Can we avoid dark energy?

TL;DR

This paper evaluates void models as alternatives to dark energy, finding they require fine-tuning or implausibly low Hubble rates, and are strongly constrained by baryon acoustic scale measurements.

Contribution

It demonstrates that void models face significant challenges from observational data, questioning their viability as dark energy alternatives.

Findings

Void models can fit CMB and supernova data with fine-tuning.

Radial baryon acoustic scale measurements strongly constrain void models.

Void models are challenged by the need for low Hubble rates or fine-tuning.

Abstract

The idea that we live near the centre of a large, nonlinear void has attracted attention recently as an alternative to dark energy or modified gravity. We show that an appropriate void profile can fit both the latest cosmic microwave background and supernova data. However, this requires either a fine-tuned primordial spectrum or a Hubble rate so low as to rule these models out. We also show that measurements of the radial baryon acoustic scale can provide very strong constraints. Our results present a serious challenge to void models of acceleration.