Measuring nonlocal Lagrangian peak bias
  We investigate nonlocal Lagrangian bias contributions involving gradients of
the linear density field, for which we have predictions from the excursion set
peak formalism. We begin by writing down a bias expansion which includes all
the bias terms, including the nonlocal ones. Having checked that the model
furnishes a reasonable fit to the halo mass function, we develop a 1-point
cross-correlation technique to measure bias factors associated with
2-distributed quantities. We validate the method with numerical realizations of
peaks of Gaussian random fields before we apply it to N-body simulations. We
focus on the lowest (quadratic) order nonlocal contributions. We can reproduce
our measurement of \chi_{10} if we allow for an offset between the Lagrangian
halo center-of-mass and the peak position. The sign and magnitude of \chi_{10}
is consistent with Lagrangian haloes sitting near linear density maxima. The
resulting contribution to the halo bias can safely be ignored for M = 10^13
Msun/h, but could become relevant at larger halo masses. For the second
nonlocal bias \chi_{01} however, we measure a much larger magnitude than
predicted by our model. We speculate that some of this discrepancy might
originate from nonlocal Lagrangian contributions induced by nonspherical
collapse.
