Implications of the measured image size for the radio afterglow of GRB 030329

Jonathan Granot, Enrico Ramirez-Ruiz, Abraham Loeb

Research output: Contribution to journalArticlepeer-review


We use data on the image size of the radio afterglow of GRB 030329 to constrain the physical parameters of this explosion. Together with the observed broadband spectrum, this data overconstrains the physical parameters, thus enabling us to test different GRB jet models for consistency. We consider two extreme models for the lateral spreading of the jet: model 1, with relativistic expansion in the local rest frame, and model 2, with little lateral expansion as long as the jet is highly relativistic. We find that both models are consistent with the data for a uniform external medium, while for a stellar wind environment model 1 is consistent with the data but model 2 is disfavored by the data. Our derivations can be used to place tighter constraints on the dynamics and structure of GRB jets in future afterglows, following a denser monitoring campaign for the temporal evolution of their image size.

Original languageEnglish
Pages (from-to)413-425
Number of pages13
JournalAstrophysical Journal
Issue number1 I
StatePublished - 1 Jan 2005
Externally publishedYes


  • Gamma rays: bursts
  • Ism: jets and outflows
  • Polarization
  • Radiation mechanisms: nonthermal
  • Relativity
  • Shock waves


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