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arXiv 1701.05901astro-ph.GA
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在高红移时强烈的恒星形成尘埃星系中的高密度气体分数

High dense gas fraction in intensely star-forming dusty galaxies at high redshift

I. Oteo, Z-Y. Zhang, C. Yang, R. J. Ivison, A. Omont, M. Bremer, S. Bussmann, A. Cooray, P. Cox, H. Dannerbauer, L. Dunne, S. Eales, C. Furlanetto, R. Gavazzi, … 展开作者

I. Oteo, Z-Y. Zhang, C. Yang, R. J. Ivison, A. Omont, M. Bremer, S. Bussmann, A. Cooray, P. Cox, H. Dannerbauer, L. Dunne, S. Eales, C. Furlanetto, R. Gavazzi, H. Nayyeri, M. Negrello, R. Neri, D. Riechers, P. Van der Werf

摘要:

本文介绍了从{\it Herschel}-ATLAS巡天中选出的两个透镜状高红移恒星爆发中致密分子气体示踪剂HCN、HCO $^+$和HNC的ALMA和VLA探测:{\it H}-ATLAS\,J090740.0 $-$ 004200(SDP.9,$z \sim 1.6$)和{\it H}-ATLAS\,J091043.1 $-$ 000321(SDP.11,$z \sim 1.8$)。ALMA在两个源中都观察到了$J = 3-2$跃迁,而VLA在SDP中观察到了$J = 1-0$跃迁。9.我们已经在SDP. 9和SDP. 11中检测到所有观察到的HCN和HCO $^+$线,以及在SDP. 9中检测到HNC(3 - 2)。这两个星系的放大系数已确定从分角秒分辨率CO和尘埃排放观测NOEMA和SMA进行。SDP.9中的HNC(1--0)/HCN(1--0)线比表明存在光子主导区域,正如大多数局部(U)LIRG所发生的那样。的CO,HCN和HCO $^+$ SLEDs的SDP. 9是兼容的许多本地,红外(IR)明亮的星系中发现的,这表明在本地和高红移尘埃星暴的分子气体可以有类似的激发条件。我们得到了SDP. 9和SDP. 11的总红外光度($L_{\rm IR}$)和密线光度($L_{\rm dense}$)与本星系的相关关系可以用一个单一的关系式来表示。分散的$L_{\rm IR} - L_{\rm dense}$相关性,加上缺乏敏感的高密度分子气体示踪观测高红移星系的均匀样本,使我们无法区分不同的趋势与红移。我们的研究结果表明,在一些高红移的尘埃,发光的恒星爆发中发现的激烈的恒星形成与更大质量的致密分子气体库和更高密度的分子气体馏分。

英文摘要:

We present ALMA and VLA detections of the dense molecular gas tracers HCN, HCO$^+$ and HNC in two lensed, high-redshift starbursts selected from the {\it Herschel}-ATLAS survey: {\it H}-ATLAS\,J090740.0$-$004200 (SDP.9, $z \sim 1.6$) and {\it H}-ATLAS\,J091043.1$-$000321 (SDP.11, $z \sim 1.8$). ALMA observed the $J = 3-2$ transitions in both sources, while the VLA observed the $J = 1-0$ transitions in SDP.9. We have detected all observed HCN and HCO$^+$ lines in SDP.9 and SDP.11, and also HNC(3--2) in SDP.9. The amplification factors for both galaxies have been determined from sub-arcsec resolution CO and dust emission observations carried out with NOEMA and the SMA. The HNC(1--0)/HCN(1--0) line ratio in SDP.9 suggests the presence of photon-dominated regions, as it happens to most local (U)LIRGs. The CO, HCN and HCO$^+$ SLEDs of SDP.9 are compatible to those found for many local, infrared (IR) bright galaxies, indicating that the molecular gas in local and high-redshift dusty starbursts can have similar excitation conditions. We obtain that the correlation between total IR ($L_{\rm IR}$) and dense line ($L_{\rm dense}$) luminosity in SDP.9 and SDP.11 and local star-forming galaxies can be represented by a single relation. The scatter of the $L_{\rm IR} - L_{\rm dense}$ correlation, together with the lack of sensitive dense molecular gas tracer observations for a homogeneous sample of high-redshift galaxies, prevents us from distinguishing differential trends with redshift. Our results suggest that the intense star formation found in some high-redshift dusty, luminous starbursts is associated with more massive dense molecular gas reservoirs and higher dense molecular gas fractions.

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