We present an analysis of time-resolved optical emissions observed from the gamma-ray burst GRB 081126 during the prompt phase. The analysis employed time resolved photometry using optical data obtained by the TAROT telescope, using BAT data from the Swift spacecraft and time resolved spectroscopy at high energies from the GBM instrument onboard the Fermi spacecraft. The optical emission of GRB...

background: the equivalent dose in the human body due to the natural gamma-emitting radionucides (238u, 232th and 40k) in the surface soil surrounding the consolidated tin mine site in bukuru-jos, nigeria has been determined in this study. materials and methods: measurements of the soil natural radioactivity were made using a multi-channel pulseheight analyzer (canberra series 10 plus) coupled ...

The energy spectra of TeV gamma-rays from blazars, after being corrected for intergalatic absorption in the Extragalactic Background Light (EBL), appear unusually hard, a fact that poses challenges to the conventional models of particle acceleration in TeV blazars and/or to the EBL models. In this paper we show that the internal absorption of gamma-rays caused by interactions with dense narrow-...

If gamma ray bursts are highly collimated, radiating into only a small fraction of the sky, the energy requirements of each event may be reduced by several (∼ 4–6) orders of magnitude, and the event rate increased correspondingly. Extreme conditions in gamma ray bursters lead to highly relativistic motions (bulk Lorentz factors Γ ∼> 100). This results in strong forward beaming of the emitted ra...

Gamma-ray bursters emit a small fraction of their flux in X rays, and because X-ray detectors are often very sensitive they may probe the gamma-ray burst universe more deeply than the current best gamma-ray instruments. On the reasonable assumptions that spectra of bursts observed by BATSE may be used to predict the X-ray fluxes of gamma-ray bursts, and that any corona of bursts around M31 is s...