Molecular gas in the Herschel-selected strongly lensed submillimeter galaxies at z~2-4 as probed by multi-J CO lines
Molecular gas in the Herschel-selected strongly lensed submillimeter galaxies at z~2-4 as probed by multi-J CO lines
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DOI：
10.1051/0004-6361/201731391
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发表时间：
2017-09
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通讯作者：
C. Yang;A. Omont;A. Beelen;Y. Gao;P. Werf;R. Gavazzi;Z. Zhang;R. Ivison;M. Lehnert;D. Liu;I. Oteo;E. Gonz'alez-Alfonso;H. Dannerbauer;P. Cox;M. Krips;R. Neri;D. Riechers;A. Baker;M. Michałowski;A. Cooray;I. S. Pmo;IAS-Orsay;Ucas;China Iap;Upmc;Leiden;U. Edinburgh;Eső;MPIfA;Universidad de Alcal'a;Instituto de Astrof'isica de Canarias-Instituto-de-Astrof'isica-de-Canarias-1410640555;U. L. Laguna;Jao;Iram;C. University;Rutgers;Adam Mickiewicz University;UC Irvine;D. University
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作者：
C. Yang;A. Omont;A. Beelen;Y. Gao;P. Werf;R. Gavazzi;Z. Zhang;R. Ivison;M. Lehnert;D. Liu;I. Oteo;E. Gonz'alez-Alfonso;H. Dannerbauer;P. Cox;M. Krips;R. Neri;D. Riechers;A. Baker;M. Michałowski;A. Cooray;I. S. Pmo;IAS-Orsay;Ucas;China Iap;Upmc;Leiden;U. Edinburgh;Eső;MPIfA;Universidad de Alcal'a;Instituto de Astrof'isica de Canarias-Instituto-de-Astrof'isica-de-Canarias-1410640555;U. L. Laguna;Jao;Iram;C. University;Rutgers;Adam Mickiewicz University;UC Irvine;D. University
我们给出了红移~2-4 Herschel-ATLAS SMGs样品中多J-CO和CI谱线的IRAM-30M观测结果。对于CO发射线，发现了一个不可忽略的微分透镜效应，这可能会导致对线宽的严重低估，从而导致动力学质量的低估。发现CO雪橇与本地恒星暴为主的ULIRG和以前研究过的SMG的雪橇相似。在对透镜放大进行校正后，我们利用非LTE辐射传输模型导出了SMGs中分子气体的整体性质。研究发现，气体热压与恒星形成效率有关。进一步将CO雪橇分解为两个激发分量，我们发现一个低激发分量与恒星形成的相关性较小，一个高激发分量与正在进行的恒星形成活动密切相关。此外，对于J5$CO谱线，还证实了FIR谱线与CO谱线之间的紧密线性关联，这意味着这些CO谱线是恒星形成的良好示踪物。[CI](2-1)谱线与局域星暴中的CO(1-0)谱线和[CI](2-1)谱线之间存在紧密的线性相关关系，表明CI谱线可以作为高红移SMG的良好的全分子气体质量示踪剂。分子气藏的总质量为(1~30)×10^{10M_(ODOT)$，表明典型的分子气耗竭时间约为20~100Myr，气尘质量比约为~30~100。SMGs的CO谱线光度与尘埃质量的比值随红移而缓慢增大，这一点还有待进一步证实。最后，通过比较CO和H2O谱线的线宽，我们发现它们在几乎所有的SMG中都符合得很好，证实了发射区位于同一空间位置。
(abridged) We present the IRAM-30m observations of multiple-J CO and CI line emission in a sample of redshift ~2-4 Herschel-ATLAS SMGs. A non-negligible effect of differential lensing is found for the CO emission lines, which could have caused significant underestimations of the linewidths, hence of the dynamical masses. The CO SLEDs are found to be similar to those of the local starburst-dominated ULIRGs and of the previously studied SMGs. After correcting for lensing amplification, we derived the global properties of the bulk of molecular gas in the SMGs using non-LTE radiative transfer modelling. The gas thermal pressure is found to be correlated with star formation efficiency. Further decomposing the CO SLEDs into two excitation components, we find a low-excitation component, which is less correlated with star formation, and a high-excitation one which is tightly related to the on-going star-forming activity. Additionally, tight linear correlations between the FIR and CO line luminosities have been confirmed for the $J \ge 5$ CO lines, implying that these CO lines are good tracers of star formation. The [CI](2-1) lines follow the tight linear correlation between the luminosities of the [CI](2-1) and the CO(1-0) line found in local starbursts, indicating that CI lines could serve as good total molecular gas mass tracers for high-redshift SMGs. The total mass of the molecular gas reservoir, $(1-30) \times 10^{10} M_\odot$, suggests a typical molecular gas depletion time ~20-100 Myr and a gas to dust mass ratio ${\delta}_{\rm GDR}$~30-100. The ratio between CO line luminosity and the dust mass appears to be slowly increasing with redshift for the SMGs, which need to be further confirmed. Finally, through comparing the linewidth of CO and H2O lines, we find that they agree well in almost all our SMGs, confirming that the emitting regions are co-spatially located.