Connecting Lyα and Ionizing Photon Escape in the Sunburst Arc

We investigate the Ly α and Lyman continuum (LyC) properties of the Sunburst Arc, a z = 2.37 gravitationally lensed galaxy with a multiply imaged, compact region leaking LyC and a triple-peaked Ly α profile indicating direct Ly α escape. Non-LyC-leaking regions show a redshifted Ly α peak, a redshifted and central Ly α peak, or a triple-peaked Ly α profile. We measure the properties of the Ly α profile from different regions of the galaxy using R ∼ 5000 Magellan/Magellan Echellette spectra. We compare the Ly α spectral properties to LyC and narrowband Ly α maps from Hubble Space Telescope imaging to explore the subgalactic Ly α −LyC connection. We find strong correlations (Pearson correlation coefficient r > 0.6) between the LyC escape fraction ( f esc LyC ) and Ly α (1) peak separation v sep , (2) ratio of the minimum flux density between the redshifted and blueshifted Ly α peaks to continuum flux density f min / f cont , and (3) equivalent width. We favor a complex H i geometry to explain the Ly α profiles from non-LyC-leaking regions and suggest two H i geometries that could diffuse and/or rescatter the central Ly α peak from the LyC-leaking region into our sight line across transverse distances of several hundred parsecs. Our results emphasize the complexity of Ly α radiative transfer and its sensitivity to the anisotropies of H i gas on subgalactic scales. Large differences in the physical scales on which we observe spatially variable direct-escape Ly α , blueshifted Ly α , and escaping LyC photons in the Sunburst Arc underscore the importance of resolving the physical scales that govern Ly α and LyC escape.