Unraveling the faintest radiation sources in the Universe
Low-luminosity galaxies account for an increasingly large fraction of the overall galaxy population towards high-redshift, as indicated by the steepening of the faint-end slope of the rest-frame UV luminosity function. Direct studies of these faint galaxies at high-redshift are extremely challenging. In this talk I will present new methods to predict their abundance and, possibly, even their contribution to the ionizing background, using extended line emission around more massive/luminous galaxies and cross-correlations with other cosmic density tracers. I will also discuss the detectability of the faint emission line halos with future facilities such as the James Webb Space Telescope.