JWST Observations of M82: Massive Star Clusters and the Base of the Galactic Wind

by Rebecca Levy (STScI, Baltimore)

Wednesday Mar 26, 2025, 4:00 PM → 5:30 PM Europe/Madrid

The M82 galaxy is the archetypal starburst galaxy in the local Universe and is often used as a laboratory to understand star-formation and feedback in early cosmic epochs. In this talk, I will present new observations of the central 1 kpc of M82 obtained with JWST NIRCam. 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) at a spatial resolution of ~0.05"-0.1" (~1-2 pc). I will present the catalog of >1300 massive (M*>10^4 Msun) star cluster candidates.  The star cluster candidates have Av~3-24 mag, meaning that there is still appreciable dust extinction towards these clusters into the near infrared. The stellar masses of the star cluster candidates are estimated using SSP models, assuming an age for the stellar population. Next, I will show results on the base of the galactic superwind. The 3.3 micron PAH emission shows prominent plumes extending outward from the central starburst region, together with a network of complex filamentary substructure and edge-brightened bubble-like features. The plumes have typical widths of ~50 pc, are at least 200-300 pc in length, and consistent of smaller “clouds” of PAH emission. Somewhat surprisingly, the PAH emission is strongly correlated with the ionized gas, suggesting that the PAHs are embedded in a combination of neutral, molecular, and photoionized gas, though they avoid regions of strong X-ray emission. Comparison to cloud-crushing simulations indicates that the observed PAH clouds survived break-out from the disk rather than being destroyed by the hot wind. Finally, I will show work in progress relating to the larger-scale galactic outflow with new NIRCam and MIRI mosaics.