High-energy neutrinos and hard $\gamma$-rays in coincidence with Gamma Ray Bursts

The observations suggest that $\gamma$-ray bursts (GRBs) are produced by jets of relativistic cannonballs (CBs), emitted in supernova (SN) explosions. The CBs, reheated by their collision with the SN shell, emit radiation and Doppler-boost it to the few-hundred keV energy of the GRB's photons. Chaperoning the GRB, there should be an intense flux of neutrinos of a few hundreds of GeV energy, made in $\pi^\pm$ decays: the SN shell acts as a dump of the beam of CBs. The $\nu$ beam carries almost all of the emitted energy, but is much narrower than the GRB beam and should only be detected in coincidence with the small fraction of GRBs whose CBs are very precisely pointing to us. The $\pi^0$s made in the transparent outskirts of the SN shell decay into energetic $\gamma$-rays (EGRs) of energy of ${\cal{O}}$(100) GeV. The EGR beam, whose energy fluence is comparable to that of the companion GRB, is as wide as the GRB beam and should be observable, in coincidence with GRBs, with existing or planned detectors.