第一亿年内超大质量星系的加速形成
Accelerated Formation of Ultra-Massive Galaxies in the First Billion Years
AI总结：
基于JWST FRESCO巡天数据，系统研究36个红移5至9的大质量尘埃星系，发现三个超大质量星系需50%重子转化为恒星，挑战现有星系形成模型，但整体与ΛCDM无冲突。
摘要：
最近的詹姆斯·韦伯太空望远镜（JWST）观测揭示了早期宇宙中大量大质量星系候选体的意外存在，这些候选体在红移上延伸得更远，光度也比亚毫米巡天先前发现的更低。这些JWST候选体被解释为对ΛCDM宇宙学模型的挑战，但迄今为止，它们大多仅依赖于静止系紫外数据，缺乏对其红移的光谱确认。在此，我们报告了来自JWST FRESCO巡天的36个大质量尘埃遮蔽星系的系统研究，这些星系的光谱红移在z_spec=5至9之间。在我们的样本中，我们未发现与ΛCDM模型存在张力。然而，三个超大质量星系（log M_star/M_sun ≳11.0）需要异常高的50%的重子转化为恒星的比例——这比后期纪元中最高效的星系还要高出两到三倍。由于它们的延展发射，活动星系核的贡献不太可能。在z~5至6时，超大质量星系占宇宙总恒星形成率密度的多达17%。
英文摘要：
Recent JWST observations have revealed an unexpected abundance of massive galaxy candidates in the early Universe, extending further in redshift and to lower luminosity than what had previously been found by sub-millimeter surveys. These JWST candidates have been interpreted as challenging the $Λ$CDM cosmology, but, so far, they have mostly relied only on rest-frame ultraviolet data and lacked spectroscopic confirmation of their redshifts. Here we report a systematic study of 36 massive dust-obscured galaxies with spectroscopic redshifts between $z_{\rm spec}=5-9$ from the JWST FRESCO survey. We find no tension with the $Λ$CDM model in our sample. However, three ultra-massive galaxies (log$M_{\star}/M_{\odot}$ $\gtrsim11.0$) require an exceptional fraction of 50% of baryons converted into stars -- two to three times higher than even the most efficient galaxies at later epochs. The contribution from an active nucleus is unlikely because of their extended emission. Ultra-massive galaxies account for as much as 17% of the total cosmic star formation rate density at $z\sim5-6$.
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