On a possible nonequilibrium imprint in the cosmic background at low frequencies

TL;DR

This paper proposes a nonequilibrium mechanism involving stochastic frequency-diffusion to explain deviations in the cosmic background radiation at low frequencies, aligning predictions with observations below 20 MHz.

Contribution

It introduces a modified Kompaneets equation incorporating stochastic frequency-diffusion, explaining low-frequency cosmic background anomalies as a nonequilibrium echo.

Findings

Predicted frequency distribution matches measurements down to 20 MHz.

Proposes a new mechanism for photon cooling in the early universe.

Interprets 'space roar' as a nonequilibrium imprint from primordial plasma.

Abstract

The cosmic background radiation has been observed to deviate from the Planck law expected from a blackbody at $\sim$ 2.7 K at frequencies below $\sim 3$ GHz. We discuss the abundance of the low-energy photons from the perspective of nonequilibrium statistical mechanics. We propose a mechanism of stochastic frequency-diffusion, the counterpart to stochastic acceleration for charged particles in a turbulent plasma, to modify the standard Kompaneets equation. The resulting violation of the Einstein relation allows to take advantage of low-frequency localization and finally leads to photon cooling. The new equation predicts a frequency distribution in agreement with the absolute temperature measurements of the cosmic background radiation down to about 20 MHz, for which we offer here an updated compilation. In that sense, the so called 'space roar' we observe today is interpreted as a nonequilibrium echo of the early universe, and of nonequilibrium conditions in the primordial plasma more specifically.