On the relative bias of void tracers in the Dark Energy Survey
  Luminous tracers of large-scale structure are not entirely representative of
the distribution of mass in our Universe. As they arise from the highest peaks
in the matter density field, the spatial distribution of luminous objects is
biased towards those peaks. On large scales, where density fluctuations are
mild, this bias simply amounts to a constant offset in the clustering amplitude
of the tracer, known as linear bias. In this work we focus on the relative bias
between galaxies and galaxy clusters that are located inside and in the
vicinity of cosmic voids, extended regions of relatively low density in the
large-scale structure of the Universe. With the help of hydro-dynamical
simulations we verify that the relation between galaxy and cluster overdensity
around voids remains linear. Hence, the void-centric density profiles of
different tracers can be linked by a single multiplicative constant. This
amounts to the same value as the relative linear bias between tracers for the
largest voids in the sample. For voids of small sizes, which typically arise in
higher density regions, this constant has a higher value, possibly showing an
environmental dependence similar to that observed for the linear bias itself.
We confirm our findings by analysing mocks and data obtained during the first
year of observations by the Dark Energy Survey. As a side product, we present
the first catalogue of three-dimensional voids extracted from a photometric
survey with a controlled photo-z uncertainty. Our results will be relevant in
forthcoming analyses that attempt to use voids as cosmological probes.
