Observational Constraints in Delta-gravity: CMB and Supernovae

Delta-gravity (DG) is a gravitational model based on an extension of general relativity given by a new symmetry called (d) over tilde. In this model, new matter fields are added to the original matter fields, motivated by the additional symmetry. We call them (d) over tilde matter fields. This model predicts an accelerating universe without the need to introduce a cosmological constant. In this work, we study the scalar cosmic microwave background (CMB) temperature (TT) power spectrum predicted by DG using an analytical hydrodynamic 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 Type Ia supernovae (SNe Ia) and CMB observations in the DG context. Finally, we obtain the scalar CMB TT power spectrum and the fitted parameters needed to explain both SN Ia data and CMB measurements. The results are in reasonable agreement with both observations considering the analytical approximation. We also discuss whether the Hubble constant and the accelerating universe are in concordance with the observational evidence in the DG context.

Automated summary

Delta-gravity (DG) is a gravitational model that extends general relativity based on a new symmetry called (d) over tilde, predicting an accelerating universe without a cosmological constant. The study uses an analytical approach to analyze the scalar cosmic microwave background temperature power spectrum predicted by DG, fitting the data from the Planck satellite. Results show reasonable agreement with observations, and the compatibility between Type Ia supernovae and CMB observations in the DG context is also discussed.