等时面与γ射线暴余辉  

SURFACE OF EQUAL ARRIVAL TIME AND GRB AFTERGLOW

作　　者：黎卓[1] 戴子高[1] 

机构地区：[1]南京大学天文系,南京210093

出　　处：《天文学报》1999年第3期225-229,共5页Acta Astronomica Sinica

摘　　要：在γ射线暴（ 简称γ暴） 的火球模型下，γ暴余辉存在等时面，面上发射的光子会同时被观测到．通过对等时面积分来计算辐射流量Ｆν（ｔ） 。The afterglow of γ ray burst (GRB) can be well interpreted by the fireball model, in which a thin relativistic shell emits a delayed afterglow while colliding with the ISM. The observed surface of afterglow is the surface of equal arrival time (SEAT for simplicity) of radiation from the shell, rather than the surface of the shell itself. Not only the SEAT determines the observed size of afterglow, but also the evolution of the SEAT determines the observed spectral evolution and the light curve of afterglow. Since each “point” on the SEAT has a different Lorentz factor (hence different synchrotron spectrum and brightness), the observed fluxes should be the surface integrated fluxes on the SEAT. This paper provides results of calculations and comes to some conclusions, which are significantly different from those deduced from the usual simple model. Firstly, the peak flux of the spectrum increases with time while it is constant in the simple model. Secondly, the flux at a fixed frequency increases faster at the beginning and decreases more slowly after reaching the peak value. Therefore, the influence of the SEAT cannot be neglected in accurate calculations.

关 键 词：Γ射线暴 余辉 辐射机制 火球演化 

分 类 号：P162[天文地球—天文学] P172.3