Beyond w0−wa and Phantom Crossing: Testing Models of Coupled Dark Sector
Abstract
The combination of cosmic microwave background (CMB) measurements with distance measurements from baryon acoustic oscillations (BAO) and type Ia supernovae (SNIa) suggests that dark energy is dynamical, with an equation of state crossing the phantom divide at low redshifts. This feature can not be described within canonically normalized, minimally coupled, self-interacting scalar field models. We investigate the possibility of achieving phantom crossing by introducing an interaction in the dark sector such that the dark matter particle mass is dependent on the dark energy field ϕ as m ∝ ϕα. We consider a self-interacting potential of the inverse power-law form V ∝ ϕ−β. We implement this model both at the background and perturbative levels in a Boltzmann solver and use a bayesian framework to constrain its parameters using using CMB, BAO and SNIa data. We find best-fits that have similar goodness-of-fits as the commonly used phenomenological w0−wa parameterization, providing a more fundamental understanding of the dark sector.
Related
- Quantifying and testing the evidence for a phantom crossing
- Distinguishing Coupled Dark Matter Dark Energy from Kinematic Phantom Crossing
- Addressing the DESI DR2 phantom-crossing anomaly and enhanced H 0 tension with reconstructed scalar-tensor gravity
- Viable Phantom Crossing in Softly Broken Shift Symmetric Gravity
- Constraints on Horndeski gravity with phantom crossing
BibTeX
@misc{pompeu2026beyond,
title = {{Beyond $w_0-w_a$ and Phantom Crossing: Testing Models of Coupled Dark Sector}},
author = {Kaynan R. de O. Pompeu and João Rebouças and Rogerio Rosenfeld},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2608.23712},
eprint = {2608.23712},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2608.23712},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Beyond w_0−w_a and Phantom Crossing: Testing Models of Coupled Dark Sector
AU - Kaynan R. de O. Pompeu
AU - João Rebouças
AU - Rogerio Rosenfeld
PY - 2026
DA - 2026/09/10
PB - arXiv
DO - 10.48550/arxiv.2608.23712
UR - https://arxiv.org/abs/2608.23712
AB - The combination of cosmic microwave background (CMB) measurements with distance measurements from baryon acoustic oscillations (BAO) and type Ia supernovae (SNIa) suggests that dark energy is dynamical, with an equation of state crossing the phantom divide at low redshifts. This feature can not be described within canonically normalized, minimally coupled, self-interacting scalar field models. We investigate the possibility of achieving phantom crossing by introducing an interaction in the dark sector such that the dark matter particle mass is dependent on the dark energy field ϕ as m ∝ ϕ^α. We consider a self-interacting potential of the inverse power-law form V ∝ ϕ^−β. We implement this model both at the background and perturbative levels in a Boltzmann solver and use a bayesian framework to constrain its parameters using using CMB, BAO and SNIa data. We find best-fits that have similar goodness-of-fits as the commonly used phenomenological w_0−w_a parameterization, providing a more fundamental understanding of the dark sector.
ER -