Spinning up black holes with super-critical accretion flows

Understand

We study the process of spinning up black holes by accretion from slim disks in a wide range of accretion rates.

• We show that for super-Eddington accretion rates and low values of the viscosity parameter alpha (\lesssim 0.01) the limiting value of the dimensionless spin parameter a_* can reach values higher than a_*=0.9978 inferred by Thorne (1974) in his seminal study.
• For \mdot=10\mdot_{Edd} and alpha=0.01 spin equilibrium is reached at a_*=0.9994.
• We show that the equilibrium spin value depends strongly on the assumed value of alpha.