COMBINED CO AND DUST SCALING RELATIONS OF DEPLETION TIME AND MOLECULAR GAS FRACTIONS WITH COSMIC TIME, SPECIFIC STAR-FORMATION RATE, AND STELLAR MASS
COMBINED CO AND DUST SCALING RELATIONS OF DEPLETION TIME AND MOLECULAR GAS FRACTIONS WITH COSMIC TIME, SPECIFIC STAR-FORMATION RATE, AND STELLAR MASS
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DOI：
10.1088/0004-637x/800/1/20
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发表时间：
2014-09
期刊：
影响因子：
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通讯作者：
R. Genzel;L. Tacconi;D. Lutz;A. Saintonge;S. Berta;B. Magnelli;F. Combes;S. Garcia-Burillo
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文献类型：
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作者：
R. Genzel;L. Tacconi;D. Lutz;A. Saintonge;S. Berta;B. Magnelli;F. Combes;S. Garcia-Burillo
我们结合联合收割机分子气体质量推断CO排放在500恒星形成星系（SFG）之间的z = 0和3，从IRAM-COLDGASS，PHIBSS 1/2，和其他调查，气体质量来自赫歇尔远红外尘埃测量在512星系堆栈在相同的恒星质量/红移范围。我们约束的标度关系的分子气体耗尽时标（tdepl）和气体恒星质量比（Mmol气体/M*）的SFG附近的星星形成的“主序列”的红移，特定的恒星形成率（sSFR），和恒星质量（M*）。CO和灰尘的标度关系同意非常好。这表明CO → H2质量转换因子在主序列±0.6 dex内变化很小（sSFR（ms，z，M*）），并且在整个红移范围内小于0.3 dex。这项研究建立在并加强了早期工作的成果。我们发现tdepl的尺度为（1 + z）−0.3 ×（sSFR/sSFR（ms，z，M*））−0.5，对M* 的依赖性很小。由此产生的陡峭的红移依赖Mmol气体/M* ψ（1 + z）3的镜子，sSFR和可能反映的气体供应率。在高M* 下的减少的气体分数由SFR-M* 关系的平坦化驱动。在整个探测的红移范围内，增加的气体分数和减少的耗尽时间尺度的组合导致在常数M* 下的更大的sSFR。因此，星系综合样品的Mmol气体SFR率关系表现出超线性的斜率，这与sSFR的范围增加。有了这些新的关系式，现在可以确定Mmol气体的相对精度为±0.1 dex，包括系统不确定性在内的精度为±0.2 dex。
We combine molecular gas masses inferred from CO emission in 500 star-forming galaxies (SFGs) between z = 0 and 3, from the IRAM-COLDGASS, PHIBSS1/2, and other surveys, with gas masses derived from Herschel far-IR dust measurements in 512 galaxy stacks over the same stellar mass/redshift range. We constrain the scaling relations of molecular gas depletion timescale (tdepl) and gas to stellar mass ratio (Mmol gas/M*) of SFGs near the star formation “main-sequence” with redshift, specific star-formation rate (sSFR), and stellar mass (M*). The CO- and dust-based scaling relations agree remarkably well. This suggests that the CO → H2 mass conversion factor varies little within ±0.6 dex of the main sequence (sSFR(ms, z, M*)), and less than 0.3 dex throughout this redshift range. This study builds on and strengthens the results of earlier work. We find that tdepl scales as (1 + z)−0.3 × (sSFR/sSFR(ms, z, M*))−0.5, with little dependence on M*. The resulting steep redshift dependence of Mmol gas/M* ≈ (1 + z)3 mirrors that of the sSFR and probably reflects the gas supply rate. The decreasing gas fractions at high M* are driven by the flattening of the SFR–M* relation. Throughout the probed redshift range a combination of an increasing gas fraction and a decreasing depletion timescale causes a larger sSFR at constant M*. As a result, galaxy integrated samples of the Mmol gas–SFR rate relation exhibit a super-linear slope, which increases with the range of sSFR. With these new relations it is now possible to determine Mmol gas with an accuracy of ±0.1 dex in relative terms, and ±0.2 dex including systematic uncertainties.