This is an image from a cosmological simulation of the Universe performed by the Enzo multi-physics hydrodynamics code. Enzo is used to study the physical processes present in the evolution of the cosmos. To learn more, read Ray Tracing the Cosmos by Texascale.
The visualization was performed using a modified version of the yt open source data analysis and visualization package. The yt-project grew out of the Enzo community to satisfy a need to visualize and analyze the large data resulting from the Enzo simulations. Collaborators at TACC and the National Center for Supercomputing Applications (NCSA) modified the yt framework to utilize a ray tracing back end called GraviT to perform volume rendering of the adaptive mesh refinement data. This image shows a volume rendering of density in which the color and opacity are mapped to the density distribution.