James Webb Space Telescope Feed Post

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

NIRCam mosaics of the center of M 82, with focal plane orientation. The F140M, F250M, and F360M are primarily continuum bands. The F164N, F212N, and F335M are a combination of continuum and emission: F164N covers the 1.64 µm [FeII] fine structure transition, F212N covers H2 vibrational emission at 2.12 µm, and the diffuse emission from the 3.3 µm aromatic feature is evident in F335M. Contamination by PAH-associated emission can also be seen in F360M. Position offsets are referred to 09h 55m51. s 60, +69? 40'45.''6 (J2000). 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.