Cosmography of the minimally extended Varying Speed of Light Model

TL;DR

This paper applies cosmography, a model-independent approach, to a minimally extended varying speed of light model to compare it with standard cosmology and explore how luminosity distance can constrain model parameters.

Contribution

It introduces a cosmographic analysis of a minimally extended VSL model without assuming the Robertson-Walker metric, enabling direct comparison with observational data.

Findings

Cosmography can distinguish VSL from standard cosmology using luminosity distance.

Luminosity distance effectively constrains VSL model parameters.

The approach offers a model-independent way to test varying speed of light theories.

Abstract

Cosmography, as an integral branch of cosmology, strives to characterize the Universe without relying on pre-determined cosmological models. This model-independent approach utilizes Taylor series expansions around the current epoch, providing a direct correlation with cosmological observations and the potential to constrain theoretical models. Cosmologists can describe many measurable aspects of cosmology by using various combinations of cosmographic parameters. The varying speed of light model can be naturally implemented, provided that we do not make any further assumptions from the Robertson-Walker metric for cosmological time dilation. Therefore, we apply cosmography to the so-called minimally extended varying speed of light model. In this case, other cosmographic parameters can be used to construct the Hubble parameter for both the standard model and the varying speed-of-light model. On the other hand, distinct combinations of cosmographic values for the luminosity distance indicate the two models. Hence, luminosity distance might provide a method to constrain the parameters in varying speed-of-light models.