通过远紫外光谱探测器解决银河间介质中电离的结构
概括
早期宇宙结构是由中性 (H I) 和电离 (He II) 的吸收揭示出来的. 观测显示He II莱曼α吸收,大多数特征具有H I对应物,即使在低密度区域也表明结构.
科学领域:
- 宇宙学和天体物理学
- 早期宇宙研究 早期宇宙研究
- 星系间介质 星系间介质
背景情况:
- 量子星光谱显示中性 (H I) 和电离 (He II) 的吸收.
- 这些吸收特征探测了早期宇宙中的宇宙结构.
研究的目的:
- 为了分析早期宇宙中的He II莱曼α (Lyalpha) 吸收.
- 为了研究He II和H I柱密度之间的关系.
- 了解导致II电离的来源.
主要方法:
- 利用远紫外光谱探测器 (FUSE) 的观测结果.
- 分析了类星体HE2347-4342在1000至1187安格斯特罗姆频段的光谱.
- 在红移2.3-2.7.7处确定He II Lyalpha吸收线.
主要成果:
- 解决了He II Lyalpha吸收作为一个离散的线条森林.
- 在大约50%的He II特征中发现了H I对应物.
- 观察到He II到H I列密度比率从1到>1000不等,平均约为80.
- 识别了缺乏H I对应物的He II Lyalpha吸收器.
结论:
- 观察到的He II和H I柱密度比率表明类星体的光离子化,还有来自星爆星系或过类星体辐射的额外贡献.
- 在没有H I对应物的情况下存在He II吸收器,表明结构在低密度地区.
- 这些发现与由引力不稳定驱动的结构形成模型相一致.
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