The 21cm bispectrum during reionization: a tracer of the ionization topology

Understand

We compute the bispectra of the 21cm signal during the Epoch of Reionization for three different reionization scenarios that are based on a dark matter N-body simulation combined with a self-consistent, semi-numerical model of galaxy evolution and reionization.

• Our reionization scenarios differ in their trends of ionizing escape fractions ($f_\mathrm{esc}$) with the underlying galaxy properties and cover the physically plausible range, i.e.
• $f_\mathrm{esc}$ effectively decreasing, being constant, or increasing with halo mass.
• We find the 21cm bispectrum to be sensitive to the resulting ionization topologies that significantly differ in their size distribution of ionized and neutral regions throughout reionization.