一个尘埃,在再电离时代的正常星系
Darach Watson1, Lise Christensen1, Kirsten Kraiberg Knudsen2
1Dark Cosmology Centre, Niels Bohr Institute, University of Copenhagen, Juliane Maries Vej 32, København Ø, 2100, Denmark.
Nature
|March 4, 2015
概括
早期宇宙中的红移z>7的星系对于理解宇宙恒星形成至关重要. 这项研究检测了来自z=7.5的星系A1689-zD1的热尘排放,揭示了它是一个尘埃覆盖的,进化系统代表这个时代.
科学领域:
- 太空进化的宇宙进化
- 银河系的形成和进化
- 早期宇宙天体物理学 天体物理学
背景情况:
- 许多早期宇宙星系 (红移z > 7) 已经通过紫外线成像识别出来,但它们的表征具有挑战性.
- 对尘埃和气体排放的远红外观测可以揭示这些星系的详细性质.
- 之前在遥远星系中检测到的尘埃辐射仅限于z = 3.2,在z ≥ 7的典型星系中对尘埃存在的怀疑.
研究的目的:
- 为了研究宇宙早期的原型恒星形成星系中的尘埃的存在和属性.
- 用其尘埃和恒星连续辐射来描述星系A1689-zD1,这是早期恒星形成的候选者.
- 为了确定它们是否进化,在z > 7的较弱恒星形成群体内存在尘土星系.
主要方法:
- 用光谱检测恒星连续和莱曼-α断裂来确定红移.
- 分析热尘排放以探测星系属性.
- 将尘埃与气体的比率与像银河系这样的局部星系进行比较.
主要成果:
- 来自星系A1689-zD1.1.的热尘排放的检测.
- 用光谱测定z = 7.5 ± 0.2.2. 的红移.
- 描述A1689-zD1作为一个高度进化的星系,具有显著的恒星质量和尘埃丰富,与银河系相比较.
- 估计总恒星形成速度大约为每年12个太阳质量.
- 证实A1689-zD1是再电离时代恒星形成群体的代表.
结论:
- 在早期宇宙的恒星形成群体中,在z > 7时,已进化的尘土星系存在.
- 银河系A1689-zD1提供了在再电离时代银河系中大量尘埃丰富的证据.
- 这些发现挑战了以前对典型的早期星系中尘埃和分子存在的怀疑.
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