Numerical modelling of powerful outflows from super-Eddington accreting supermassive black holes

Abstract

Accretion onto massive black holes produces bright astrophysical systems and generates feedback to host galaxies. Under certain scenarios, super-Eddington accretion rates can be achieved in these systems, producing powerful outflows.

This thesis investigates the dynamics and other properties of outflows, in particular the non-relativistic winds, launched from super-Eddington accretion disks around supermassive black holes. This study is aided by conducting simulations of super-Eddington accretion disks in magnetically arrested disk state, using a state-of-the-art global three-dimensional general relativistic radiation magnetohydrodynamic code. Aiming towards a complete understanding of the magnetized outflows launched from supermassive black hole accretion disks, I performed a series of simulations in a large box size with various black hole accretion rates and black hole spins. Through systematic analysis, I quantify outflow properties – including mass flux, velocity, gas density, and energy - and establish their dependence on fundamental parameters such as black hole spin and black hole accretion rate.

My results provide novel insights into these magnetized, energetic outflows, challenging some prior theoretical predictions while aligning with recent observations. I demonstrate that these powerful outflows can carry away large amounts of mass and energy, therefore causing significant feedback to the surrounding environment. Furthermore, I find that black hole accretion rate plays a vital role in determining the amount of energy and mass flux carried by the wind, while black hole spin mainly affects the energy flux. These findings have important implications for the understanding of the accretion and feedback from supermassive black holes, particularly under extreme accretion conditions.