The Euler Characteristic as a Measure of the Topology of Cosmic Reionization

Abstract

We present here an introduction to the use of the Euler Characteristic in large-scale simulations of cosmic reionization. To characterize the topology of the ionization fraction field, we calculate the evolution of its Euler Characteristic. We find that the evolution of the topology during the first half of reionization is consistent with inside-out reionization of a (log) Gaussian density field.