Minisymposium Presentation

I will discuss ray tracing for astrophysics applications, with a focus on black hole imaging. Astrophysical black holes, i.e., those which astronomers do observe in a near and far Universe, are not always surrounded by vacuum but are often embedded in extremely hot swirl of plasma rotating almost at the speed of light. The physical conditions in such environment are not achievable in our Earth laboratories hence observations of plasma in a close vicinity of black holes enable studies of plethora of exotic phenomena such as particle acceleration to extreme energies, light bending in strong gravity, or gravitational energy conversion to other forms of energy. Ray tracing is used to simulate emission intensity in black hole accretion flows, creating high-resolution synthetic images. Parameter estimation of black holes based on experimental data requires comparison against a large number of these synthetic images, which is computationally intensive. By adapting a general relativistic ray-tracing code for GPU execution, significant speedups are obtained relative to CPU execution. Though high resolution images are necessary to observe fine features in the system, such as photon rings, features in black holes range over a wide range of scale, requiring a multiscale approach to generating images.