A Probable Origin and Radiation Mechanism for Gamma-Ray Bursts

A model of the old and hot neutron stars (age γ～10⁸～10⁹ yr, temperature T_N～10⁷-10⁸ K) with the low magnetic field (B～10⁹-10¹⁰ Gauss) as the sources of Gamma-ray bursts is presented. In the range of medium energy (E < 400 KeV), the main radiation mechanism is still the thermal synchrotron radiation. The absorp tion features of the low frequency (E < 50 KeV) are resulted from the superposition of the blackbody spectrum emitted by the hot neutron star itself and the thermal synchrotron spectrum with self-absorption. And the spectrum for the high energy part (E > 400 KeV, including the emission features) is due to the annihilation emission from the unthermalized positrons and electrons. Using this model, we adopt the three component spectra to fit four representative spectra of Gamma-ray bursts. The results are satisfactory. Our model also avoids some difficulties existed in other modela.