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

Active galactic nuclei (AGN) can significantly impact the evolution of their host galaxies, as they can quench star formation by either expelling large fractions of gas with radiation and/or wide-angle outflows, or by heating up the halo gas with jets. Still a question for debate is how the AGN energy is transferred to the galaxy in either of the feedback modes. In this talk I will summarize my dissertation research, which 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, I will present our unprecedented measurements of the gas turbulent velocities in the cores of 13 nearby giant elliptical galaxies, which we obtained by statistically combining resonant scattering and direct line broadening techniques applied to deep XMM-Newton' Reflection Grating Spectrometer observations. This allowed us to explore the precise nature of the hot gas motions in massive galaxies for the first time. We found that the turbulent heat dissipation is sufficient to offset radiative cooling. In addition, I will also discuss how we have successfully applied our technique to the Hitomi observation of the Perseus Cluster. Second, I will introduce an improved Bayesian framework to modelling deep spectra of nearby AGN with X-ray detected outflows. This approach treats the ionizing spectrum and wind absorption self-consistently within an MCMC analysis. For the first time we are able to perform robust model selection, while keeping all of the parameter space open. By way of example, we apply our approach to a new, deep observation of the Seyfert-1 galaxy NGC 4051 (700 ks of Chandra High Energy Transmission Grating), where we successfully map multiple absorbing components moving at ~few 1000 km/s, and obtain one of the tightest outflow density constraints in the literature, thereby constraining wind's impact on the galaxy. Finally, I will conclude my talk by discussing the potential of both techniques within the context of upcoming high spectral resolution X-ray missions, such as XRISM, Arcus, and ATHENA.