Gamma-ray bursts are the most luminous explosions in the Universe, and their origin and mechanism are the focus of intense research and debate. More than three decades after their discovery, and after pioneering breakthroughs from space and ground experiments, their study is entering a new phase with the recently launched Swift satellite. The interplay between these observations and theoretical models of the prompt gamma-ray burst and its afterglow is reviewed.

https://iopscience.iop.org/article/10.1088/0034-4885/69/8/R01/pdf

Gamma-ray bursts

THE spatial and luminosity distribution of γ-ray bursts as observed by the BATSE instrument on the Compton Gamma Ray Observatory1,2 provides support for the revival of the idea3,4 that the burst sources are at cosmological distances5. I present here a new model for γ-ray bursts at cosmological distances, based on the formation of rapidly rotating neutron stars with surface magnetic fields of the order of 1015. Such objects could form by the gravitational collapse of accreting white dwarfs with anomalously high magnetic fields in binaries, as in magnetic cataclysmic binaries. Once formed, such rapidly rotating and strongly magnetized neutron stars would lose their rotational kinetic energy catastrophically, on a timescale of seconds or less: rotation of the magnetic field creates a strong electric field, and hence an electron–positron plasma, which I show to be optically thick and in quasi-thermodynamic equilibrium. This plasma flows away from the neutron star at relativistic speeds, and X-ray and γ-ray emission at the photosphere of this relativistic wind may then reproduce the observational characteristics of a γ-ray burst.

Millisecond pulsars with extremely strong magnetic fields as a cosmological source of γ-ray bursts

The physics of gamma-ray bursts & relativistic jets

We provide a comprehensive review of major developments in our understanding of gamma-ray bursts, with particular focus on the discoveries made within the last fifteen years when their true nature was uncovered. We describe the observational properties of photons from the radio to multi-GeV bands, both in the prompt emission and the afterglow phases. Mechanisms for the generation of these photons in GRBs are discussed and confronted with observations to shed light on the physical properties of these explosions, their progenitor stars and the surrounding medium. After presenting observational evidence that a powerful, collimated, jet moving at close to the speed of light is produced in these explosions, we describe our current understanding regarding the generation, acceleration, and dissipation of the jet and compare these properties with jets associated with AGNs and pulsars. We discuss mounting observational evidence that long duration GRBs are produced when massive stars die, and that at least some short duration bursts are associated with old, roughly solar mass, compact stars. The question of whether a black-hole or a strongly magnetized, rapidly rotating neutron star is produced in these explosions is also discussed. We provide a brief summary of what we have learned about relativistic collisionless shocks and particle acceleration from GRB afterglow studies, and discuss the current understanding of radiation mechanism during the prompt emission phase. We discuss theoretical predictions of possible high-energy neutrino emission from GRBs and the current observational constraints. Finally, we discuss how these explosions may be used to study cosmology, e.g. star formation, metal enrichment, reionization history, as well as the formation of first stars and galaxies in the universe.

/pdf/the-physics-of-gamma-ray-bursts-and-relativistic-jets-571z4a98ye.pdf

The Physics of Gamma-Ray Bursts and Relativistic Jets

The cosmological gamma-ray burst (GRB) phenomenon is reviewed. The broad observational facts and empirical phenomenological relations of the GRB prompt emission and afterglow are outlined. A well-tested, successful fireball shock model is introduced in a pedagogical manner. Several important uncertainties in the current understanding of the phenomenon are reviewed, and prospects of how future experiments and extensive observational and theoretical efforts may address these problems are discussed.

Gamma-Ray Bursts: Progress, Problems & Prospects

/pdf/a-qualitative-study-of-cosmic-fireballs-and-g-ray-bursts-51mezykp9y.pdf

G. Cavallo

Papers

A qualitative study of cosmic fireballs and γ-ray bursts