Large Scale Cosmological Anomalies and Inhomogeneous Dark Energy

TL;DR

This paper reviews large-scale cosmic anomalies and explores inhomogeneous dark energy models as potential explanations, highlighting the lack of strong observational constraints on dark energy inhomogeneities and their implications for cosmology.

Contribution

It provides a comprehensive overview of theoretical models of inhomogeneous dark energy and discusses their observational constraints and relevance to cosmic anomalies.

Findings

Inhomogeneous dark energy models can potentially explain large-scale cosmic anomalies.

Current observations place limited constraints on dark energy inhomogeneities.

Theoretical models suggest inhomogeneous dark energy could depart from the cosmological principle.

Abstract

A wide range of large scale observations hint towards possible modifications on the standard cosmological model which is based on a homogeneous and isotropic universe with a small cosmological constant and matter. These observations, also known as "cosmic anomalies" include unexpected Cosmic Microwave Background perturbations on large angular scales, large dipolar peculiar velocity flows of galaxies ("bulk flows"), the measurement of inhomogenous values of the fine structure constant on cosmological scales ("alpha dipole") and other effects. The presence of the observational anomalies could either be a large statistical fluctuation in the context of {\lcdm} or it could indicate a non-trivial departure from the cosmological principle on Hubble scales. Such a departure is very much constrained by cosmological observations for matter. For dark energy however there are no significant observational constraints for Hubble scale inhomogeneities. In this brief review I discuss some of the theoretical models that can naturally lead to inhomogeneous dark energy, their observational constraints and their potential to explain the large scale cosmic anomalies.