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arXiv 1506.03079astro-ph.HEastro-ph.COastro-ph.GA
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高红移伽马射线暴GRB140515A

The high-redshift gamma-ray burst GRB140515A

A. Melandri, M. G. Bernardini, P. D'Avanzo, R. Sanchez-Ramirez, F. Nappo, L. Nava, J. Japelj, A. de Ugarte Postigo, S. Oates, S. Campana, S. Covino, V. D'Elia, … 展开作者

A. Melandri, M. G. Bernardini, P. D'Avanzo, R. Sanchez-Ramirez, F. Nappo, L. Nava, J. Japelj, A. de Ugarte Postigo, S. Oates, S. Campana, S. Covino, V. D'Elia, G. Ghirlanda, E. Gafton, G. Ghisellini, N. Gnedin, P. Goldoni, J. Gorosabel, T. Libbrecht, D. Malesani, R. Salvaterra, C. C. Thone, S. D. Vergani, D. Xu, G. Tagliaferri

摘要:

高红移的伽马射线暴对于研究遥远的宇宙有几个好处,它提供了关于发生爆炸的星系的结构和性质的独特信息。大型地面望远镜的光谱识别提高了我们对这类遥远事件的认识。本文介绍了高$z$斯威夫特伽马射线暴GRB 140515 A($z = 6.327$)的多波长分析。星系际介质(IGM)的中性氢分数对爆发的最佳估计是$x_{HI} \leq 0.002$。这次事件探测到的光谱吸收线是在伽马射线暴余辉中观测到的最弱的谱线,表明GRB 140515 A在一个非常低密度的环境中爆炸。其环爆介质的特征是平均消光(A $_{\rm V} \sim 0.1$),这似乎是典型的$z \ge 6$事件。所观察到的多波段光变曲线可以用非常平坦的注入光谱($p = 1.7$)或多组分发射($p = 2.1$)来解释。在第二种情况下,需要一个持久的中央发动机活动,以解释后期的X射线发射。GRB 140515A可能起源于Pop III(或来自Pop II星,其局部环境被Pop III富集)大质量恒星。

英文摘要:

High-redshift gamma-ray bursts have several advantages for the study of the distant universe, providing unique information about the structure and properties of the galaxies in which they exploded. Spectroscopic identification with large ground-based telescopes has improved our knowledge of the class of such distant events. We present the multi-wavelength analysis of the high-$z$ Swift gamma-ray burst GRB140515A ($z = 6.327$). The best estimate of the neutral hydrogen fraction of the intergalactic medium (IGM) towards the burst is $x_{HI} \leq 0.002$. The spectral absorption lines detected for this event are the weakest lines ever observed in gamma-ray burst afterglows, suggesting that GRB140515A exploded in a very low density environment. Its circum-burst medium is characterised by an average extinction (A$_{\rm V} \sim 0.1$) that seems to be typical of $z \ge 6$ events. The observed multi-band light curves are explained either with a very flat injected spectrum ($p = 1.7$) or with a multi-component emission ($p = 2.1$). In the second case a long-lasting central engine activity is needed in order to explain the late time X-ray emission. The possible origin of GRB140515A from a Pop III (or from a Pop II stars with local environment enriched by Pop III) massive star is unlikely.

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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