Schedule by Session

Astrophysical black holes are characterised by two properties: mass and angular momentum, commonly called spin. A significant body of past and current literature has been devoted to study the mass growth of supermassive black holes over cosmic time by means of cosmological simulations. However, the spin of black holes has been often neglected in large scale simulations despite it plays a crucial role in modulating both mass accretion and power emission, driving jet feedback, and determining recoil velocities of merging black hole binaries. We have implemented a new sub-grid accretion model in the moving mesh code Arepo that evolves the mass and the spin of a central black hole as a consequence of mass accretion and gravitomagnetic coupling with a thin accretion disc. The model is able to reproduce the expected spin evolution for rather light supermassive black hole (~1e6-1e7 Msol), when the fast alignment of the black hole and accretion disc angular momenta enforces the spin-up of the black hole, as well as for heavier black holes (lager than 1e8 Msol), whose spin evolution is dictated by the degree of anisotropy of the inflowing material. We will show the first results from small scale simulations of the evolution of the black hole spin in circumnuclear discs and turbulent clouds. We will also discuss the applicability of the model to galaxy merger simulations with the aim of directly linking the merger dynamics to the gravitational recoil velocities.