EDP Sciences
Free access
Volume 368, Number 2, March III 2001
Page(s) 464 - 470
Section Formation, structure and evolution of stars
DOI http://dx.doi.org/10.1051/0004-6361:20000352

A&A 368, 464-470 (2001)
DOI: 10.1051/0004-6361:20000352

Gamma-ray burst afterglows from jetted shocks in wind environments

L. J. Gou1, Z. G. Dai1, 2, Y. F. Huang1, 3 and T. Lu1, 2

1  Department of Astronomy, Nanjing University, Nanjing 210093, PR China
    e-mail: daizigao@public1.ptt.js.cn
2  IHEP, Chinese Academy of Sciences, Beijing 100039, PR China
3  Astronomical and Astrophysical Center of East China, Nanjing University, Nanjing 210093, PR China

(Received 6 June 2000 / Accepted 22 September 2000)

Gamma-ray bursts with long durations are widely thought to arise from the collapse of massive stars, where the wind environment is unavoidable. It is also believed that $\gamma$-ray bursts come from jets. Considering these two points in this paper, we calculate the evolution of a highly collimated jet that expands in a stellar wind environment and the expected afterglow from such a jet. We use a set of refined dynamical equations and a realistic lateral speed of the jet, and find: (1) There is no observable break at the time when the Lorentz factor of the jet is equal to the inverse of its initial half-opening angle. (2) No obvious break appears at the time when the blast wave transits from the relativistic to the non-relativistic phase. (3) For the wind case, there is no flattening tendency even up to 109 s. (4) Compared with the homogeneous medium case, our calculated flux is weaker in the stellar wind case. Finally, we find that two kinds of GRB models (neutron star mergers and massive star collapses) may be discriminated in our numerical results.

Key words: gamma-rays: bursts -- ISM: jets and outflows -- stars: mass loss - shock waves

Offprint request: L. J. Gou, tlu@nju.edu.cn

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