Inhomogeneous accretion disk simulations. Left panel: microlensing magnification map. The red line shows the trajectory that best fits the long-term microlensing trend (see Fig. 8). Middle panel: microlensing magnified accretion disk profile, including a Gaussian hotspot orbiting the central black hole. The radius of the circular orbit is determined by the period, which is a free parameter, and the black hole mass, fixed to 1.6 × 10⁸ M_⊙. Right panel: observed (red) and simulated (blue) flux ratios for the best-fit parameters. An animated version of this figure is available online.