We propose a dedicated, ultra-deep spectroscopic survey in the near infrared (NIR), that will target a mass-limited sample of galaxies during two of the most fundamental epochs of cosmic evolution: the formation of the first galaxies (at z \(\gtrsim \) 6; comsmic dawn), and at the peak of galaxy formation activity (at redshift z\(\sim \)1–3; cosmic noon). By way of NIR observations (λ= 0.8–2μ m), it is possible to study the UV Lyman-α region in the former, and the optical rest-frame in the latter, allowing us to extract fundamental observables such as gas and stellar kinematics, chemical abundances, and ages, providing a unique legacy database covering these two crucial stages of cosmic evolution. The need to work in the NIR at extremely low flux levels makes a ground-based approach unfeasible due to atmospheric emission and absorption. Only with the largest facilities of the future (e.g. ELT) will be possible to observe a reduced set of targets, comprising at most of order thousands of galaxies. Likewise, from space, the small field of view of JWST and its use as a general purpose facility will yield a rather small set of high quality NIR spectra of distant galaxies (in the thousands, at best). Our project (codename Chronos) aims to produce \(\sim \)1 million high quality spectra, with a high S/N in the continuum, where information about the underlying stellar populations is encoded. The main science drivers are:

• The connection between the star formation history and the mass assembly history.

• The role of AGN and supernova feedback in shaping the formation histories of galaxies, with a quantitative estimate of quenching timescales.

• The formation of the first galaxies.

• The source of reionization.

• Evolution of the metallicity-mass relation, including [α/Fe] and individual abundances.

• Precision cosmology through detailed studies of the “baryon physics” of galaxy formation, probing the power spectrum over scales k\(\sim \)1 Mpc^− 1.

我们提议在近红外 (NIR) 中进行专门的超深光谱调查，它将在宇宙演化的两个最基本时期：第一个星系的形成（在 z \( \gtrsim \) 6；宇宙黎明），以及星系形成活动的顶峰（在红移 z \(\sim \) 1–3；宇宙正午）。通过 NIR 观测（λ = 0.8-2 μ m），可以研究 UV Lyman- α前者是区域，后者是光学静止坐标系，使我们能够提取基本的可观测数据，如气体和恒星运动学、化学丰度和年龄，提供了一个独特的遗留数据库，涵盖了宇宙演化的这两个关键阶段。由于大气发射和吸收，需要在极低通量水平下在 NIR 中工作，使得基于地面的方法不可行。只有使用未来最大的设施（例如ELT）才有可能观察到一组减少的目标，最多包括数千个星系。同样，从太空看，JWST的小视野并且将其用作通用设施将产生一组相当小的遥远星系的高质量 NIR 光谱（最多数以千计）。我们的项目（代号Chronos）旨在产生\(\sim \) 100 万个高质量光谱，在连续谱中具有高 S/N ，其中编码了有关潜在恒星种群的信息。主要的科学驱动因素是：

• 恒星形成史与质量聚集史之间的联系。

• AGN 和超新星反馈在塑造星系形成历史中的作用，以及对淬灭时间尺度的定量估计。

• 第一个星系的形成。

• 再电离的来源。

• 金属丰度-质量关系的演变，包括 [ α /Fe] 和个体丰度。

• 通过对星系形成的“重子物理学”的详细研究，探索 k \(\sim \) 1 Mpc ^{− 1}尺度上的功率谱，从而获得精确的宇宙学。