Specific energy and angular momentum fluxes in the NT and MAD models. (panel (a): specific energy flux. The NT energy flux, e _NT, on the BH remains positive and decreases rapidly at high prograde spin (blue-dashed–dotted curve). In an MAD, the hydrodynamic portion, e _HD, stays close to unity (orange-dashed line), although it shows a slight decrease near a = 1 (orange squares). Additionally accounting for the EM contribution leads to the total specific MAD energy flux, e _MAD (red dots connected by the light red line). (Panel (b): in the NT model, the specific angular momentum flux, l _in,NT, decreases with increasing spin (blue-dashed–dotted line). Surprisingly, in an MAD, l _in,HD is much smaller than the NT value (orange squares) and roughly constant at all spins: the MAD specific angular momentum flux is significantly sub-NT. In fact, the hydrodynamic component of the angular momentum flux is essentially constant across all values of spin (orange-dashed line). In our semi-analytic model of MAD spin-down, we use the two (constant) fits shown with the dashed orange lines, l _HD and e _HD. The thickness of the red lines following l _MAD and e _MAD data points does not represent uncertainty. The red lines show the spline interpolation through the simulated data points, and horizontal orange lines in panels (a) and (b) represent the best fit for e _HD and l _HD, respectively, that we use in our semi-analytic model shown in Figure 5.