Probing the physics of AGN feedback with high resolution X-ray spectroscopy

Active galactic nuclei (AGN) significantly impact the evolution of their host galaxies, as they can prevent star formation by either expelling large fractions of gas with wide-angle outflows, or by heating up the halo gas with jets. However, how the AGN energy is transferred to the galaxy in either of these feedback modes is still not known. My dissertation research involves novel applications of modern inference techniques to high resolution X-ray spectra in order to gain new insights into the physical processes behind AGN feedback. First, our improved Bayesian framework for the self-consistent modelling of deep spectra from nearby AGN with X-ray detected outflows is introduced. For the first time we are able to perform robust model selection, while keeping all of the parameter space open. We applied our approach to a new, deep Chandra High Energy Transmission Grating observation of the Seyfert-1 galaxy NGC 4051, where we successfully mapped multiple absorbing components moving at a few 1000 km/s. We obtained one of the tightest outflow density constraints to date, thereby measuring the wind's impact on the galaxy. Second, our unprecedented measurements of the gas turbulent velocities in the cores of 13 nearby giant elliptical galaxies are presented. These new constraints were obtained by statistically combining resonant scattering and direct line broadening, studied with deep XMM-Newton Reflection Grating Spectrometer observations. This allowed us to explore the precise nature of the hot gas motions in massive galaxies and constrain models of AGN feedback in these objects. Then, a successful application of our resonant scattering analysis to the first X-ray microcalorimeter observation, the Hitomi Perseus Cluster spectrum, is discussed. This analysis allowed us to place constraints on the hot gas turbulence in a galaxy cluster that are independent of direct line width measurements. This technique can also provide unique clues to the three dimensional structure of the gas velocity field when statistical uncertainties are minimized. Both of the presented analyses will naturally extend to new data sets from the upcoming high spectral resolution X-ray missions, such as XRISM, ATHENA, Arcus, and Lynx.