cuRRay - CUDA Relativistic Raytracer

cuRRay stands for CUDA relativistic raytracer and is a software capable of creating images of black holes and objects in their vicinity. According to Einstein's general theory of relativity, light is deflected by gravity (see figure 1). This leads to images of objects near black holes being distorted or even appearing multiple times. Black holes exhibit an extreme gravitational filed an thus the light bending effect is very strong. By analysing the images created by cuRRay, one can get insight into the curvature of spacetime, which is the reason for gravity in Einstein's theory, outside of black holes.

Lichtablenkung durch schwarzes Loch
Figure 1: Two light rays γ1 and γ2 sent by the light source Q are deflected by the black hole L and arrive at the observer B. The observer sees two images I1 und I2 of the source at angles α1 and α2.

Repository

The software cuRRay as well as some images created by it and the PDF of the project (german and english) can be found on my GitLab repository.

PDF logoenglish translation of the project

PDF logooriginal german version of the project

Some Results

Stars behind black hole
Figure 2: Stars in the background of a static black hole are warped into arcs around the hole. Image of the Milky Way: ESO/S. Brunier.
Video 1: Animated version of figure 2. The observer spins around the black hole and thus sees different parts of the Milky Way in the background.
Sphere behind black hole
Figure 3: Sphere behind static black hole is warped into a ring.
Video 2: Animated version of figure 3. The sphere rotates around the black hole.
Ring around black hole
Figure 4: Ring around static black hole. The upper side (green) and the lower side (magenta) are both visible at the same time.
Ring around rotating black hole
Figure 5: Ring around rotating black hole. The spacetime is dragged around in the direction of rotation. This leads to light rays fighting against the flow or following it, depending on which side of the hole they pass. This leads to an asymmetrical immage.