Covino 2007 GRB060418 and GRB060607A余辉的开始时间

主要内容:
余辉的开始时间影响对初始洛仑兹\gamma_0的估计。这两个暴的\Gamma_0约为400

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文章信息:
The afterglow onset for GRB060418 and GRB060607A

Authors: S. Covino, S.D. Vergani,et.al

(Submitted on 3 Oct 2007)

Abstract: Gamma-ray burst are thought to be produced by highly relativistic outflows. Although upper and lower limits for the outflow initial Lorentz factor $\Gamma_0$ are available, observational efforts to derive a direct determination of $\Gamma_0$ have so far failed or provided ambiguous results. As a matter of fact, the shape of the early-time afterglow light curve is strongly sensitive on $\Gamma_0$ which determines the time of the afterglow peak, i.e. when the outflow and the shocked circumburst material share a comparable amount of energy. We now comment early-time observations of the near-infrared afterglows of GRB 060418 and GRB 060607A performed by the REM robotic telescope. For both events, the afterglow peak was singled out and allowed us to determine the initial fireball Lorentz, $\Gamma_0\sim 400$.

Comments:	This contribution is part of the proceedings of the Frascati Workshop 2007, edited by F. Giovannelli and L. Sabau-Graziati, published in a special volume of the Chinese Journal of Astronomy and Astrophysics (ChJAA)
Subjects:	Astrophysics (astro-ph)
Cite as:	arXiv:0710.0727v1 [astro-ph]