We calculate the proton cooling efficiency including pion-multiplicity, and proton-inelasticity in photomeson production under the internal shock model of gamma-ray bursts (GRBs) by using the simulation kit GEANT4. We confirm the validity of analytic approximate treatments based on GRB fiducial parameter sets, but also find that the effects of multiplicity and high inelasticity can be important for both proton cooling and the resulting spectra in some cases. We can estimate the maximum energy of accelerated protons in GRBs by considering various cooling processes. Using the obtained results, we can evaluate the neutrino flux from one burst and a diffuse neutrino background more quantitatively than past works. We assume that the GRB rate traces the star formation rate to obtain the diffuse neutrino background. We also take into account the cooling processes of pions and muons, which are crucial to the resulting neutrino spectra. We introduce the nonthermal baryon-loading factor, rather than assume that GRBs are the main sources of ultra-high-enegy-cosmic- rays (UHECRs). We find that the obtained neutrino background can be comparable with the prediction of Waxman & Bahcall, although our ground in the estimation is different from theirs. This means sufficient photon density and accelerated protons may lead to the higher neutrino flux, which may be difficult to achieve. We study various parameters because there are many parameters in the model. The detection of high energy neutrinos from GRBs will provide a piece of strong evidences that protons are accelerated to very high energy in GRBs. Furthermore, the observations of a neutrino background has a possibility for not only testing the internal shock model of GRBs but also giving us information about the parameters in the model and about whether GRBs are sources of UHECRs or not.
|Original language||English (US)|
|Number of pages||4|
|Journal||Journal of the Korean Physical Society|
|Issue number||4 I|
|State||Published - Oct 2006|
All Science Journal Classification (ASJC) codes
- Physics and Astronomy(all)