标题： 推断的CANDELS星系在0.5 < z < 3.0范围内的冷气体性质演化 显示英文标题

标题： The inferred evolution of the cold gas properties of CANDELS galaxies at 0.5 < z < 3.0

摘要： 我们推导了大约24000个星系的总冷气体、原子氢和分子气体质量，覆盖四个数量级的恒星质量，在红移0.5 < z < 3.0范围内，数据来自CANDELS调查。 我们的推断基于基于分子氢的恒星形成定律的反演，并结合一种分离原子气和分子气的方法。 我们发现： 1）在红移z = 3时，已经存在恒星质量低至10^8 Msun的星系中推断的冷气体（HI和H2）、HI和H2质量与恒星质量之间的增长趋势；2）冷气体的分子分数随着恒星质量的增加和回溯时间的增加而增加；3）在固定恒星质量下，星系的平均HI含量几乎没有演化；4）星系的冷气体分数和分子氢的相对量随时间以相对恒定的速率减少，与恒星质量无关；5）存在大量由原子气主导的低恒星质量星系。这些星系非常富含气体，但只有很小一部分气体是分子的；6）在固定恒星质量下，星系的恒星形成率（SFR）与推断的总冷气体质量（HI + H2）的比率（即恒星形成效率；SFE）随着恒星形成率的增加而增加。 由于该方法简单，因此对于评估选择偏差对直接观测气体质量小样本的影响以及将比例关系扩展到目前难以通过直接测量气体含量探测的恒星质量范围和红移范围是有价值的。 显示英文摘要

摘要： We derive the total cold gas, atomic hydrogen, and molecular gas masses of approximately 24 000 galaxies covering four decades in stellar mass at redshifts 0.5 < z < 3.0, taken from the CANDELS survey. Our inferences are based on the inversion of a molecular hydrogen based star formation law, coupled with a prescription to separate atomic and molecular gas. We find that: 1) there is an increasing trend between the inferred cold gas (HI and H2), HI, and H2 mass and the stellar mass of galaxies down to stellar masses of 10^8 Msun already in place at z = 3; 2) the molecular fractions of cold gas increase with increasing stellar mass and look-back time; 3) there is hardly any evolution in the mean HI content of galaxies at fixed stellar mass; 4) the cold gas fraction and relative amount of molecular hydrogen in galaxies decrease at a relatively constant rate with time, independent of stellar mass; 5) there is a large population of low-stellar mass galaxies dominated by atomic gas. These galaxies are very gas rich, but only a minor fraction of their gas is molecular; 6) the ratio between star-formation rate (SFR) and inferred total cold gas mass (HI + H2) of galaxies (i.e., star-formation efficiency; SFE) increases with star-formation at fixed stellar masses. Due to its simplicity, the presented approach is valuable to assess the impact of selection biases on small samples of directly-observed gas masses and to extend scaling relations down to stellar mass ranges and redshifts that are currently difficult to probe with direct measurements of gas content.