Speaker
Description
A major question in ΛCDM is what this theory truly predicts for the properties of subhalo populations. Subhalos are difficult to simulate and to find within simulations, and this propagates into uncertainty in theoretical predictions for satellite galaxies. I present Symfind, a new particle-tracking-based subhalo finder, and demonstrate that it can track subhalos to orders-of-magnitude lower masses than the commonly used halo-finding tools, Rockstar and consistent-trees. These longer survival times allow Symfind to find tens-to-hundreds of percent more subhalos, depending on simulation resolution and the specifics of the subhalo population. We perform extensive numerical testing and comparisons against high-resolution idealized simulations. We combine these tests together into a new system for evaluating the performance of subhalo finders and show that Symfind is able to track subhalos until the point of likely galaxy disruption without orphan modeling, while Rockstar cannot and converges to a false solution. This allows for the elimination of a substantial source of systematic uncertainty in clustering measurements, galaxy models, and subhalo-based cosmological tests.
