费米GRB170826B时间分辨谱的同步辐射拟合

Synchrotron Radiation Fitting of Fermi GRB170826B Time-resolved Spectrum

采用光滑截断双幂律谱(Band)、单幂率同步(SYNPL)和拐折幂率同步(SYNBPL)三个模型拟合费米GBM亮暴GRB170826B的时间分辨谱,并计算谱宽度W和谱锐度角θ,得到以下结果:(1)三个模型对该暴的能谱拟合较好并且拟合结果基本一致,表明同步模型能够解释该暴的能谱;(2)GRB170826B的单幂率同步p指数在4.88左右,Band和SYNBPL给出它的高能光谱比较陡,并且需要更多的高能光子来准确限制高能谱指数;(3)使用谱宽度W和谱锐度角θ等辅助量来测试同步模型解释伽马暴谱能力的方法存在争议,因为比较同步谱和伽马暴谱的这两个量表明有些伽马暴谱不能被同步解释,而这些谱却能被同步模型拟合.

Smooth break double power-law spectrum(Band),Single power-law synchrotron(SYNPL)and break power-law synchrotron(SYNBPL)are used to fit the time-resolved spectrum of Fermi GBM bright burst GRB170826B,and the spectral width W and spectral sharpness angleθare calculated.Then the following conclusions are obtained:(1)the three models fit the energy spectrum of the burst well and the fitting results are basically the same,indicating that the synchrotron model can explain the energy spectrum of the burst;(2)Band and SYNBPL show that its high-energy spectrum is relatively steep,and more high-energy photons are needed to accurately limit the high-energy spectral index;(3)The use of auxiliary quantities such as spectral width W and spectral sharpness angleθto test the ability of synchrotron radiation to interpret the GRB spectrum is controversial,because comparing these two quantities of the synchrotron spectrum and the GRB spectrum indicates that some GRB spectrums cannot be explained,and these spectra can be fitted by a synchrotron model.