We present the first estimate, based on direct Hi 21 cm observations, of the Hi mass function (HiMF) of star-forming galaxies at z ≈ 1, obtained by combining our measurement of the scaling relation between Hi mass (M _Hi ) and B-band luminosity (M _B ) of star-forming galaxies with a literature estimate of the B-band luminosity function at z ≈ 1. We determined the M _Hi –M _B relation by using the GMRT-CATz1 survey of the DEEP2 fields to measure the average Hi mass of blue galaxies at z = 0.74–1.45 in three separate M _B subsamples. This was done by separately stacking the Hi 21 cm emission signals of the galaxies in each subsample to detect, at (3.5–4.4)σ significance, the average Hi 21 cm emission of each subsample. We find that the M _Hi –M _B relation at z ≈ 1 is consistent with that at z ≈ 0. We combine our estimate of the M _Hi –M _B relation at z ≈ 1 with the B-band luminosity function at z ≈ 1 to determine the HiMF at z ≈ 1. We find that the number density of galaxies with M _Hi > 10¹⁰ M _⊙ (higher than the knee of the local Hi mass function) at z ≈ 1 is a factor of ≈4–5 higher than that at z ≈ 0, for a wide range of assumed scatters in the M _Hi –M _B relation. We rule out the hypothesis that the number density of galaxies with M _Hi > 10¹⁰ M _⊙ remains unchanged between z ≈ 1 and z ≈ 0 at ≳99.7% confidence. This is the first statistically significant evidence for evolution in the HiMF of galaxies from the epoch of cosmic noon.

中文翻译：

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z ≈ 1 处恒星形成星系的 Hi 质量函数

我们提出第一个估计，基于直接 H我21 厘米观测值，H我质量函数（H我MF) 的恒星形成星系z≈ 1，通过结合我们对 H 之间的缩放关系的测量而获得我大量的 （中号 _H我 ） 和乙波段光度（中号 _乙 ）的恒星形成星系及其文献估计乙波段光度函数z≈ 1. 我们确定中号 _H我 –中号 _乙 使用 GMRT-CAT 的关系z1 对 DEEP2 场进行调查以测量平均 H我蓝色星系的质量z= 0.74–1.45 在三个单独的中号 _乙 子样本。这是通过单独堆叠 H 来完成的我每个子样本中要检测的星系的 21 cm 发射信号，位于 (3.5–4.4)σ显着性，平均 H我每个子样本的 21 cm 发射量。我们发现中号 _H我 –中号 _乙 关系于z≈ 1 与 处的值一致z≈ 0。我们结合我们的估计中号 _H我 –中号 _乙 关系于z≈ 1 与乙波段光度函数z≈ 1 来确定 H我中频在z≈ 1. 我们发现星系的数密度中号 _H我 > 10 ¹⁰ 中号 _⊙（高于局部H的拐点我质量函数）在z≈ 1 比以下情况高出 ≈4–5 倍z≈ 0，对于大范围的假设散射中号 _H我 –中号 _乙 关系。我们排除了星系数密度为中号 _H我 > 10 ¹⁰ 中号 _⊙之间保持不变z≈ 1 且z≈ 0，置信度≳99.7%。这是 H 进化的第一个具有统计学意义的证据。我宇宙正午时期的星系 MF。