Our home galaxy, the Milky Way, plays host to a super-massive black hole (SMBH) at its centre, dubbed Sagittarius A*, with a mass more than 4 million times that of the sun. SMBHs reside in the centres of most (if not all) galaxies, from low-mass dwarf galaxies to giant ellipticals in vast galaxy clusters. Despite their small sizes compared to the galaxies that host them, SMBH and galaxy properties are intimately linked through co-evolution. SMBHs represent some of the most extreme objects in the Universe and act as incredibly efficient engines that can convert a large fraction of the rest mass energy (remember Einstein's famous equation E=mc^2) of material that falls under their gravitational spell into energy, known as feedback, in the form of radiation, winds and jets. These processes give the SMBH its voice, allowing it to communicate across a vast range of scales, from the black hole event horizon to far beyond the host galaxy.
Over the coming decade and beyond, many missions (e.g. SKA, Athena, Euclid, JWST and LISA) will provide observations of the Universe not only in light but with LISA also in gravitational waves, and hence revolutionise multi-messenger astronomy of SMBHs. Systems ranging from SMBH binaries to individual galaxies, up to vast clusters that represent the most massive objects in the Universe and contain thousands of galaxies, will be observed in the local Universe and out to when it was less than a quarter of its current age. We will receive more data than ever before providing insights into the co-evolution of SMBHs and their galaxies over cosmic time.
To help to interpret the plethora of new observational data, it is vital to have robust and realistic theoretical models to compare to. The vast array of complex physical processes that shape the properties of SMBHs and their cosmic environment and the huge range of scales involved presents a formidable challenge. Using powerful supercomputers, I will perform state-of-the-art simulations that combine novel new models and techniques to provide a unique method for capturing a wide range of physical processes on multiple scales and in different environments. This includes small-scale simulations of pairs of SMBHs in binaries and the gas discs that surround them, high-resolution simulations of individual galaxies, groups and clusters, and large cosmological boxes that capture a representative volume of the Universe. These simulations will combine to provide answers to a range of questions related to SMBHs, such as:
- How does energy released by SMBHs shape galaxy, group and cluster properties?
- How does the state of a cluster, such as how turbulent it is or the properties of its magnetic fields, impact feedback from the SMBHs?
- How can we use galaxy clusters to probe the underlying properties of the Universe (Cosmology)?
- On what scales can feedback from SMBHs have a significant influence?
- How do SMBHs come together and merge?
- What are the multi-messenger signatures of SMBH mergers?
Overall, the simulations and their outputs will provide a vital resource for interpreting the many observational missions launching over the next two decades, and it is by working in tandem that the combination of theory and observation will enhance our understanding of both astrophysics and cosmology.
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