eprintid: 26906
rev_number: 15
eprint_status: archive
userid: 4592
dir: disk0/00/02/69/06
datestamp: 2019-08-06 06:09:48
lastmod: 2019-09-10 15:48:05
status_changed: 2019-08-06 06:09:48
type: doctoralThesis
metadata_visibility: show
creators_name: Bustamante Jaramillo, Sebastian
title: Modelling supermassive black hole spins and the metallicity evolution of merging galaxies in a cosmological context
subjects: ddc-520
subjects: ddc-530
divisions: i-130001
adv_faculty: af-13
cterms_swd: quasars:  supermassive  black  holes
cterms_swd: quasars:  accretion discs
cterms_swd: methods: numerical
abstract: Galaxy mergers are a key process in the current paradigm of hierarchical galaxy formation. 
They are responsible for many galaxy transformations. For instance, they can drive
changes in galaxy morphology and colour, boost the star formation activity and trigger
strong inflows of pristine gas that dilute the central gas metallicity and feed the central
supermassive black hole. To which extent and how galaxy mergers affect some of the
galaxy properties are still open questions. In the first part of this thesis, we use simulations
and observations to study the processes of merger-induced gas metallicity dilution and
star formation enhancement. We find that merging and post-merger galaxies constitute a
prominent outlier population in the fundamental metallicity relation, a relation that links
the galaxy stellar mass with the star formation rate and the gas metallicity. In the second
part of this thesis, we present a sub-grid model of supermassive black hole spin evolution in
cosmological simulations of galaxy formation. We find that the accretion discs of low-mass
black holes accrete mass in a coherent fashion, resulting in high spin values. On the other
hand, high-mass black holes have lower spins because gas accretion is either chaotic or
completely suppressed, in which case black hole binary coalescence resulting from galaxy
mergers is the only relevant evolution channel. Finally, we test a hypothesis in which the
black hole energy feedback transitions from a thermal mode to a kinetic mode at the onset
of self-gravity fragmentation in the accretion disc, and is thus coupled to the spin evolution
of the black hole. We find that our conjecture reproduces the galaxy colour bimodality and
the colour-morphology relation.
date: 2019
id_scheme: DOI
id_number: 10.11588/heidok.00026906
ppn_swb: 1676086412
own_urn: urn:nbn:de:bsz:16-heidok-269061
date_accepted: 2019-07-24
advisor: HASH(0x559e37e486b8)
language: eng
bibsort: BUSTAMANTEMODELLINGS2019
full_text_status: public
citation:   Bustamante Jaramillo, Sebastian  (2019) Modelling supermassive black hole spins and the metallicity evolution of merging galaxies in a cosmological context.  [Dissertation]     
document_url: https://archiv.ub.uni-heidelberg.de/volltextserver/26906/1/Dissertation_Sebastian_Bustamante.pdf