/ 97 06 08 4 v 1 9 J un 1 99 7 Radio scintillation of gamma - ray - burst afterglows ⋆

ar X iv : a st ro - p h / 97 06 07 4 v 1 8 J un 1 99 7 The radioastronomical ” Time Machine ” effect and the solution of gamma ray bursts mystery

The possible low-frequency radio emission from the progenitors of gamma ray bursts can experience a delay from tens of seconds to hours on the way to the observer due to the dispersion in galactic and extragalactic plasma, and thus reach the observer as a radio afterglow of the burst. This opens a unique possibility (peculiar ”Time Machine”) of seeing what happened in that place before the cata...

ar X iv : a st ro - p h / 97 06 06 5 v 1 6 J un 1 99 7 Discovery of the X - Ray Afterglow of the Gamma - Ray Burst of February 28 1997

ar X iv : a st ro - p h / 97 11 35 4 v 1 2 8 N ov 1 99 7 Theoretical Models of Gamma - Ray Bursts 1

Models of gamma ray bursts are reviewed in the light of recent observations of afterglows which point towards a cosmological origin. The physics of fireball shock models is discussed, with attention to the type of light histories and spectra during the gamma-ray phase. The evolution of the remnants and their afterglows is considered, as well as their implications for our current understanding o...

ar X iv : a st ro - p h / 97 06 06 0 v 1 6 J un 1 99 7 The afterglow of gamma ray bursts II

Highly radiative expansion of a relativistic shell is shown to explain all observed features of the afterglows of the two bursts GRB 970228 and GRB 970508. In particular, in the first case the observed time–dependence ∝ t −1.32 of the soft X–ray flux is easily reproduced. The same model, when the surrounding matter density scales as a r −2 , explains the afterglow of GRB 970508, which may at fi...

Radio scintillation of gamma-ray-burst afterglows ?

Stars twinkle to the eye through atmospheric turbulence, but planets, because of their larger angular size, do not. Similarly, scintillation due to the local interstellar medium will modulate the radio flux of gamma-ray-burst afterglows and may permit indirect measurements of their angular sizes. The amplitude of refractive scintillation is of order ten percent at ten gigahertz unless the sourc...