Central powering of the largest Lyman-α nebula is revealed by polarized radiation
Central powering of the largest Lyman-α nebula is revealed by polarized radiation
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DOI：
10.1038/nature10320
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发表时间：
2011-08
期刊：
影响因子：
64.8
通讯作者：
M. Hayes;C. Scarlata;B. Siana
中科院分区：
文献类型：
--
作者：
M. Hayes;C. Scarlata;B. Siana
高红移的莱曼-α（Lyα）斑点是一种延伸的、发光的但罕见的结构，似乎与宇宙物质密度的最高峰有关。它们的能量输出和形态与强大的射电星系相似，但光度的来源尚不清楚。一些斑点与紫外或红外明亮的星系有关，这表明一个极端的恒星爆发事件或吸积到中央黑洞。另一种可能性是气体被超新星冲击激发。但并不是所有的斑点都与星系有关，这些斑点可能是由落入暗物质晕的气体加热的。原则上，Lyα发射的偏振可以区分这些选项，在这里，我们报告了对来自斑点LAB 1的偏振Lyα的观测（参考文献）。虽然中心区域没有显示出可测量的极化，但极化部分（P）在半径为45千秒差距的地方增加到20%，形成了一个几乎完整的极化环。偏振辐射的检测与Lyα光子的原位产生不一致，我们得出结论，它们一定是在星云内的星系中产生的，并被中性氢重新散射。
High-redshift Lyman-α (Lyα) blobs,are extended, luminous but rare structures that seem to be associated with the highest peaks in the matter density of the Universe,,,. Their energy output and morphology are similar to those of powerful radio galaxies, but the source of the luminosity is unclear. Some blobs are associated with ultraviolet or infrared bright galaxies, suggesting an extreme starburst event or accretion onto a central black hole,,. Another possibility is gas that is shock-excited by supernovae,. But not all blobs are associated with galaxies,, and these ones may instead be heated by gas falling into a dark-matter halo,,,,. The polarization of the Lyα emission can in principle distinguish between these options,,, but a previous attempt to detect this signature returned a null detection. Here we report observations of polarized Lyα from the blob LAB1 (ref. ). Although the central region shows no measurable polarization, the polarized fraction (P) increases to ∼20 per cent at a radius of 45 kiloparsecs, forming an almost complete polarized ring. The detection of polarized radiation is inconsistent with thein situproduction of Lyα photons, and we conclude that they must have been produced in the galaxies hosted within the nebula, and re-scattered by neutral hydrogen.