Possible nonequilibrium imprint in the cosmic background at low frequencies
Abstract
Cosmic background radiation has been observed to deviate from the Planck law expected from a blackbody at ∼ 2.7 K at frequencies below ∼3 GHz. We discuss the abundance of the lowenergy 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 us to take advantage of lowfrequency localization and finally leads to photon cooling. The modified 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 an updated compilation. In that sense, the socalled space roar we observe today is interpreted as a nonequilibrium echo of the early universe and more specifically of nonequilibrium conditions in the primordial plasma.
 Publication:

Physical Review Research
 Pub Date:
 February 2020
 DOI:
 10.1103/PhysRevResearch.2.013210
 arXiv:
 arXiv:1908.08876
 Bibcode:
 2020PhRvR...2a3210B
 Keywords:

 Astrophysics  Cosmology and Nongalactic Astrophysics;
 Condensed Matter  Statistical Mechanics
 EPrint:
 14 pages, 3 figures, 1 table. Figure 2 replaced to fix a mistake due to an exchange of files: the printed version is now accompanied by an Erratum