Chiral gravitational waves from thermalized neutrinos in the early Universe

Philipp Gubler, Naoki Yamamoto, Di-Lun Yang

Research output: Contribution to journalArticlepeer-review

Abstract

We investigate polarized gravitational waves generated by chiral fermions in the early Universe. In particular, we focus on the contribution from left-handed neutrinos in thermal equilibrium with finite temperature and chemical potential in the radiation dominated era. We compute the correlation functions of gravitational fields pertinent to the Stokes parameter V characterizing the circular polarization of gravitational waves in the Minkowski and expanding spacetime backgrounds. In the expanding universe, we find that the thermalized neutrinos induce a non-vanishing V linear to the neutrino degeneracy parameter and wavenumber of gravitational waves in the long wavelength region. While the magnitude of the gravitational waves generated by thermal neutrinos is too small to be detectable by current and planned third generation gravitational wave detectors, their observations by future generation detectors for ultra-high frequency regimes could provide information on the neutrino degeneracy parameter in the early Universe.

Original languageEnglish
Article number025
JournalJournal of Cosmology and Astroparticle Physics
Volume2022
Issue number9
DOIs
Publication statusPublished - 2022 Sep 1

Keywords

  • cosmological neutrinos
  • gravitational waves / sources
  • particle physics - cosmology connection
  • primordial gravitational waves (theory)

ASJC Scopus subject areas

  • Astronomy and Astrophysics

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