The Origin of Double-peaked Narrow Lines in Active Galactic Nuclei II: Kinematic Classifications for the Population at z < 0.1

Abstract

We present optical longslit observations of the complete sample of 71 Type 2 active galactic nuclei (AGNs) with double-peaked narrow emission lines at $z < 0.1$ in the Sloan Digital Sky Survey. Double-peaked emission lines are produced by a variety of mechanisms including disk rotation, kpc-scale dual AGNs, and NLR kinematics (outflows or inflows). We develop a novel kinematic classification technique to determine the nature of these objects using longslit spectroscopy alone. We determine that 86% of the double-peaked profiles are produced by moderate luminosity AGN outflows, 6% are produced by rotation, and 8% are ambiguous. While we are unable to directly identify dual AGNs with longslit data alone, we explore their potential kinematic classifications with this method. We also find a positive correlation between the narrow-line region (NLR) size and luminosity of the AGN NLRs (R$_{\mathrm{NLR}}\propto \; {\mathrm{L}_{\mathrm{[OIII]}}}^{0.21 \pm 0.05}$), indicating a clumpy two-zone ionization model for the NLR.