Chaotic Shadows of Black Holes: A Short Review

Understand

We give a brief review on the formation and the calculation of black hole shadow.

• Firstly, we introduce the conception of black hole shadow and the current works on a variety of black hole shadows.
• Secondly, we present main methods of calculating photon sphere radius and shadow radius, and then explain how the photon sphere affect the boundary of black hole shadow.
• We review the analytical calculation for black hole shadows which have analytic expressions for shadow boundary due to the integrable photon motion system.