Best-case scenarios for neutrino capture experiments

Kyrylo Bondarenko, Alexey Boyarsky, Josef Pradler, Anastasia Sokolenko

Publications: Contribution to journalArticlePeer Reviewed


A direct discovery of the cosmic neutrino background would bring to a closure the searches for relic left-over radiation predicted by the Hot Big Bang cosmology. Recently, the KATRIN experiment put a limit on the local relic neutrino overdensity with respect to the cosmological predicted average value at η ≲ 1011 [Phys. Rev. Lett. 129 (2022) 011806]. In this work, we first examine to what extent such values of η are conceivable. We show that even under cavalier assumptions, a cosmic origin of η ≳ 104 seems out of reach (with the caveat of forming bound objects under a new force,) but find that a hypothetical local source of low-energy neutrinos could achieve η ∼ 1011. Second, when such values are considered, we point out that the experimental signature in KATRIN and other neutrino-capture experiments changes, contrary to what has hitherto been assumed. Our results are model-independent and maximally accommodating as they only assume the Pauli exclusion principle. As intermittent physics target in the quest for CνB detection, we identify an experimental sensitivity to η ∼ 104 for which conceivable sources exist; to resolve the effect of a degenerate Fermi gas for such overdensity an energy resolution of 10 meV is required.

Original languageEnglish
Article number026
Number of pages15
JournalJournal of Cosmology and Astroparticle Physics
Issue number10
Publication statusPublished - 1 Oct 2023

Austrian Fields of Science 2012

  • 103036 Theoretical physics
  • 103041 Astroparticle physics


  • cosmological neutrinos
  • cosmology of theories beyond the SM
  • neutrino properties


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