Ring-Shaped Jets in Gamma-Ray Bursts  

作　　者：Ming Xu Yong-Feng Huang Si-Wei Kong 

机构地区：[1]Department of Astronomy, Nanjing University, Nanjing 210093, China

出　　处：《Chinese Journal of Astronomy and Astrophysics》2008年第4期411-420,共10页中国天文和天体物理学报（英文版）

基　　金：the National Natural Science Foundation of China(Grants 10625313 and 10221001)

摘　　要：When the axis of a gamma-ray burst （GRB） does not coincide with the spin axis of its source, there may result a ring-shaped jet. Using some refined jet dynamics, we calculate multi-wavelength afterglow light curves for such ring-shaped jets. In the R-band we find an obvious break in the afterglow light curve due to the beaming effect and the break is affected by many parameters, such as the electron energy fraction ζe, the magnetic energy fraction ζB^2, the width of ring △θ and the medium number density n. The overall light curve can be divided into three power-law stages, i.e., an ultra-relativistic stage, an after-break stage and a deep Newtonian stage. For each stage the power-law index is larger in the ring-shaped jet than in the corresponding conical jet.When the axis of a gamma-ray burst （GRB） does not coincide with the spin axis of its source, there may result a ring-shaped jet. Using some refined jet dynamics, we calculate multi-wavelength afterglow light curves for such ring-shaped jets. In the R-band we find an obvious break in the afterglow light curve due to the beaming effect and the break is affected by many parameters, such as the electron energy fraction ζe, the magnetic energy fraction ζB^2, the width of ring △θ and the medium number density n. The overall light curve can be divided into three power-law stages, i.e., an ultra-relativistic stage, an after-break stage and a deep Newtonian stage. For each stage the power-law index is larger in the ring-shaped jet than in the corresponding conical jet.

关 键 词：gamma rays bursts - ISM jets and outflows 

分 类 号：P172.3[天文地球—天文学]