A deep, multi-epoch Chandra HETG study of the ionized outflow from NGC 4051

Active Galactic Nuclei (AGN) significantly impact the evolution of their host galaxies by expelling large fractions of gas with wide-angle outflows. The X-ray band is key to understanding how these winds affect their environment, because they are heated to high, X-ray temperatures. In this talk, I will introduce our Bayesian framework for characterizing AGN outflows, which provides substantial improvements in our ability to explore parameter space and perform robust model selection. We applied this framework to new and archival deep Chandra HETG observation of the Seyfert galaxy NGC 4051. We detected six components, spanning velocities from 100s to 10,000s km/s, and mapped their evolution across an eight year period. The most significant wind component is collisionally ionized and remains remarkably stable between the two epochs. This is the first detection in absorption of such an AGN outflow, which was enabled by using a Bayesian approach. The estimated total outflow power surpasses 5% of the AGN bolometric luminosity, making it important in the context of galaxy-black hole interactions. Additionally, our framework allows us to disentangle the absorption by the Milky Way hot halo from AGN absorption and place competitive constraints on its properties. This and similar analysis approaches will be important in the upcoming era of high resolution X-ray spectroscopy and missions such as XRISM and ATHENA.