论文标题
一系列发光Z〜6莱曼破裂星系的平均吸收线光谱
The Mean Absorption Line Spectra of a Selection of Luminous z~6 Lyman Break Galaxies
论文作者
论文摘要
我们使用与Subaru和GTC望远镜上的焦点和Osiris光谱仪一起使用的数据，检查了Redshift Z〜6的31个发光（M_UV = -23）样品的吸收线光谱。对于其中两个来源，我们提供了以ESO的X射击光谱仪从较高频谱分辨率获取的更长的暴露数据。使用这些数据，我们证明了堆叠较低分辨率数据的实用性，以测量各种星体和恒星吸收线的深度，以探测低电离气体的覆盖部分，以及在宇宙电离时代结束时的气相和恒星金属性。从SIII1260和CII1334的最大吸收线深度，我们推断出样品的平均覆盖率> 0.85 +/- 0.16。这要大于使用类似方法在稍低的红移下使用类似方法确定的方法，这表明最发光的星系似乎比较低的星系具有较低的逃生分数，因此在结论中可能不会发挥重要作用。使用各种星际吸收系线，我们推断出接近太阳能的气相金属性，指示大量早期富集。使用选定的恒星吸收线，我们使用在较低红移下成功使用的技术对光谱进行建模，并推断出0.4 +0.3/-0.1太阳能的恒星金属性，与恒星质量 - 恒星质量 - 恒星金属关系一致。我们讨论了这些金属性估计值对我们发光星系的典型年龄的含义，并得出结论我们的结果意味着在红移Z〜10处的初始恒星形成与早期对象的独立分析一致。
We examine the absorption line spectra of a sample of 31 luminous (M_UV=-23) Lyman break galaxies at redshift z~6 using data taken with the FOCAS and OSIRIS spectrographs on the Subaru and GTC telescopes. For two of these sources we present longer exposure data taken at higher spectral resolution from ESO's X-shooter spectrograph. Using these data, we demonstrate the practicality of stacking our lower resolution data to measure the depth of various interstellar and stellar absorption lines to probe the covering fraction of low ionization gas and the gas-phase and stellar metallicities near the end of the era of cosmic reionization. From maximum absorption line depths of SiII1260 and CII1334, we infer a mean covering fraction of >0.85+/-0.16 for our sample. This is larger than that determined using similar methods for lower luminosity galaxies at slightly lower redshifts, suggesting that the most luminous galaxies appear to have a lower escape fraction than fainter galaxies, and therefore may not play a prominent role in concluding reionization. Using various interstellar absorption lines we deduce gas-phase metallicities close to solar indicative of substantial early enrichment. Using selected stellar absorption lines, we model our spectra with a range of metallicities using techniques successfully employed at lower redshift and deduce a stellar metallicity of 0.4 +0.3/-0.1 solar, consistent with the stellar mass - stellar metallicity relation recently found at z~3-5. We discuss the implications of these metallicity estimates for the typical ages of our luminous galaxies and conclude our results imply initial star formation at redshifts z~10, consistent with independent analyses of earlier objects.
