On the jet structure and magnetic field configuration of GRB 020813

D. Lazzati, S. Covino, J. Gorosabel, E. Rossi, G. Ghisellini, E. Rol, J. M.C. Cerón, A. J. Castro-Tirado, M. Delia Valle, S. Di Serego Alighieri, A. S. Fruchter, J. P.U. Fynbo, P. Goldoni, J. Hjorth, G. L. Israel, L. Kaper, N. Kawai, E. Le Floc'h, D. Malesani, N. MasettiP. Mazzali, F. Mirabel, P. Møller, S. Ortolani, E. Palazzi, E. Pian, J. Rhoads, G. Ricker, J. D. Salmonson, L. Stella, G. Tagliaferri, N. Tanvir, E. Van Den Heuvel, R. A.M.J. Wijers, F. M. Zerbi

Research output: Contribution to journalArticlepeer-review

44 Scopus citations


The polarization curve of GRB 020813 is discussed and compared to different models for the structure, evolution and magnetisation properties of the jet and the interstellar medium onto which the fireball impacts. GRB 020813 is best suited for this kind of analysis for the smoothness of its afterglow light curve, ensuring the applicability of current models. The polarization dataset allows us to rule out the standard GRB jet, in which the energy and Lorentz factor have a well defined value inside the jet opening angle and the magnetic field is generated at the shock front. We explore alternative models finding that a structured jet or a jet with a toroidal component of the magnetic field can fit equally well the polarization curve. Stronger conclusions cannot be drawn due to the incomplete sampling of the polarization curve. A more dense sampling, especially at early times, is required to pin down the structure of the jet and the geometry of its magnetic field.

Original languageEnglish (US)
Pages (from-to)121-128
Number of pages8
JournalAstronomy and Astrophysics
Issue number1
StatePublished - Jul 2004
Externally publishedYes


  • Gamma rays: bursts
  • Polarization radiation mechanisms: non-thermal

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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