Measurement of Void Bias Using Separate Universe Simulations
  Cosmic voids are biased tracers of the large-scale structure of the universe.
Separate universe simulations (SUS) enable accurate measurements of this
biasing relation by implementing the peak-background split (PBS). In this work,
we apply the SUS technique to measure the void bias parameters. We confirm that
the PBS argument works well for underdense tracers. The response of the void
size distribution depends on the void radius. For voids larger (smaller) than
the size at the peak of the distribution, the void abundance responds
negatively (positively) to a long wavelength mode. The linear bias from the SUS
is in good agreement with the cross power spectrum measurement on large scales.
Using the SUS, we have detected the quadratic void bias for the first time in
simulations. We find that $ b_2 $ is negative when the magnitude of $ b_1 $ is
small, and that it becomes positive and increases rapidly when $ |b_1| $
increases. We compare the results from voids identified in the halo density
field with those from the dark matter distribution, and find that the results
are qualitatively similar, but the biases generally shift to the larger voids
sizes.
