Abstract
ABSTRACT We scrutinize the paradigm that conventional long-duration gamma-ray bursts (GRBs) are the dominant source of the ultrahigh energy cosmic rays (UHECRs) within the internal shock scenario by describing UHECR spectrum and composition and by studying the predicted (source and cosmogenic) neutrino fluxes. Since it has been demonstrated that the stacking searches for astrophysical GRB neutrinos strongly constrain the parameter space in single-zone models, we focus on the dynamics of multiple collisions for which different messengers are expected to come from different regions of the same object. We propose a model that can describe both stochastic and deterministic engines, which we study in a systematic way. We find that GRBs can indeed describe the UHECRs for a wide range of different model assumptions with comparable quality albeit with the previously known problematic energy requirements; the heavy mass fraction at injection is found to be larger than 70 per cent ($95 {{\ \rm per\ cent}}$ CL). We demonstrate that the post-dicted (from UHECR data) neutrino fluxes from sources and UHECR propagation are indeed below the current sensitivities but will be reached by the next generation of experiments. We finally critically review the required source energetics with the specific examples found in this study.
Highlights
Gamma-ray bursts (GRBs) have been proposed to be powerful enough to describe ultrahigh energy cosmic rays (UHECRs) (Vietri 1995; Waxman 1995)
We find that the kinetic energy of the outflow is ∼ 1055 − 1056 erg per gamma-ray bursts (GRBs) if the longduration GRBs are the sole sources of UHECRs
Models that provide a heavy distribution of nuclear mass fractions at the onset of the core collapse are chosen in this paper, and such compositions are used as output of lowluminosity GRBs with internal shock model, that are supposed to power the UHECR flux at the Earth
Summary
Most GRB multicollision models do not jointly describe the UHECR spectrum and composition – except Globus et al (2015a) and Globus, Allard & Parizot (2015b), who performed a complete investigation of the multicollision model in the context of UHECR including nuclei for a smooth, continuous outflow that corresponds to a single-peaked light curve without a short-time variability or an intermittent engine. They draw a self-consistent picture for one set of parameters and one collision model, with a neutrino flux prediction close to the current stacking limit. We aim to conclude whether the absence of associations of IceCube neutrinos with GRBs (Abbasi et al 2012) really disfavours, or even excludes, those as a dominant source of UHECRs when a more sophisticated model for the multimessenger production is used
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