The Great Escape: Understanding the Connection Between Ly$\alpha$ Emission and LyC Escape in Simulated JWST Analogues

Understand

Constraining the escape fraction of Lyman Continuum (LyC) photons from high-redshift galaxies is crucial to understanding reionization.

• Recent observations have demonstrated that various characteristics of the Ly$\alpha$ emission line correlate with the inferred LyC escape fraction ($f_{\rm esc}^{\rm LyC}$) of low-redshift galaxies.
• Using a data-set of 9,600 mock Ly$\alpha$ spectra of star-forming galaxies at $4.64 \leq z \leq 6$ from the SPHINX$^{20}$ cosmological radiation hydrodynamical simulation, we study the escape of Ly$\alpha$ and LyC photons.
• We find that our mock Ly$\alpha$ observations are representative of high-redshift observations and that typical observational methods tend to over-predict the Ly$\alpha$ escape fraction ($f_{\rm esc}^{\rm Ly\alpha}$) by as much as two dex.