Accretion of matter onto black holes regulates their growth. During the accretion process, a significant portion of the matter can be expelled as powerful outflows, which impact the surrounding environment. Therefore, the interplay between accretion and outflow is crucial for many astrophysical phenomena and processes, such as the AGN feedback regulating the co-evolution between galaxies and massive black holes. In my PhD work, I focus on studying the outflows produced when the accretion rate onto the black hole is very high, and I aim to connect their theoretical Modelling to observable properties.
I introduce a comprehensive theoretical model that captures X-ray reverberation signatures within a realistic extreme accretion geometry. This model reveals unique observational features of Fe lines generated by extreme accretion flows, contrasting them with those originating from standard accretion flows. Notably, the Fe lines exhibit pronounced blueshifts in energy, more symmetric line profiles, and significantly shorter time lags. I also examine the continuum emission from extreme accretion flows, such as tidal disruption events (TDEs). My work demonstrates that the spectral energy distribution of TDEs depends on the observer's inclination and the accretion rate, which explains their observed diversity and dynamic evolution.