Conformally Coupled Scalar- Field Dark Energy: Cosmological Dynamics with Early- and Late- Measurements
Abstract
In this work, the cosmology of the conformal interacting dark energy model is investigated by introducing a scalar field representing dark energy (DE) coupled to dark matter (DM) via a conformal transformation. This coupling yields a class of scalar+tensor theories; the interaction term Q, which indicates the flow of energy between the dark sectors, is proportional to the trace of the energy-momentum tensor of the DM fluid, TDMμν, as Q=C'(ϕ)/2C(ϕ)gμνTDMμν, where C(ϕ) is the conformal function of a scalar potential (coupling) field. We assume the power-law parametrization C(ϕ)∝ (1+ϕ)m, with m as the coupling parameter, and determine the direction and magnitude of energy flow between the DM and DE scalar-field components. We model DE in three scenarios: conformally interacting dark energy (CIDE) coupled to a scalar field, uncoupled scalar+field DE (UCSFDE), and standard $ Λ$CDM models. We confront these models with cosmological measurements to test the viability of CIDE and UCSFED against ΛCDM and constrain them using a combination of early and late time data, namely: Cosmic Microwave Background measurements from Planck 2018 Legacy (\texttt{CMB}); Baryon Acoustic Oscillation (BAO) data from the Dark Energy Survey (\texttt{ DESI DR2 DR2 BAO}); and Supernova Type Ia distance compilations (\texttt{PantheonPlus, PantheonPlus + SH0ES, Union3}, and \texttt{DES+Dovekie}). We perform parameter inference with Monte Carlo Markov Chain (\texttt{MCMC}) simulations using \texttt{COBAYA} and a modified \texttt{CLASS} ...
Related
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- Cosmological Constraints on Interacting Scalar-Field Dark Matter and Early Dark Energy mediated by a Kinetic Kernel
- Cosmology with a Non-minimally Coupled Dark Matter Fluid II. Cosmological Perturbations
- Improving cosmological distance measurements at high redshift using Lyman-Alpha forest BAO reconstruction
BibTeX
@misc{sahlu2026conformally,
title = {{Conformally Coupled Scalar- Field Dark Energy: Cosmological Dynamics with Early- and Late- Measurements}},
author = {Shambel Sahlu and Abunie Gezahegn and Amare Abebe and Gonzalo J. Olmo and Diego Rubiera-Garcia},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2609.07343},
eprint = {2609.07343},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.07343},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Conformally Coupled Scalar- Field Dark Energy: Cosmological Dynamics with Early- and Late- Measurements
AU - Shambel Sahlu
AU - Abunie Gezahegn
AU - Amare Abebe
AU - Gonzalo J. Olmo
AU - Diego Rubiera-Garcia
PY - 2026
DA - 2026/10/29
PB - arXiv
DO - 10.48550/arxiv.2609.07343
UR - https://arxiv.org/abs/2609.07343
AB - In this work, the cosmology of the conformal interacting dark energy model is investigated by introducing a scalar field representing dark energy (DE) coupled to dark matter (DM) via a conformal transformation. This coupling yields a class of scalar+tensor theories; the interaction term Q, which indicates the flow of energy between the dark sectors, is proportional to the trace of the energy-momentum tensor of the DM fluid, T^DM_μν, as Q=C'(ϕ)/2C(ϕ)g^μνT^DM_μν, where C(ϕ) is the conformal function of a scalar potential (coupling) field. We assume the power-law parametrization C(ϕ)∝ (1+ϕ)^m, with m as the coupling parameter, and determine the direction and magnitude of energy flow between the DM and DE scalar-field components. We model DE in three scenarios: conformally interacting dark energy (CIDE) coupled to a scalar field, uncoupled scalar+field DE (UCSFDE), and standard $ Λ$CDM models. We confront these models with cosmological measurements to test the viability of CIDE and UCSFED against ΛCDM and constrain them using a combination of early and late time data, namely: Cosmic Microwave Background measurements from Planck 2018 Legacy (\texttt{CMB}); Baryon Acoustic Oscillation (BAO) data from the Dark Energy Survey (\texttt{ DESI DR2 DR2 BAO}); and Supernova Type Ia distance compilations (\texttt{PantheonPlus, PantheonPlus + SH0ES, Union3}, and \texttt{DES+Dovekie}). We perform parameter inference with Monte Carlo Markov Chain (\texttt{MCMC}) simulations using \texttt{COBAYA} and a modified \texttt{CLASS} ...
ER -