Lowredshift tests of Newtonian cosmologies with a timevarying gravitational constant
Abstract
In this work, we investigate Newtonian cosmologies with a timevarying gravitational constant, G(t). We examine whether such models can reproduce the lowredshift cosmological observations without a cosmological constant, or any other sort of explicit dark energy fluid. Starting with a modified Newton's second law, where G is taken as a function of time, we derive the first FriedmannLemaître equation, where a second parameter, G*, appears as the gravitational constant. This parameter is related to the original G from the second law, which remains in the acceleration equation. We use this approach to reproduce various cosmological scenarios that are studied in the literature, and we test these models with lowredshift probes: typeIa supernovae (SNIa), baryon acoustic oscillations, and cosmic chronometers, taking also into account a possible change in the supernovae intrinsic luminosity with redshift. As a result, we obtain several models with similar χ^{2} values as the standard ΛCDM cosmology. When we allow for a redshiftdependence of the SNIa intrinsic luminosity, a model with a G exponentially decreasing to zero while remaining positive (model 4) can explain the observations without acceleration. When we assume no redshiftdependence of SNIa, the observations favour a negative G at large scales, while G* remains positive for most of these models. We conclude that these models offer interesting interpretations to the lowredshift cosmological observations, without needing a dark energy term.
 Publication:

Monthly Notices of the Royal Astronomical Society
 Pub Date:
 October 2020
 DOI:
 10.1093/mnras/staa2310
 arXiv:
 arXiv:1906.11219
 Bibcode:
 2020MNRAS.497.4407H
 Keywords:

 gravitation;
 cosmology: observations;
 cosmology: theory;
 Astrophysics  Cosmology and Nongalactic Astrophysics
 EPrint:
 Matching the version published at MNRAS, https://doi.org/10.1093/mnras/staa2310