First Results from the JWST Early Release Science Program Q3D: Benchmark Comparison of Optical and Mid-infrared Tracers of a Dusty, Ionized Red Quasar Wind at z = 0.435

The [O iii ] 5007 Å emission line is the most common tracer of warm, ionized outflows in active galactic nuclei across cosmic time. JWST newly allows us to use mid-IR spectral features at both high spatial and spectral resolution to probe these same winds. Here we present a comparison of ground-based, seeing-limited [O iii ] and space-based, diffraction-limited [S iv ] 10.51 μ m maps of the powerful, kiloparsec-scale outflow in the Type 1 red quasar SDSS J110648.32+480712.3. The JWST data are from the Mid-InfraRed Instrument. There is a close match in resolution between the data sets (∼0.″6), in ionization potential of the O ^+2 and S ^+3 ions (35 eV) and in line sensitivity (1–2 × 10 ^−17 erg s ^−1 cm ^−2 arcsec ^−2 ). The [O iii ] and [S iv ] line shapes match in velocity and line width over much of the 20 kpc outflowing nebula, and [S iv ] is the brightest line in the rest-frame 3.5–19.5 μ m range, demonstrating its usefulness as a mid-IR probe of quasar outflows. [O iii ] is nevertheless intrinsically brighter and provides better contrast with the point-source continuum, which is strong in the mid-IR. There is a strong anticorrelation of [O iii ]/[S iv ] with average velocity, which is consistent with a scenario of differential obscuration between the approaching (blueshifted) and receding (redshifted) sides of the flow. The dust in the wind may also obscure the central quasar, consistent with models that attribute red quasar extinction to dusty winds.