2025/08/14 by Fischer, Travis C., Cothard, Nicholas F., Nayak, Omnarayani +3
#Astrophysics of Galaxies (astro-ph.GA) #FOS: Physical sciences
paper · doi:10.48550/arxiv.2508.11044
We present James Webb Space Telescope (JWST) NIRCam imaging of the nearby Seyfert 1.9 galaxy NGC 4258, which hosts strong star formation regions as well as an anomalous jet-like radio structure that extends through a significant portion of its disk. This galaxy provides a unique environment to study Active Galactic Nucleus (AGN)-driven shocks and their impact on the interstellar medium (ISM) as its proximity allows for narrow-band observations of various near-infrared tracers sensitive to multiple levels of shock and radiative excitation: [Fe II] (1.64 μm), Paα (1.87 μm), H2 (2.21 μm), 3.3 μm polycyclic aromatic hydrocarbon (PAH) emission, Brα (4.05 μm), and Pfβ (4.66 μm), allowing us to trace shocks with parsec-scale resolution. Comparing these near-infrared observations with available ultraviolet, optical, radio, and X-ray imaging, we find that shocks present in the brightest regions of the anomalous radio structure are likely of low-velocity (50-100 km s-1), suggesting that these features originate from AGN-driven winds that interact with the host medium and mechanically impart energy into the disk. Further, while co-spatial [Fe II] and H2 emission indicate multi-phase shocks, PAH emission is relatively weaker or absent in the most shock-excited regions, consistent with the destruction of small dust grains. Finally, we propose that surveys identifying enhanced [Fe II] in AGN host galaxies may systematically reveal a key population where AGN feedback is significantly coupled with the surrounding ISM and actively shaping galaxy evolution.