Fig. 2: Constraints on the M87 BH spin and accretion disk morphology in the a–ro (outer radius of the precessing disk) parameter space.
From: Co-precession of a curved jet and compact accretion disk in M87
The upper (lower) panels are for prograde (retrograde) disks. A larger profile index ζ represents a disk that is more concentrated inwards. The shaded areas enclose the allowed region where rISCO < rin < ro. The red curves represent the cases where rin = 6rg, which was motivated by the finding from the simulations that the inner radius for prograde tilted disks is insensitive to the BH spin26 for a weakly magnetized disk. The red curves serve as a guiding and limiting case.
