How does radiative feedback from a UV background impact reionization?

Understand

An ionizing UV background (UVB) inhibits gas accretion and photo-evaporates gas from the shallow potential wells of small, dwarf galaxies.

• During cosmological reionization, this effect can result in negative feedback: suppressing star-formation inside HII regions, thus impeding their continued growth.
• It is difficult to model this process, given the enormous range of scales involved.
• We tackle this problem using a tiered approach: combining parameterized results from single-halo collapse simulations with large-scale models of reionization.