Most galaxies contain a central black hole of a million to a billion Solar masses. Accretion of gas by these black holes is a key topic in astrophysics because the hole and the galaxy are thought to have formed together. Gravitational energy released during accretion makes the nuclei of some galaxies so luminous they are detected at cosmological distances and used to probe the early Universe. Energetic photons and outflows from the nucleus can modify the host galaxy and the surrounding intergalactic medium. In other galaxies, including our own, the nucleus accretes gas at a trickle and is under-luminous. Computational studies are essential for finding how the accretion flows work because, even in our own galaxy, the innermost flow subtends a small angle on the sky and has not yet been imaged. The lectures will focus on the basic observational picture built up from the spectra and brightness variations of galactic nuclei; our current understanding of the processes that convert gravitational energy to radiation; and some areas where further numerical work might be productive.
Presentation (ZIP File)
Lecture Notes (PDF File)
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