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arXiv 0904.4479astro-ph.CO
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z~1.9发光成星星系团的IRS光谱和多波长研究

IRS Spectroscopy and Multi-wavelength Study of Luminous Star-forming Galaxies at z~1.9

J. -S. Huang, S. M. Faber, E. Daddi, E. S. Laird, K. Lai, A. Omont, Y. Wu, J. D. Younger, K. Bundy, A. Cattaneo, S. C. Chapman, C. J. Conselice, M. Dickinson, E… 展开作者

J. -S. Huang, S. M. Faber, E. Daddi, E. S. Laird, K. Lai, A. Omont, Y. Wu, J. D. Younger, K. Bundy, A. Cattaneo, S. C. Chapman, C. J. Conselice, M. Dickinson, E. Egami, G. G. Fazio, M. Im, D. Koo, E. Le Floc'h, C. Papovich, D. Rigopoulou, I. Smail, M. Song, P. P. Van de Werf, T. M. A. Webb, C. N. A. Willmer, S. P. Willner, L. Yan

摘要:

我们分析了一个样本的星系选择有F24>0.5 mJy,并满足一定的IRAC颜色标准。IRS光谱产生红移,光谱类型,和PAH光度,我们添加多波长宽带测光。恒星星族模型和IRS光谱一起表明,用于选择该样本的双重标准有效地隔离了z~1.9的大质量恒星形成星系。这是第一个以星暴为主的ULIRG样本在高红移与总红外光度直接从FIR和毫米测光测量,因此给了我们第一个准确的看法宽带SED的星暴星系在极高的光度和所有波长。类似的宽带数据组装的其他三个星系样本-本地星暴星系,本地AGN/ULIRGS,和第二个24 μ发光z~1.9的样本占主导地位的AGN。新的z~1.9星暴样本的L(PAH)/L(IR)是有史以来最高的,比局部星暴高出约3倍,而在活动星系核中,这一比值低于星暴趋势,往往严重。一些证据表明,活动星系核存在于这个以星爆为主的样本中,除了其中两个样本甚至拥有非常强的活动星系核,而它们仍然有非常强的PAH发射。ACS图像显示大多数物体在静止帧UV波段具有非常扩展的形态,从而扩展了PAH分子的分布。这样一个扩展的分布阻止了中心活动星系核对多环芳烃分子的进一步破坏。我们的结论是,该样本中的天体是主要由星暴提供能量的超红外类星体;这类天体贡献的总红外光度密度为0.9- 2.6 × 10^7 Lsol/Mpc ^3。

英文摘要:

We analyze a sample of galaxies chosen to have F24>0.5 mJy and satisfy a certain IRAC color criterion. IRS spectra yield redshifts, spectral types, and PAH luminosities, to which we add multi-wavelength broadband photometry. Stellar population modeling and IRS spectra together demonstrate that the double criteria used to select this sample have efficiently isolated massive star-forming galaxies at z~1.9. This is the first starburst-dominated ULIRG sample at high redshift with total infrared luminosity measured directly from FIR and millimeter photometry, and as such gives us the first accurate view of broadband SEDs for starburst galaxies at extremely high luminosity and at all wavelengths. Similar broadband data are assembled for three other galaxy samples -- local starburst galaxies, local AGN/ULIRGS, and a second 24mu-luminous z~1.9 sample dominated by AGN. L(PAH)/L(IR) for the new z~1.9 starburst sample is the highest ever seen, some three times higher than in local starbursts, whereas in AGNs this ratio is depressed below the starburst trend, often severely. Several pieces of evidence imply that AGNs exist in this starburst dominated sample, except two of which even host very strong AGN, while they still have very strong PAH emission. The ACS images show most objects have very extended morphologies in the rest-frame UV band, thus extended distribution of PAH molecules. Such an extended distribution prevents further destruction PAH molecules by central AGNs. We conclude that objects in this sample are ULIRGs powered mainly by starburst; and the total infrared luminosity density contributed by this type of objects is 0.9-2.6x 10^7 Lsol/Mpc^3.

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