2017ApJ...850L..17L

We report the detection of a highly collimated linear emission-line structure in the spiral galaxy NGC 232 through the use of integral field spectroscopy data from the All-weather MUse Supernova Integral field Nearby Galaxies survey. This jet-like feature extends radially from the nucleus and is primarily detected in [O III]λ5007 without clear evidence of an optical continuum counterpart. The length of the radial structure projected on sky reaches ∼3 kpc, which makes NGC 232 the second-longest emission-line jet reported. The ionized gas presents extreme [O III]/Hβ and [N II]/Hα line ratios, increasing along the jet-like structure. We discuss three possible scenarios to explain the observed structure: (i) direct ionization of infalling material from the intergalactic medium by the AGN, (ii) photoionization by an undetected optical counterpart of the radio jet, and (iii) fast shock ionization due to the lateral expansion of the radio jet across the interstellar medium. Our analysis favors in situ ionization.