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在金属贫困星系中,尘埃的稀有性
David B Fisher1, Alberto D Bolatto2, Rodrigo Herrera-Camus2
11] Department of Astronomy, Laboratory for Millimeter-wave Astronomy and Joint Space Institute, University of Maryland, College Park, Maryland 20742, USA [2] Centre for Astrophysics and Supercomputing, Swinburne University, PO Box 218, Hawthorn, Victoria 3122, Australia.
Nature
|December 10, 2013
概括
像希米科 (z = 6.6) 这样的早期星系很少显示冷尘,这对于恒星形成至关重要. 对本地模拟星系I Zwicky 18的观测揭示了极低的尘埃与气体比率,这表明早期星系的尘埃可能比以前认为的要少得多.
科学领域:
- 宇宙进化的宇宙进化.
- 银河系的形成和演变.
- 天体化学是天体化学.
背景情况:
- 红移z > 6 (宇宙年龄小于10亿年) 的星系很少表现出冷尘.
- 冷尘是局部宇宙中恒星形成的关键组成部分.
- 在局部宇宙中,尘埃与气体的质量比率大约为1%.
研究的目的:
- 为了研究原始星系的尘埃含量.
- 使用当地的矮星系I Zwicky 18 (I Zw18) 作为高红移星系的类比.
- 为了限制早期恒星形成星系中的尘埃特性.
主要方法:
- 来自I Zwicky 18的尘埃排放的观察.
- 在I Zw18.18中确定尘埃质量和比率.
- 将I Zw18的属性与像Himiko这样的高红移星系进行比较.
主要成果:
- 在I Zw18中的尘埃质量确定为450-1,800太阳质量.
- 在I Zw18中,尘埃与恒星的质量比为~10−6到10−5.
- 在I Zw18中,尘埃与气体的质量比为3.213 × 10−6,明显低于局部宇宙.
结论:
- I Zw18,作为一个潜在的类比,表明Himiko的尘埃质量可能是~50,000太阳质量,比上限低100倍.
- 如果大多数高z星系类似于Himiko,那么在它们中检测气体和尘埃可能比预期的更具挑战性.
- 原始星系的尘埃含量可能比局部星系低得多,这影响了早期恒星形成的模型.
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