Spectral Hardness Evolution of Gamma-Ray Bursts Due to the Doppler Effect of Fireballs
Spectral Hardness Evolution of Gamma-Ray Bursts Due to the Doppler Effect of Fireballs
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DOI：
10.1086/518732
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发表时间：
2007-07
期刊：
影响因子：
--
通讯作者：
R. Lu;Z. Peng;W. Dong
中科院分区：
文献类型：
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作者：
R. Lu;Z. Peng;W. Dong
基于高度对称的膨胀火球模型，研究了膨胀火球表面多普勒效应对观测到的谱硬度Ep（其中Ep为νFν谱的最大值）的影响，发现Ep的演化曲线经历了由下降到上升再到衰减的演化过程（分别为A、B和C相）. A相在对应的光变曲线脉冲的开始处达到峰值。由于多普勒效应在对应于脉冲的上升部分的B相位中不太突出，因此B相位的斜率反映了对应的本征频谱演变及其局部脉冲的形状。对应于脉冲的衰减部分的C相，其中多普勒效应占主导地位，总是单调地减小，并且不一定反映相应的固有频谱演变。研究了12个FRED脉冲的样本（它们的峰值能量可以在Kaneko等人的工作中找到）。结果表明，FRED脉冲拟合峰值能量的演化特征与我们的预测符合得很好。
We have investigated the evolution of observed spectral hardness Ep (where Ep is the maximum of the νFν spectrum) based on the model of highly symmetric expanding fireballs, where the Doppler effect of the expanding fireball surface is the key factor concerned, and find that the evolutionary curve of Ep undergoes a drop to rise to decay evolution (the A, B, and C phases, respectively). The A phase peaks at the very onset of the corresponding light-curve pulse. Since the Doppler effect is less prominent in the B phase, corresponding to the rising portion of the pulse, the slope of the B phase reflects both the corresponding intrinsic spectral evolution and the shape of its local pulse. The C phase, corresponding to the decay portion of the pulse, where the Doppler effect dominates, always decreases monotonically and does not necessarily reflect the corresponding intrinsic spectral evolution. Investigation of a sample of 12 FRED pulses (their peak energy can be found in the work of Kaneko et al.) shows that the evolutionary characteristics of the fitted peak energy in the FRED pulses are in good agreement with our predictions.