title: Understanding the Era of Reionization via  Numerical Methods for Radiative Transfer
creator: Peter, Toni
subject: ddc-520
subject: 520 Astronomy and allied sciences
description: The goal of this thesis are numerical studies of the era of reionization, which took place  at about a 150 million years to a billion years after the Big Bang. Since reionization is  a process driven by radiation, a major fraction of this work is dedicated to numerical  methods for radiative transfer. In particular, we develop the Sweep method, which  allows us to study reionization within large cosmological simulations. We begin by in-  troducing the basics of the Sweep algorithm and its implementation in the simulation  code Arepo. We discuss the motivation behind it, how it integrates with the rest of  Arepo and perform a number of tests to assess its performance and physical accuracy.  We find that the Sweep method does not only produce physically accurate results, but  does so in a very efficient manner, even when applied to large simulations on a large  number of processors. We then proceed by introducing the standalone radiative trans-  fer postprocessing code Subsweep in which we add a variety of improvements to the  original Sweep method, in particular the addition of sub-timesteps. We perform a  number of additional tests to verify that Subsweep correctly solves a number of physi-  cal problems and show that sub-timesteps can drastically improve performance of the  Sweep algorithm when applied to problems with heterogeneous environments without  sacrificing accuracy. Finally, we apply Subsweep to the cosmological simulation suite  TNG in order to recreate the era of reionization in the TNG universe. We find that  Subsweep allows us to study the spatial structure of reionization in detail and that we  can reproduce the observational constraints on the history of reionization reasonably  well.
date: 2024
type: Dissertation
type: info:eu-repo/semantics/doctoralThesis
type: NonPeerReviewed
format: application/pdf
identifier: https://archiv.ub.uni-heidelberg.de/volltextserverhttps://archiv.ub.uni-heidelberg.de/volltextserver/34774/1/main.pdf
identifier: DOI:10.11588/heidok.00034774
identifier: urn:nbn:de:bsz:16-heidok-347746
identifier:   Peter, Toni  (2024) Understanding the Era of Reionization via Numerical Methods for Radiative Transfer.  [Dissertation]     
relation: https://archiv.ub.uni-heidelberg.de/volltextserver/34774/
rights: info:eu-repo/semantics/openAccess
rights: http://archiv.ub.uni-heidelberg.de/volltextserver/help/license_urhg.html
language: eng