High-energy photons from Gamma-Ray Bursts, but no neutrinos

TL;DR

This work argues that the CannonBall (CB) model provides a coherent account of very-high-energy gamma rays from a subset of long GRBs, tying their origin to inverse-Compton scattering of glory photons and subsequent hadronic processes in the SN wind. By combining CB dynamics, wind attenuation, and laboratory data from forward LHC physics, the paper derives plausible energy distributions for protons within CBs that produce TeV photons, and predicts a TeV-scale mean proton energy around $E_p[CB]\approx 2.34\ \mathrm{TeV}$. It also links the predicted GRB-generated positron flux to AMS observations, and explains why HE neutrinos have eluded detection due to their far smaller interaction cross sections and current detector capabilities. The analysis emphasizes the importance of CB Lorentz-factor distributions, wind densities, and forward-physics scaling, concluding that the CB framework can describe both the HE gamma-ray signals and the non-detection of concomitant neutrinos, while recognizing remaining uncertainties in viewing angles and CB parameters. Overall, the paper argues for a multi-messenger context in which VHE GRB photons arise from CB interactions in the wind, with laboratory and astrophysical data jointly constraining the model.

Abstract

The Cannon-Ball model of Gamma-Ray Bursts and their afterglows--described in the text and in innumerable previous occasions--is extremely successful and predictive. In a few intrinsically bright GRBs, gamma-rays with energies in the TeV range have been observed. The CB model, I argue, has no difficulty in describing the origin and approximate properties of these high-energy gamma rays and the extreme difficulty of observing their accompanying neutrinos.

Figures (13)

• Figure 1: New reconstructed image (left) and contour plot (right) of a 300 mas field around SN1987A from speckle data recorded with a 10 nm Wide Filter centered at 653.6 nm. Note that two of the noise spikes (in the lower left and right) do not show up in the contour plot because their intensity falls below the lowest contour level (1%).
• Figure 2: Opening angles of a conventional GRB (the blue range) and of an XRF (the black arrow), compared to the ones of the high-energy beams of $\gamma$ rays and neutrinos. An observer is very unlikely to be where the eyes are.
• Figure 3: Peak or "break" energy distribution of long GRBs Preece. The blue curve is independently extracted from the CB-model analysis of GRB afterglows DD2004.
• Figure 4: In red $D(\gamma)$, Eq.(\ref{['eq:Dgamma']}). In blue $\bar{N}_{\rm out}(\gamma)$, Eq.(\ref{['eq:Dbar']}). Both distribution are arbitrarily normalized in the figure.
• Figure 5: Adopted diffuse term (red) and calculated source term (blue), and their sum (black, dashed). The calculated source term has been diminished by 20% ADReplus. The diffuse term used in the sum is the one labelled "Lipari" Lipari.