2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/14329Within the standard internal shock scenario, synchrotron emission would produce a spectrum with slope F(v) proportional to v^(-1/2), as immediate consequence of the cooling timescale being shorter than the integration time. This is in disagreement with the harder observed spectra, indicating that a different mechanism is responsible for the burst emission. Furthermore in this scenario pair production is expected when photons produced by inverse Compton emission are taken into account.4 pages, contributed paper for the meeting: "Gamma-ray bursts: the first three minutes", Editors: J. Poutanen and R. SvenssonAstrophysicstext