SKA重点科学项目：宇宙再电离和第一束光的射电观测
SKA Key science project: Radio observations of cosmic reionization and first light
摘要：
我更新SKA关键科学计划（KSP）的第一光和宇宙再电离。KSP有两个主题：（i）利用中性氢的21厘米谱线作为宇宙再电离期间中性星系间介质演变的最直接探测器。这样的HI 21 cm研究可能是自CMB发现以来宇宙学最重要的新窗口。(ii)观测第一个星系和活动星系核的气体、尘埃、恒星形成和动力学。在厘米和毫米波长的观测，提供了一个清晰的视图星系形成内的大爆炸1 Gyr，是一个理想的补充研究的恒星，电离气体，和AGN使用近红外望远镜完成。我总结了HI 21厘米信号，挑战和正在建设中的望远镜。我还讨论了研究银河系前介质的前景，在第一光之前，在月球上使用低频望远镜。然后，我回顾了目前的最已知的遥远星系（z > 6）的毫米和厘米观测的状态。我提出一个简单的论点，即使是10%的SKA高演示器也会对第一个星系的研究产生深远的影响。特别是，将SKA扩展到45 GHz的“自然”大气极限（由O_2线设定），将热发射的有效灵敏度增加了另一个因子4。
英文摘要：
I update the SKA key science program (KSP) on first light and cosmic reionization. The KSP has two themes: (i) Using the 21cm line of neutral hydrogen as the most direct probe into the evolution of the neutral intergalactic medium during cosmic reionization. Such HI 21cm studies are potentially the most important new window on cosmology since the discovery of the CMB. (ii) Observing the gas, dust, star formation, and dynamics, of the first galaxies and AGN. Observations at cm and mm wavelengths, provide an unobscured view of galaxy formation within 1 Gyr of the Big Bang, and are an ideal complement to the study of stars, ionized gas, and AGN done using near-IR telescopes. I summarize HI 21cm signals, challenges, and telescopes under construction. I also discuss the prospects for studying the pre-galactic medium, prior to first light, using a low frequency telescope on the Moon. I then review the current status of mm and cm observations of the most known distant galaxies (z > 6). I make the simple argument that even a 10% SKA-high demonstrator will have a profound impact on the study of the first galaxies. In particular, extending the SKA to the 'natural' atmospheric limit (set by the O_2 line) of 45 GHz, increases the effective sensitivity to thermal emission by another factor four.
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