Speaker
Description
AGN-driven galactic outflows are a central ingredient of galaxy evolution models, yet quantitative comparisons between simulations and observations remain challenging because key observables - most notably the mass outflow rate - are not uniquely defined. In this project, we investigate how inferred relationships between outflow properties and host-galaxy/AGN characteristics depend on the methodological choices used to identify outflowing gas and to compute the mass outflow rate.
We analyze high-resolution hydrodynamical simulations, focusing on the IllustrisTNG50 framework, and complement this with controlled, idealized experiments based on GADGET-3 snapshots to isolate systematic effects. Outflows are selected using kinematic criteria combined with thermodynamic information, motivated by an analysis of the density–temperature phase structure, in order to reduce contamination from turbulent ambient gas. We then quantify the sensitivity of mass outflow rate estimates to commonly adopted measurement paradigms, including Eulerian shell-based approaches, Lagrangian crossing methods, and observationally motivated line-of-sight/projection-based estimators. Particular attention is paid to “hyperparameters” such as radial aperture, velocity thresholds, time sampling between snapshots and projection direction, which can drive substantial variation even for the same physical outflow.
By mapping how these methodological degrees of freedom propagate into inferred scaling relations with stellar mass, star formation rate, and AGN luminosity, we aim to establish which trends are robust and which are measurement-dependent. The broader goal is to provide a practical, simulation-to-observation consistent framework for reporting mass outflow rates and for interpreting discrepancies between theoretical predictions and observational constraints, including comparisons to semi-analytic outflow models.