Brans-Dicke model constrained from Big Bang nucleosynthesis and magnitude redshift relations of Supernovae

TL;DR

This paper constrains the Brans-Dicke cosmological model using Big Bang nucleosynthesis data and supernovae redshift observations, finding it compatible with a constant cosmological term of 0.7, despite insensitivity of parameters to the $m-z$ relation.

Contribution

It provides new constraints on the Brans-Dicke model parameters from nucleosynthesis and supernova data, including the role of a constant cosmological term.

Findings

Model with cosmological constant 0.7 fits supernova data

Parameters are insensitive to the $m-z$ relation

Constraints from nucleosynthesis are consistent with observations

Abstract

The Brans-Dicke model with a variable cosmological term ($BD\Lambda$) has been investigated with use of the coupling constant of $\omega=10^4$. Parameters inherent in this model are constrained from comparison between Big Bang nucleosynthesis and the observed abundances. Furthermore, the magnitude redshift ($m-z$) relations are studied for $BD\Lambda$ with and without another constant cosmological term in a flat universe. Observational data of Type Ia Supernovae are used in the redshift range of $0.01<z<2$. It is found that our model with energy density of the constant cosmological term with the value of 0.7 can explain the SNIa observations, though the model parameters are insensitive to the $m-z$ relation.