REM observations of GRB 060418 : the fireball Lorentz factor de - termination
نویسنده
چکیده
— We measured the fireball Lorentz factor of GRB 060418 by the direct observation of the onset of the NIR afterglow carried with the REM telescope. We found Γ0 ∼ 400. PACS 98.70.Rz – gamma-ray bursts..
منابع مشابه
REM observations of GRB 060418 and GRB 060607A: the onset of the afterglow and the initial fireball Lorentz factor determination
Context. Gamma-ray burst (GRB) emission is believed to originate in highly relativistic fireballs. Aims. Currently, only lower limits were securely set to the initial fireball Lorentz factor Γ0. We aim to provide a direct measure of Γ0. Methods. The early-time afterglow light curve carries information about Γ0, which determines the time of the afterglow peak. We have obtained early observations...
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Gamma-ray burst are thought to be produced by highly relativistic outflows. Although upper and lower limits for the outflow initial Lorentz factor Γ0 are available, observational efforts to derive a direct determination of Γ0 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 Γ0 which determines the t...
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