Cyclotron resonant scattering in the spectra ofγ-ray bursts

Fits of theoretical spectra from Monte Carlo radiation-transfer calculations to dips at ≊20 and 40 keV in a spectrum of the ‘‘classical’’ γ-ray burst GB 880 205 give best-fit values and 68%-confidence intervals B=(1.71±0.07)×${10}^{12}$ G, $N_e$=(1.2±0.6)×${10}^{21}$ electrons/${\mathrm{cm}}^2$, and μ=cosθ=0.31±0.05, where θ is the viewing angle relative to the field. Physical self-consistent fixes the temperature at $T_C$ ${=5.3\mathrm{}}_{\mathrm{-}0.2}^{+0.3\mathrm{}}$ keV. These results suggest that this γ-ray burst and many others which exhibit a low-energy dip originate from strong magnetic neutron stars and are galactic in origin.