eprintid: 34774
rev_number: 14
eprint_status: archive
userid: 8125
dir: disk0/00/03/47/74
datestamp: 2024-05-14 07:20:04
lastmod: 2024-05-27 13:51:21
status_changed: 2024-05-14 07:20:04
type: doctoralThesis
metadata_visibility: show
creators_name: Peter, Toni
title: Understanding the Era of Reionization via
Numerical Methods for Radiative Transfer
subjects: ddc-520
divisions: i-130001
divisions: i-714200
adv_faculty: af-13
cterms_swd: Astronomie
cterms_swd: Strahlungstransport
cterms_swd: Kosmologie
abstract: 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
id_scheme: DOI
id_number: 10.11588/heidok.00034774
ppn_swb: 1889929212
own_urn: urn:nbn:de:bsz:16-heidok-347746
date_accepted: 2024-04-23
advisor: HASH(0x558ea6eeeba8)
language: eng
bibsort: PETERTONIUNDERSTAND20240428
full_text_status: public
place_of_pub: Heidelberg
citation:   Peter, Toni  (2024) Understanding the Era of Reionization via Numerical Methods for Radiative Transfer.  [Dissertation]     
document_url: https://archiv.ub.uni-heidelberg.de/volltextserver/34774/1/main.pdf