Big-bang nucleosynthesis and cosmic microwave background constraints on nonminimally coupled theories of gravity
Abstract
In this paper, we show that the baryon-to-photon ratio η is in general not conserved before decoupling in nonminimally coupled theories of gravity. We use big-bang nucleosynthesis and cosmic microwave background (CMB) limits on the baryon-to-photon ratio η to derive new constraints on modified gravity theories with a universal nonminimal coupling between matter and curvature, showing that they rule out a specific class of models previously considered in the literature as a substitute for the dark matter. We also compare these new constraints with the ones obtained from the COBE-FIRAS limits on CMB spectral distortions, highlighting the complementarity between them.
- Publication:
-
Physical Review D
- Pub Date:
- September 2018
- DOI:
- 10.1103/PhysRevD.98.064045
- arXiv:
- arXiv:1807.00798
- Bibcode:
- 2018PhRvD..98f4045A
- Keywords:
-
- General Relativity and Quantum Cosmology;
- Astrophysics - Cosmology and Nongalactic Astrophysics
- E-Print:
- 6 pages