Figure 14

Figure 14: Escape cones in the Schwarzschild metric, for five values of rO. For an observer at radius rO, light sources distributed at a radius rS with rS > rO and rS > 3m illuminate a disk whose angular radius d is given by Equation (107View Equation). The boundary of this disk corresponds to light rays that spiral towards the light sphere at r = 3m. The disk becomes smaller and smaller for rO --> 2m. Figure 9 illustrates that the notion of escape cones is meaningful for any spherically symmetric and static spacetime where R has one minimum and no other extrema [253]. For the Schwarzschild spacetime, the escape cones were first mentioned in [249, 223], and explicitly calculated in [320]. A picture similar to this one can be found, e.g., in [54].