Non-local gravity and comparison with observational datasets

TL;DR

This paper evaluates two non-local gravity models against observational data, finding they fit cosmological datasets as well as the standard Lambda-CDM model and may better reconcile local measurements of the Hubble constant.

Contribution

It introduces and tests two non-local gravity models, implementing their perturbations into a Boltzmann code and comparing their predictions with observational datasets.

Findings

Non-local models fit CMB, BAO, and supernova data as well as Lambda-CDM.

Parameter estimation yields higher H_0 in non-local models, aligning better with local measurements.

Non-local models have the same number of parameters as Lambda-CDM.

Abstract

We study the cosmological predictions of two recently proposed non-local modifications of General Relativity. Both models have the same number of parameters as $\Lambda$CDM, with a mass parameter $m$ replacing the cosmological constant. We implement the cosmological perturbations of the non-local models into a modification of the CLASS Boltzmann code, and we make a full comparison to CMB, BAO and supernova data. We find that the non-local models fit these datasets as well as $\Lambda$CDM. For both non-local models parameter estimation using Planck+JLA+BAO data gives a value of $H_0$ higher than in $\Lambda$CDM, and in better agreement with the values obtained from local measurements.