JWST Observations of Starbursts: A Young Bubble in NGC 253's Central Starburst

We present a multi-wavelength analysis of a young bubble in the nuclear starburst of NGC 253 using new JWST MIRI-MRS observations together with archival ALMA (100, 350, 690 GHz) and Chandra data. The MIRI maps reveal a prominent bubble-like structure in both ionized and molecular emission lines. The bubble is spatially coincident with one of the least embedded massive young clusters detected with ALMA, suggesting that the cluster is driving the expansion. We measure a radius of $\sim 11.5\pm 3.4$ pc and an expansion velocity of $\sim 90\pm 44$ km s${}^{-1}$, implying a dynamical age of $\sim 0.1\pm 0.1$ Myr. Using RADEX modeling of multiple CO transitions, we infer a molecular mass in the range of $(1.3\pm 0.3)\times {10}^4$ to $(2.8\pm 0.8)\times {10}^5$ $M_{\odot }$. We derive a kinetic energy of order ${10}^{51}$-${10}^{52}$ erg, consistent with mechanical input from Wolf-Rayet stellar winds or supernovae in a $\sim {10}^6$ $M_{\odot }$ cluster. The existence of a large population of Wolf-Rayet stars or past supernovae is supported by the presence of coincident X-ray emission. Our results provide direct evidence that individual clusters in a nuclear environment can carve out coherent structures on parsec scales and inject significant energy and momentum into the surrounding interstellar medium, which can contribute to the nuclear outflow in NGC 253.