Paper detail

Discovery of the disturbed radio morphology in the interacting binary quasar FIRST J164311.3+315618

We report the high resolution radio observations and their analysis of a radio-loud compact steep spectrum (CSS) quasar FIRST J164311.3+315618, one of the members of a binary system. The second component of the system is a radio-quiet AGN. The projected separation of this pair is 2.3 arcsec (15 kpc) and it is one of the known smallest separation binary quasars. The multi-band images of this binary system made with the Hubble Space Telescope showed that the host galaxy of the radio-loud quasar is highly disturbed. The radio observations presented here were made with the multi-element radio linked interferometer network (MERLIN) at 1.66 GHz and 5 GHz. We show that the radio morphology of FIRST J164311.3+315618 is complex on both frequencies and exhibits four components, which indicate on the intermittent activity with a possible rapid change of the jet direction and/or restart of the jet due to the interaction with the companion. The radio components that are no longer powered by the jet can quickly fade away. We suggest that this makes the potential distortions of the radio structure to be short-lived phenomena. On the other hand, our numerical simulations show that the influence of the companion can lead to the prolonged current and future activity. FIRST J164311.3+315618 is an unusual and statistically very rare low redshift binary quasar in which probably the first close encounter is just taking place.