Fluorescent rings around star-freedark matter haloes
Between the two regimes of dark and star-forming haloes, a narrow mass range exists within which haloes remain star-free, but contain a small, dense core of neutral gas. This gas produces fluorescent recombination line emission driven by the UV background, which is limb-brightened when seen in projection to yield a distinctive ring-shaped morphology. Using a specially-designed radiative transfer code, I determined the expected properties and abundance of these fluorescent rings, and found that their properties can provide constraints on the shape and amplitude of the UV background, the nature of dark matter, and the primordial abundance of helium.
