2021/10/07 by Ze-Lin Zhang, Ruo-Yu Liu, Xiang-Yu Wang +1
Physics and Astronomy · #Acceleration #Afterglow #Astrophysics #Astrophysics and Cosmic Phenomena #Classical mechanics #Cosmic ray #Gamma-ray burst #Gamma-ray bursts and supernovae #Jet (fluid) #Particle acceleration #Physics #Pierre Auger Observatory #Pulsars and Gravitational Waves Research #Ultra-high-energy cosmic ray #astro-ph.HE
paper · pdf · doi:10.1103/physrevd.104.103005
14 pages, 6 figures, 1 table, accepted for publication in PRD
arxiv created 2021/10/07 · openalex publication_date 2021/11/05 · arxiv updated 2021/11/17 · openalex created_date 2021/11/22 · openalex updated_date 2026/06/26
The origin of ultrahigh-energy cosmic rays (UHECRs) remains a mystery. It has been suggested that UHECRs can be produced by the stochastic acceleration in relativistic jets of gamma-ray bursts (GRBs) at the early afterglow phase. We develop a time-dependent model for proton energization by cascading compressible waves in GRB jets while considering the concurrent effect of the jet's dynamics and the mutual interactions between turbulent waves and particles. Considering the fast mode of a magnetosonic wave as the dominant particle scatterer and assuming the interstellar medium for the circumburst environment, our numerical results suggest that protons can be accelerated up to 1019 eV during the early afterglow. An estimation shows that ultrahigh-energy nuclei can easily survive photodisintegration in the external shocks in most cases, thus allowing the acceleration of 1020 eV cosmic-ray nuclei in the proposed frame. The spectral slope can be as hard as dN/dE\ensuremath∝E0, which is consistent with the requirement for the interpretation of the intermediate-mass composition of the UHECRs as measured by the Pierre Auger Observatory.