Disclosing the gamma-ray burst circumburst ambient with XMM-Newton

Long Gammaray Bursts (GRBs) signal the death of massive stars. The afterglowemission can be used to probe the progenitor ambient through a detailed study ofthe absorption pattern. Taking advantage of Swift observations, we propose hereto observe bright GRB afterglows within 9 hr from their explosions withXMMNewton. These constraints will allow us to have access to an unprecedentedstatistics. Detailed studies of the absorption pattern imprinted in the Xrayspectrum by the circumburst material will be carried out, leading to infer theprogenitor initial mass, initial metallicity and rotational velocity. truncated!, Please see actual data for full text [truncated!, Please see actual data for full text]