Oral Abstract

Oral Contribution (O0.5) Anne Hutter ()

Simulating the first galaxies and reionization with ASTRAEUS

The Epoch of Reionization represents an important epoch in the history in the Universe, when the first stars and galaxies gradually ionize the neutral hydrogen in the intergalactic medium (IGM). Understanding the nature of the ionizing sources, the associated ionization of the IGM, and its impact on subsequent structure formation and galaxy evolution by means of radiative feedback effects, represent key outstanding questions in current astrophysics.

We aim to tackle these questions by performing simulations of galaxy evolution and reionization. For this purpose, we have developed the new framework ASTRAEUS that couples a semi-analytical galaxy evolution model with a semi-numerical reionization scheme and uses the merger trees and density distribution of a dark matter-only N-body simulation. This model includes key processes of galaxy evolution, such as gas accretion, mergers, star formation, supernovae and radiative feedback, and describes the spatial ionization of the IGM accounting for inhomogeneous recombinations that follow the spatial density distribution and ionization history.

In order to investigate the interplay between galaxy evolution and reionization, we have implemented different models of radiative feedback and studied its impact on observables such as the UV luminosity function or the 21cm signal from the neutral regions in the IGM during reionization. In my talk, I will briefly describe our new framework ASTRAEUS, and discuss the effect of radiative feedback on the underlying galaxy population and observables as well as whether the IGM ionization topology could provide constraints on radiative feedback or is more sensitive to galactic properties such as the ionizing escape fraction from galaxies.