Cosmology when living near the Great Attractor

TL;DR

Living near the Great Attractor can significantly bias cosmological parameter estimates, such as the universe's age and Hubble constant, highlighting the importance of local structure in cosmological observations.

Contribution

This study quantifies how local massive overdensities like the Great Attractor affect inferred cosmological parameters from observational data.

Findings

Local overdensities can alter the inferred Hubble parameter by about 3%.

The universe's age estimate can be biased by approximately 3% due to local structures.

Accounting for local structures improves the accuracy of cosmological measurements.

Abstract

If we live in the vicinity of the hypothesized Great Attractor, the age of the universe as inferred from the local expansion rate can be off by three per cent. We study the effect that living inside or near a massive overdensity has on cosmological parameters induced from observations of supernovae, the Hubble parameter and the Cosmic Microwave Background. We compare the results to those for an observer in a perfectly homogeneous LCDM universe. We find that for instance the inferred value for the global Hubble parameter changes by around three per cent if we happen to live inside a massive overdensity such as the hypothesized Great Attractor. Taking into account the effect of such structures on our perception of the universe makes cosmology perhaps less precise, but more accurate.