Possible Origins of Dispersion of the Peak Energy-Brightness Correlations of Gamma-Ray Bursts
Possible Origins of Dispersion of the Peak Energy-Brightness Correlations of Gamma-Ray Bursts
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DOI：
10.1093/pasj/62.6.1495
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发表时间：
2010-12
影响因子：
2.3
通讯作者：
D. Yonetoku;T. Murakami;Ryo Tsutsui;Takashi Nakamura;Y. Morihara;Keitaro Takahashi
中科院分区：
文献类型：
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作者：
D. Yonetoku;T. Murakami;Ryo Tsutsui;Takashi Nakamura;Y. Morihara;Keitaro Takahashi
我们收集并重新分析了截至2009年底观测到的约200个已知红移的伽玛暴瞬发数据，选择了101个光谱参数良好的伽玛暴，以确定光谱峰值能量(Ep)、1秒峰值光度(Lp)和各向同性能量(Eiso)。利用我们新建立的101个伽玛暴数据库，我们首先对EP-LP和EP-EISO关联进行了修正。修正后相关系数分别为：EP-LP相关的99个自由度的相关系数为0.889，EP-EISO相关的96个自由度的相关系数为0.867。这些值分别对应于2.18�10�35和4.27�10�31的机会概率。这是一个非常重要的问题，这些紧密关联是伽玛暴的固有性质，还是由观测的某些选择效应造成的。在这篇文章中，我们研究了探测器灵敏度的截断对关联的影响，并得出结论，它们肯定是伽玛暴的固有性质。接下来，我们通过研究关联的亮度和红移相关性来研究关联色散的来源。这里，亮度(通量或通量)相关性将被认为是由于探测器阈值引起的偏差的估计器。在2�统计水平上，我们发现Ep-Eiso关联中存在弱的通量依赖关系，而Ep-Lp关联中存在红移依赖关系。这两个效应可能导致关联的色散，而色散比统计不确定性更大。我们讨论了这些相关性的可能原因，并对未来改善相关性进行了展望。
We collected and reanalyzed about 200 GRB data of prompt-emission with known redshift observed until the end of 2009, and selected 101 GRBs that were well-observed to have good spectral parameters in order to determine the spectral peak energy (Ep), 1-second peak luminosity (Lp) and isotropic energy (Eiso). Using our newly constructed database with 101 GRBs, we first revised the Ep–Lp and Ep–Eiso correlations. The correlation coefficients of the revised correlations were 0.889 for 99 degrees of freedom for the Ep–Lp correlation and 0.867 for 96 degrees of freedom for the Ep–Eiso correlation. These values correspond to a chance probability of 2.18 � 10 � 35 and 4.27 � 10 � 31 , respectively. It is a very important issue whether these tight correlations are an intrinsic property of GRBs, or are caused by some selection effect of observations. In this paper, we examine how the truncation of the detector sensitivity affects the correlations, and conclude they are surely intrinsic properties of GRBs. Next we investigate origins of the dispersion of the correlations by studying their brightness and redshift dependence. Here, the brightness (flux or fluence) dependence would be regarded as being an estimator of the bias due to the detector threshold. We found a weak fluence-dependence in the Ep–Eiso correlations and a redshift dependence in the Ep– Lp correlation both at the 2 � statistical level. These two effects may contribute to the dispersion of the correlations, which is larger than the statistical uncertainty. We discuss a possible reason of these dependences and give a future prospect to improve the correlations.