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arXiv 1401.7785astro-ph.GAastro-ph.CO
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具有超宽红翼的z ~ 5.7Ly α发射线

A z ~ 5.7 Lyα Emission Line with an Ultra Broad Red Wing

Huan Yang, JunXian Wang, Zhen-Ya Zheng, Sangeeta Malhotra, James E. Rhoads, Leopoldo Infante

摘要:

利用Lyα发射线作为高红移恒星形成星系的示踪剂,已探测到数百个z > 5的Lyα发射线星系(LAEs)。这些LAE被认为是低质量的年轻星系,对宇宙的再电离和环星系介质(CGM)和星系际介质(IGM)的金属富集至关重要。假设LAEs的外流可以帮助电离光子和Lyα光子逃离星系。然而,由于观测上的困难,特别是在红移> 5的情况下,我们对高红移LAEs的外流仍然知之甚少。Lyα辐射转移模型预测了在有外流的LAEs中具有宽红翼的不对称Lyα线轮廓。本文报道了一条z ~ 5.7Ly α谱线,它有一个宽的红翼,相对于Lyα谱线的峰值延伸到> 1000 km/s,迄今为止,这条谱线只在几个z > 5的LAEs中被探测到。如果将宽红翼归因于气体外流而不是活动星系核活动,则外流速度可能大于z ~ 5.7 LAEs典型晕质量的逃逸速度(~ 500 km/s),这与LAEs外流将金属分散到CGM和IGM的图像相一致。

英文摘要:

Using Lyα emission line as a tracer of high redshift star forming galaxies, hundreds of Lyα emission line galaxies (LAEs) at z > 5 have been detected. These LAEs are considered to be low mass young galaxies, critical to the reionization of the universe and the metal enrichment of circumgalactic medium (CGM) and intergalactic medium (IGM). It is assumed that outflows in LAEs can help ionizing photons and Lyα photons escape out of galaxies. However we still know little about the outflows in high redshifts LAEs due to observational difficulties, especially at redshift > 5. Models of Lyα radiative transfer predict asymmetric Lyα line profiles with broad red wing in LAEs with outflows. Here we report a z ~ 5.7 Lyα emission line with a broad red wing extending to > 1000 km/s relative to the peak of Lyα line, which has been detected in only a couple of z > 5 LAEs till now. If the broad red wing is ascribed to gas outflow instead of AGN activity, the outflow velocity could be larger than the escape velocity (~ 500 km/s) of typical halo mass of z ~ 5.7 LAEs, being consistent with the picture that outflows in LAEs disperse metals to CGM and IGM.

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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