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arXiv 0704.0791astro-ph
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红移已知的雨燕长伽玛暴的谱分析

Spectral analysis of Swift long GRBs with known redshift

J. I. Cabrera, C. Firmani, V. Avila-Reese, G. Ghirlanda, G. Ghisellini, L. Nava

摘要:

我们研究了雨燕卫星探测到的47个具有已知红移的长持续时间伽马射线暴(GRB)的光谱和能量学性质。由于Swift-BAT探测器的能量范围较窄(15-150 keV),因此光谱拟合仅适用于具有2个或3个参数的拟合模型。由于预计误差之间存在高度不确定性和相关性,因此有必要对误差进行仔细分析。我们拟合的幂律(PL,2参数)和截止幂律(CPL,3参数)模型的时间积分谱的47个爆发,并提出了相应的参数,其不确定性,以及不确定性之间的相关性。CPL模型是可靠的,只有29爆发,我们估计的nuf_nu峰值能量Epk。对于这些伽玛暴,我们计算了能量注量和静止坐标系各向同性等效辐射能量Eiso,以及它们之间的传播不确定性和相关性。我们探讨了我们的均匀样本的伽玛暴的分布上的休息框架图E 'pk与Eiso。我们确认这两个数量之间的显着相关性(“阿马蒂”关系),我们验证,在不确定性范围内,没有离群值。我们还将谱拟合到一个带模型中,并将高能幂律指数冻结到-2.3,得到了与非雨燕伽玛暴的“Amati”关系相当好的一致性。

英文摘要:

We study the spectral and energetics properties of 47 long-duration gamma-ray bursts (GRBs) with known redshift, all of them detected by the Swift satellite. Due to the narrow energy range (15-150 keV) of the Swift-BAT detector, the spectral fitting is reliable only for fitting models with 2 or 3 parameters. As high uncertainty and correlation among the errors is expected, a careful analysis of the errors is necessary. We fit both the power law (PL, 2 parameters) and cut--off power law (CPL, 3 parameters) models to the time-integrated spectra of the 47 bursts, and present the corresponding parameters, their uncertainties, and the correlations among the uncertainties. The CPL model is reliable only for 29 bursts for which we estimate the nuf_nu peak energy Epk. For these GRBs, we calculate the energy fluence and the rest- frame isotropic-equivalent radiated energy, Eiso, as well as the propagated uncertainties and correlations among them. We explore the distribution of our homogeneous sample of GRBs on the rest-frame diagram E'pk vs Eiso. We confirm a significant correlation between these two quantities (the "Amati" relation) and we verify that, within the uncertainty limits, no outliers are present. We also fit the spectra to a Band model with the high energy power law index frozen to -2.3, obtaining a rather good agreement with the "Amati" relation of non-Swift GRBs.

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