Astrophysics Colloquium Multiphase Winds from X-ray Irradiated Accretion Disks of Active Galactic Nuclei Presented by Daniel Proga Department of Astronomy, University of Nevada, Las Vegas Thursday, May 6, 2021 11:00 A.M. in Virtual Event and on Webex Abstract Large-scale mass outflows from AGN provide a natural link between a galaxy and its central black hole. This link is likely a very efficient mode of the so-called AGN feedback. However, quantifying AGN feedback is very challenging because one has to account for multi-dimensional fluid dynamics, energy dissipation, radiative processes, effects of dust, magnetic processes etc. In other words, studies of AGN feedback require incorporation of processes and their interplay that are typically considered separately in specialized areas of astrophysics. For example, the mechanism of thermal driving for launching accretion disk winds is interconnected with classical thermal instability (TI). We recently demonstrated that as a result of this interconnectedness, radial wind solutions of X-ray heated flows are prone to becoming clumpy. However, in over two decades of numerical work, only smooth thermally driven disk wind solutions that approach a steady state have been found. Although smooth solutions are easier to model and analyze they are likely more difficult to test against the observations. In this talk, I will summarize the main results from Waters, Proga, and Dannen (2021), where we investigated the stability of thermally driven disk winds. In particular, I will discuss the following three issues: The physical conditions under which TI should accompany thermal driving, resulting in clumpy disk wind solutions The reasons for why in disk winds, TI seeds the formation of hot spots in the disk atmosphere that consequently produces large scale vortices and results in the continual production of characteristic cold phase structures that we refer to as irradiated atmospheric fragments (IAFs) Observational consequences of IAFs. Specifically, I will show that X-ray absorption lines can reveal these complicated dynamics through spectral signatures such as a less sudden desaturation of O VIII Lyα and multiple absorption troughs in Fe XXV Kα. JPL Contact: Paul Goldsmith   Site Manager: Webmaster: CL 08-3220