Stacking the Synchrotron Cosmic Web with FIGARO
  Recently Vernstrom et al. (2021) reported the first definitive detection of
the synchrotron cosmic web, obtained by `stacking' hundreds of thousands of
pairs of close-proximity clusters in low-frequency radio observations and
looking for a residual excess signal spanning the intercluster bridge. We
attempt to reproduce these results by stacking similarly close-proximity
clusters from the FIlaments and GAlactic RadiO (FIGARO; Hodgson et al., 2021a)
simulation. We do so to understand whether these empirical cosmic web detection
results are consistent with our current best models of the radio sky, as well
as to understand and constrain any potential confounding factors that could
introduce false positive signals. Specifically, in addition to testing whether
the cosmic web itself produces excess intercluster emission, we also test
whether the stacking signal is polluted by the presence of the intervening
radio population of active galactic nucleii and star forming galaxies, the low
luminosity population of radio halos, and the effect of the sidelobes of the
interferometric dirty beam. Ultimately, we find that we are unable to reproduce
their excess intercluster emission in our own stacks, either due to the cosmic
web or any additional polluting factors. We do, however, predict the appearance
of excess emission on the immediate interiors of cluster pairs as a result of
asymmetric, `radio relic'-like shocks surrounding cluster cores, and which we
predict to be on the cusp of detection in their stacks. This difference in the
location of excess emission in the stacked signal prohibits a simple resolution
in the form of a scaling factor, leaving the discrepancy between these
simulation results and the empirical observations of Vernstrom et al.
unresolved.
