How Biased Are Halo Properties in Cosmological Simulations?
  Cosmological N-body simulations have been a major tool of theorists for
decades, yet many of the numerical issues that these simulations face are still
unexplored. This paper measures numerical biases in these large, dark
matter-only simulations that affect the properties of their dark matter haloes.
We compare many simulation suites in order to provide several tools for
simulators and analysts which help mitigate these biases. We summarise our
comparisons with practical `convergence limits' that can be applied to a wide
range of halo properties, including halo properties which are traditionally
overlooked by the testing literature. We also find that the halo properties
predicted by different simulations can diverge from one another at unexpectedly
high resolutions. We demonstrate that many halo properties depend strongly on
force softening scale and that this dependence leads to much of the measured
divergence between simulations. We offer an empirical model to estimate the
impact of such effects on the rotation curves of a halo population. This model
can serve as a template for future empirical models of the biases in other halo
properties.
