关键词: γ射线暴, 辐射机制, 弯曲磁场

Abstract: The frequently cited fireball-shock model of Gamma-Ray Burst (hereafter, GRB) can explain well the main features and processes after the burst. This model, however, is challenged by the latest high-resolution observational results during the last few years, which present some clues on the incompleteness of its theoretical considerations. For example, one basic assumption of the fireball model is using the standard synchrotron radiation mechanism to approximate the high energy emissions from GRBs. This is equivalent to claim that the magnetic field inside GRB is uniformly distributed, which smears out most of the important information of magnetic field configuration other than the field strength. In the study of GRB shocks, it is generally believed that most of the physical quantities, such as density and pressure, are inhomogeneous throughout the shocked region. Then why is it plausible to assume the shocked magnetic field alone to be homogeneous, which originates from perturbation mechanism?
In this paper, we analysis this problem in details, and regard that the radiation induced by curvature of shocked magnetic field lines plays a significant role in GRB emissions. The traditional fireball-shock model meets difficulties in explaining some latest observational results. This may be caused by ignorance of that important portion of radiation above. Making application of the formulae of synchro-curvature radiation, which can treat analytically the particle radiations in the curved magnetic field, we fit well a series of new GRB spectra, and present a unified interpretation toward the turnoff point and energy excess in the high-energy portion of the spectra. These features above are difficult to explain within the past synchrotron radiation framework. Furthermore, the fitting of a series of GRB spectra allows us to give some new constraints on the magnetic structure of the emission district, origin of the shocked magnetic field, and the mechanism of shock acceleration.

Key words: gamma-ray burst, radiating Mechanism, curved magnetic field.