A robust measurement of the first higher-derivative bias of dark matter
  halos
  We present a new simulation technique in which any chosen mode $\mathbf{k}$
of the density contrast field can be amplified by an amplitude $\Delta$. These
amplified-mode simulations allow us to study the response of the halo density
field to a long-wavelength mode other than the DC mode. In this sense they are
a generalization of the separate-universe simulations to finite-wavelength
modes. In particular, we use these simulations to obtain robust measurements of
the first higher-derivative bias of dark matter halos $b_{\nabla^2 \delta}$. We
find a negative bias at all mass considered, roughly following the $-R_L^2(M)$
relation, the Lagrangian radius of halos squared, as naively expected. We
compare our results with those obtained from a fit to the 1-loop halo-matter
power spectrum, as well as with the recent results from Abidi and Baldauf
(2018), and to the prediction from the peak theory.
