Separate Universe Void Bias
  Voids have emerged as a novel probe of cosmology and large-scale structure.
These regions of extreme underdensity are sensitive to physics beyond the
standard model of cosmology, and can potentially be used as a testing ground to
constrain new physics. We present the first determination of the linear void
bias measured in separate universe simulations. Our methods are validated by
comparing the separate universe response bias with the clustering bias of
voids. We find excellent agreement between the two methods for voids identified
in the halo field and the down-sampled dark matter field. For voids traced by
halos, we identify two different contributions to the bias. The first is due to
the bias of the underlying halo field used to identify voids, while the second
we attribute to the dynamical impact of long-wavelength density perturbations
on void formation and expansion. By measuring these contributions individually,
we demonstrate that their sum is consistent with the total void bias. We also
measure the void profiles in our simulations, and determine their separate
universe response. These can be interpreted as the sensitivity of the profiles
to the background density of the Universe.
