How Improbable is Our Universe? The Uncorrelated Anomalies of the Cosmic Microwave Background

The cosmic microwave background (CMB) can be described as a snapshot of the early Universe. It provides us with essential information on the origin and evolution of the Universe. Using the CMB, we are able to place constraints on the current standard model of cosmology, ΛCDM. Conventionally, ΛCDM treats the Universe as statistically homogeneous and isotropic, i.e. the same in every location and in every direction. However, there are several unexpected features of the large scale fluctuations in the CMB that are inconsistent with statistical isotropy. These are referred to as the large-scale anomalies. Each of these anomalies has a small chance of occurring (0.01 - 1%), but they are often individually excused as statistical flukes. In this project, we seek to answer the question of whether or not these anomalies are correlated. In particular, we are interested in the lack of large-angle correlation, the odd-parity preference, the quadrupole-octupole alignment, and the hemispherical asymmetry anomalies. We find that the anomalies we have considered are uncorrelated in the tails of their distributions, meaning that their joint probability is significantly lower. We place an upper limit of 0.003% on ΛCDM reproducing our CMB. This provides strong evidence against the existence of statistical isotropy in our Universe.