在再电离时代的正常,尘埃覆盖的星系
Y Fudamoto1,2,3, P A Oesch4,5, S Schouws6
1Department of Astronomy, University of Geneva, Versoix, Switzerland. yoshinobu.fudamoto@gmail.com.
Nature
|September 23, 2021
概括
我们在再电离时代发现了两个被尘埃覆盖的星系. 这些星系被紫外线观测所遗漏, 揭示了早期宇宙中未被估计的恒星形成的贡献.
科学领域:
- 宇宙学
- 银河系的演变
- 早期宇宙的天体物理学
背景情况:
- 休息紫外线 (UV) 观测在再电离时代发现了红移 (z) > 6 的发光星系.
- 在这些早期被尘埃覆盖的星系是难以捉摸的,
- 之前的研究表明,在z > 6时,尘埃遮蔽的星系对宇宙恒星形成密度的贡献是次要的.
研究的目的:
- 在再电离时代 (z > 6) 调查尘埃遮蔽的恒星形成星系的存在和贡献.
- 描述这些模糊的星系,并确定它们在早期宇宙恒星形成率密度中的作用.
主要方法:
- 使用远红外观测,特别针对[C II]线和尘埃连续辐射.
- 发现隐藏的星系是已知的紫外线发光星系的伴侣.
- 分析了红外发光率和恒星形成率来分类星系群体.
主要成果:
- 报道了在z=6.68和z=7.35处发现两个尘埃遮蔽的恒星形成星系.
- 这些星系在休息的紫外线数据中没有被检测到,而是通过远红外辐射被发现.
- 发现这些星系的红外发光率和恒星形成率低于极端星爆,与典型的恒星形成星系在z ≈ 7对齐.
结论:
- 在z > 6的宇宙恒星形成率密度中,被重度尘埃遮蔽的星系似乎贡献了10-25%.
- 这一发现表明,在再电离的时代,模糊的恒星形成的作用比以前认为的更为重要.
- 暗示远红外观测对早期星系人口的完整普查至关重要.
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