Fermi伽玛暴时间分辨谱拐折幂率拟合的模型限制  

Model Limitation of Break Power-Law Fitting of the Fermi GRB Time-Resolved Spectra

作　　者：王道周 彭朝阳[1] 常学钊 陈家明 王晨 罗双玲[1] Wang Daozhou;Peng Zhaoyang;Chang Xuezhao;Chen Jiaming;Wang Chen;Luo Shuangling(College of Physics and Electronic Information,Yunnan Normal University,Kunming 650500,China)

机构地区：[1]云南师范大学物理与电子信息学院,云南昆明650500

出　　处：《天文研究与技术》2021年第1期43-51,共9页Astronomical Research & Technology

基　　金：国家自然科学基金(11763009)资助.

摘　　要：使用平滑拐折幂率(Smoothly Broken Power Law,SBPL)模型、折线幂率(Broken Power Law,BPL)模型和波段函数(Band)模型拟合8个费米(Fermi)亮暴,得到165个最佳模型拟合谱,然后根据这165个谱的能量流量得出3个模型拟合数据的范围和一些结论。折线幂率模型能很好地拟合较暗的暴(F e<5×10^-5 erg·cm^-2),而较亮的暴用波段函数模型(5×10^-5 erg·cm^-2<F e<2.0×10^-4 erg·cm^-2)和平滑拐折幂率模型(2.0×10^-4 erg·cm^-2<F e<3.8×10^-4 erg·cm^-2)可以得到更好的拟合结果。样本中大约一半的谱用折线幂率模型拟合较好,表明有些较暗的暴的谱形接近折线形状,即谱拐折比较尖锐。虽然多数光谱中最佳拟合模型是折线幂率模型,但波段函数模型和平滑拐折幂率模型拟合也能得到可以接受的结果,并且高能光子少以至于现有的数据不能很好地排除一些能谱模型。另外,目前的拟合结果可能受到仪器响应矩阵的影响,不能很好地确定真实的物理模型,也就是说伽玛暴谱看似能被模型解释,但可能不是真实的。We use the models SBPL(smooth break power-law),BPL(power-law connecting broken line)and Band to fit 8 Fermi bright bursts to get 165 best model fitting spectra.Then based on the energy flux Fluence of these 165 spectra,the range of the three model fitting data and some conclusions are obtained.Obtaining BPL can fit darker bursts well(F e<5×10^-5 erg·cm^-2),while brighter bursts can get better fit with Band(5×10^-5 erg·cm^-2<F e<2.0×10^-4 erg·cm^-2)and SBPL(2.0×10^-4 erg·cm^-2<F e<3.8×10^-4 erg·cm^-2).Nearly half of the spectra in the sample is fitted well by BPL,indicating that the spectral shape of some dark bursts is close to the shape of the polyline,that is,the spectral inflection is sharper.Although the best fitting model in most spectra is BPL,Band and SBPL also get acceptable fits,and there are so few high-energy photons that the existing data cannot well exclude some energy spectrum models.In addition,the current fitting may be affected by the response matrix of the instrument,and it is not possible to determine the true physical model very well,that is,the GRB spectrum may be explained by the model,but it may not be true.

关 键 词：伽玛射线暴 瞬时辐射 光谱拟合 数据分析 

分 类 号：P172.3[天文地球—天文学]