Tidal disruption events (TDEs) provide a unique opportunity to study the environments and accretion mechanisms of otherwise quiescent supermassive black holes (SMBHs). This dissertation explores the physical properties of the circumnuclear dust, gas, and stellar populations in TDE host galaxies, connecting small-scale processes around SMBHs to galaxy-wide characteristics. Using high-cadence photometry and spectroscopy, we probe the dynamics and composition of material near SMBHs during and after TDE flares.
In Chapter 2, we analyze the TDE AT 2020mot, discovering a near-infrared dust echo produced by concentric rings of dust within ∼0.1 pc of a 6x10^6 M⊙ SMBH. This represents one of the smallest scales at which dust has been inferred near a SMBH, highlighting the potential of TDEs for uncovering subparsec dust structures when near-infrared observations are included in transient studies. In Chapter 3, we present AT2022upj, the first confirmed TDE with simultaneous-at-peak extreme coronal line emission. This discovery links high-ionization gas to TDE flares and reveals a stratified distribution of circumnuclear material, with coronal gas within 0.1 pc and dust at ∼0.4 pc. Finally, in Chapter 4, we utilize HST/STIS spectroscopy of the post-starburst TDE host ASASSN-14li to uncover a stellar age gradient, with a younger starburst near the nucleus (∼230 Myr) and an older population at 87 pc (∼550 Myr). We also measure a stellar density of ∼5900 M⊙/pc^3 within 30 pc, suggesting a highly concentrated nuclear star cluster.
Together, these studies demonstrate how TDEs illuminate the complex environments of SMBHs, from subparsec dust and gas structures to the nuclear stellar populations that govern TDE rates. By combining observations across wavelengths and spatial scales, this work advances our understanding of SMBH-host galaxy interactions in the unique environments of TDE hosts.