Program: GN-2023B-Q-220

Lyman Continuum (LyC) photons play important role in terms of the galaxy evolution and cosmic reionization. Direct observation of LyC is difficult due to its large cross section. Instead, Lyman alpha emission is considered to be a promising indicator for LyC photons. One possible scenario for LyC and Lyman alpha escape from a galaxy is that they are released in the optically thin HII regions, which are density bounded and have low HI column densities. In order to trace such optically thin regions, we propose to use [SII] deficiency. By comparing the spatial distribution of [SII] deficiency with the existing Lyman alpha emission map, we would be able to answer the question about the physical process regulating LyC escape Eventually, our work will provide clues about the evolution of ISM and the environment of the primordial galaxies that led to the reionization period of the universe.