Abstract. We severely criticize the consuetudinary analysis of the afterglows of gamma-ray bursts (GRBs) in the conical-ejection fireball scenarios. We argue that, instead, recent observations imply that the long-duration GRBs and their afterglows are produced by highly relativistic jets of cannonballs (CBs) emitted in supernova explosions. The CBs are heated by their collision with the supernova shell. The GRB is the boosted surface radiation the CBs emit as they reach the transparent outskirts of the shell. The exiting CBs further decelerate by sweeping up interstellar matter (ISM). The early X-ray afterglow is dominated by thermal bremsstrahlung from the cooling CBs, the optical afterglow by synchrotron radiation from the ISM electrons swept up by the CBs. We show that this model fits simply and remarkably well all the measured optical afterglows of the 15 GRBs with known redshift, including that of GRB 990123, for which unusually prompt data are available. We demonstrate that GRB 980425 was a normal GRB produced by SN1998bw, with standard X-ray and optical afterglows. We find that the very peculiar afterglow of GRB 970508 can be explained if its CBs encountered a significant jump in density as they moved through the ISM. The afterglows of the nearest 8 of the known-redshift GRBs show various degrees of evidence for an association with a supernova akin to SN1998bw. In all other cases such an association, even if present, would have been undetectable with the best current photometric sensitivities. This gives strong support to the proposition that most, maybe all, of the long-duration GRBs are associated with supernovae. Although our emphasis is on optical afterglows, we also provide an excellent description of X-ray afterglows.

Striking similarities exist between high energy gamma ray emission from active galactic nuclei (AGN) and gamma ray bursts (GRBs). They suggest that GRBs are generated by inverse Compton scattering from highly relativistic electrons in transient jets. Such jets may be produced along the axis of an accretion disk formed around stellar black holes (BH) or neutron stars (NS) in BH-NS and NS-NS mergers and in accretion induced collapse of magnetized white dwarfs (WD) or neutron stars in close binary systems. Such events may produce the cosmological GRBs. Transient jets formed by single old magnetized neutron stars in an extended Galactic halo may produce a local population of GRBs. Here we show that jet production of GRBs by inverse Compton scattering can explain quite simply the striking correlations that exist between various temporal features of GRBs, their duration histogram, the power spectrum of their complex multipeak light curves, their power-law high energy spectra and other features of GRBs. Some additional predictions are made including the expected polarization of gamma-rays in the bursts.

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Gamma Ray Bursts (GRBs) are notorious for their diversity. Yet, they have a series of common features. The typical energy of their γ rays is a fraction of an MeV. The energy distributions are well described by a "Band spectrum", with "peak energies" spanning a surprisingly narrow range. The time structure of a GRB consists of pulses, superimposed or not, rising and decreasing fast. The number of photons in a pulse, the pulses' widths and their total energy vary within broad but specific ranges. Within a pulse, the energy spectrum softens with increasing time. The duration of a pulse decreases at higher energies and its peak intensity shifts to earlier time. Many other correlations between pairs of GRB observables have been identified. Last (and based on one measured event!) the γ-ray polarization is very large. A satisfactory theory of GRBs should naturally and very simply explain, among others, all these facts. We show that the "cannonball" (CB) model does it. In the CB model the process leading to the ejection of highly relativistic jetted CBs in core-collapse supernova (SN) explosions is akin to the one observed in quasars and microquasars. The prompt γ-ray emission -the GRB-is explained extremely well by inverse Compton scattering of light in the near environment of the SN by the electrons in the CBs' plasma. We have previously shown that the CB-model's description of GRB afterglows as synchrotron radiation from ambient electrons -swept in and accelerated within the CBs-is also simple, universal and very successful. The only obstacle still separating the CB model from a complete theory of GRBs is the theoretical understanding of the CBs' ejection mechanism in SN explosions. most dense star-burst regions, was found to be insufficient to explain the γ-ray fluence of the most powerful GRBs, such as GRB 990213. We shall see that, in the CB model, this problem -the dearth of "target" light-does not arise.In the CB model, long-duration GRBs are made by core-collapse supernovae (SNe). As we asserted in Dar & De Rújula (2000a) "the light from the SN shell is Compton upscattered to MeV energies, but its contribution to a GRB is sub-dominant". That assertion is correct: the light from the SN shell is too underluminous and too radially directed to generate GRBs of the observed fluence and individual-photon energy. With our collaborator Shlomo Dado, we have developed a very complete, simple and -we contend-extremely successful analysis of GRB AGs (Dado, Dar & De Rújula 2002a,b,c, 2003a. This thorough analysis has taught us that there should be another, much more intense and more isotropic, source of scattered light: the SN's "glory". The glory is the "echo" (or ambient) light from the SN, permeating the "wind-fed" circumburst density profile, previously ionized by the early extreme UV flash accompanying a SN explosion, or by the enhanced UV emission that precedes it. In Sections 2 and 3 we summarize the observations of pre-SN winds, early SN luminosities, and the UV flashes of SNe, to obtain the reference values of the v...