Dressing a naked quasar : star formation and AGN feedback in HE 0450 − 2958

We present Australia Telescope Compact Array radio continuum observations of the quasar/galaxy system HE0450−2958. An asymetric triple linear morphology is observed, with the central radio component coincident with the quasar core and a second radio component associated with a companion galaxy at a projected distance of 7 kpc from the quasar. The system obeys the far-infrared to radio continuum correlation, implying the radio emission is energetically dominated by star formation activity. However, there is undoubtedly some contribution to the overall radio emission from a low-luminosity AGN core and a pair of radio lobes. Long baseline radio interferometric observations of the quasar core place a 3σ upper limit of 0.6mJy at 1400MHz on the AGN contribution to the quasar’s radio emission; less than 30% of the total. The remaining 70% of the radio emission from the quasar is associated with star formation activity and provides the first direct evidence for the quasar’s host galaxy. A re-anlaysis of the VLT spectroscopic data shows extended emission line regions aligned with the radio axis and extended on scales of ∼20 kpc. This is interpreted as evidence for jetcloud interactions, similar to those observed in radio galaxies and Seyferts. The CSIRO Australia Telescope National Facility, PO Box 76 Epping NSW 1710 Australia Institut fur Astronomie, ETH, 8093, Zurich, Switzerland