The Properties of the Gamma-ray Bursts with High-energy Spectral Component

Spectral properties of some GRB with presence of high-energy component are discussed. The energy spectra shape of GRBs with high energy emission presence can follows the Band model (or power law or broken power law) up to some tens or hundreds of MeV (as for GRB 100724B and GRB 021008) or contains additional high energy power law component (for example, GRB 050525B and GRB 090902B). Both GRBs types were registered since CGRO mission has begun. The analysis of their energy spectra has shown that the break between low energy spectral part (described by either Band or power law or broken power law etc. models) and additional component was in energy region 2 - 200 MeV. The Fermi/LAT low energy threshold is lower than CGRO/BATSE one and the very low-energy spectral component described by power law with index δ and characterised X-ray emission in the range E<50 keV was introduced for several bursts energy spectra approximation. Moreover, for several GRBs this spectral parameter δ similar to Γ (characterizing gamma-emission in the band E >100 MeV) and the question about formation of wide range emission during GRB due to single mechanism arises again.