Cosmological Signatures of Curvature-Coupled Dark Energy
Abstract
We study a curvature-coupled dark energy model that can modify cosmological evolution both before recombination and during the late-time accelerated era. The model belongs to the class of scalar-tensor theories, in which a quintessence field is non-minimally coupled to the Ricci scalar. We specify the model through a shifted quartic coupling, f(φ)=α(φ2−φtoday2)2, and an inverse power-law potential, V(φ)=Λφ−σ, where φtoday is a constant fixed by requiring the effective Planck mass to recover its present-day normalization. We implement the model in a modified version of hi_class and compute its background and linear cosmological predictions. This specific form of non-minimal coupling allows an effective crossing of the phantom divide at late times while naturally suppressing deviations from standard gravity today and satisfying local gravity constraints. At the same time, the scalar field can modify the expansion history before recombination, shifting the acoustic scale in the direction required to alleviate the H0 tension, while remaining dynamically relevant as dark energy at low redshift. For the parameter choices studied here, we find tens-of-percent deviations from ΛCDM in the expansion history, matter clustering, and metric-potential spectra. The modified evolution of the gravitational potentials leaves characteristic signatures in relativistic observables, with weak-lensing power suppressed by 𝒪(20-40%) at low multipoles and order-unity changes in the late Integrated Sachs-Wolfe signal. Together, these results reveal a broad, scale-dependent phenomenology that motivates both a full parameter-space analysis and an extension of the present linear treatment to a dedicated non-linear N-body implementation.
Related
- Conformally Coupled Scalar- Field Dark Energy: Cosmological Dynamics with Early- and Late- Measurements
- Cosmological stasis and the coupled dark sector of the Dark Dimension
- Updated observational constraints on ϕCDM dynamical dark energy cosmological models
- Cosmology with a Non-minimally Coupled Dark Matter Fluid II. Cosmological Perturbations
- Dark Energy Constraints and Joint Cosmological Inference from Mutually Inconsistent Observations
BibTeX
@misc{banihashemi2026cosmological,
title = {{Cosmological Signatures of Curvature-Coupled Dark Energy}},
author = {Abdolali Banihashemi and Farbod Hassani and Alessandro Casalino and David F. Mota and Emilio Bellini},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.15836},
eprint = {2609.15836},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.15836},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Cosmological Signatures of Curvature-Coupled Dark Energy
AU - Abdolali Banihashemi
AU - Farbod Hassani
AU - Alessandro Casalino
AU - David F. Mota
AU - Emilio Bellini
PY - 2026
DA - 2026/09/14
PB - arXiv
DO - 10.48550/arxiv.2609.15836
UR - https://arxiv.org/abs/2609.15836
AB - We study a curvature-coupled dark energy model that can modify cosmological evolution both before recombination and during the late-time accelerated era. The model belongs to the class of scalar-tensor theories, in which a quintessence field is non-minimally coupled to the Ricci scalar. We specify the model through a shifted quartic coupling, f(φ)=α(φ^2−φ_today^2)^2, and an inverse power-law potential, V(φ)=Λφ^−σ, where φ_today is a constant fixed by requiring the effective Planck mass to recover its present-day normalization. We implement the model in a modified version of hi_class and compute its background and linear cosmological predictions. This specific form of non-minimal coupling allows an effective crossing of the phantom divide at late times while naturally suppressing deviations from standard gravity today and satisfying local gravity constraints. At the same time, the scalar field can modify the expansion history before recombination, shifting the acoustic scale in the direction required to alleviate the H_0 tension, while remaining dynamically relevant as dark energy at low redshift. For the parameter choices studied here, we find tens-of-percent deviations from ΛCDM in the expansion history, matter clustering, and metric-potential spectra. The modified evolution of the gravitational potentials leaves characteristic signatures in relativistic observables, with weak-lensing power suppressed by 𝒪(20-40%) at low multipoles and order-unity changes in the late Integrated Sachs-Wolfe signal. Together, these results reveal a broad, scale-dependent phenomenology that motivates both a full parameter-space analysis and an extension of the present linear treatment to a dedicated non-linear N-body implementation.
ER -