JWST Q3D Program: Active Galactic Nucleus Photoionization and Shock Ionization in a Red Quasar at z = 0.4

Red quasars, often associated with potent [O iii] outflows on both galactic and circumgalactic scales, may play a pivotal role in galactic evolution and black hole feedback. In this work, we explore the [Fe ii] emission in one such quasar at z = 0.4352-F2M J110648.32+480712.3 using the integral field unit mode of the Near Infrared Spectrograph aboard the JWST. Our observations reveal clumpy [Fe ii] gas located to the south of the quasar. By comparing the kinematics of [Fe ii] and [O iii], we find that the clumpy [Fe ii] gas in the southeast and southwest aligns with the outflow, exhibiting similar median velocities up to v₅₀ = 1200 km s⁻¹ and high velocity widths W₈₀ > 1000 km s⁻¹. In contrast, the [Fe ii] gas to the south shows kinematics inconsistent with the outflow, with W₈₀ ∼ 500 km s⁻¹, significantly smaller than the [O iii] at the same location, suggesting that the [Fe ii] may be confined within the host galaxy. Utilizing standard emission-line diagnostic ratios, we map the ionization sources of the gas. According to the MAPPINGS III shock models for [Fe ii]/Paβ, the regions to the southwest and southeast of the quasar are primarily photoionized. Conversely, the [Fe ii] emission to the south is likely excited by shocks generated by the back-pressure of the outflow on the galaxy disk, a direct signature of the impact of the quasar on its host.