Statistics of biased tracers in variance-suppressed simulations
  Cosmological simulations play an increasingly important role in analysing the
observed large-scale structure of the Universe. Recently, they have been
particularly important in building hybrid models that combine a perturbative
bias expansion with displacement fields extracted from N-body simulations to
describe the clustering of biased tracers. Here, we show that simulations that
employ a technique referred to as "Fixing-and-pairing" (F&P) can dramatically
improve the statistical precision of such hybrid models. Specifically, by
numerical and analytic means, we show that F&P simulations provide unbiased
estimates for all statistics employed by hybrid models while reducing, by up to
two orders of magnitude, their uncertainty on large scales. This roughly
implies that an EUCLID-like survey could be analysed using simulations of 2Gpc
a side -- a 10% of the survey volume. Our work establishes the robustness of
F&P for current hybrid theoretical models for galaxy clustering, an important
step towards achieving an optimal exploitation of large-scale structure
measurements.
