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Abstract We present first results from James Webb Space Telescope Near-Infrared Spectrograph, Mid-Infrared Instrument, and Keck Cosmic Webb Imager integral field spectroscopy of the powerful but highly obscured host galaxy of the jetted radio source Cygnus A. We detect 169 infrared emission lines at 1.7–27μm and explore the kinematics and physical properties of the extended narrow-line region (NLR) in unprecedented detail. The density-stratified NLR appears to be shaped by the initial blow-out and ongoing interaction of the radio jet with the interstellar medium, creating a multiphase bicone with a layered structure composed of molecular and ionized gas. The NLR spectrum, with strong coronal emission at kiloparsec scale, is well modeled by active galactic nucleus photoionization. We find evidence that the NLR is rotating around the radio axis, perhaps mediated by magnetic fields and driven by angular momentum transfer from the radio jet. The overall velocity field of the NLR is well described by 250 km s⁻¹outflow along biconical spiral flow lines, combining both rotation and outflow signatures. There is particularly bright [Feii]λ1.644μm emission from a dense, high-velocity dispersion, photoionized clump of clouds found near the projected radio axis. Outflows of 600–2000 km s⁻¹are found in bullets and streamers of ionized gas that may be ablated by the radio jet from these clouds, driving a local outflow rate of 40M_⊙yr⁻¹. 

Abstract 3C 186, a radio-loud quasar at z = 1.0685, was previously reported to have both velocity and spatial offsets from its host galaxy, and has been considered as a promising candidate for a gravitational wave recoiling black hole triggered by a black hole merger. Another possible scenario is that 3C 186 is in an ongoing galaxy merger, exhibiting a temporary displacement. In this study, we present analyses of new deep images from the Hubble Space Telescope WFC3-IR and Advanced Camera for Surveys, aiming to characterize the host galaxy and test this alternative scenario. We carefully measure the light-weighted center of the host and reveal a significant spatial offset from the quasar core (11.1 ± 0.1 kpc). The direction of the confirmed offset aligns almost perpendicularly to the radio jet. We do not find evidence of a recent merger, such as a young starburst in disturbed outskirts, but only marginal light concentration in F160W at ∼30 kpc. The host consists of mature (≳200 Myr) stellar populations and one compact star-forming region. We compare with hydrodynamical simulations and find that those observed features are consistently seen in late-stage merger remnants. Taken together, those pieces of evidence indicate that the system is not an ongoing/young merger remnant, suggesting that the recoiling black hole scenario is still a plausible explanation for the puzzling nature of 3C 186.