DASH: a library of dynamical subhalo evolution
  The abundance and demographics of dark matter substructure is important for
many areas in astrophysics and cosmological $N$-body simulations have been the
primary tool used to investigate them. However, it has recently become clear
that the simulations are subject to numerical artefacts, which hampers a proper
treatment of the tidal evolution of subhaloes. Unfortunately, no analytical
models that accurately describe subhalo evolution exist either. We therefore
present a library of idealized, high resolution $N$-body simulations of the
tidal evolution of individual subhaloes that can be used to calibrate
semi-analytical models and to complement cosmological simulations. The
simulations focus on minor mergers, i.e., the mass of the subhalo is much
smaller than that of the host halo, such that the impact of dynamical friction
is negligible. This setup allows the adoption of a fixed analytical potential
for modelling the host halo. The dynamical evolution of subhaloes is followed
with $N$-body computations. In the library, four parameters, two of which
characterize the subhalo orbit with respect to the host halo, and the two
concentrations of the host- and subhalo, are varied over the ranges encountered
in cosmological simulations. We show several representative examples from the
library that illustrate the evolution of the subhalo mass and velocity
dispersion profiles. Additionally, we make publicly available a pre-trained
non-parametric model of the subhalo mass evolution based on random forest
regression. This model is able to interpolate the simulation data at the
0.1\,dex level and provides efficient access to the data for further use in
modelling.
