JWST Discovery of High-velocity Mid-infrared Ionized Outflows in Ultraluminous Infrared Galaxies F11119+3257 and F05189-2524

Abstract Ultrafast outflows (UFOs) are thought to be a driving mechanism of large-scale winds driven by active galactic nuclei (AGN), which cause significant galactic feedback through quenching star formation and regulating supermassive black hole growth. We present James Webb Space Telescope (JWST) Mid-Infrared Instrument Medium-Resolution Spectrometer observations of two nearby ultraluminous infrared galaxies, F11119+3257 and F05189-2524, with nuclear X-ray detected UFOs and kiloparsec-scale outflow. These galaxies show remarkably similar mid-infrared continuum and emission line features, notably including a high-velocity v 90 ∼ 4000 km s −1 outflow detected in highly ionized neon emission lines, e.g., [Ne VI ]. In F05189-2524, we see a slightly slower biconical outflow extending up to ∼2 kpc in the same neon emission lines. Both sources show evidence of AGN-driven radiative feedback through a deficit of rotational molecular hydrogen lines in the nuclear region, <1 kpc from the central quasar, but no clear evidence of any molecular gas entrained in the quasar-driven outflow. Energetic analysis shows that the warm ionized gas in both of these sources contributes minimally (∼0.1%–5%) to the momentum outflow rate of these sources and leaves the conclusions of previous literature unchanged: the energetics of these sources are broadly consistent with a momentum-conserving outflow.