He 1127-1304: the largest radio quasar

Abstract

We report the discovery of a giant radio structure associated with the quasar HE 1127-1304 at z= 0.6337, found in a programme of radio follow-up of the Hamburg-ESO survey for bright QSOs in the southern sky. With a size of 2.4 Mpc, this is the largest known radio quasar as well as the largest radio source known at its redshift and beyond. The optical spectrum of this quasar shows an exceptionally deep Mg II absorption line at λ_rest=2798 Å.