ar X iv : a st ro - p h / 98 06 33 3 v 1 2 5 Ju n 19 98 Gamma - ray bursts : postburst evolution of fireballs

ar X iv : a st ro - p h / 98 06 25 6 v 1 1 8 Ju n 19 98 Gamma Ray Bursts from Stellar

Received ; accepted – 2 – ABSTRACT We propose that the cosmological gamma ray bursts arise from the collapse of neutron stars to black holes triggered by collisions or mergers with main sequence stars. This scenario represents a cosmological history qualitatively different from most previous theories because it contains a significant contribution from an old stellar population, namely the globu...

ar X iv : a st ro - p h / 98 06 18 3 v 2 1 6 Ju l 1 99 8 The Edge of a Gamma Ray Burst Afterglow

We discuss the formation of spectral features in the decelerating ejecta of gamma-ray bursts, including the possible effect of inhomogeneities. These should lead to blueshifted and broadened absorption edges and resonant features, especially from H and He. An external neutral ISM could produce detectable H and He, as well as Fe X-ray absorption edges and lines. Hypernova scenarios may be diagno...

ar X iv : a st ro - p h / 98 08 19 1 v 2 2 7 Fe b 19 99 Can precessing jets explain the light curves of Gamma - ray Bursts ?

We present a phenomenological model to explain the light curves of gamma-ray bursts. In the model a black hole is orbited by a precessing accretion disc which is fed by a neutron star. Gamma-rays are produced in a highly collimated beam via the Blandford-Znajek mechanism. The gamma-ray beam sweeps through space due to the precession of the slaved accretion disc. The light curve expected from su...

ar X iv : h ep - p h / 98 10 33 5 v 1 1 3 O ct 1 99 8 Gamma - Ray Bursts and Dark Matter - a joint origin ?

ar X iv : a st ro - p h / 06 06 66 3 v 1 2 7 Ju n 20 06 Astrophysics in 2005

We bring you, as usual, the sun and moon and stars, plus some galaxies and a new section on astrobiology. Some highlights are short (the newly identified class of gamma-ray bursts, and the Deep Impact on Comet 9P/Tempel 1), some long (the age of the universe, which will be found to have the Earth at its center), and a few metonymic, for instance the term “down-sizing” to describe the evolution ...