A new method to measure galaxy bias
  We present a new approach for modelling galaxy/halo bias that utilizes the
full non-linear information contained in the moments of the matter density
field, which we derive using a set of numerical simulations. Although our
method is general, we perform a case study based on the local Eulerian bias
scheme truncated to second-order. Using 200 N-body simulations covering a total
comoving volume of 675 (Gpc/h)^3, we measure several 2- and 3-point statistics
of the halo distribution to unprecedented accuracy. We use the bias model to
fit the halo-halo power spectrum, the halo-matter cross spectrum and the
corresponding three bispectra for wavenumbers in the range 0.04 < k < 0.12 h
Mpc^-1. We find the constraints on the bias parameters obtained using the full
non-linear information differ significantly from those derived using standard
perturbation theory at leading order. Hence, neglecting the full non-linear
information leads to biased results for this particular scale range. We also
test the validity of the second-order Eulerian local biasing scheme by
comparing the parameter constraints derived from different statistics. Analysis
of the halo-matter cross-correlation coefficients defined for the 2- and
3-point statistics reveals further inconsistencies contained in the
second-order Eulerian bias scheme, suggesting it is too simple a model to
describe halo bias with high accuracy.
