Speaker
Description
Since the early studies of extragalactic jets (collimated flows of relativistic plasmas), a central question has persisted: how far can such jets propagate in space? The discovery of the 4.1 mega-parsec (Mpc) jet in the radio galaxy 3C-236 in 1974 set the benchmark for decades, later surpassed by J1420-0545 (radio galaxy with a jet extending to 4.69 Mpc) discovered in 2008. For a long time, this scale appeared to be the physical limit of jet propagation, with the recently identified 5 Mpc source Alcyoneus (2022) reinforcing the idea of a possible upper bound to jet propagation scales in space. This assumption was dramatically challenged by the 2024 discovery of Porphyron, a 7 Mpc giant jet, which not only reopens the question of what controls jet growth in the cosmos (rarer environment, jet power, long age, or jet restart?) but also challenges the fundamental limits of jet physics: How do such plasma columns preserve thrust, and collimation over these extreme distances despite magneto-hydrodynamical plasma instabilities? Furthermore, the recent surge in such giant jet detections, driven by recent radio telescopes, complicates the picture with discoveries of examples and counter-examples challenging the proposed models explaining their formation. In this presentation, we outline an ongoing simulation campaign using GPU-accelerated codes to investigate the physical mechanisms behind these extraordinary jets and forecast how the upcoming mega-science facilities may transform our understanding of jet physics on cosmic scales.
