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The accretion of material onto compact objects powers some of the most luminous objects in the Universe, and as a physical process is often accompanied by energetic outflows in the form of winds and jets. These outflows represent a vital step in our understanding of cosmic history as they can sculpt the evolution of entire galaxies. Fundamental questions regarding the physical conditions under which outflows are launched from accretion flows, and their subsequent evolution through a galaxy, remain unanswered, hampered by the long evolutionary timescales of individual active galactic nuclei. In the last decade a powerful new method of detecting and studying accretion onto previously quiescent supermassive black holes (SMBHs) has emerged, through the discovery and follow-up of objects known as tidal disruption events (TDEs). A TDE is initiated by the destruction of a star scattered close to the central SMBH by tidal forces. In the process of being accreted, this stellar debris temporarily increases the luminosity of the SMBH to super-Eddington rates, which then fades over years-to-decades, providing the unique opportunity to witness the real-time evolution of an accretion flow around an SMBH. Accompanying this accretion are outflows launched at speeds approaching a significant fraction of the speed of light, which then produce synchrotron emission observable at radio frequencies from shocks between these outflows and the ambient gas surrounding the SMBH. In this talk, I will present an overview of research progress to date in the field of TDEs, discuss the long-standing fundamental questions which TDE observations are addressing, and look forward to future progress which we can expect as the field matures from the study of single events to large statistically significant samples in the era of the LSST and SKA. I will provide an overview of my work on elucidating the origins of radio emission in TDEs, including contributions to our understanding of the scale invariance of accretion-outflow coupling, the fundamental mechanisms that launch outflows in TDEs, and how we can use observations of TDE outflows to measure the sub-parsec gas density profiles in quiescent galaxies. |
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