Evidence gathered over the last decade suggests that the growth of galaxies and supermassive black holes (SMBHs) are coupled, and that energetic feedback from active galactic nuclei (AGN) strongly

influences galaxy evolution. The discovery of AGN induced cavities in the hot halos surrounding many massive galaxies has strengthened this idea by revealing that AGN mechanical heating is capable of regulating halo radiative cooling. Current models of

radio-mode AGN feedback posit that cooling processes in a galaxy's hot halo drives mass accretion onto a central SMBH, promoting AGN activity that eventually offsets halo cooling via a thermally regulated feedback loop. While there is direct evidence that halo cooling and feedback are linked, the observational constraints on how AGN are fueled and powered are more difficult to establish. Gas accretion alone can, in principle, fuel most AGN. However, for some relatively gas-poor systems hosting energetic AGN

where the output exceeds 1061 erg, it appears that gas accretion alone may have difficulty sustaining their AGN unless the accretion is unusually efficient. This problem has lead to speculation that some BCGs may host ultramassive black holes (> 1010 solar masses), or that some AGN are powered by the release of energy stored in a rapidly-spinning SMBH. I investigate these issues by studying systems hosting ICM cavities and placing constraints on the AGN outburst energetics and determining how these outbursts may have been powered. Galaxy formation models further divide feedback into two generic modes (quasar and radio) that form a unified schema. However, how these modes interact, and what processes are involved in transitioning from one to the other, are still poorly understood. I investigate this dichotomy by analyzing rare objects which have the properties of both quasar and radio mode feedback in hopes of using these “transition” systems to  understand how most massive galaxies at higher redshifts evolve from quasar-mode into radio-mode.