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arXiv 1712.04460astro-ph.GA
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VALES:IV。利用APEX/SEPIA Band-5和ALMA探测正常星系和星暴星系的恒星形成效率转换

VALES: IV. Exploring the transition of star formation efficiencies between normal and starburst galaxies using APEX/SEPIA Band-5 and ALMA at low redshift

C. Cheng, E. Ibar, T. M. Hughes, V. Villanueva, R. Leiton, G. Orellana, A. Munoz-Arancibia, N. Lu, C. K. Xu, C. N. A. Willmer, J. Huang, T. Cao, C. Yang, Y. Q. Xue, K. Torstensson

摘要:

在这项工作中,我们提出了新的APEX/SEPIA带5观测目标的CO($J=2\text{-}1$)发射线的24个赫歇尔探测星系在$z=0.1-0.2$。结合我们最近的瓦尔帕莱索ALMA谱线发射巡天(VALES),我们研究了低红移星系的恒星形成效率(SFE = SFR/ $M_{\rm H_{2}}$)。我们发现我们的样本的SFE桥梁正常恒星形成星系和超亮红外星系(ULIRGs),这被认为是由不同的恒星形成模式触发之间的差距。考虑到$\rm SFE'$作为SFR和$L'_{\rm CO}$比,我们的数据显示了一个连续和平滑的增量作为红外光度(或恒星形成率)的函数,散射约0.5 dex,而不是一个陡峭的跳跃与双峰行为。这一结果是由于使用了具有大得多的sSFR/sSFR $_{\rm ms}$范围的样品,该样品使用LIRG,其中光度覆盖正常和ULRG之间的范围。我们的结论是控制恒星形成星系中SFE散射的主要参数是$α_{\rm CO}$转换因子的系统不确定性,气体分数和物理尺寸。

英文摘要:

In this work we present new APEX/SEPIA Band-5 observations targeting the CO ($J=2\text{-}1$) emission line of 24 Herschel-detected galaxies at $z=0.1-0.2$. Combining this sample {with} our recent new Valparaíso ALMA Line Emission Survey (VALES), we investigate the star formation efficiencies (SFEs = SFR/$M_{\rm H_{2}}$) of galaxies at low redshift. We find the SFE of our sample bridges the gap between normal star-forming galaxies and Ultra-Luminous Infrared Galaxies (ULIRGs), which are thought to be triggered by different star formation modes. Considering the $\rm SFE'$ as the SFR and the $L'_{\rm CO}$ ratio, our data show a continuous and smooth increment as a function of infrared luminosity (or star formation rate) with a scatter about 0.5 dex, instead of a steep jump with a bimodal behaviour. This result is due to the use of a sample with a much larger range of sSFR/sSFR$_{\rm ms}$ using LIRGs, with luminosities covering the range between normal and ULIRGs. We conclude that the main parameters controlling the scatter of the SFE in star-forming galaxies are the systematic uncertainty of the $α_{\rm CO}$ conversion factor, the gas fraction and physical size.

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