Abstract
Aim. We discuss neutrino and cosmic ray emission from gamma-ray bursts (GRBs) with the injection of nuclei, where we take into account that a nuclear cascade from photodisintegration can fully develop in the source. Our main objective is to test whether recent results from the IceCube and the Pierre Auger Observatory can be accommodated within the paradigm that GRBs are the sources of ultra-high-energy cosmic rays (UHECRs). Methods. We simulate this scenario in a combined source-propagation model. While our key results are obtained using an internal shock model of the source, we discuss how the secondary emission from a GRB shell can be interpreted in terms of other astrophysical models. Results. We demonstrate that the expected neutrino flux from GRBs weakly depends on the injection composition for the same injection spectra and luminosities, which implies that prompt neutrinos from GRBs can efficiently test the GRB-UHECR paradigm even if the UHECRs are nuclei. We show that the UHECR spectrum and composition, as measured by the Pierre Auger Observatory, can be self-consistently reproduced. In an attempt to describe the energy range including the ankle, we find tension with the IceCube bounds from the GRB stacking analyses. In an alternative scenario, where only the UHECRs beyond the ankle originate from GRBs, the requirement for a joint description of cosmic ray and neutrino observations favors lower luminosities, which does not correspond to the typical expectation from γ-ray observations.
Highlights
The origin of ultra-high-energy cosmic rays (UHECRs) at the highest energies 1018 eV, which are most likely of extragalactic origin, is one of the unsolved mysteries in astroparticle physics
Our main objective is to test whether recent results from the IceCube and the Pierre Auger Observatory can be accommodated within the paradigm that gamma-ray bursts (GRBs) are the sources of ultra-high-energy cosmic rays (UHECRs)
We demonstrate that the expected neutrino flux from GRBs weakly depends on the injection composition for the same injection spectra and luminosities, which implies that prompt neutrinos from GRBs can efficiently test the GRB-UHECR paradigm even if the UHECRs are nuclei
Summary
The origin of ultra-high-energy cosmic rays (UHECRs) at the highest energies 1018 eV, which are most likely of extragalactic origin, is one of the unsolved mysteries in astroparticle physics. In Boncioli et al (2017) the nuclear cascade in a GRB shell has been self-consistently computed with a disintegration model at a level of sophistication comparable to CRPropa used for the cosmic ray propagation (Kampert et al 2013), and it has been demonstrated that the feed-down to lower masses can have an impact on the ejected cosmic ray (and the neutrino) flux. In order to test the GRB-UHECR paradigm, a combined source-propagation model is needed: the accelerated nuclei are injected into the radiation zone, where the secondaries are produced, escape from that zone, and are propagated through the extragalactic space to Earth (see Baerwald et al 2015; Globus et al 2015a; Unger et al 2015, for examples). While most of our results are derived for the internal shock model, we demonstrate how our results can be translated into other emissions scenarios; the key parameters used in this study are emission radius R, gamma-ray luminosity Lγ, baryonic loading ξi, and injection isotope
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