How galaxies populate haloes in very low-density environments? An
  analysis of the Halo Occupation Distribution in cosmic voids
  Evidence shows properties of dark matter haloes may vary with large-scale
environment. By studying the halo occupation distribution in cosmic voids it is
possible to obtain useful information that can shed light on the subject. The
history of the formation of the haloes and galaxies residing in these regions
is likely to differ from the global behaviour given their extreme environment.
We use two public access simulated galaxy catalogues constructed with different
methods: a semi-analytical model and a hydrodynamic simulation. In both, we
identify cosmic voids and we measure the halo occupation distribution inside
these regions for different absolute magnitude thresholds. We compare these
determinations with the overall results and we study the dependence of
different characteristics of the voids. Also, we analyze the stellar content
and the formation time of the haloes inside voids and confront the general halo
population results. Inside the voids, we find a significantly different halo
occupation distribution with respect to the general results. This is present in
all absolute magnitude ranges explored. We obtain no signs of variation related
to void characteristics indicating that the effects depend only on the density
of the large-scale environment. Additionally, we find that the stellar mass
content also differs within voids, which host haloes with less massive central
galaxies (10%) as well as satellites with significantly lower stellar mass
content (30%). Finally, we find a slight difference between the formation times
of the haloes which are younger in voids than the average population. These
characteristics indicate that haloes populating voids have had a different
formation history, inducing significant changes on the halo occupation
distribution.
