论文标题
当地宇宙中冷气的宇宙丰度
The cosmic abundance of cold gas in the local Universe
论文作者
论文摘要
我们从XCOLD GASS调查中确定了本地宇宙中分子氢（H2）的宇宙丰度。为了限制低质量的H2质量函数，并在XCOLD GASS调查中纠正了较低的恒星质量极限为10^9 mSUN的影响，我们根据观察到的缩放率和气体质量之间观察到的缩放关系，使用经验方法。我们还使用XGASS调查来限制HI和HI+H2质量函数，并将其与苜蓿调查的HI质量函数进行比较。我们发现本地宇宙中分子气的宇宙丰度为omega_h2 =（5.34 +/- 0.47）x10^-5 H^-1。分子气占冷气总丰度的19.6 +/- 3.9％，omega_hi+H2 =（4.66 +/- 0.70）x10^-4 H^-1。恒星质量超过10^9 MSUN的星系占当地宇宙中分子气的89％，而相比之下，此类星系仅包含由HI 21cm线所追踪的73％的冷原子气体。 XCOLD GASS CO，分子气和冷气体质量功能和Omega_H2测量值为星系演化模型提供了约束，并有助于锚定试图确定高红移下分子气体的盲人Alma和Noema调查。
We determine the cosmic abundance of molecular hydrogen (H2) in the local universe from the xCOLD GASS survey. To constrain the H2 mass function at low masses and correct for the effect of the lower stellar mass limit of 10^9 Msun in the xCOLD GASS survey, we use an empirical approach based on an observed scaling relation between star formation rate and gas mass. We also constrain the HI and HI+H2 mass functions using the xGASS survey, and compare it to the HI mass function from the ALFALFA survey. We find the cosmic abundance of molecular gas in the local Universe to be Omega_H2=(5.34+/-0.47)x10^-5 h^-1. Molecular gas accounts for 19.6 +/- 3.9% of the total abundance of cold gas, Omega_HI+H2=(4.66+/-0.70)x10^-4 h^-1. Galaxies with stellar masses in excess of 10^9 Msun account for 89% of the molecular gas in the local Universe, while in comparison such galaxies only contain 73% of the cold atomic gas as traced by the HI 21cm line. The xCOLD GASS CO, molecular gas and cold gas mass functions and Omega_H2 measurements provide constraints for models of galaxy evolution and help to anchor blind ALMA and NOEMA surveys attempting to determine the abundance of molecular gas at high redshifts.
