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

TL;DR

This study uses longslit spectroscopy to classify the kinematic origins of double-peaked emission lines in local AGNs, revealing that most are due to outflows, with a correlation between NLR size and luminosity.

Contribution

The paper introduces a novel kinematic classification method using longslit spectroscopy to analyze the origins of double-peaked emission lines in AGNs.

Findings

86% of double-peaked lines caused by AGN outflows

6% caused by rotation, 8% ambiguous

Positive correlation between NLR size and luminosity

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.