Astronomy Colloquium

When the launching of powerful SMBH jets persists over millions of years, megaparsec-long flows of thermal, magnetic, and cosmic ray energy emerge. These giant feedback systems to the Cosmic Web are the largest galaxy-made structures in the Universe. Over the last years, thanks to sensitivity gains of large-scale radio surveys, such as LOFAR's, it has become clear that megajets — generally thought to be rare and cosmologically insignificant only years ago — are not only common, but possibly the dominant source of black hole feedback to the Cosmic Web. A renewed interest in megajets coincides with the realisation that leading cosmological simulations feature insufficient large-scale baryon feedback, affecting cosmologists' ability to infer cosmological parameters from the newest surveys, such as DESI's, Euclid's, and the LSST.

To improve simulations and realise precision late-time cosmology with these flagship surveys, it is a priority to understand the origin and cosmological impact of megajets. This talk presents recent results on the host galaxies of megajets, their feedback potential, and the low–surface brightness relativistic electron populations indicative of feedback that new radio surveys are starting to pick up.