Conformal Killing Gravity: New Constraints from DESI DR2 BAO datasets
Abstract
We investigate a geometric approach referred to as the Conformal Killing Gravity (CKG), in which the dark energy sector emerges naturally from the conformal Killing symmetry of the Robertson--Walker space-time. Within this framework, the divergence-free conformal Killing tensor behaves as an effective perfect fluid, giving rise to a dynamical dark-energy component whose density, pressure, and equation of state are uniquely determined by the underlying geometry, without introducing any empirical dark-energy parametrization. The resulting CKG model extends the standard ΛCDM cosmology through a single additional parameter while recovering the ΛCDM limit in the absence of the geometric contribution. We constrain the model using Planck PR4 (NPIPE) CMB temperature, polarization, and lensing observations, ACT DR6 CMB lensing, DESI DR2 baryon acoustic oscillation measurements, and the Pantheon+, DES-Dovekie, and Union3 Type Ia supernova compilations. The analysis shows that the CKG favors a quintessence-like dark-energy evolution with no evidence for phantom crossing, while the reconstructed equation of state rapidly approaches the cosmological constant at earlier cosmic times. Furthermore, the model predicts a future critical redshift in the range −0.8 ≲ zc ≲ −0.7, indicating that the present cosmic expansion eventually reaches a turning point before the formal singular limit at z=−1. Since the geometric contribution modifies only the post-recombination expansion history, the sound horizon remains essentially unchanged and the model does not provide a complete solution to the H0 tension. Our results demonstrate that the CKG provides a simple, physically motivated, and observationally favored framework for describing the late-time accelerated expansion of the Universe.
Versions
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BibTeX
@misc{chaudhary2026conformal,
title = {{Conformal Killing Gravity: New Constraints from DESI DR2 BAO datasets}},
author = {Himanshu Chaudhary and Salvatore Capozziello and Carlo Alberto Mantica and Luca Guido Molinari and Dhruba Jyoti Gogoi and Ghulam Mustafa},
howpublished = {arXiv},
year = {2026},
month = aug,
doi = {10.48550/arxiv.2608.07313},
eprint = {2608.07313},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2608.07313},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Conformal Killing Gravity: New Constraints from DESI DR2 BAO datasets
AU - Himanshu Chaudhary
AU - Salvatore Capozziello
AU - Carlo Alberto Mantica
AU - Luca Guido Molinari
AU - Dhruba Jyoti Gogoi
AU - Ghulam Mustafa
PY - 2026
DA - 2026/08/07
PB - arXiv
DO - 10.48550/arxiv.2608.07313
UR - https://arxiv.org/abs/2608.07313
AB - We investigate a geometric approach referred to as the Conformal Killing Gravity (CKG), in which the dark energy sector emerges naturally from the conformal Killing symmetry of the Robertson--Walker space-time. Within this framework, the divergence-free conformal Killing tensor behaves as an effective perfect fluid, giving rise to a dynamical dark-energy component whose density, pressure, and equation of state are uniquely determined by the underlying geometry, without introducing any empirical dark-energy parametrization. The resulting CKG model extends the standard ΛCDM cosmology through a single additional parameter while recovering the ΛCDM limit in the absence of the geometric contribution. We constrain the model using Planck PR4 (NPIPE) CMB temperature, polarization, and lensing observations, ACT DR6 CMB lensing, DESI DR2 baryon acoustic oscillation measurements, and the Pantheon+, DES-Dovekie, and Union3 Type Ia supernova compilations. The analysis shows that the CKG favors a quintessence-like dark-energy evolution with no evidence for phantom crossing, while the reconstructed equation of state rapidly approaches the cosmological constant at earlier cosmic times. Furthermore, the model predicts a future critical redshift in the range −0.8 ≲ z_c ≲ −0.7, indicating that the present cosmic expansion eventually reaches a turning point before the formal singular limit at z=−1. Since the geometric contribution modifies only the post-recombination expansion history, the sound horizon remains essentially unchanged and the model does not provide a complete solution to the H_0 tension. Our results demonstrate that the CKG provides a simple, physically motivated, and observationally favored framework for describing the late-time accelerated expansion of the Universe.
ER -