The launch of the James Webb Space Telescope (JWST) in late 2021 marks a new start for studies of galaxy formation at high redshift ( z ≳ 6) during the era of cosmic reionization. JWST can capture sensitive, high-resolution images and multiobject spectroscopy in the IR that will transform our view of galaxy formation during the first billion years of cosmic history. This review summarizes our current knowledge of the role of galaxies in reionizing intergalactic hydrogen ahead of JWST, achieved through observations with the Hubble Space Telescope and ground-based facilities including Keck, the Very Large Telescope, Subaru, and the Atacama Large Millimeter/Submillimeter Array. We identify outstanding questions in the field that JWST can address during its mission lifetime, including with the planned JWST Cycle 1 programs. These findings include the following: ▪ Surveys with JWST have sufficient sensitivity and area to complete the census of galaxy formation at the current redshift frontier ( z ∼ 8–10). ▪ Rest-frame optical spectroscopy with JWST of galaxies will newly enable measures of star-formation rate, metallicity, and ionization at z ∼ 8–9, allowing for the astrophysics of early galaxies to be constrained. ▪ The presence of evolved stellar populations at z ∼ 8–10 can be definitively tested by JWST, which would provide evidence of star formation out to z ∼ 15.

中文翻译：

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星系形成和再电离：詹姆斯·韦伯太空望远镜的关键未知数和预期突破


詹姆斯·韦伯太空望远镜 (JWST) 于 2021 年底发射，标志着宇宙再电离时代高红移 ( z ≳ 6) 星系形成研究的新起点。 JWST 可以在红外中捕获敏感的高分辨率图像和多目标光谱，这将改变我们对宇宙历史前十亿年星系形成的看法。这篇综述总结了我们目前对星系在 JWST 之前重新电离星际氢中的作用的了解，这是通过哈勃太空望远镜和地面设施（包括凯克、甚大望远镜、斯巴鲁和阿塔卡马大型毫米/亚毫米阵列）的观测获得的。我们确定了 JWST 在其任务生命周期内可以解决的领域突出问题，包括计划中的 JWST 第 1 周期项目。这些发现包括以下内容： ▪ JWST 的巡天具有足够的灵敏度和面积来完成当前红移前沿 (z ∼ 8-10) 处星系形成的普查。 ▪ JWST 星系的静止框架光谱将能够测量 z ∼ 8-9 处的恒星形成率、金属丰度和电离，从而限制早期星系的天体物理学。 ▪ JWST 可以明确测试 z ∼ 8-10 处演化恒星群的存在，这将提供 z ∼ 15 处恒星形成的证据。