MURALES survey. I. 3C 459 data cube.

We detected diffuse nuclear emission and a filamentary ionized gas structure forming a one-sided, triangular-shaped region extending out to ~80kpc. The central emission line region is dominated by two compact knots of similar flux: the first (N1) cospatial with the radio core and the (N2) second located 1.2" (5.3kpc) to the SE.

The two regions differ dramatically from the point of view of velocity (with an offset of ~400km/s), line widths, and line ratios. This suggests that we are observing a dual AGN system formed by a radio loud AGN and type 2 QSO companion, which is the result of the recent merger that also produced its disturbed host morphology. The alternative possibility that N2 is just a bright emission line knot resulting from, for example, a jet-cloud interaction, is disfavored because of 1) the presence of a high ionization bicone whose apex is located at N2; 2) the observed narrow line widths; 3) its line luminosity (~10^42^erg/s) typical of luminous QSOs; and 4) its location, which is offset from the jet path.