Spatially Resolved [O III] Emission Line Kinematics of Reverberation-mapped Active Galactic Nuclei with the Keck Cosmic Web Imager
October 2025 • 2025ApJ...992...42R
Abstract • We present optical integral-field spectroscopic data of ten nearby (0.02 ≤ z ≤ 0.05) Seyfert 1 galaxies taken with the Keck Cosmic Web Imager. We map the spatially resolved kinematics of the [O III] gas and stars, and investigate the alignments between their global kinematic position angles (PAs). Large-scale gas motions are primarily dominated by rotation and are kinematically aligned with the stars (ΔPA ≤ 30°). However, eight galaxies exhibit nonrotational kinematic signatures (e.g., kinematic twists, possible outflows) in their ionized gas velocity fields near the nucleus. We compare aperture-wide measurements of the gas and stellar velocity dispersions (σgas and σ⋆) to test the use of the width of the [O III] line core as a surrogate for σ⋆. Direct comparisons between σgas and σ⋆ show that σgas tends to underestimate σ⋆, and thus is not a reliable tracer of σ⋆ for our selected galaxies. We measure the extent of the narrow-line region (NLR) using several definitions, resulting in sizes of ∼0.1–10 kpc. For a given [O III] luminosity, our NLR sizes derived from the [O III]/Hβ flux ratio or an [O III] isophotal radius are an order of magnitude larger than those measured from past imaging data.
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