A wide and collimated radio jet in 3C84 on the scale of a few hundred gravitational radii

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A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
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Nature Astronomy, Volume 2, issue 6
Understanding the formation of relativistic jets in active galactic nuclei remains an elusive problem 1 .This is partly because observational tests of jet formation models suffer from the limited angular resolution of ground-based very-long-baseline interferometry that has thus far been able to probe the structure of the jet acceleration and collimation region in only two sources 2,3 . Here, we report observations of 3C84 (NGC 1275)-the central galaxy of the Perseus cluster-made with an interferometric array including the orbiting radio telescope of the RadioAstron 4 mission. The data transversely resolve the edge-brightened jet in 3C84 only 30 μas from the core, which is ten times closer to the central engine than was possible in previous ground-based observations 5 and allows us to measure the jet collimation profile from ~102 to ~104 gravitational radii (r g) from the black hole. The previously found 5, almost cylindrical jet profile on scales larger than a few thousand r g is seen to continue at least down to a few hundred r g from the black hole, and we find a broad jet with a transverse radius of â‰250 r g at only 350 r g from the core. This implies that either the bright outer jet layer goes through a very rapid lateral expansion on scales â‰102 r g or it is launched from the accretion disk.
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Giovannini , G , Savolainen , T , Orienti , M , Nakamura , M , Nagai , H , Kino , M , Giroletti , M , Hada , K , Bruni , G , Kovalev , Y Y , Anderson , J M , D'Ammando , F , Hodgson , J , Honma , M , Krichbaum , T P , Lee , S S , Lico , R , Lisakov , M M , Lobanov , A P , Petrov , L , Sohn , B W , Sokolovsky , K V , Voitsik , P A , Zensus , J A & Tingay , S 2018 , ' A wide and collimated radio jet in 3C84 on the scale of a few hundred gravitational radii ' , Nature Astronomy , vol. 2 , no. 6 , pp. 472-477 . https://doi.org/10.1038/s41550-018-0431-2