Canonical Hubble-Tension-Resolving Early Dark Energy Cosmologies Are Inconsistent with the Lyman-α Forest.

Area of Science:

• Cosmology
• Astrophysics
• Particle Physics

Background:

• Cosmological data show a discrepancy in the expansion rate (H0) measurements.
• Early dark energy (EDE) is a proposed solution, fitting cosmic microwave background (CMB) data but altering structure formation parameters.
• The spectral index of scalar perturbations (ns) is a key parameter affected by EDE.

Purpose of the Study:

• To constrain axionlike early dark energy models using Lyman-alpha forest data.
• To investigate the impact of Lyman-alpha forest measurements on the Hubble tension and EDE parameters.
• To compare EDE model predictions with CMB and baryon acoustic oscillation (BAO) data.

Main Methods:

• Utilizing two independent measurements of the 1D Lyα forest flux power spectrum from SDSS eBOSS and MIKE/HIRES/X-Shooter spectrographs.
• Combining Lyα forest data with Planck CMB and BAO datasets.
• Calculating constraints on the maximum fractional contribution of EDE (f_EDE) and the Hubble constant (H0).

Main Results:

• Lyman-alpha forest data significantly reduce the upper bound on f_EDE from 0.07 to 0.03.
• Constrained H0 to 67.9 km/s/Mpc (68% C.L.), showing tension with direct measurements.
• Lyα forest data favor lower ns values, conflicting with EDE models that fit Planck CMB data.

Conclusions:

• Lyα forest data severely constrain canonical EDE models proposed to solve the Hubble tension.
• The preference for lower ns values in Lyα data challenges EDE's ability to reconcile cosmological tensions.
• Further investigation is needed to understand the implications for early dark energy scenarios.