PHIBSS: Unified Scaling Relations of Gas Depletion Time and Molecular Gas Fractions
PHIBSS: Unified Scaling Relations of Gas Depletion Time and Molecular Gas Fractions
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DOI：
10.3847/1538-4357/aaa4b4
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发表时间：
2017-02
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影响因子：
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通讯作者：
L. Tacconi;R. Genzel;A. Saintonge;F. Combes;S. Garcia-Burillo;R. Neri;A. Bolatto;T. Contini
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作者：
L. Tacconi;R. Genzel;A. Saintonge;F. Combes;S. Garcia-Burillo;R. Neri;A. Bolatto;T. Contini
在星星形成主序列（MS）的框架内，本文更新了我们以前的星系积分分子气体质量、恒星质量和星星形成速率（SFR）之间的标度关系，主要目的是检验可能的系统效应。为此，我们的新研究结合了三个独立的方法来确定分子气体质量的CO线通量，远红外尘埃光谱能量分布，和1001毫米尘埃测光，在z = 0和4之间的1444个恒星形成星系的大样本。该样本涵盖了log（M*/M）= 9.0-11.8的恒星质量范围，以及相对于MS的SFR，δMS = SFR/SFR（MS），从10−1.3到102.2。我们最重要的发现是，所有的数据集，尽管使用不同的技术和分析方法，遵循相同的缩放趋势，一旦方法到方法的零点偏移最小化和不确定性得到适当的考虑。分子气体耗尽时间tdepl，定义为分子气体质量与SFR的比值，标度为（1 + z）−0.6 ×（δMS）−0.44，仅弱依赖于恒星质量。分子质量与恒星质量之比μ气体取决于（1 + z）2.5 ×（δ MS）0.52 ×（M *）− 0.36，它跟踪特定SFR的演化。μ气体的红移依赖性需要一个曲率项，tdepl和μ气体的质量依赖性也是如此。我们发现tdepl和μ气体与光学尺寸R或表面密度没有或只有很弱的相关性，但我们警告说，光学尺寸可能不适合高z的高气体和尘埃柱。
This paper provides an update of our previous scaling relations between galaxy-integrated molecular gas masses, stellar masses, and star formation rates (SFRs), in the framework of the star formation main sequence (MS), with the main goal of testing for possible systematic effects. For this purpose our new study combines three independent methods of determining molecular gas masses from CO line fluxes, far-infrared dust spectral energy distributions, and ∼1 mm dust photometry, in a large sample of 1444 star-forming galaxies between z = 0 and 4. The sample covers the stellar mass range log(M*/M⊙) = 9.0–11.8, and SFRs relative to that on the MS, δMS = SFR/SFR(MS), from 10−1.3 to 102.2. Our most important finding is that all data sets, despite the different techniques and analysis methods used, follow the same scaling trends, once method-to-method zero-point offsets are minimized and uncertainties are properly taken into account. The molecular gas depletion time tdepl, defined as the ratio of molecular gas mass to SFR, scales as (1 + z)−0.6 × (δMS)−0.44 and is only weakly dependent on stellar mass. The ratio of molecular to stellar mass μgas depends on ( 1 + z ) 2.5 × ( δ MS ) 0.52 × ( M * ) − 0.36 , which tracks the evolution of the specific SFR. The redshift dependence of μgas requires a curvature term, as may the mass dependences of tdepl and μgas. We find no or only weak correlations of tdepl and μgas with optical size R or surface density once one removes the above scalings, but we caution that optical sizes may not be appropriate for the high gas and dust columns at high z.