Explaining Cosmological Anisotropy: Evidence for Causal Horizons from
  CMB data
  The origin of power asymmetry and other measures of statistical anisotropy on
the largest scales of the universe, as manifested in Cosmic Microwave
Background (CMB) and large-scale structure data, is a long-standing open
question in cosmology. In this paper we analyze the Planck Legacy temperature
anisotropy data and find strong evidence for a violation of the Cosmological
principle of isotropy, with a probability of being a statistical fluctuation of
order ~ 10^-9. The detected anisotropy is related to large-scale directional
LCDM cosmological parameter variations across the CMB sky, that are sourced by
three distinct patches in the maps with circularly-averaged sizes between 40 to
70 degrees in radius. We discuss the robustness of our findings to different
foreground separation methods and analysis choices, and find consistent results
from WMAP data when limiting the analysis to the same scales. We argue that
these well-defined regions within the cosmological parameter maps may reflect
finite and casually disjoint horizons across the observable universe. In
particular we show that the observed relation between horizon size and mean
dark energy density within a given horizon is in good agreement with
expectations from a recently proposed model of the universe that explains
cosmic acceleration and cosmological parameter tensions between the high and
low redshift universe from the existence of casual horizons within our
universe.
