Tidal tracks and artificial disruption of cold dark matter haloes

We describe a simple extension to existing models for the tidal heating of dark matter subhaloes which takes into account second-order terms in the impulse approximation for tidal heating. We show that this revised model can accurately match the tidal tracks along which subhaloes evolve as measured in high-resolution N-body simulations. We further demonstrate that, when a constant density core is introduced into a subhalo, this model is able to quantitatively reproduce the evolution and artificial disruption of N-body subhaloes arising from finite resolution effects. Combining these results we confirm prior work indicating that artificial disruption in N-body simulations can result in a factor two underestimate of the subhalo mass function in the inner regions of host haloes, and a 10–20 per cent reduction over the entire virial volume.