Distortion of the stellar sky by a Schwarzschild black hole

Abstract

The optical appearance of the stellar sky for an observer in the vicinity of a black hole is dominated by bending of light, the frequency shift, and the magnification caused by gravitational lensing and aberration. Due to the finite aperture of an observer’s eye or a telescope, Fraunhofer diffraction has to be taken into account. We have used high performance graphics hardware and developed a program that enables the user to interactively explore the stellar sky in the vicinity of a Schwarzschild black hole. To do so, we determine what an observer, who can either move quasistatically around the black hole or follow a timelike radial geodesic, would actually see.