ar X iv : a st ro - p h / 03 06 24 6 v 1 1 2 Ju n 20 03 GRB 980425 , SN 1998 BW AND THE EMBH MODEL

The EMBH model, previously developed using GRB 991216 as a prototype, is here applied to GRB 980425. We fit the luminosity observed in the 40–700 keV, 2–26 keV and 2–10 keV bands by the BeppoSAX satellite. In addition we present a novel scenario in which the supernova SN1998bw is the outcome of an " induced gravitational collapse " triggered by GRB 980425, in agreement with the GRB-Supernova Time Sequence (GSTS) paradigm (Ruffini et al. 2001c). A further outcome of this astrophysically exceptional sequence of events is the formation of a young neutron star generated by the SN1998bw event. A coordinated observational activity is recommended to further enlighten the underlying scenario of this most unique astrophysical system. INTRODUCTION The aim of this talk is to present the application of the EMBH theory, previously successfully applied to GRB 991216 used as a prototype, to the case of GRB 980425 (Pian et al., 2000) and SN1998bw (Galama et al., 1998). This is a particularly important test for the validity of the EMBH theory over a range of energies of 6 orders of magnitude: as we will see, both sources appear to be spherically symmetric and the respective total energies are E tot ≃ 5 × 10 53 ergs and E tot ≃ 10 48 ergs. We recall that the EMBH theory (see Ruffini et al., 2003b) depends only on three parameters, the energy of the dyadosphere E dya , the B parameter and the factor R describing the interstellar medium (ISM) porosity. The theory, therefore, explains all the observed features of the bolometric intensity variations of the afterglow as well as the spectral properties of the source and, in the specific case of GRB 980425, it also allows to clarify the general astrophysical scenario in which the GRB actually occurs. In this system, in fact, we propose that GRB 980425 has been the trigger of a phenomenon of " induced gravitational collapse " (Ruffini et al., 2001c) originating the supernova explosion and we also witness the birth of a young neutron star out of the supernova event. This extraordinary coincidence of these three astrophysical events represents an unprecedented scenario of fundamental importance in the field of relativistic astrophysics. Using the EMBH theory we shall explore: a) the process of black hole formation in the event GRB 980425 (Pian et al., 2000), b) the concept of " induced gravitational collapse " , introduced in …