在两个星系的[C ii]发射气体中以6.8的红移旋转
Renske Smit1,2, Rychard J Bouwens3, Stefano Carniani1,2
1Cavendish Laboratory, University of Cambridge, 19 JJ Thomson Avenue, Cambridge CB3 0HE, UK.
Nature
|January 12, 2018
概括
研究人员发现了两个早期星系的二氧化碳 ([C ii]) 排放线,为再电离时代提供了新的见解. 这些发现揭示了令人惊的[C ii]信号,
科学领域:
- 宇宙学和天体物理学
- 早期的宇宙研究
- 银河系的演变
背景情况:
- 在宇宙的第一个十亿年里, 再电离的时代是早期星系电离中性的时代.
- 研究这个时代需要检测遥远的高红移星系的光谱特征.
- 之前对这些早期星系的莱曼-α和碳-II ([C ii]) 辐射的搜索因散射和昏迷而面临挑战.
研究的目的:
- 识别和描述早期宇宙中的星系的光谱特征,特别是在再电离时代.
- 在高红移星系中研究碳-II ([C ii]) 发射线的亮度和特性.
- 为了比较这些早期星系的动态与后来的宇宙历史.
主要方法:
- 使用近红外光学选择高红移候选星系.
- 从选定的候选物质中确定二氧化碳 ([C ii]) λ=157.74 μm的排放线.
- 对已识别的星系的红移光谱确认 (z=6.8540和z=6.8076).
主要成果:
- 来自两个星系的[C ii] λ=157.74μm发射在红移z=6.8540和z=6.8076的检测.
- 观测到的[C ii]亮度明显高于以前发现的红移大于6.5的星系.
- 对[C ii]线的分析显示速度梯度表明旋转动态,与"宇宙中午"的星系可比.
结论:
- 这项研究成功地确定了宇宙最初10亿年内两个星系的[C ii]辐射.
- 这些发现挑战了关于早期星系中[C ii]的淡度的先前假设,并为理解再电离提供了关键数据.
- 从[C ii]线推断出的动态特性表明早期星系可能具有类似于后来的宇宙时代的复杂结构和旋转.
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