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arXiv 0706.0810astro-ph
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z~1的Lyman Break Galerkin和恒星形成星系中尘埃衰减随红移的演化

Lyman Break Galaxies at z~1 and the evolution of the dust attenuation in star-forming galaxies with the redshift

D. Burgarella, E. Le Floc'h, T. T. Takeuchi, J. S. Huang, V. Buat, G. H. Rieke, K. D. Tyler

摘要:

从GALEX中选择了紫外线星系。在它们的光谱能量分布中FUV-脱落的存在被证明是一个非常完整的(83.3%),但不是非常有效的(21.4%)的工具,用于识别在z~1处的Lyman Break Galerkin(LBG)。我们将LBG样品分为两个子类:在24微米处检测到的红色LBG(RLBG),其主要是发光IR半导体(LIRG),以及在24微米处未检测到的蓝色LBG(BLBG),其低至83微焦。在70微米处也检测到两个RLBG。RLBG的SED中值与尘埃星爆HR 10相似(λ ~1微米以上)。然而,与本地(U)LIRG不同,RLBG是UV明亮的对象。我们认为,这些物体包含大量的尘埃,但一些裸露的恒星星族也是直接可见的。中位SED的BLBG是一致的,它们包含相同的恒星星族的RLBG,但具有较低的尘埃含量。我们的LBG样品在z~1处的光度函数与相同红移的NUV选择星系的光度函数相似。z~1 LBG和NUV选择星系的积分亮度密度非常一致。我们发现,恒星形成率(SFR)估计从紫外线测量和使用IRX-β方法校正提供平均总SFR_TOT与SFR_UV + SFR_dust一致。然而,基于IRX-β的SFR_TOT显示出大的分散。总结所探测到的天体的UV(1150 A静止坐标系)和IR基恒星形成率,我们发现,尽管z~1处的大部分LBG都是BLBG,但只有三分之一的LBG SFR(即UV +尘埃)存在于BLBG中,三分之二存在于RLBG中。另一方面,在z~1处,LBG的总SFR仅占总SFR的11%。最后,我们观察到的L_TIR / L_FUV从z=0到z~2的UV选择的样品有规律地减少。

英文摘要:

Ultraviolet (UV) galaxies have been selected from GALEX. The presence of a FUV-dropout in their spectral energy distributions proved to be a very complete (83.3%) but not very efficient (21.4%) tool for identifying Lyman Break Galaxies (LBGs) at z~1. We divide the LBG sample into two sub-classes: red LBGs (RLBGs) detected at 24 micron which are mainly Luminous IR Galaxies (LIRGs) and blue LBGs (BLBGs) undetected at 24 microns down to 83 microJy. Two of the RLBGs are also detected at 70 micron. The median SED of the RLBGs is similar (above lambda~1 micron) to the dusty starburst HR10. However, unlike local (U)LIRGs, RLBGs are UV bright objects. We suggest that these objects contain a large amount of dust but that some bare stellar populations are also directly visible. The median SED of the BLBGs is consistent with their containing the same stellar population as the RLBGs but with a lower dust content. The luminosity function of our LBG sample at z~1 is similar to the luminosity function of NUV-selected galaxies at the same redshift. The integrated luminosity densities of z~1 LBGs and NUV-selected galaxies are very consistent. We show that star formation rates (SFRs) estimated from UV measurements and corrected using the IRX-beta method provide average total SFR_TOT in agreement with SFR_UV + SFR_dust. However, IRX-beta-based SFR_TOT shows a large dispersion. Summing up the detected UV (1150A rest-frame) and IR-based star formation rates of the detected objects, we find that only one third of the total (i.e. UV + dust) LBG SFR resides in BLBGs and two thirds in RLBGs, even though most LBGs at z~1 are BLBGs. On the other hand, the total SFR of LBGs accounts for only 11% of the total SFR at z~1. Finally, we observe a regular decrease of L_TIR / L_FUV from z=0 to z~2 for UV-selected samples.

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