Low-redshift tests of cosmologies with a time-varying gravitational constant

2019/06/30 by Ekim Taylan Hanımeli, I. Tutusaus, Isaac Tutusaus +2
Physics and Astronomy · #Astronomy #Astrophysics #Astrophysics and Cosmic Phenomena #Baryon acoustic oscillations #Classical mechanics #Computer science #Constant (computer programming) #Cosmological constant #Cosmology #Cosmology and Gravitation Theories #Dark energy #Deceleration parameter #Galaxies: Formation, Evolution, Phenomena #Galaxy #Gravitation #Gravitational constant #Gravitational redshift #Luminosity #Luminosity distance #Physics #Redshift #Solar and Space Plasma Dynamics #Supernova #Theoretical physics #astro-ph.CO

paper · pdf · doi:10.1093/mnras/staa2310

published as Monthly Notices of the Royal Astronomical Society, Volume 497, Issue 4, October 2020, Pages 4407-4415 · Matching the version published at MNRAS, https://doi.org/10.1093/mnras/staa2310

openalex publication_date 2019/08/01 · arxiv created 2020/08/29 · arxiv updated 2020/09/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05

Abstract

In this work, we investigate Newtonian cosmologies with a time-varying gravitational constant, G(t). We examine whether such models can reproduce the low-redshift 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 Friedmann--Lema\ⁱtre 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 low-redshift probes: type-Ia 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 χ² values as the standard ΛCDM cosmology. When we allow for a redshift-dependence 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 redshift-dependence 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 low-redshift cosmological observations, without needing a dark energy term.

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