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在温热的星系间介质中观测缺失的巴里昂
F Nicastro1,2, J Kaastra3, Y Krongold4
1Istituto Nazionale di Astrofisica (INAF), Osservatorio Astronomico di Roma, Rome, Italy. fabrizio.nicastro@oa-roma.inaf.it.
Nature
|June 22, 2018
概括
天文学家在温暖的星系间介质中发现了缺失的子,它们构成了宇宙的30-40%的子物质. 在类星体光谱中观察到高度电离的氧 (O VII) 吸收器证实了它们在富含星系的区域中的存在.
科学领域:
- 宇宙学和天体物理学
- 星际媒介研究
- 巴里昂人口普查
背景情况:
- 与大爆炸核合成预测相比,长期存在的宇宙学难题是观测到的子中30-40%的缺陷.
- 理论模型提出这些缺失的子存在于热热星系间介质 (WHIM),这是星系之间的热,微薄的气体.
- 检测WHIM是具有挑战性的,因为紫外线光谱的信号噪声比较低,因为大部分是电离化的,因此是不可见的.
研究的目的:
- 为了检测和确认在温暖的星际介质中缺失的子的存在.
- 通过X射线光谱研究热热星际介质的特性和位置.
主要方法:
- 在红移>0.4的类星体高信号噪声比X射线光谱的分析.
- 从高度电离氧 (O VII) 中识别吸收特征作为WHIM的标记物.
- 评估吸收器变异性和相关的冷吸收,以排除其他来源 (例如类星体外流,银河系ISM).
主要成果:
- 在类星体的X射线光谱中检测到两个O VII吸收器,
- 吸收剂在两年内没有变化,缺乏相关的冷吸收,排除局部来源.
- 在高星系密度的区域发现了O VII系统,与WHIM预测和模拟一致.
结论:
- 观察到的O VII吸收器归因于热热的星系间介质,为其存在提供了有力的证据.
- 这一发现解决了长期存在的缺失子问题,
- 这些发现验证了宇宙结构形成的数值模拟和宇宙中的微子物质分布.
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