Simulations and symmetries
  We investigate the range of applicability of a model for the real-space power
spectrum based on N-body dynamics and a (quadratic) Lagrangian bias expansion.
This combination uses the highly accurate particle displacements that can be
efficiently achieved by modern N-body methods with a symmetries-based bias
expansion which describes the clustering of any tracer on large scales. We show
that at low redshifts, and for moderately biased tracers, the substitution of
N-body-determined dynamics improves over an equivalent model using perturbation
theory by more than a factor of two in scale, while at high redshifts and for
highly biased tracers the gains are more modest. This hybrid approach lends
itself well to emulation. By removing the need to identify halos and subhalos,
and by not requiring any galaxy-formation-related parameters to be included,
the emulation task is significantly simplified at the cost of modeling a more
limited range in scale.
