2004/03/31 by C. D. Dermer, Charles D. Dermer · 2 citations
Physics and Astronomy · #Adiabatic process #Afterglow #Astronomy #Astrophysics #Astrophysics and Cosmic Phenomena #Blast wave #Classical mechanics #Curvature #Energy flux #Flux (metallurgy) #Gamma-ray burst #Gamma-ray bursts and supernovae #Jet (fluid) #Lorentz factor #Lorentz transformation #Mechanics #Optics #Photon #Physics #Pulsars and Gravitational Waves Research #Quantum mechanics #Radiative cooling #Radiative transfer #Shock wave #astro-ph
paper · pdf · doi:10.1086/426532
published as Astrophys.J. 614 (2004) 284-292 · 13 pages, 5 figures, added back-of-envelope estimate of curvature relation, minor corrections, ApJ, in press, v. 614, 10 Oct 2004
arxiv created 2004/07/06 · openalex publication_date 2004/10/08 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
An elementary kinematic model for emission produced by relativistic spherical colliding shells is studied. The case of a uniform blast-wave shell with jet opening angle θ j ≫ 1/Γ is considered, where Γ is the Lorentz factor of the emitting shell. The shell, with comoving width Δ r ', is assumed to be illuminated for a comoving time Δ t ' and to radiate a broken-power-law ν L ν spectrum peaking at comoving photon energy . Synthetic gamma-ray burst (GRB) pulses are calculated, and the relation between energy flux and internal comoving energy density is quantified. Curvature effects dictate that the measured ν F ν flux at the measured peak photon energy pk be proportional to in the declining phase of a GRB pulse. Possible reasons for discrepancies with observations are discussed, including adiabatic and radiative cooling processes that extend the decay timescale, a nonuniform jet, and the formation of pulses by external shock processes. A prediction of a correlation between prompt emission properties and times of the optical afterglow beaming breaks is made for a cooling model, which can be tested with Swift .