Hungry black holes - AGN fueling and central engines in the millimetre

Elford, Jacob 2024. Hungry black holes - AGN fueling and central engines in the millimetre. PhD Thesis, Cardiff University. Item availability restricted.

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Abstract

The energetic output from active galactic nuclei (AGN) may have a noticeable impact on the di;erent phases of the interstellar medium (ISM) that surrounds it. In this thesis I use high resolution multi-wavelength data of nearby galaxies to understand this connection. I utilise data from the mm-Wave Interferometric Survey of Dark Object Masses (WISDOM) project and the Close AGN Reference Survey (CARS) to directly study the connection between the AGN and the ISM. I find that the amount of cold molecular gas surrounding AGN does not correlate with the current level of AGN activity, which conflicts with previous results. This could indicate that AGN fuelling is not a ubiquitous process. However, I also find that the AGN can impact both the high density molecular gas that surrounds it by heating or destroying it and the lower density gas in the warm ionized medium (WIM). Understanding the underlying accretion mechanism in AGN is also key to understanding the interplay between AGN and their host galaxies. In this thesis I present the newly discovered millimetre fundamental plane of black hole accretion which appears to be followed by both high and low accretion rate sources as well as stellar mass black holes in X-ray binaries (XRBs). I find that radiatively ine;icient processes such as advection dominated accretion flows (ADAFs) or compact jets may explain this fundamental plane which could have important implication for the underlying accretion process and structure of AGN. In summary, the work presented in this thesis will aide in the study of AGN and how they connect with their host galaxies. This work will also emphasise the need for further multi-wavelength observations of AGN to fully understand the fuelling/feedback picture and the underlying accretion mechanism in these objects.

Item Type:	Thesis (PhD)
Date Type:	Completion
Status:	Unpublished
Schools:	Physics and Astronomy
Subjects:	Q Science > QC Physics
Uncontrolled Keywords:	Astronomy, Galaxies, AGN, Black holes, Supermassive black holes, Molecular Gas, Fueling, Feedback, Accretion, Submillimeter, X-ray, Optical
Funders:	STFC
Date of First Compliant Deposit:	6 January 2025
Last Modified:	06 Jan 2025 14:55
URI:	https://orca.cardiff.ac.uk/id/eprint/175011

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