Shadow of a collapsing star in a regular spacetime

Abstract

We describe the dynamical formation of the shadow of a collapsing star in a Hayward spacetime in terms of an observer far away from the center and a free falling observer. By solving the time-like and light-like radial geodesics we determine the angular size of the shadow as a function of time. We found that the formation of the shadow is a finite process for both observers and its size is affected by the Hayward spacetime parameters. We consider several scenarios, from the Schwarzschild limit to an extreme Hayward black hole.