Optické dosvity gama záblesků: prvních deset minut

Maleňáková, Alžběta

The transition sharpness of the optical forward-shock onset in gamma-ray bursts (GRBs) has not been systematically quantified. I introduce a hyperbola parametrisa- tion for afterglow light curves that measures the transition width log R at the onset peak, offering more stable MCMC convergence than standard smooth broken power laws. The method is applied to eight GRB afterglows: three events observed in detail with the D50, SBT, and FRAM at La Palma; three archival afterglows reprocessed from published data, including observations from BART, D50, and FRAM at Auger; and two further bursts from recent group work. A linear correlation between log R and p, the electron power-law index, is found across seven of these bursts: harder spectra correspond to sharper onset transitions. An errors-in-variables MCMC fit confirms a significant negative slope with small intrinsic scatter. The parametrisation provides a stable and extensible framework for characterising the afterglow onset across large archival samples.

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