2013MNRAS.436.2244H

We present multicolour Hubble Space Telescope images of the powerful z = 2.4 radio galaxy MRC 0406-244 and model its complex morphology with several components including a host galaxy, a point source and extended nebular and continuum emission. We suggest that the main progenitor of this radio galaxy was a normal, albeit massive (M{sstarf} ∼ 10¹¹M_☉), star-forming galaxy. The optical stellar disc of the host galaxy is smooth and well described by a Sérsic profile, which argues against a recent major merger; however, there is also a point-source component which may be the remnant of a minor merger. The half-light radius of the optical disc is constrained to lie in the range 3.5 to 8.2kpc, which is of similar size to coeval star-forming galaxies. Biconical shells of nebular emission and ultraviolet-bright continuum extend out from the host galaxy along the radio jet axis, which is also the minor axis of the host galaxy. The origin of the continuum emission is uncertain, but it is most likely to be young stars or dust-scattered light from the active galactic nucleus, and it is possible that stars are forming from this material at a rate of 200^+1420_-110M_☉ yr^-1 .