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arXiv 2402.18543astro-ph.GAastro-ph.CO
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宇宙黎明时期由≥15个致密恒星形成团块组成的原初旋转盘

Primordial Rotating Disk Composed of $\geq$15 Dense Star-Forming Clumps at Cosmic Dawn

S. Fujimoto, M. Ouchi, K. Kohno, F. Valentino, C. Giménez-Arteaga, G. B. Brammer, L. J. Furtak, M. Kohandel, M. Oguri, A. Pallottini, J. Richard, A. Zitrin, F. … 展开作者

S. Fujimoto, M. Ouchi, K. Kohno, F. Valentino, C. Giménez-Arteaga, G. B. Brammer, L. J. Furtak, M. Kohandel, M. Oguri, A. Pallottini, J. Richard, A. Zitrin, F. E. Bauer, M. Boylan-Kolchin, M. Dessauges-Zavadsky, E. Egami, S. L. Finkelstein, Z. Ma, I. Smail, D. Watson, T. A. Hutchison, J. R. Rigby, B. D. Welch, Y. Ao, L. D. Bradley, G. B. Caminha, K. I. Caputi, D. Espada, R. Endsley, Y. Fudamoto, J. González-López, B. Hatsukade, A. M. Koekemoer, V. Kokorev, N. Laporte, M. Lee, G. E. Magdis, Y. Ono, F. Rizzo, T. Shibuya, K. Shimasaku, F. Sun, S. Toft, H. Umehata, T. Wang, H. Yajima

AI总结:

本研究通过强透镜高分辨率观测,在红移6.072的年轻星系“宇宙葡萄”中分解出至少15个致密恒星形成团块,揭示其由引力不稳定的旋转盘形成,挑战了早期星系演化模型,并有助于解释亮星系丰度和暗物质核-尖点问题。

摘要:

早期星系形成由暗物质和气体聚集启动,通过频繁的合并和反馈过程演化为动力学上炽热、混沌的结构。相比之下,在大爆炸后仅14亿年的大质量演化星系中观测到了动力学上冷、平滑的旋转盘,这表明早期宇宙中形态和动力学演化迅速。探究这一演化机制需要对年轻星系进行研究,但相关努力一直受限于灵敏度和空间分辨率的观测局限。本文报告了对一个强透镜且五重成像、低光度、年轻星系(称为“宇宙葡萄”)在红移$z=6.072$(大爆炸后9.3亿年)的高分辨率观测。经引力透镜放大后,该星系被分解为至少15个独立的恒星形成团块,其有效半径$r_{\rm e}\backsimeq$10--60秒差距(pc),这些团块主导了星系总通量的约70%。冷气体发射揭示了一个平滑的、潜在的旋转盘,其特征是高旋转与随机运动比以及引力不稳定状态(Toomre $Q \backsimeq$ 0.2--0.3),表面气体密度高,与局部尘埃星暴星系相当,约为$10^{3-5}$ $M_{\odot}$/pc$^{2}$。这些气体性质表明,众多恒星形成团块是通过盘不稳定性形成的,且反馈效应较弱。“宇宙葡萄”的团块程度显著超过后期时代的星系以及当前模拟对早期星系的预测。我们的发现为星系内部子结构及其与早期形成阶段潜在动力学和反馈机制的关系提供了新见解,可能解释早期宇宙中观测到的高丰度亮星系以及暗物质核-尖点问题。

英文摘要:

Early galaxy formation, initiated by the dark matter and gas assembly, evolves through frequent mergers and feedback processes into dynamically hot, chaotic structures. In contrast, dynamically cold, smooth rotating disks have been observed in massive evolved galaxies merely 1.4 billion years after the Big Bang, suggesting rapid morphological and dynamical evolution in the early Universe. Probing this evolution mechanism necessitates studies of young galaxies, yet efforts have been hindered by observational limitations in both sensitivity and spatial resolution. Here we report high-resolution observations of a strongly lensed and quintuply imaged, low-luminosity, young galaxy at $z=6.072$ (dubbed the Cosmic Grapes), 930 million years after the Big Bang. Magnified by gravitational lensing, the galaxy is resolved into at least 15 individual star-forming clumps with effective radii of $r_{\rm e}\simeq$ 10--60 parsec (pc), which dominate $\simeq$ 70\% of the galaxy's total flux. The cool gas emission unveils a smooth, underlying rotating disk characterized by a high rotational-to-random motion ratio and a gravitationally unstable state (Toomre $Q \simeq$ 0.2--0.3), with high surface gas densities comparable to local dusty starbursts with $\simeq10^{3-5}$ $M_{\odot}$/pc$^{2}$. These gas properties suggest that the numerous star-forming clumps are formed through disk instabilities with weak feedback effects. The clumpiness of the Cosmic Grapes significantly exceeds that of galaxies at later epochs and the predictions from current simulations for early galaxies. Our findings shed new light on internal galaxy substructures and their relation to the underlying dynamics and feedback mechanisms at play during their early formation phases, potentially explaining the high abundance of bright galaxies observed in the early Universe and the dark matter core-cusp problem.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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