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在年轻宇宙中的正常大质量恒星形成星系中,高分子气体分数存在
L J Tacconi1, R Genzel, R Neri
1Max-Planck-Institut für extraterrestrische Physik (MPE), Giessenbachstr. 1, 85748 Garching, Germany. linda@mpe.mpg.de
Nature
|February 12, 2010
概括
遥远的星系富含分子气体,为快速恒星形成提供了燃料. 这种气体含量明显高于当今星系的含量,这表明早期宇宙中存在连续的气体补充机制.
科学领域:
- 天文学 天文学
- 宇宙学的宇宙学是什么?
- 天体物理学 天体物理学
背景情况:
- 恒星是由冷的分子星际气体形成的,这在本地很少见,限制了银河系的恒星形成.
- 遥远的宇宙中的巨大星系形成恒星的速度要快得多,这意味着分子气体含量更高.
- 以前的分子气体观测仅限于稀有,发光的物体,如聚变和类星体.
研究的目的:
- 为了研究典型的大质量恒星形成星系在红移 z ≈ 1.2 和 z ≈ 2.3.3 的分子气体含量.
- 了解早期大质量星系中的气体丰富性和恒星形成效率.
- 将遥远星系中的气体分数与当地的宇宙中的气体分数进行比较.
主要方法:
- 在典型的大型恒星形成星系的样本中对分子气体进行了调查.
- 分析的星系的平均红移
大约为1.2和2.3. - 测量了冷气相对于银河系总质量的冷气分数.
主要成果:
- 遥远的恒星形成星系显著富含气体,其分子气体分数比局部大质量螺旋星系高3-10倍.
- 在z = 2.3时,平均冷气分数为~44%;在z = 1.2时,它是~34%.
- 恒星形成的效率并不强烈地取决于宇宙时代.
结论:
- 年轻的大质量星系的分子气体比以前所认为的要丰富得多.
- 观察到的气体分数表明,早期星系需要一种半连续补充新鲜气体的机制.
- 这一发现有助于解释早期宇宙中恒星形成的快速速度.
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