Speaker
Description
The profound influence of supermassive black holes (SMBHs) on their host galaxies includes altering the orbits of stars, regulating star formation, modifying gas distribution, to name a few. To understand these processes we need to first understand how SMBHs grow through gas accretion and their associated feedback into the surrounding environment. These factors remain a current crucial challenge in astrophysics.
To better understand the fueling of supermassive black holes from galactic (tens of kiloparsec) to event horizon scales (milliparsec), we set up a suite of general relativistic magnetohydrodynamic multi-scale simulations by using the Athena++ code with GPU support through the Kokkos library. We include a variety of physical processes: radiative cooling, heating, turbulence, and magnetic fields.
On event horizon scales, modeling of accretion flows is limited in part by a dependence on ad-hoc initial conditions (ICs). While most simulations use idealized ICs, we employ massive elliptical galaxies from the IllustrisTNG project. We select a total of $\sim10$ central galaxies hosted by $M > M_{200}^{z=0} > 8 \times 10^{11}M_\odot$ halos. We extract their gas properties, magnetic field and gravitational potential from the unstructured moving-mesh of the IllustrisTNG simulations, using a 2nd order voronoi method to project these quantities onto a nested cartesian-mesh. The mesh is progressively refined with a total of 22 levels of mesh refinement towards smaller radii to resolve the event horizon. This way we resolve the thermodynamics of the multiphase gas and the magnetic structure across all scales during the accretion process. By connecting physics at multiple scales, our approach aims to bridge the gap between the galactic scale and the event horizon for SMBHs in elliptical galaxies.
We compare the SMBH mass accretion rates, angular momentum, magnetic flux and jet power as given by our simulations to those of IllustrisTNG for a range of galaxy masses and redshifts. This allows us to provide a comprehensive sub-grid model of black hole accretion and feedback for large-scale galaxy formation cosmological simulations. Additionally, we analyze the disk stresses and angular momentum transfer and provide mock observations of the multiphase gas from different angles, enabling direct comparisons with observational data.
