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arXiv 0902.0121astro-ph.COastro-ph.GA
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具有亚毫米阵列的发光红外Galerkin:II。局域和高红移亮红外星系的CO(3-2)尺寸和亮度的比较

Luminous Infrared Galaxies with the Submillimeter Array: II. Comparing the CO(3-2) Sizes and Luminosities of Local and High-Redshift Luminous Infrared Galaxies

Daisuke Iono, Christine D. Wilson, Min S. Yun, Andrew J. Baker, Glen R. Petitpas, Alison B. Peck, Melanie Krips, T. J. Cox, Satoki Matsushita, J. Christopher Mihos, Ylva Pihlstrom

摘要:

本文详细比较了一个本地的亮红外星系(U/LIRGs)和一个高红移星系(包括亚毫米选择星系(SMG)、类星体和莱曼破裂星系(LBG))的CO(3-2)发射分子气体。U/LIRG样本包括我们最近使用亚毫米波阵列进行的CO(3-2)测量,而高红移群体的CO(3-2)数据来自文献。我们发现L(CO(3-2))和L(FIR)的关系在五个数量级上是相关的,这表明CO(3-2)辐射中追踪的分子气体是尘埃星形成活动的一个强有力的示踪剂。从这个关系式的拟合中得到的接近单位斜率为0.93 +/- 0.03,表明恒星形成效率在不同类型的星系中是恒定的,在两个因素之内居住在非常不同的时代。CO(3-2)尺寸测量表明,局域U/LIRG(0.3 - 3.1 kpc)中的分子气盘比SMG(3 - 16 kpc)致密得多,SMG的尺寸尺度与我们样品中广泛分离的U/LIRG核的核分离(5 - 40 kpc)相当。我们认为,从这些结果中,SMG研究在这里主要是中间阶段合并,以及更宽的线宽产生的暴力合并的两个大规模的富含气体的星系发生在一个巨大的晕势深处。

英文摘要:

We present a detailed comparison of the CO(3-2) emitting molecular gas between a local sample of luminous infrared galaxies (U/LIRGs) and a high redshift sample that comprises submm selected galaxies (SMGs), quasars, and Lyman Break Galaxies (LBGs). The U/LIRG sample consists of our recent CO(3-2) survey using the Submillimeter Array while the CO(3-2) data for the high redshift population are obtained from the literature. We find that the L(CO(3-2)) and L(FIR) relation is correlated over five orders of magnitude, which suggests that the molecular gas traced in CO(3-2) emission is a robust tracer of dusty star formation activity. The near unity slope of 0.93 +/- 0.03 obtained from a fit to this relation suggests that the star formation efficiency is constant to within a factor of two across different types of galaxies residing in vastly different epochs. The CO(3-2) size measurements suggest that the molecular gas disks in local U/LIRGs (0.3 - 3.1 kpc) are much more compact than the SMGs (3 - 16 kpc), and that the size scales of SMGs are comparable to the nuclear separation (5 - 40 kpc) of the widely separated nuclei of U/LIRGs in our sample. We argue from these results that the SMGs studied here are predominantly intermediate stage mergers, and that the wider line-widths arise from the violent merger of two massive gas-rich galaxies taking place deep in a massive halo potential.

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