Lowering the Horizon on Dark Energy: A Late-Time Response to Early Solutions for the Hubble Tension

Abstract

We present a model-independent null test of the late-time cosmological response to a reduced sound horizon, as typically required by early-universe solutions to the Hubble tension. In this approach, we phenomenologically impose a shorter sound horizon without modeling early-universe physics to isolate its impact on late-time dark energy inference. Using baryon acoustic oscillations (BAO), supernovae (SN), big bang nucleosynthesis (BBN), and local $H_0$ data, while explicitly avoiding CMB anisotropies, we examine how this calibration shift propagates into constraints on the dark energy equation of state. We find that lowering $r_d$ systematically drives the $w_0$-$w_a$ posterior toward less dynamical, quintessence-like behavior, bringing it closer to $\Lambda$CDM. This result underscores that some of the apparent evidence for evolving or phantom-like dark energy may reflect early-universe assumptions rather than genuine late-time dynamics. More broadly, our analysis highlights the importance of carefully disentangling calibration effects from physical evolution in interpreting forthcoming results from DESI and future surveys.

5 pages, 2 figures, 1 table

References in corpus (36)

• A Comprehensive Measurement of the Local Value of the Hubble Constant with 1 km/s/Mpc Uncertainty from the Hubble Space Telescope and the SH0ES Team
• In the Realm of the Hubble tension $-$ a Review of Solutions
• The Pantheon+ Analysis: Cosmological Constraints
• DESI 2024 VI: Cosmological Constraints from the Measurements of Baryon Acoustic Oscillations
• Cosmic Distances Calibrated to 1% Precision with Gaia EDR3 Parallaxes and Hubble Space Telescope Photometry of 75 Milky Way Cepheids Confirm Tension with LambdaCDM
• Cobaya: Code for Bayesian Analysis of hierarchical physical models
• DESI DR2 Results II: Measurements of Baryon Acoustic Oscillations and Cosmological Constraints
• The $H_0$ Olympics: A fair ranking of proposed models
• Early dark energy, the Hubble-parameter tension, and the string axiverse
• Seven hints that early-time new physics alone is not sufficient to solve the Hubble tension
• Early Dark Energy Does Not Restore Cosmological Concordance
• The CosmoVerse White Paper: Addressing observational tensions in cosmology with systematics and fundamental physics
• Resolving the Hubble Tension with New Early Dark Energy
• Relieving the Hubble tension with primordial magnetic fields
• Consistency tests of $\Lambda$CDM from the early integrated Sachs-Wolfe effect: Implications for early-time new physics and the Hubble tension
• Dark energy and curvature from a future baryonic acoustic oscillation survey using the Lyman-alpha forest
• Early modified gravity in light of the $H_0$ tension and LSS data
• Small Magellanic Cloud Cepheids Observed with the Hubble Space Telescope Provide a New Anchor for the SH0ES Distance Ladder
• A larger value for $H_0$ by an evolving gravitational constant
• Scalar-tensor theories of gravity, neutrino physics, and the $H_0$ tension
• Gravity in the Era of Equality: Towards solutions to the Hubble problem without fine-tuned initial conditions
• DESI DR2 Results I: Baryon Acoustic Oscillations from the Lyman Alpha Forest
• Underdetermination of dark energy
• Can Conformally Coupled Modified Gravity Solve The Hubble Tension?
• Robustness of dark energy phenomenology across different parameterizations
• The $H_0$ tension: $\Delta G_N$ vs. $\Delta N_{\mathrm{eff}}$
• Testing H0 in Acoustic Dark Energy Models with Planck and ACT Polarization
• Dynamical Dark Energy in light of the DESI DR2 Baryonic Acoustic Oscillations Measurements
• Multidimensionality of the Hubble tension: the roles of ${\Omega }_m$ and ${\omega }_c$
• Scalar field dark energy models: Current and forecast constraints
• Probing Early Modification of Gravity with Planck, ACT and SPT
• Is Dynamical Dark Energy Necessary? DESI BAO and Modified Recombination
• On DESI's DR2 exclusion of $\Lambda$CDM
• Non-minimally coupled gravity constraints from DESI DR2 data
• Hints of Primordial Magnetic Fields at Recombination and Implications for the Hubble Tension
• A General Model for Dark Energy Crossing the Phantom Divide

Cited by in corpus (1)

• Dark Energy in the DESI Era: A Brief Review of Evidence, Beyond-$\Lambda$CDM Interpretations, and Tensions