1997/10/31 by Thomas J. Weiler · 17 citations
Physics and Astronomy · #Annihilation #Astrophysics and Cosmic Phenomena #Cosmic ray #Dark Matter and Cosmic Phenomena #Dark matter #Galactic halo #Halo #Neutrino #Neutrino Physics Research #Neutrino detector #Nucleon #Photon #astro-ph #hep-ph
paper · pdf · doi:10.1016/s0927-6505(98)00068-1
published as Astropart.Phys.11:303-316,1999 · 26 pages, 1 .ps figure, LaTex; version to appear in Astropart. Phys.; material added in response to referee(s)
arxiv created 1998/12/23 · openalex publication_date 1999/07/01 · arxiv updated 2010/11/30 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
If neutrinos are a significant contributor to the matter density of the universe, then they should have ∼ eV mass and cluster in galactic (super) cluster halos, and possibly in galactic halos as well. It was noted in the early 1980's that cosmic ray neutrinos with energy within δE/ER=ΓZ/MZ ∼ 3% of the peak energy ER=4 (eV/mν)× 1021 eV will annihilate on the nonrelativistic relic antineutrinos (and vice versa) to produce the Z-boson with an enhanced, resonant cross section of \cal O(GF)∼ 10-32cm2. The result of the resonant neutrino annihilation is a hadronic Z-burst 70% of the time, which contains, on average, thirty photons and 2.7 nucleons with energies near or above the GZK cutoff energy of 5× 1019 eV. These photons and nucleons produced within our Supergalactic halo may easily propagate to earth and initiate super-GZK air showers. Here we show that the probability for each neutrino flavor at its resonant energy to annihilate within the halo of our Supergalactic cluster is likely within an order of magnitude of 1%, with the exact value depending on unknown aspects of neutrino mixing and relic neutrino clustering. The absolute lower bound in a hot Big Bang universe for the probability to annihilate within a 50 Mpc radius (roughly a nucleon propagation distance) of earth is 0.036%. From fragmentation data for Z-decay, we estimate that the nucleons are more energetic than the photons by a factor ∼ 10. Several tests of the hypothesis are indicated.