Speaker
Description
The distribution of matter within dark matter halos contains key information about the nature and the properties of dark matter. Knowledge of the exact local dark matter density is not only important for cosmology, but also essential for precise calculations in both direct and indirect detection experiments. Getting the most out of the simulations from which the density profiles are inferred is therefore fundamental for the study of dark matter on all scales.
We introduce a new dynamics-based method to calculate dark matter density profiles from halo simulations. Each particle in a snapshot is ‘smeared’ over its orbit to obtain a profile which is averaged over a dynamical time.
The profiles calculated using this technique are in excellent agreement with the traditional ‘binned’ estimates and show significant reduction in Poisson noise. The profiles are generated subject to two main assumptions: phase mixing and spherical symmetry, both of which are widely used in dynamical analyses for their simplicity. Our work confirms the validity of these assumptions to recover the correct density structure in simulated halos for the majority of their radial extent.
Including information about the spherically-averaged dynamics of the particles also allows for calculation of the gravitational potential at radii below the softening length of the simulation. This makes it possible to extrapolate the behaviour of the dynamical density profile below the softening scale, which shows promising results when compared to a higher resolution version of the same snapshot.
