Unified thermal model for photohadronic neutrino production in astrophysical sources

Abstract

High-energy astrophysical neutrino fluxes are, for many applications, modeled as simple power laws as a function of energy. While this is reasonable in the case of neutrino production in hadronuclear pp sources, it typically does not capture the behavior in photohadronic pγ sources: in that case, the neutrino spectrum depends on the properties of the target photons the cosmic rays collide with and on possible magnetic-field effects on the secondary pions and muons. We show that the neutrino production from known photohadronic sources can be reproduced by a thermal (black-body) target-photon spectrum if one suitably adjusts the temperature, thanks to multi-pion production processes. This allows discussing neutrino production from most known pγ sources, such as gamma-ray bursts, active galactic nuclei and tidal disruption events, in terms of a few parameters. We apply this thermal model to study the sensitivity of different classes of neutrino telescopes to photohadronic sources: we classify the model parameter space according to which experiment is most suitable for detection of a specific source class and demonstrate that different experiment classes, such as dense arrays, conventional neutrino telescopes, or radio-detection experiments, cover different parts of the parameter space. Since the model can also reproduce the flavor and neutrino-antineutrino composition, we study the impact on the track-to-shower ratio and the Glashow resonance.

The TeV Diffuse Cosmic Neutrino Spectrum and the Nature of Astrophysical Neutrino Sources

“…A neutrino-emitting, γ-ray-opaque region could be, but not limited to, in the vicinity of a supermassive black hole (e.g., Guépin et al 2018;Inoue et al 2019;Kheirandish et al 2021;Murase et al 2020;Stein et al 2021;van Velzen et al 2021;Oikonomou et al 2021;Fiorillo et al 2021;Rodrigues et al 2021) or associated with a stellar explosion or merger (e.g., Murase & Ioka 2013;Fang et al 2014;Fang & Metzger 2017;Fang et al 2019;Peretti et al 2020;Fasano et al 2021;Sarmah et al 2022).…”

Status and perspectives of neutrino physics

“…In that case, the neutrino spectrum dN/dE ∝ E −α+β−1 emerges in the ∆-resonance approximation, which only follows the primary spectrum if β 1. Therefore, the physics of pγ sources is typically more complicated, and the frequently used assumption of an E −2 neutrino spectrum does not hold; see [669] for a more detailed discussion.…”

High-energy neutrino transients and the future of multi-messenger astronomy

“…A softer photon spectrum or significant secondary energy losses can significantly modify the slope of the neutrino spectrum. Similar to the study of steady HE neutrino sources 37 , simple detectability criteria can be calculated using the total energy channelled in neutrinos and the properties of their spectrum, together with the sensitivities of HE to UHE neutrino experiments 19,26,34,38 .…”

“…In order to distinguish the most plausible associations, theoretical vetoes -simple analytical criteria that can reject a possible association, e.g. 19,26,38,168 -could be implemented within alert programs. From an observational point of view, narrowing down the search area in the sky will require a precise reconstruction of the neutrino arrival direction.…”