The Sunburst Arc with JWST. IV. The Importance of Interaction, Turbulence, and Feedback for Lyman-continuum Escape

Abstract At present, the best opportunity for detailed Lyman continuum (LyC) escape studies is in gravitationally lensed galaxies at z ≳ 2. Only one such galaxy currently exists in the literature with sufficient magnification and spatial resolution: the Sunburst Arc at redshift z = 2.37. Here, we present rest-frame optical JWST NIRSpec integral field observations of the Sunburst Arc that cover a large fraction of the source plane. From this dataset, we generate precise maps of interstellar medium (ISM) kinematics, dust geometry, ionization, and chemical enrichment. We extract a stacked spectrum of five gravitationally lensed images of the LyC leaking star cluster, as well as a μ −1 weighted, integrated spectrum of most of the galaxy, enabling a direct comparison to other LyC leakers in the literature. We find that the galaxy rotates but also shows strong, possibly dominant, signatures of turbulence, which are indicative of recent or ongoing major interaction. The cluster that leaks ionizing photons shows little difference from the rest of the galaxy in terms of kinematics or dust coverage, but dramatically elevated ionization, indicating that photoionization is the predominant mechanism that creates paths for LyC escape. We propose that tidal stripping of H i gas due to an interaction may have removed a large portion of the neutral ISM around the LyC emitting cluster, making it easier for the cluster to completely ionize the rest.