Cosmic Microwave Background as a Thermal Gas of SU(2)‎ Photons: Implications for the High-z Cosmological Model and the Value of H0

Abstract EN

Presently, we are facing a 3σ tension in the most basic cosmological parameter, the Hubble constant H0.

This tension arises when fitting the Lambda-cold-dark-matter model (ΛCDM) to the high-precision temperature-temperature (TT) power spectrum of the Cosmic Microwave Background (CMB) and to local cosmological observations.

We propose a resolution of this problem by postulating that the thermal photon gas of the CMB obeys an SU(2) rather than U(1) gauge principle, suggesting a high-z cosmological model which is void of dark-matter.

Observationally, we rely on precise low-frequency intensity measurements in the CMB spectrum and on a recent model independent (low-z) extraction of the relation between the comoving sound horizon rs at the end of the baryon drag epoch and H0 (rsH0=const).

We point out that the commonly employed condition for baryon-velocity freeze-out is imprecise, judged by a careful inspection of the formal solution to the associated Euler equation.

As a consequence, the above-mentioned 3σ tension actually transforms into a 5σ discrepancy.

To make contact with successful low-z ΛCDM cosmology we propose an interpolation based on percolated/depercolated vortices of a Planck-scale axion condensate.

For a first consistency test of such an all-z model we compute the angular scale of the sound horizon at photon decoupling.