The chemical evolution of galaxies explored through multi-object integral field spectroscopy
type: CreativeWork
description: Galaxies are expected to grow and evolve via a series of physical processes relating to gas flows into and out of the galaxy. Inflows of gas from the surrounding cosmic web provide fuel for star formation, which subsequently causes an enrichment of the interstellar medium (ISM) with the metals produced within stars, whilst supernovae-driven outflows drive gas out of the galaxy, re-distributing metals in the process. In this way, measurements of chemical abundances within galaxies can provide insight into the different physical processes that drive galaxy evolution. The interplay between these different processes has been well studied in the local Universe by large spectroscopic surveys that have established a number of scaling relations between stellar mass, star formation rate and gas-phase metallicity. However, the existence of such relations at earlier times in the Universe is less well studied. The aim of this thesis is to investigate the evolution of chemical abundances within galaxies across cosmic time, making use of integral field spectroscopic data obtained through the KLEVER survey. In the first part of this thesis, I compare the galaxy-integrated properties of galaxies at z=2 to those found in local galaxies, with a particular focus of the abundance of nitrogen relative to oxygen (N/O). I find that high redshift galaxies have similar N/O values to local galaxies at a fixed metallicity, but much lower N/O values than local galaxies at a fixed stellar mass. I then demonstrate that an anti-correlation exists locally between N/O and star formation rate, such that at a fixed stellar mass galaxies with higher star formation rates have lower N/O values. In light of this, I parameterise a three-dimensional relationship between stellar mass, star formation rate and N/O abundance, before demonstrating that this relationship accurately predicts the N/O ratios of galaxies at z=2 as well as those observed locally. As such, I name this relationship the fundamental nitr…
abstract: Galaxies are expected to grow and evolve via a series of physical processes relating to gas flows into and out of the galaxy. Inflows of gas from the surrounding cosmic web provide fuel for star formation, which subsequently causes an enrichment of the interstellar medium (ISM) with the metals produced within stars, whilst supernovae-driven outflows drive gas out of the galaxy, re-distributing metals in the process. In this way, measurements of chemical abundances within galaxies can provide insight into the different physical processes that drive galaxy evolution. The interplay between these different processes has been well studied in the local Universe by large spectroscopic surveys that have established a number of scaling relations between stellar mass, star formation rate and gas-phase metallicity. However, the existence of such relations at earlier times in the Universe is less well studied. The aim of this thesis is to investigate the evolution of chemical abundances within galaxies across cosmic time, making use of integral field spectroscopic data obtained through the KLEVER survey. In the first part of this thesis, I compare the galaxy-integrated properties of galaxies at z=2 to those found in local galaxies, with a particular focus of the abundance of nitrogen relative to oxygen (N/O). I find that high redshift galaxies have similar N/O values to local galaxies at a fixed metallicity, but much lower N/O values than local galaxies at a fixed stellar mass. I then demonstrate that an anti-correlation exists locally between N/O and star formation rate, such that at a fixed stellar mass galaxies with higher star formation rates have lower N/O values. In light of this, I parameterise a three-dimensional relationship between stellar mass, star formation rate and N/O abundance, before demonstrating that this relationship accurately predicts the N/O ratios of galaxies at z=2 as well as those observed locally. As such, I name this relationship the fundamental nitr…
author: Hayden-Pawson, Connor
language: eng
keywords: astrophysics, galaxies
license: https://creativecommons.org/licenses/by-nc/4.0/
date published: 2022-09-30
date modified: 2026-07-22T22:23:54Z
provider: Cambridge University
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: University of Cambridge

PropertyValue
property ID: DOI
value: 10.17863/CAM.95776