James Webb Space Telescope Feed Post

JWST Observations of Starbursts: Polycyclic Aromatic Hydrocarbon Emission at the base of the M 82 Galactic Wind

Three color image with F335M, F250M, and F164N for red, green, and blue respectively. Dust throughout the base of the galactic wind lights up in the 3.35 µm filter (red) due to PAH emission. The bright F335M emission appears to outline a truncated bi-cone corresponding to the edge of the outflow base, particularly on the left side “wall”. In this scenario, the elongated streaks correspond to the front and back surfaces of the bi-cone, seen in projection against the middle regions north and south of the starburst (image credit A. Pagan). Abstract: We present new observations of the central 1 kpc of the M 82 starburst obtained with the James Webb Space Telescope (JWST) near-infrared camera (NIRCam) instrument at a resolution ~0.05"-0.1" (~1-2 pc). The data comprises images in three mostly continuum filters (F140M, F250M, and F360M), and filters that contain [FeII] (F164N), H2 v=1-0 (F212N), and the 3.3 um PAH feature (F335M). We find prominent plumes of PAH emission extending outward from the central starburst region, together with a network of complex filamentary substructure and edge-brightened bubble-like features. The structure of the PAH emission closely resembles that of the ionized gas, as revealed in Paschen alpha and free-free radio emission. We discuss the origin of the structure, and suggest the PAHs are embedded in a combination of neutral, molecular, and photoionized gas.