Star formation in half of massive galaxies was quenched by the time the Universe was 3 billion years old¹. Very low amounts of molecular gas seem to be responsible for this, at least in some cases^2,3,4,5,6,7, although morphological gas stabilization, shock heating or activity associated with accretion onto a central supermassive black hole are invoked in other cases^8,9,10,11. Recent studies of quenching by gas depletion have been based on upper limits that are insufficiently sensitive to determine this robustly^2,3,4,5,6,7, or stacked emission with its problems of averaging^8,9. Here we report 1.3 mm observations of dust emission from 6 strongly lensed galaxies where star formation has been quenched, with magnifications of up to a factor of 30. Four of the six galaxies are undetected in dust emission, with an estimated upper limit on the dust mass of 0.0001 times the stellar mass, and by proxy (assuming a Milky Way molecular gas-to-dust ratio) 0.01 times the stellar mass in molecular gas. This is two orders of magnitude less molecular gas per unit stellar mass than seen in star forming galaxies at similar redshifts^12,13,14. It remains difficult to extrapolate from these small samples, but these observations establish that gas depletion is responsible for a cessation of star formation in some fraction of high-redshift galaxies.

到宇宙 30 亿岁¹时，一半大质量星系中的恒星形成已经熄灭。极少量的分子气体似乎是造成这种情况的原因，至少在某些情况下^2,3,4,5,6,7，尽管调用了与吸积到中央超大质量黑洞相关的形态气体稳定、冲击加热或活动在其他情况下^8,9,10,11。最近对气体耗尽猝灭的研究基于的上限不够敏感，无法确定这种稳健的^2,3,4,5,6,7或堆叠排放，其问题是平均^8,9. 在这里，我们报告了对 6 个强透镜星系的尘埃排放的 1.3 毫米观测结果，这些星系的恒星形成已经熄灭，放大倍数高达 30 倍。六个星系中有四个在尘埃发射中未被发现，估计尘埃的上限质量是恒星质量的 0.0001 倍，代用（假设银河系分子气尘比）是恒星质量的 0.01 倍。^{这比在类似红移12,13,14}的恒星形成星系中看到的每单位恒星质量的分子气体少两个数量级。从这些小样本中推断仍然很困难，但这些观察结果表明，气体消耗是导致部分高红移星系中恒星形成停止的原因。