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arXiv 1202.1745astro-ph.CO
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引力透镜星系“8点钟弧”的星云和全球性质

Nebular and global properties of the gravitationally lensed galaxy "the 8 o'clock arc"

M. Dessauges-Zavadsky, L. Christensen, S. D'Odorico, D. Schaerer, J. Richard

摘要:

本文分析了用VLT/X-shooter获得的引力透镜星系“8点钟弧”在z_sys = 2.7350的新的近红外中分辨率光谱。这些静止帧光学数据,结合HST和斯皮策图像,提供了非常有价值的信息,很好地补充了我们以前详细的静止帧紫外光谱分析。从高分辨率的HST图像,我们重建的弧源平面的形态,并确定源是由两个主要部分,主要的星系组成部分和一个较小的斑点分离的1.2千秒差距的投影距离。具有两倍放大因子的斑点在光谱中被分辨。检测到的星云发射线的多高斯拟合和可用的多波长测光的光谱能量分布建模提供了普查的气体和恒星尘埃的丰度,气相金属丰度,恒星形成率(SFR),恒星,气体和动力学质量的主星系和斑点。因此,8点钟弧显示出一个边际趋势,更衰减的电离气体比恒星,并支持依赖的尘埃性质的SFR。这个透镜状莱曼破裂星系具有很高的比恒星形成率,SSFR = 33+/-19 Gyr^{-1},偏离了质量-SFR关系,其特征是年龄为40 + 25 - 20 Myr,气体含量约为72%。8点钟方向的弧满足基本质量、SFR和金属丰度关系,并有利于它在z~2.5以上的情况下保持不变。我们认为,具有气体质量M_gas =(2.2+/-0.9 x10 ^{9} Msun(比星系质量低一个数量级),半光半径r1/2 = 0.53+/-0.05 kpc,恒星形成速率SFR_H α = 33+/-19 Msun yr^{-1},并围绕星系的主核心旋转,是z>1恒星形成星系中常见的恒星形成团块之一。(节录)

英文摘要:

We present the analysis of new NIR, intermediate-resolution spectra of the gravitationally lensed galaxy "the 8 o'clock arc" at z_sys = 2.7350 obtained with VLT/X-shooter. These rest-frame optical data, combined with HST and Spitzer images, provide very valuable information, which nicely complement our previous detailed rest-frame UV spectral analysis. From high-resolution HST images, we reconstruct the morphology of the arc in the source plane, and identify that the source is formed of two majors parts, the main galaxy component and a smaller blob separated by 1.2 kpc in projected distance. The blob, with a twice larger magnification factor, is resolved in the spectra. The multi-Gaussian fitting of detected nebular emission lines and the spectral energy distribution modeling of the available multi-wavelength photometry provide the census of gaseous and stellar dust extinctions, gas-phase metallicities, star-formation rates (SFRs), and stellar, gas, and dynamical masses for both the main galaxy and the blob. As a result, the 8 o'clock arc shows a marginal trend for a more attenuated ionized gas than stars, and supports a dependence of the dust properties on the SFR. With a high specific star-formation rate, SSFR = 33+/-19 Gyr^{-1}, this lensed Lyman-break galaxy deviates from the mass-SFR relation, and is characterized by a young age of 40^{+25}_{-20} Myr and a high gas fraction of about 72%. The 8 o'clock arc satisfies the fundamental mass, SFR, and metallicity relation, and favors that it holds up beyond z~2.5. We believe that the blob, with a gas mass M_gas = (2.2+/-0.9)x10^{9} Msun (one order of magnitude lower than the mass of the galaxy), a half-light radius r1/2 = 0.53+/-0.05 kpc, a star-formation rate SFR_Halpha = 33+/-19 Msun yr^{-1}, and in rotation around the main core of the galaxy, is one of these star-forming clumps commonly observed in z>1 star-forming galaxies. (Abridged)

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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