High-energy cosmic-ray nuclei from high- and low-luminosity gamma-ray bursts and implications for multimessenger astronomy

Abstract

Gamma-ray bursts (GRBs) are one of the candidates of ultra-high-energy ( 10 18.5 eV) cosmicray (UHECR) sources. We investigate high-energy cosmic-ray acceleration including heavy nuclei in GRBs by using Geant 4, and discuss its various implications, taking both of high-luminosity (HL) and low-luminosity (LL) GRBs into account. This is because LL GRBs may also make a significant contribution to the observed UHECR flux if they form a distinct population. We show that not only protons but also heavier nuclei can be accelerated up to ultra-high energies in the internal, (external) reverse and forward shock models. We also show that the condition for ultra-high-energy heavy nuclei such as iron to survive is almost the same as that for ∼ TeV gamma-rays to escape from the source and for high-energy neutrinos not to be much produced. The multi-messenger astronomy by neutrino and GeV-TeV gamma-ray telescopes such as IceCube and KM3Net, GLAST and MAGIC will be important to see whether GRBs can be accelerators of ultra-high-energy heavy nuclei. We also demonstrate expected spectra of high-energy neutrinos and gamma rays, and discuss their detectabilities. In addition, we discuss implictaions of the GRB-UHECR hypothesis. We point out, since the number densities of HL-GRBs and LL-GRBs are quite different, its detemination by UHECR observations is also important.PACS numbers: 95.85. Ry, 98.70.Rz, 14.60.Lm, 96.50.Pw, 98.70.Sa

Extragalactic propagation of ultrahigh energy cosmic-rays

“…In terms of source models, pure nuclei compositions have of course very different implications from mixed composition models as they would imply the suppression of protons acceleration in UHECR sources at all energies. Let us note that some scenarios have been proposed to accelerate dominantly UHECR heavy nuclei, for instance, in magnetars or GRBs [81,82,83] although there is no strong consensus on the UHECR composition expected to be accelerated by these sources (see for instance [84] in the case of magnetars and [85,86] for GRBs).…”

Ultrahigh-energy cosmic ray production by turbulence in gamma-ray burst jets and cosmogenic neutrinos

“…The observed GRB * asanok@icrr.u-tokyo.ac.jp † nnp@psu.edu rate [12] is so low that the required cosmic ray luminosity to agree with the observed UHECR flux is 30-100 times the gamma-ray luminosity or more [see e.g. 13,14]. Such a high luminosity seems unfavorable in the light of the available energy budget.…”

“…Assuming a cosmic ray luminosity much larger than the gamma-ray luminosity, the secondary neutrino flux has been calculated by many authors [e.g. [13][14][15][16][17]. However, the IceCube neutrino telescope has detected no significant high-energy neutrino emission associated with classical GRBs [18][19][20].…”

Extended clustering analyses to constrain the deflection angular scale and source density of the ultra-high-energy cosmic rays

“…Here, we simply assumed that all sources have the same intrinsic luminosity. This may apply if the main sources are "candle events" (such as, possibly, gamma-ray bursts, Murase et al 2008), but it is almost certainly not the case if AGNs are the main sources. However, without a favoured model for the UHECR sources, we chose not to add another set of free parameters to describe the luminosity distribution.…”