title: Characterising Galactic Feedback Through Multiwavelength Observations Across Cosmic Time
Creators: name: Molyneux, S
Publisher: name: Liverpool John Moores University
Year: 2023

description: Understanding how and when galaxies form as well as how they evolve across cosmic time is a fundamental question in our studies of the Universe. From our current understanding galaxies form some time in the first few hundred million years after the big bang. These first galaxies and the stars within them release high energy photons that ionise their surroundings, changing the state of the Universe from being neutral to ionised. The period of the Universe in which these first galaxies form is therefore known as the epoch of reionisation and lasts until roughly one billion years after the big bang, at around a redshift of 6. During the lifetime of galaxies from formation to the present day they can evolve via several processes. There are external processes such as the environment of the galaxy\com{,} as well as merging with other galaxies which are crucial to building up from masses of several thousand solar masses to billions of solar masses. There are also internal processes within galaxies that can impact upon galaxy evolution. One of the vital internal processes to understand is the relation between galaxies and their central supermassive black holes. In particular\com{,} the case of growing supermassive black holes (known active galactic nuclei). These active galactic nuclei can release large amounts of energy into their host galaxy which can impact upon the galaxies ability to form stars and change how galaxies evolve. Here I present work covering the general topic of galaxy evolution from galaxies in the epoch of reionisation to those in the local universe which are known to host active galactic nuclei. I begin with the spectroscopic redshift confirmation of a galaxy in the very early Universe, as well as some basic analysis of some of the properties of this galaxy including the kinematics of the gas and comparisons to galaxies in the local Universe. Studies of these early galaxies are important to give insights into the first galaxies that form and the environment of the early Universe. These galaxies are also the building blocks that go on to shape the galaxy population we see today, and so are crucial to understand the processes of galaxy formation and evolution. I will then present a series of multi-wavelength observations performed to analyse the relationship between active galactic nuclei and their host galaxies. In particular, feedback from active galactic nuclei in the form of radio jets and how this impacts upon the prevalence of ionised outflows and the excitation of molecular gas in their host galaxies. These studies provide insights into the connection between central supermassive black holes and their host galaxies which is plays a vital contribution in galaxy evolution. The questions that will be addressed in this thesis are: 1) What are the properties of galaxies in the epoch of reionisation\com{,} and 2) How do AGN and quasars impact upon the multi-phase interstellar medium of their host galaxies, including the mechanism by which AGN feedback takes place.