Direct Numerical Simulations of Cosmological Reionization: Field Comparison: Ionization Fraction

The light from early galaxies had a dramatic impact on the gasses filling the universe. This video highlights the spatial structure of the light's effect, by comparing two simulations: one with a self-consistent radiation field (radiative), and one without (non-radiative), each with a very high dynamic range. Ionization fraction is the amount of the gas that has been ionized. Looking at this quantity from the simulations side-by-side one can clearly see differences but it can be difficult to decipher how the regions of concentration in the two simulations relate to one another. However, because the simulations have the same initial conditions, we can directly compare them, by looking at the relative difference of the ionization fraction in a single view. The yellow and red regions show where the gas has been ionized in the radiative simulation, while at the center of these blobs are small blue regions where the ionized gas from the non-radiative simulation is concentrated. The purple illustrates the boundary at the advancing edge of the ionization from the radiative simulation, where the two simulations are the same.