JWST Resolves Jet-driven H ₂ and Ionized Outflows in Radio Galaxy 3C 305

We present JWST MIRI medium-resolution spectrometer (MRS), NIRSpec, NIRCam, and MIRI imaging observations of 3C 305, a radio galaxy with a compact jet that is confined within the galaxy. We utilize the H 2 0–0 S(1)–S(7) lines, several mid-infrared (MIR) fine structure lines, and polycyclic aromatic hydrocarbon (PAH) emission in the MIRI MRS spectrum to conduct a multiphase study of the radio jet’s impact on the interstellar medium. Multiple tracers, including H 2 /PAH 11.3 μ m and [Fe II ] 5.34 μ m, provide evidence for shocks at the jet termination locations. Two Gaussian components are required to reproduce the kinematics of warm H 2 adequately, with one representing the bulk low-velocity component, while the other corresponds to an outflow. The ionized gas attains higher outflow velocities than the H 2 outflow. The stark increase in velocities at the jet hotspots points to jet-driven outflows. We fit the H 2 excitation diagram with a power-law temperature distribution and find that the hotspots exhibit flatter slopes, indicating a larger warm/hot gas mass fraction at these locations. Our MAPPINGS line-ratio analysis indicates that most of the MIR ionized gas can be fit by a “shock+precursor” model. We find that strong radiative losses dominated by line cooling, along with moderate kinetic power of the molecular + ionized gas outflows, can account for all of the estimated jet power, indicating high jet coupling efficiency in 3C 305. Our results, in tandem with other studies on multiphase gas, show that jets efficiently shock-heat and accelerate the gas that comes in contact with them, driving massive, kiloparsec-scale, multiphase outflows.