Observational constraints in Delta Gravity: CMB and supernovas

TL;DR

This paper investigates Delta Gravity, an extension of General Relativity, and assesses its predictions for the CMB and supernova data, finding reasonable agreement with observations without requiring a cosmological constant.

Contribution

The study provides an analytical approach to test Delta Gravity against CMB and supernova observations, demonstrating its viability as an alternative to standard cosmology.

Findings

Delta Gravity predicts an accelerating universe without a cosmological constant.

The model's predictions align reasonably with Planck CMB data.

Compatibility between SNe-Ia and CMB observations is supported in this framework.

Abstract

Delta Gravity is a gravitational model based on an extension of General Relativity given by a new symmetry called $\tilde{\delta}$. In this model, new matter fields are added to the original matter fields, motivated by the additional symmetry. We call them $\tilde{\delta}$ matter fields. This model predicts an accelerating Universe without the need to introduce a cosmological constant. In this work, we study the Delta Gravity prediction about the scalar CMB TT power spectrum using an analytical hydrodynamical approach. To fit the Planck satellite's data with the DG model, we used a Markov Chain Monte Carlo analysis. We also include a study about the compatibility between SNe-Ia and CMB observations in the Delta Gravity Context. Finally, we obtain the scalar CMB TT power spectrum and the fitted parameters needed to explain both SNe-Ia Data and CMB measurements. The results are in a reasonable agreement with both observations considering the analytical approximation. We also discuss if the Hubble Constant and the Accelerating Universe are in concordance with the observational evidence in the Delta Gravity context.