We illustrate the extraordinary discovery potential for extragalactic astrophysics of a far-infrared/submillimetre (far-IR/submm) all-sky spectroscopic survey with a 3-m-class space telescope. Spectroscopy provides a three-dimensional view of the Universe and allows us to take full advantage of the sensitivity of present-day instrumentation, close to fundamental limits, overcoming the spatial confusion that affects broadband far-IR/submm surveys. A space telescope of the 3-m class (which has already been described in recent papers) will detect emission lines powered by star formation in galaxies out to $z\,{\simeq}\,8$ . It will specifically provide measurements of spectroscopic redshifts, star-formation rates (SFRs), dust masses, and metal content for millions of galaxies at the peak epoch of cosmic star formation and of hundreds of them at the epoch of reionisation. Many of these star-forming galaxies will be strongly lensed; the brightness amplification and stretching of their sizes will make it possible to investigate (by means of follow-up observations with high-resolution instruments like ALMA, JWST, and SKA) their internal structure and dynamics on the scales of giant molecular clouds (40–100 pc). This will provide direct information on the physics driving the evolution of star-forming galaxies. Furthermore, the arcmin resolution of the telescope at submm wavelengths is ideal for detecting the cores of galaxy proto-clusters, out to the epoch of reionisation. Due to the integrated emission of member galaxies, such objects (as well as strongly lensed sources) will dominate at the highest apparent far-IR luminosities. Tens of millions of these galaxy-clusters-in-formation will be detected at $z \simeq 2 - 3$ –3, with a tail extending out to $z\,{\simeq}\,7$ , and thousands of detections at $6\,{<}\,z\,{<}\,7$ . Their study will allow us to track the growth of the most massive halos well beyond what is possible with classical cluster surveys (mostly limited to $z\,\lesssim\, 1.5 - 2$ –2), tracing the history of star formation in dense environments and teaching us how star formation and galaxy-cluster formation are related across all epochs. The obscured cosmic SFR density of the Universe will thereby be constrained. Such a survey will overcome the current lack of spectroscopic redshifts of dusty star-forming galaxies and galaxy proto-clusters, representing a quantum leap in far-IR/submm extragalactic astrophysics.

中文翻译：

---

通过全天亚毫米光谱调查了解星系的形成和演化

我们展示了使用 3 米级太空望远镜进行远红外/亚毫米（远红外/亚毫米）全天光谱调查的河外天体物理学的非凡发现潜力。光谱学提供了宇宙的三维视图，使我们能够充分利用当今仪器的灵敏度，接近基本极限，克服影响宽带远红外/亚毫米测量的空间混乱。3 米级太空望远镜（已在最近的论文中描述）将探测到由星系中恒星形成驱动的发射线 $z\,{\simeq}\,8$ . 它将专门为数百万个星系在宇宙恒星形成的高峰时期和数百个在再电离时期的星系提供光谱红移、恒星形成率 (SFR)、尘埃质量和金属含量的测量。这些恒星形成星系中的许多将被强烈透镜化；它们大小的亮度放大和拉伸将使研究成为可能（通过使用 ALMA 等高分辨率仪器的后续观察，JWST和 SKA）它们在巨大分子云（40-100 pc）尺度上的内部结构和动力学。这将提供有关推动恒星形成星系演化的物理学的直接信息。此外，望远镜在亚毫米波长下的 arcmin 分辨率非常适合探测星系原星团的核心，直至再电离时代。由于成员星系的综合发射，这些天体（以及强透镜光源）将在最高的远红外光度中占主导地位。数以千万计的这些星系团信息将被探测到 $z \simeq 2 - 3$ –3，尾巴延伸到 $z\,{\simeq}\,7$ ，以及数千次检测 $6\,{<}\,z\,{<}\,7$ . 他们的研究将使我们能够跟踪最大规模光晕的增长，远远超出经典集群调查（主要限于 $z\,\lesssim\, 1.5 - 2$ –2），追溯稠密环境中恒星形成的历史，并教我们恒星形成和星系团形成如何在所有时代相关联。宇宙中模糊不清的宇宙恒星形成率密度将因此受到限制。这样的调查将克服目前缺乏尘埃恒星形成星系和星系原星团光谱红移的问题，代表了远红外/亚毫米河外天体物理学的巨大飞跃。