Diffuse neutrino flux from blazars via cosmic-ray propagation in extragalactic medium

Saikat Das, Nayantara Gupta, Soebur Razzaque

Research output: Contribution to journalConference articlepeer-review


The origin of the cosmic neutrino signal measured by IceCube is still unknown. A general correlation between the sources of high-energy γ-ray sources with IceCube neutrinos is expected since hadronic interactions are the crucial precursors of both messengers at such high energies. Blazars dominate the extragalactic γ-ray sky. However, neutrinos originating from inside the blazar jets cannot account for more than ∼ 30% of the diffuse flux. We study ultrahigh-energy cosmic-ray contribution to the diffuse flux through photopion interactions on cosmic background photons. The extragalactic background light, consisting of IR/UV/optical photons require a proton energy threshold of Ethp, π ≈ 1017 eV for pion production. The latter can yield PeV neutrinos. We analyze the total contribution from resolved and unresolved blazars by using a luminosity-dependent density evolution of blazars. The latest Fermi-LAT 4LAC catalog sheds light on the redshift distribution of the diffuse neutrino flux for resolved γ-ray blazars.

Original languageEnglish
Article number1003
JournalProceedings of Science
Publication statusPublished - 18 Mar 2022
Event37th International Cosmic Ray Conference, ICRC 2021 - Virtual, Berlin, Germany
Duration: 12 Jul 202123 Jul 2021

ASJC Scopus subject areas

  • Multidisciplinary


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