Resolving How Black Holes Influence Galaxy Evolution

Our Milky Way galaxy is home to hundreds of billions of stars and this is just one of countless billions of galaxies in our Universe. Extragalactic astrophysics aims to understand how these galaxies formed, how they evolve, and why they have a diversity of shapes, sizes, and colours. My fellowship is aimed to establish the role in galaxy evolution played by the supermassive black holes that reside at galactic centres. These objects, which contain millions to billions times the mass of the Sun, release extraordinary levels of energy when gas falls onto them via accretion: events called ‘Active Galactic Nuclei’ (AGN). Whilst current theories of galaxy evolution assume that this energy is crucial for producing the observed properties of galaxies, many questions remain on the physical processes that connect AGN to the evolution of their host galaxies. My fellowship takes a multi-faceted approach to tackling this complex problem. Firstly, I will use spectroscopic surveys that observe millions of galaxies from the local Universe through to the distant Universe (that are observed as they were during the peak cosmic epoch of galaxy and black hole growth). Through my involvement in a new infrared multi-object spectrograph, it will be possible to characterise an unprecedented number of the most dusty AGN; recent evidence suggests these objects are key to understanding galaxy evolution. Secondly, these surveys have been, and will continue to be, used for careful selection of galaxies to be studied in exquisite detail using multi-wavelength facilities. This includes data from the world’s best observatories (e.g., European Southern Observatory, Atacama Large Millimeter/submillimeter Array and the James Webb Space Telescope). These observations make it possible to characterise how the energy from growing black holes is influencing dust, and the state and motions of gas in different phases (i.e., cold molecular gas and hotter ionised gas). Radio observations will be used to search for jets of charged particles (a key candidate for how AGN transfer energy into galaxies) and to map where the gas is shocked by AGN-driven outflowing gas. In parallel, bespoke, high-resolution simulations will be tailored to make meaningful comparisons to these observations. These simulations will help both interpret the observations and be used to test different theoretical models for how AGN inject energy, and interact with the dusty, multiphase gas in their host galaxies. Scientifically this fellowship aims to: (1) establish the link between AGN-driven outflows, dust, and radio emission across galaxy populations; (2) make robust measurements of the mass and energy contained in AGN-driven outflows; and (3) establish a theoretical framework that can explain the observed connection between dust, outflows, and shocks in AGN host galaxies. In addition to the core science objectives, novel methods for inspecting large and complex spectroscopic datasets will be developed throughout the fellowship. This includes sonic inspection (i.e., representing the data with sound) and new statistical tools. These will benefit astronomers using these data, will be transferable to other sectors using similar datasets, and will provide a more accessible mode of data exploration for those who require non-visual methods. Furthermore, development and engagement activities will be used to: (1) promote and enhance the UK’s involvement in developing and using ground-breaking astronomical facilities; and (2) facilitate skills transfer between academic research and non-academic sectors using large and complex datasets.