The evolution of CNO isotopes: a new window on cosmic star formation history and the stellar IMF in the age of ALMA
The evolution of CNO isotopes: a new window on cosmic star formation history and the stellar IMF in the age of ALMA
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DOI：
10.1093/mnras/stx1197
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发表时间：
2017-04
影响因子：
4.8
通讯作者：
D. Romano;F. Matteucci;F. Matteucci;Zhi-Yu Zhang;Zhi-Yu Zhang;Pantelis Papadopoulos;Pantelis Papadopoulos-P
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作者：
D. Romano;F. Matteucci;F. Matteucci;Zhi-Yu Zhang;Zhi-Yu Zhang;Pantelis Papadopoulos;Pantelis Papadopoulos-P
我们使用国家的最先进的化学模型来跟踪的CNO同位素在星际介质中的星系的宇宙演化，产生强大的约束，其恒星的初始质量函数（IMF）。我们重新评估了大质量恒星、渐近巨星分支（AGB）恒星和新星在产生稀有同位素如13 C、15 N、17 O和18 O，以及沿着12 C、14 N和16 O中的相对作用。计算了超AGB星、新星和快速旋转大质量星的CNO同位素产额。复制了现有的同位素富集数据在太阳附近，整个银河系，并评估了我们的模型的敏感性，其余的不确定性，如新星产量和星星形成的历史，我们表明，我们可以有意义地限制恒星IMF在星系中使用C，O和N同位素丰度比。在星爆星系，多同位素线的数据是可用的，我们发现令人信服的新证据头重脚轻的恒星IMF，其星星的形成率和效率的深远影响，也许也是他们的恒星质量。无论是化学分馏，也没有选择性的光解可以显着扰动全球平均同位素丰度比远离相应的同位素，因为这两个过程通常只会影响小质量分数的分子云在星系中。因此，阿塔卡马大型毫米波阵列现在已经准备好探测恒星IMF，甚至是恒星形成星系中特定星暴事件的年龄，这些事件不受困扰光学/近红外研究的尘埃遮蔽效应的影响。
We use state-of-the-art chemical models to track the cosmic evolution of the CNO isotopes in the interstellar medium of galaxies, yielding powerful constraints on their stellar initial mass function (IMF). We re-assess the relative roles of massive stars, asymptotic giant branch (AGB) stars and novae in the production of rare isotopes such as 13C, 15N, 17O and 18O, along with 12C, 14N and 16O. The CNO isotope yields of super-AGB stars, novae and fast-rotating massive stars are included. Having reproduced the available isotope enrichment data in the solar neighbourhood, and across the Galaxy, and having assessed the sensitivity of our models to the remaining uncertainties, e.g. nova yields and star formation history, we show that we can meaningfully constrain the stellar IMF in galaxies using C, O and N isotope abundance ratios. In starburst galaxies, where data for multiple isotopologue lines are available, we find compelling new evidence for a top-heavy stellar IMF, with profound implications for their star formation rates and efficiencies, perhaps also their stellar masses. Neither chemical fractionation nor selective photodissociation can significantly perturb globally averaged isotopologue abundance ratios away from the corresponding isotope ones, as both these processes will typically affect only small mass fractions of molecular clouds in galaxies. Thus, the Atacama Large Millimeter Array now stands ready to probe the stellar IMF, and even the ages of specific starburst events in star-forming galaxies across cosmic time unaffected by the dust obscuration effects that plague optical/near-infrared studies.