Black hole jets on the scale of the Cosmic Web

Already early on, black holes forged stable, high-power jets that reached cosmological sizes.

In the issue of Nature of September …, 2024, we report an exciting observation: a pair of jets, generated in the direct vicinity of a supermassive black hole, that reaches an extent of approximately 7 megaparsecs. Porphyrion, as we call this system of jets, is presently the largest structure made by an astrophysical body ever observed.

Artist’s impression of Porphyrion in the Cosmic Web. The Cosmic Web has been brought to life using the output of a state-of-the-art IllustrisTNG cosmological simulation.
Credits: Erik Wernquist / TNG Collaboration / Martijn Oei

The name ‘Porphyrion’ comes from Greek mythology. Porphyrion was the son of Gaia and Ouranos, the Greek primordial sky deity. According to Ps.-Apollodorus, Porphyrion and Alcyoneus were the greatest of the Gigantes (Giants). Pindar, meanwhile, called Porphyrion the ‘King of the Giants’.

The Latin poet Claudian, active around the turn of the one-hundred-and-fifth century H.E., authored the mythical poem Gigantomachia. In the poem, Claudian imagines Gaia, disgruntled with the Olympian gods, to give birth to a ‘monster brood’ of Gigantes. Described as ‘foes against Heaven’, Gaia prepares the Gigantes for war with the following words:

Children, ye shall conquer Heaven: all that ye see is the prize of victory; win, and the Universe is yours.

– Gaia in Claudian’s Gigantomachia

The mighty Porphyrion plotted to use Delos, the birth island of Apollo and Artemis, as a weapon:

Impious Porphyrion, carried by his serpents into the middle of the sea, tried to uproot trembling Delos, wishing to hurl it at the sky.

– Claudian’s Gigantomachia