Two modes of LyC escape from bursty star formation: implications for [C II] deficits and the sources of reionization

We use the SPHINX20 cosmological radiation hydrodynamics simulation to study how Lyman continuum (LyC) photons escape from galaxies and the observational signatures of this escape. We define two classes of LyC leaker: Bursty Leakers and Remnant Leakers, based on their star formation rates (SFRs) that are averaged over 10 Myr (SFR10) or 100 Myr (SFR100). Both have fesc > 20 per cent and experienced an extreme burst of star formation, but Bursty Leakers have SFR10 > SFR100, while Remnant Leakers have SFR10 20 per cent dominate the ionizing photon budget at z ≳ 7.5 but the contribution from galaxies with fesc < 5 per cent becomes significant at the tail-end of reionization