Neutrino cooling of primordial hot regions

Abstract

© 2020 by the authors. The effect of neutrino cooling of possible primary regions filled by hot matter is discussed. Such regions could be obtained from the primordial density inhomogeneities and survive up to the modern epoch. The inhomogeneities could be caused by a symmetry breaking during the inflationary stage. We show that the final temperature of such region should be ~10 keV provided that the initial temperature is within the interval 10 keV ÷ 100 MeV. The cooling is realized due to the weak nuclear reactions containing n - p transition. The lower limit 10 keV is accounted for by suppression of the reactions rates because of the threshold effect and particle concentration decrease.