Cosmic spherical void via coarse-graining and averaging non-spherical
  structures
  Inhomogeneous cosmological models are able to fit cosmological observations
without dark energy under the assumption that we live close to the "center" of
a very large-scale under-dense region. Most studies fitting observations by
means of inhomogeneities also assume spherical symmetry, and thus being at (or
very near) the center may imply being located at a very special and unlikely
observation point. We argue that such spherical voids should be treated only as
a gross first approximation to configurations that follow from a suitable
smoothing out of the non-spherical part of the inhomogeneities on angular
scales. In this Letter we present a toy construction that supports the above
statement. The construction uses parts of the Szekeres model, which is
inhomogeneous and anisotropic thus it also addresses the limitations of
spherical inhomogeneities. By using the thin-shell approximation (which means
that the Israel-Darmois continuity conditions are not fulfilled between the
shells) we construct a model of evolving cosmic structures, containing several
elongated supercluster-like structures with underdense regions between them,
which altogether provides a reasonable coarse-grained description of cosmic
structures. While this configuration is not spherically symmetric, its proper
volume average yields a spherical void profile of 250 Mpc that roughly agrees
with observations. Also, by considering a non-spherical inhomogeneity, the
definition of a "center" location becomes more nuanced, and thus the
constraints placed by fitting observations on our position with respect to this
location become less restrictive.
