ALMA is now fully operational, and has been observing in early science mode since 2011. The millimetric (mm) and sub-mm domain is ideal to tackle galaxies at high redshift, since the emission peak of the dust at 100 \(\upmu \)m is shifted in the ALMA bands (0.3–1 mm) for \(z=\) 2–9, and the CO lines, stronger at the high-J levels of the ladder, are found all over the 0.3–3 mm range. Pointed surveys and blind deep fields have been observed, and the wealth of data collected reveal a drop at high redshifts (\(z>6\)) of dusty massive objects, although surprisingly active and gas-rich objects have been unveiled through gravitational lensing. The window of the reionization epoch is now wide open, and ALMA has detected galaxies at \(z=8\)–9 mainly in continuum, [CII] and [OIII] lines. Galaxies have a gas fraction increasing steeply with redshift, as \((1+z)^2\), while their star formation efficiency increases also but more slightly, as \((1+z)^{0.6}\) to \((1+z)^1\). Individual object studies have revealed luminous quasars, with black hole masses much higher than expected, clumpy galaxies with resolved star formation rate compatible with the Kennicutt–Schmidt relation, extended cold and dense gas in a circumgalactic medium, corresponding to Lyman-\(\alpha \) blobs, and proto-clusters, traced by their brightest central galaxies.

ALMA 现已全面投入运行，自 2011 年以来一直以早期科学模式进行观测。毫米 (mm) 和亚毫米域非常适合处理高红移星系，因为尘埃的发射峰值为 100  \(\upmu \ ) m 在 ALMA 带 (0.3–1 mm) 中移动，对于\(z=\)  2–9，CO 谱线在梯子的高J水平处更强，遍布 0.3–3 mm范围。尽管通过引力透镜揭示了令人惊讶的活跃和富含气体的物体，但已经观察到了尖点勘测和盲深视场，并且收集到的大量数据揭示了尘埃大质量物体的高红移（\(z>6\) ）下降。 。再电离时代的窗口现已敞开，ALMA 已在\(z=8\) –9 处检测到星系，主要位于连续谱线、[CII] 和 [OIII] 线中。星系的气体分数随着红移急剧增加，如\((1+z)^2\)，而它们的恒星形成效率也增加，但幅度较小，如\((1+z)^{0.6}\)到\ ((1+z)^1\)。个别物体研究揭示了发光类星体，其黑洞质量远高于预期，块状星系，其恒星形成率与肯尼卡特-施密特关系一致，在环绕星系介质中存在广泛的寒冷和稠密气体，对应于莱曼- \(\alpha \)斑点和原星团，由它们最亮的中央星系追踪。