The tension: vs.
Apr 10, 2020
20 pages
Published in:
- JCAP 11 (2020) 024
- Published: Nov 12, 2020
e-Print:
- 2004.05049 [astro-ph.CO]
View in:
Citations per year
Abstract: (IOP)
We investigate whether the 4.4σ tension on H0 between SH0ES 2019 and Planck 2018 can be alleviated by a variation of Newton's constant GN between the early and the late Universe. This changes the expansion rate before recombination, similarly to the addition of Δ Neff extra relativistic degrees of freedom. We implement a varying GN in a scalar-tensor theory of gravity, with a non-minimal coupling of the form (M2+β φ2)R. If the scalar φ starts in the radiation era at an initial value φI ∼ 0.5 Mp and with β<0, a dynamical transition occurs naturally around the epoch of matter-radiation equality and the field evolves towards zero at late times. As a consequence, the H0 tension between SH0ES (2019) and Planck 2018+BAO slightly decreases, as in Δ Neff models, to the 3.8σ level. We then perform a fit to a combined Planck, BAO and supernovae (SH0ES and Pantheon) dataset. When including local constraints on Post-Newtonian (PN) parameters, we find H0=69.08−0.71+0.6 km/s/Mpc and a marginal improvement of Δχ2≃−3.2 compared to ΛCDM, at the cost of 2 extra parameters. In order to take into account scenarios where local constraints could be evaded, we also perform a fit without PN constraints and find H0=69.65−0.78+0.8 km/s/Mpc and a more significant improvement Δχ2=−5.4 with 2 extra parameters. For comparison, we find that the Δ Neff model gives H0=70.08−0.95+0.91 km/s/Mpc and Δχ2=−3.4 at the cost of one extra parameter, which disfavors the ΛCDM limit just above 2σ, since Δ Neff=0.34−0.16+0.15. Overall, our varying GN model performs similarly to the Δ Neff model in respect to the H0 tension, if a physical mechanism to remove PN constraints can be implemented.Note:
- 20 pages, 7 figures. v2: Pantheon dataset added, additional new results for model without PN constraints, additional short discussion of S8. Version accepted for publication in JCAP
- cosmological parameters from CMBR
- cosmology of theories beyond the SM
- modified gravity
- physics of the early universe
- gravitation: model
- gravitation: fundamental constant
- coupling: nonminimal
- Hubble constant
- tension
- satellite: Planck
References(59)
Figures(7)