Multi-Probe Cosmological Constraints on Clustering DBI Dark Energy Scenario
Abstract
We present a multi-probe observational analysis of a clustering tachyonic Dirac-Born-Infeld~(DBI) dark energy model. Its noncanonical kinetic term gives a subluminal sound speed, so dark energy perturbations can grow on subhorizon scales. Working in a multifluid framework that tracks both the background expansion and linear perturbations, we constrain the model with nested sampling, using Planck 2018 compressed CMB distance priors, DESI DR2 BAO, cosmic chronometers, fσ8 growth data, and three Type Ia supernova compilations: Pantheon+, DES-SN5YR, and Union3. The standard cosmological parameters agree with ΛCDM within 2σ, with DBI preferring a slightly lower H0 and higher Ωm0, with the largest shift being ≃1.8σ in H0 for Pantheon+. The Bayesian evidence favours DBI in every compilation, moderately for Pantheon+ (Δln𝒵≃3.4) and inconclusively for DES-SN5YR and Union3 (Δln𝒵≃0.6-$0.7$). The field thaws naturally. Dark energy perturbations stay several orders of magnitude below matter perturbations, yet the noncanonical sound speed still alters the Hubble friction term, raising S8 by only ≈0.5σ relative to ΛCDM. Four independent diagnostics, namely the CPL parametrization, Om(z), the statefinder hierarchy, and the growth index, all point to genuinely evolving dark energy rather than a cosmological constant. The thermal history is left intact, with negligible early dark energy. However, one limitation remains. Because wϕ=ϕ̇2−1≥−1, the phantom regime is out of reach, which is in line with the no-go theorem for a single minimally coupled scalar field, so the model cannot follow the DESI DR2 preference for an effective equation of state crossing w=−1.
Related
- Dark Energy Survey year 6 results: Cosmological constraints from galaxy clustering and weak lensing
- Updated observational constraints on ϕCDM dynamical dark energy cosmological models
- Cosmological Constraints from Full-scale Clustering and Galaxy–Galaxy Lensing with DESI DR1
- Dark Energy Constraints and Joint Cosmological Inference from Mutually Inconsistent Observations
- Dark energy perturbations and the robustness of cosmological neutrino-mass constraints
BibTeX
@misc{ganguly2026multiprobe,
title = {{Multi-Probe Cosmological Constraints on Clustering DBI Dark Energy Scenario}},
author = {Samit Ganguly and Surhud More and Goutam Manna and Kazuharu Bamba and Eduardo Guendelman and Abhijit Bhattacharyya},
howpublished = {arXiv},
year = {2026},
month = nov,
doi = {10.48550/arxiv.2611.08008},
eprint = {2611.08008},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2611.08008},
note = {CC BY-SA 4.0},
}
RIS
TY - UNPB
TI - Multi-Probe Cosmological Constraints on Clustering DBI Dark Energy Scenario
AU - Samit Ganguly
AU - Surhud More
AU - Goutam Manna
AU - Kazuharu Bamba
AU - Eduardo Guendelman
AU - Abhijit Bhattacharyya
PY - 2026
DA - 2026/11/05
PB - arXiv
DO - 10.48550/arxiv.2611.08008
UR - https://arxiv.org/abs/2611.08008
AB - We present a multi-probe observational analysis of a clustering tachyonic Dirac-Born-Infeld~(DBI) dark energy model. Its noncanonical kinetic term gives a subluminal sound speed, so dark energy perturbations can grow on subhorizon scales. Working in a multifluid framework that tracks both the background expansion and linear perturbations, we constrain the model with nested sampling, using Planck 2018 compressed CMB distance priors, DESI DR2 BAO, cosmic chronometers, fσ_8 growth data, and three Type Ia supernova compilations: Pantheon+, DES-SN5YR, and Union3. The standard cosmological parameters agree with ΛCDM within 2σ, with DBI preferring a slightly lower H_0 and higher Ω_m0, with the largest shift being ≃1.8σ in H_0 for Pantheon+. The Bayesian evidence favours DBI in every compilation, moderately for Pantheon+ (Δln𝒵≃3.4) and inconclusively for DES-SN5YR and Union3 (Δln𝒵≃0.6-$0.7$). The field thaws naturally. Dark energy perturbations stay several orders of magnitude below matter perturbations, yet the noncanonical sound speed still alters the Hubble friction term, raising S_8 by only ≈0.5σ relative to ΛCDM. Four independent diagnostics, namely the CPL parametrization, Om(z), the statefinder hierarchy, and the growth index, all point to genuinely evolving dark energy rather than a cosmological constant. The thermal history is left intact, with negligible early dark energy. However, one limitation remains. Because w_ϕ=ϕ̇^2−1≥−1, the phantom regime is out of reach, which is in line with the no-go theorem for a single minimally coupled scalar field, so the model cannot follow the DESI DR2 preference for an effective equation of state crossing w=−1.
ER -