arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 2006.02748astro-ph.HE
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结构喷流情景下短伽马射线暴的亮度分布

The Luminosity Distribution of Short Gamma-Ray Bursts under a Structured Jet Scenario

Qi Guo, Daming Wei, Yuanzhu Wang

摘要:

GRB 170817 A的亮度远低于其他sGRB。对射电余辉辐射超光速运动的测量证实了相对论性喷流的存在,结构喷流模型能很好地解释这种辐射特征。本文基于结构化的理论计算了sGRB的光度分布及其随红移的演化(高斯)喷流模型,发现附近sGRB的典型光度随红移而增加(例如光度距离小于200 Mpc)典型的伽马射线光度大约为10^47-10^48 erg s-1,这自然解释了GRB 170817 A非常低的辐射亮度。我们推导了费米GBM对sGRB的探测概率,发现在几百Mpc的距离内,sGRB的预期探测率仅为1年。我们探讨了合并时间分布的幂律指数α对观测特性的影响,发现它对观测到的光度和视角分布几乎没有影响。然而,非常有趣的是,对于不同的α值,观测到的sGRB数量的分布有很大的不同,因此可以通过观测到的sGRB数量的分布来确定α的值。我们用贝叶斯方法进行了定量分析,发现当观测到的红移已知的sGRB数大于200时,α的值是可以确定的。最后,我们将我们的γ射线亮度分布结果与红移已知的sGRB进行了比较,发现我们的结果与观测结果一致,这意味着我们的模拟结果可以很好地再现观测到的亮度分布。

英文摘要:

Luminosity of GRB 170817A is much lower than that of other sGRBs. The measurement of the superluminal movement of the radio afterglow emission confirms the presence of the relativistic jet, and the emission features can be well explained by the structured jet model. In this paper, we calculate the luminosity distribution of sGRBs and its evolution with redshift based on the structured (Gaussian) jet model, and find that the typical luminosity increase with redshift, for nearby sGRBs (such as for luminosity distance less than 200 Mpc) the typical gamma-ray luminosity is just around 10^47-10^48 erg s-1, which naturally explains the very low radiation luminosity of GRB 170817A. We derived the detection probability of sGRBs by Fermi-GBM and found that the expected detection rate of sGRBs is only about 1 yr-1 within the distance of several hundred Mpc. We explored the effect of the power-law index α of the merger time distribution on the observed characteristics and found that it had little effect on the observed luminosity and viewing-angle distributions. However, it is very interesting that, for different values of α, the distributions of the number of observed sGRBs are quite different, so it is possible to determine the value of α through observed distributions of the number of sGRBs. We used the Bayesian method to make a quantitative analysis and found that the value of α may be identified when the number of observed sGRBs with known redshifts is more than 200. Finally, we compare our results of gamma-ray luminosity distribution with sGRBs with known redshifts, and found that our results are consistent with the observation, which implies that our simulation results can reproduce the observed luminosity distribution well.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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