Correlating prompt GRB photons with neutrinos

It is standard in theoretical neutrino astrophysics to use a broken power law approximation, based on the Band function, to describe the average photon flux of the prompt emission of Gamma-Ray Bursts. We will show that this approximation overestimates the contribution of high energy γ-rays (and underestimates low energy γ-rays). As a consequence models that rely on this approximation overestimate neutrino event rate by a factor of ≈ 2 depending on Earth’s column density in the direction of the GRB. Furthermore the characteristic energy of neutrinos that trigger a km detector is typically 10 eV, higher than previously predicted. We also provide a new broken power law approximation to the Band function and show that it properly represents the photon spectra. Subject headings: Gamma-Ray Burst, Neutrinos, Neutrino Telescopes