Muon Acceleration in Cosmic-ray Sources

TL;DR

This paper investigates muon acceleration in cosmic-ray sources, showing that high-gradient accelerations significantly affect neutrino spectra and constraining models of gamma-ray bursts and magnetars.

Contribution

It demonstrates that muons can be substantially accelerated in high-gradient environments, impacting neutrino flux predictions and constraining existing astrophysical source models.

Findings

High acceleration gradients alter neutrino energy spectra.

Many source models are ruled out due to acceleration constraints.

Constraints on plasma wakefield accelerators are established.

Abstract

Many models of ultra-high energy cosmic-ray production involve acceleration in linear accelerators located in Gamma-Ray Bursts magnetars, or other sources. These source models require very high accelerating gradients, $10^{13}$ keV/cm, with the minimum gradient set by the length of the source. At gradients above 1.6 keV/cm, muons produced by hadronic interactions undergo significant acceleration before they decay. This acceleration hardens the neutrino energy spectrum and greatly increases the high-energy neutrino flux. We rule out many models of linear acceleration, setting strong constraints on plasma wakefield accelerators and on models for sources like Gamma Ray Bursts and magnetars.