Speaker: Kung-Yi Su (Harvard)
AGN jet across multiple scales
AGN jet is a problem in multiple scales. Due to the lack of a first-principles physical understanding and observational constraints on AGN, many numerical studies in the galaxy scale choose a specific sub-grid AGN feedback and black hole (BH) accretion model with parameters marginalized over certain statistical halo properties. To better address this, on the galaxy scale, we study how different AGN jet models suppress cooling flows and quench star formations. The uncertain parameters of jets include energy form (kinetic, thermal, and cosmic ray (CR) energy), energy/momentum/mass flux, magnetic field strength and geometry, jet precession angle and period, opening angle, and duty cycle. We investigate all of these parameters in 10^12- 10^14M⊙ halo using high-resolution non-cosmological MHD simulations with the FIRE-2 (Feedback In Realistic Environments) stellar feedback model, conduction, and viscosity. We concluded the criteria and parameter space for jet models to stable quench these massive galaxies without violating observational constraints. In the scale closer to the BH, where we can resolve the gravitational capture of gas, we studied how AGN jets affect the black hole (BH) accretion. We specifically focus on the early growth of BHs in high-redshift galaxies. Here we use high-resolution parsec-scale hydrodynamical simulations to study jet propagation and its effect on 100 M⊙ BH accretion in the dense, low-metallicity gas expected in early protogalaxies. We derived a universal picture of how jets propagate and how self-regulation facilitates at the scale of Bondi radius. We also narrowed down the conditions for super-Eddington accretion to happen.
