论文标题
莱曼 - 阿尔法发射的光谱形状：I。蓝光发射和红移的内在不变性
Spectral shapes of the Lyman-alpha emission from galaxies: I. blueshifted emission and intrinsic invariance with redshift
论文作者
论文摘要
我们证明了来自星形星系的H I Lyman-Alpha（Lyα）发射的光谱曲线的红移发展。在第一项研究中，我们特别注意蓝光发射的贡献。 At redshift z = 2.9-6.6, we compile spectra of a sample of 229 Lyα-selected galaxies identified with the Multi-Unit Spectroscopic Explorer at the Very Large Telescope, while at low-z (< 0.44) we use a sample of 74 ultraviolet-selected galaxies observed with the Cosmic Origin Spectrograph onboard the Hubble Space Telescope.在低Z处，其中来自乳层间培养基（IGM）的吸收可以忽略不计，我们表明lyα光度蓝色和红色线中心（L_B/R）的比率随着等效宽度的增加而迅速增加（Wlyα）。但是，这种相关性不会在z = 3-4处出现，我们使用Bootstrap模拟来证明L B/R的趋势应因IgM吸收的变化而抑制。我们的主要结果是，观察到的蓝光贡献随着红移的增加而迅速向下演变：z〜0时L_b/r〜30％，但在Z〜3时下降至15％，至3％以下，Z〜6降至3％。将IgM吸收的进一步仿真到未吸收的COS谱系中，我们证明了蓝翼贡献的减少可以完全归因于中间lyα吸收系统的增厚，而无需局部结构，伴随的星系或宇宙中的额外的H i ipacity。我们根据数值辐射转移模拟，星系的总LYα和电离输出以及在电离时代的分辨LYα光谱的实用性来讨论我们的结果。
We demonstrate the redshift-evolution of the spectral profile of H i Lyman-alpha (Lyα) emission from star-forming galaxies. In this first study we pay special attention to the contribution of blueshifted emission. At redshift z = 2.9-6.6, we compile spectra of a sample of 229 Lyα-selected galaxies identified with the Multi-Unit Spectroscopic Explorer at the Very Large Telescope, while at low-z (< 0.44) we use a sample of 74 ultraviolet-selected galaxies observed with the Cosmic Origin Spectrograph onboard the Hubble Space Telescope. At low-z, where absorption from the intergalactic medium (IGM) is negligible, we show that the ratio of Lyα luminosity bluewards and redwards of line center (L_B/R) increases rapidly with increasing equivalent width (W Lyα). This correlation does not, however, emerge at z = 3-4, and we use bootstrap simulations to demonstrate that trends in L B/R should be suppressed by variations in IGM absorption. Our main result is that the observed blueshifted contribution evolves rapidly downwards with increasing redshift: L_B/R~30 % at z~0, but drops to 15 % at z~3, and to below 3 % by z~6. Applying further simulations of the IGM absorption to the unabsorbed COS spectrum, we demonstrate that this decrease in the blue-wing contribution can be entirely attributed to the thickening of intervening Lyα absorbing systems, with no need for additional H i opacity from local structure, companion galaxies, or cosmic infall. We discuss our results in light of the numerical radiative transfer simulations, the evolving total Lyα and ionizing output of galaxies, and the utility of resolved Lyα spectra in the reionization epoch.
