GRBs, Fireballs and Precessing Gamma Jets

Abstract.

Fireballs are huge isotropic explosions models widely believed to explain Gamma Ray Burst, GRBs (Piran,1999); ever-new versions consider wide beamed (10^o) Jet explosions hitting external shells. On the contrary, since 1994-1998, we argued (Fargion 1995-2000; see also Blackman et all.1996) that GRBs (as well as Soft Gamma Repeaters SGR) are spinning and precessing Gamma Jets, produced by collimated e ⁺,e ^- Jet via Inverse Compton Scattering, in a very narrow (0.1^o) angles, blazing and flashing the observer. The Jet arises in Super-Nova (SN) explosions; its energy decays slowly from earliest SN powers (corresponding to GRB) toward lower stable power as Soft Gamma Repeaters (SGR) regimes. GRBs and SGRs shared (sometimes) same spectra and time structure: then SGRs are low-power GRBs, but without SN relics (or GRB afterglows, signatures of Jets in SN-GRBs). Moreover weak isolated X-ray precursor signals,(such as GRB980519, GRB981226, GRB000131), corresponding to huge isotropic $\sim 10^{47}$ erg s ^-1, followed by the extreme GRB $\sim 10^{52}$ erg s ^-1 powers, disagree with any Fireball explosive scenarios. We naturally interpret these X-Ray precursors as rare earliest marginal blazes of outlying X conical precessing Jet tails, surrounding the $\gamma$ Jet, later hitting in-axis as a GRB.