Extragalactic Radio Sources as a Piece of the Cosmological Jigsaw
  Early on, extragalactic radio sources have pointed to a cosmologically
evolving Universe. They were also an important piece of evidence for the
existence of supermassive black holes, now thought to be a key component of
galaxies. The observation that the power of radio sources increases with
redshift, whereas the cosmological assembly of mass proceeds vice versa means
that radio sources have their strongest impact in the early Universe. Our
simulations suggest that radio sources heat hot halo gas, boost star formation
in disc galaxies and other cold gas in the vicinity, possibly filaments, by a
surround and squash mechanism. They might cause gaseous outflows in connection
with stellar feedback. This might be an important mode of star formation for
forming massive galaxies. Analysis of the jet-environment interaction may
provide insights into black-hole physics and jet formation, e.g., rotational
energy extraction (Blandford-Znajek) or how frequent black-hole binaries or
multiple systems are. The former relates to fundamental questions about the
nature of black holes. The latter is expected from hierarchical cosmology.
Extragalactic radio sources thus continue to corroborate the cosmological
picture and lead the way towards new, exciting discoveries.
