Sizes and Kinematics of Extended Narrow-line Regions in Luminous Obscured AGN Selected by Broadband Images

Abstract

To study the impact of active galactic nuclei (AGN) feedback on their galactic ISM, we present Magellan long-slit spectroscopy of 12 luminous nearby obscured AGN ( , z  ∼ 0.1). These objects are selected from a parent sample of spectroscopically identified AGN to have high [O iii ] λ 5007 and Wide-field Infrared Survey Explorer mid-IR luminosities and extended emission in the Sloan Digital Sky Survey r -band images, suggesting the presence of extended [O iii ] λ 5007 emission. We find spatially resolved [O iii ] emission (2–35 kpc) in 8 out of 12 of these objects. Combined with samples of higher luminosity obscured AGN, we confirm that the size of the narrow-line region ( R NLR ) scales with the mid-IR luminosity until the relation flattens at R NLR  ∼ 10 kpc. Nine out of 12 objects in our sample have regions with broad [O iii ] line widths ( w 80  > 600 km s −1 ), indicating outflows. We define these regions as the kinematically disturbed region (KDR). The size of the KDR ( ) is typically smaller than R NLR by few kiloparsecs but also correlates strongly with the AGN mid-IR luminosity. Given the uncertain outflow mass, we derive a loose constraint on the outflow energy efficiency . We find no evidence for an AGN luminosity threshold below which outflows are not launched. To explain the sizes, velocity profiles, and high occurrence rates of the outflows in the most luminous AGN, we propose a scenario in which energy-conserving outflows are driven by AGN episodes with ∼10 8 year durations. Within each episode, the AGN is unlikely to be constantly luminous but could flicker on shorter timescales (≲10 7 yr) with a moderate duty cycle (∼10%).