Contributed Talk - Splinter BlackHoles

Wednesday, 15 September 2021, 15:20   (virtual BH)

Sub-grid modelling of supermassive black hole accretion, feedback and spin evolution in hydrodynamical simulations

Luca Sala
Universit√§ts-Sternwarte M√ľnchen - LMU

Active galactic nuclei (AGNs) are massive black holes (BHs) caught in the act of accreting gas at the centre of their host galaxies. In this process, a great amount of energy is released into the surrounding medium, in a process loosely referred to as AGN feedback. Numerical simulations are a powerful tool to study the complex non-linear interaction between massive BHs and their surrounding environment, but usually we are not able to resolve all the relevant scales involved due to limited computational resources, therefore we have to rely upon sub-grid, effective models. I will present my work which focuses on the design and implementation of such models for accretion and feedback, to be applied in cosmological hydrodynamical simulations. Regarding the treatment of accretion, my work aims at adding an intermediate step in the mass transfer from the resolved scales of the simulation onto the BH, through the inclusion of a sub-grid accretion disc, then self-consistently evolve its properties as well as the BH spins. This allows to obtain a population of BHs with their associated spins and track their evolution across cosmic time. Moreover, to include the effect of feedback, energy or momentum (or both) can be coupled to the nearby gas. While isotropic injection of purely thermal energy has been a common way of including a feedback mechanism, my work focuses on non-isotropic feedback models, aimed at reproducing the presence of outflows as well as the interaction of jets from AGNs with the surrounding medium, and in particular I will present results of simulations which assume a momentum-driven model in which gas particles are stochastically kicked over a bi-conical region, to mimic observed kinetic winds.