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arXiv 1012.3009astro-ph.HE
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伽马射线暴的Ep、Lp和Eiso之间相关的本征色散取决于数据集的质量

Intrisic Dispersion of Correlations among Ep, Lp, and Eiso of Gamma Ray Bursts depends on the quality of Data Set

Ryo Tsutsui, Takashi Nakamura, Daisuke Yonetoku, Toshio Murakami, Keitaro Takahashi

摘要:

利用由109个已知红移的伽玛暴(GRB)组成的数据库($E_p$、$L_p$和\Eiso),重新考虑了谱峰能量($E_p$)、1秒峰光度($L_p$)和各向同性能量(\Eiso)之间的相关性。我们根据数据质量将事件分为两组。一个(黄金数据集)由伽玛暴的峰值能量确定的带模型与四个自由参数。另一方面,另一组(青铜数据集)中的伽玛暴具有相对较差的能谱,因此其峰值能量由具有固定谱指数(即三个自由参数)的带模型或具有三个自由参数的截止幂律(CPL)模型确定。仅使用Gold数据集,我们发现$\log L_p$($=σ_{\rm int}$)中的固有色散对于\tsutsui相关性($T_L \equiv E_{\rm iso}/L_p$)和\yonetoku相关性分别为0.13和0.22。我们还发现,在青铜器数据集的伽玛暴有系统的更大的$E_p$比预期的相关性与黄金数据集。这意味着伽玛暴的$E_p$、$L_p$和\Eiso之间的相关性的内在离散度取决于数据集的质量。目前,利用\tsutsui与Gold数据的关联,我们可以确定具有$\sim 16%$误差的光度距离,这对于确定高红移$z > 3$暗能量的性质是有用的。

英文摘要:

We reconsider correlations among the spectral peak energy ($E_p$), 1-second peak luminosity ($L_p$) and isotropic energy (\Eiso), using the database constructed by \citet{yonetoku10} which consists of 109 Gamma-Ray Bursts (GRBs) whose redshifts are known and $E_p$, $L_p$ and \Eiso are well determined. We divide the events into two groups by their data quality. One (gold data set) consists of GRBs with peak energies determined by the Band model with four free parameters. On the other hand, GRBs in the other group (bronze data set) have relatively poor energy spectra so that their peak energies were determined by the Band model with fixed spectral index (i.e. three free parameters) or by the Cut-off power law (CPL) model with three free parameters. Using only the gold data set we found the intrinsic dispersion in $\log L_p$ ($=σ_{\rm int}$) is 0.13 and 0.22 for \tsutsui correlation ($T_L \equiv E_{\rm iso}/L_p$) and \yonetoku correlation, respectively. We also find that GRBs in the bronze data set have systematically larger $E_p$ than expected by the correlations constructed with the gold data set. This means that the intrinsic dispersion of correlations among $E_p$, $L_p$, and \Eiso of GRBs depends on the quality of data set. At present, using \tsutsui correlation with gold data set, we would be able to determine the luminosity distance with $\sim 16%$ error, which might be useful to determine the nature of the dark energy at high redshift $z > 3$.

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