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arXiv 0902.1522astro-ph.HE
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选择对GRB谱能量相关性的影响

Selection effects on GRB spectral-energy correlations

Lara Nava, Giancarlo Ghirlanda, Gabriele Ghisellini

摘要:

仪器选择效应会影响伽玛暴峰值能量Ep、注量F和峰值通量P的估计。如果是这种情况,那么涉及相应的静止帧量(即Ep,Eiso和峰值亮度Liso)的相关性将受到质疑。我们估计,作为Ep的函数,触发伽玛暴所需的最小峰值通量和最小注量爆发必须考虑不同的仪器(BATSE,雨燕,BeppoSAX),以确定Ep的值。我们发现,后者优于前者。然后,我们研究的Ep-fluence(和通量)的相关性在观察者平面。具有红移的伽玛暴显示出定义良好的Ep-F和Ep-P相关:在这个平面上,存在选择效应,但不确定所发现的相关性。但对于具有红移的雨燕伽玛暴,这是不正确的,因为光谱分析阈值确实会影响它们在观测者平面上的分布。将样本扩展到没有z的GRB,我们仍然发现了显着的Ep-F相关,尽管与红移GRB定义的散射相比具有更大的散射。我们发现6%是Amati相关性的异常值。有无红移暴的Ep-P关联是相同的,无红移暴没有异常值。

英文摘要:

Instrumental selection effects can act upon the estimates of the peak energy Ep, the fluence F and the peak flux P of GRBs. If this were the case, then the correlations involving the corresponding rest frame quantities (i.e. Ep, Eiso and the peak luminosity Liso) would be questioned. We estimated, as a function of Ep, the minimum peak flux necessary to trigger a GRB and the minimum fluence a burst must have to determine the value of Ep by considering different instruments (BATSE, Swift, BeppoSAX). We find that the latter dominates over the former. We then study the Ep-fluence (and flux) correlation in the observer plane. GRBs with redshift show well defined Ep-F and Ep-P correlations: in this planes the selection effects are present, but do not determine the found orrelations. This is not true for Swift GRBs with redshift, for which the spectral analysis threshold does affect their distribution in the observer planes. Extending the sample to GRBs without z, we still find a significant Ep-F correlation, although with a larger scatter than that defined by GRBs with redshift. We find that 6% are outliers of the Amati correlation. The Ep-P correlation of GRBs with or without redshift is the same and no outlier is found among bursts without redshift.

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