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Session 33 - Gamma-ray Burst Counterparts and Afterglows.
Topical, Oral session, Tuesday, June 09

[33.04] The Transition from the Gamma-Ray Burst to the Afterglow and the Total Electromagnetic Energy Associated to the Burst

E. Costa (IAS-CNR, Roma), BeppoSAX GRB Team

The discovery of afterglow X-ray sources has impacted on many aspects of the Gamma-Ray Burst Physics. The final evidence provided by optical spectra of a cosmological distance scale is furtherly stimulating the study of GRBs as tracers of the Universe at large distance. But X-ray data also show that the energy associated with the main Gamma-Ray event is only a fraction, not likely constant, of the total. An important task for present and future experiments is the build up of a "bolometric correction" for GRBs aimed to derive the total electromagnetic luminosity and check the quality of GRBs as standard candles. The evaluation of the amount of enegy to be associated to the afterglow requires an understanding of the transition from the Gamma event to the afterglow itself. Moreover, since the afterglow spectra are hard and not-thermal, this evaluation also depends on the assumptions on the extension to nearby bands of the spectra measured in the 2-10 keV range. A few cases based on the analysis of BeppoSAX data are discussed.

Program listing for Tuesday