. Centaurus A, the nearest major jet system to Earth pales in comparison, measuring just 10 Milky Way galaxies across.
In a paper published in Nature, the scientists described how the jets were among 10,000 faint megastructures observed during a sky survey made using Europe’s Low-Frequency Array radio telescope (known as LOFAR).
The newly spotted pair of jets date back to when our Universe was 6.8 billion years old – it’s currently around 13.8 billion years old. Scientists discovered that they were formed when the filaments that link galaxies (known as the cosmic web) were closer together. This means jets like Porphyrion reached across a greater portion of the cosmic web in comparison to jets formed in the present-day Universe.
The findings suggest that giant jet systems may have played a bigger role in galaxy formation than originally thought. The team were surprised to discover that Porphyrion emerged from a radiative-mode active black hole, rather than one in a jet-mode state.
A radiative black hole is where a black hole loses mass and energy through radiation whilst jet black holes don’t usually lose mass.
This finding is important as radiative-mode black holes are more common in the distant, early Universe, whilst jet-mode black holes are more typically found in the current Universe. Identifying that a radiative-mode black hole produced such a massive jet suggests there may be many more gigantic jets in the distant Universe awaiting discovery.
"Giant jets were known before we started the campaign, but we had no idea that there would turn out to be so many," said study co-author Prof Martin Hardcastle from the University of Hertfordshire.
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