论文标题
宇宙巴里昂和金属周期
The Cosmic Baryon and Metal Cycles
论文作者
论文摘要
表征星系中恒星，气体和金属之间关系的关系是了解宇宙重子循环的关键组成部分。我们在倒塌的结构，化学构成和灰尘含量中汇编了重子的当代人口普查。我们表明：宇宙的H I质量密度已很好地确定为Z〜5红移，并随着时间的流逝而显示出较小的进化。分子氢的新观察结果揭示了其进化反映了全球恒星形成速率密度的演变。恒定的宇宙分子气体耗尽时间尺度表明气体储层与恒星形成之间存在普遍关系。冷气中的金属质量密度（$ t <10^4 $ k）几乎包含恒星为z> 2.5产生的所有金属。在较低的红移，对金属总量的贡献者更加多样化。在z <1时，大多数观察到的金属都与恒星结合。总体而言，几乎没有证据表明现代人口普查中存在“缺失金属问题”。我们表征了宇宙时间中中性气体的灰尘含量，发现尘埃气和尘埃 - 金属比随着金属性的降低而下降。我们计算中性气体中的宇宙尘埃质量密度至Z〜5。宇宙尘埃含量的多个示踪剂之间存在良好的一致性。
Characterizing the relationship between stars, gas, and metals in galaxies is a critical component of understanding the cosmic baryon cycle. We compile contemporary censuses of the baryons in collapsed structures, their chemical make-up and dust content. We show that: The H I mass density of the Universe is well determined to redshifts z ~ 5 and shows minor evolution with time. New observations of molecular hydrogen reveal its evolution mirrors that of the global star formation rate density. The constant cosmic molecular gas depletion timescale points to a universal relationship between gas reservoirs and star formation. The metal mass density in cold gas ($T < 10^4$ K) contains virtually all the metals produced by stars for z > 2.5. At lower redshifts, the contributors to the total amount of metals are more diverse; at z < 1, most of the observed metals are bound in stars. Overall there is little evidence for a "missing metals problem" in modern censuses. We characterize the dust content of neutral gas over cosmic time, finding the dust-to-gas and dust-to-metals ratios fall with decreasing metallicity. We calculate the cosmological dust mass density in the neutral gas up to z ~ 5. There is good agreement between multiple tracers of the dust content of the Universe.
