Abstracted Visualization of Halo Topologies in Dark Matter Simulations

This work focuses on particle-based ΛCDM (cold dark matter) simulations. The features of interest are clusters of dark matter particles, called halos. Halos are governed by the laws of motion and gravitation, and they may, consequently, merge over time. In this paper, we present visualization methods for the topology of the resulting tree-like accumulation history of the halos, as well as for the underlying halo data. We combine direct visualization methods of merger trees, in which trajectories over time are depicted in 3D space, with novel visual topological abstracts that are obtained by mapping time to one spatial axis while projecting halo positions on the remaining two axes. The user can explore and analyze both halos and merger trees through our unified visualization interface, which uses linked views complementing each other. All of our methods pay special attention to the periodic boundary conditions that are typically used during the underlying physical simulation.