Lyα ESCAPE FROM z ∼ 0.03 STAR-FORMING GALAXIES: THE DOMINANT ROLE OF OUTFLOWS
Lyα ESCAPE FROM z ∼ 0.03 STAR-FORMING GALAXIES: THE DOMINANT ROLE OF OUTFLOWS
复制标题
Lyα 逃离 z 〜 0.03 恒星形成星系：外流的主导作用
DOI：
10.1088/0004-637x/765/2/118
复制
发表时间：
2013
期刊：
影响因子：
--
通讯作者：
J. Salzer
中科院分区：
文献类型：
--
作者：
A. Wofford;C. Leitherer;J. Salzer
H I Lyα光子在描述遥远宇宙中恒星形成的有效性受到我们对控制它们逃离星系的天体物理过程的理解的限制。这些过程只能在几个×100 MPC的范围内才能详细观察到。过去邻近的(z<；0.3)光谱研究是基于小样本和/或运动学上未分辨的数据。利用哈勃太空望远镜的宇宙起源光谱仪的高灵敏度，我们观测了位于=0.03的20Hα精选星系的Lyα线。这些星系覆盖了广泛的光度、氧气丰度和变红。在这篇文章中，我们描述了观测到的Lyα线，并与星系的基本性质建立了联系。我们发现了七个发射源。这些年轻的宿主(⩽10Myr)恒星群的静止架相当宽度在1-12？范围内，并且在COS孔径内具有1%-12%范围内的Lyα逃逸分数。其中一个发射器有一个双峰的Lyα，两个峰相距370公里，S−1和一个更强的蓝色峰。排除这个天体，发射体有Lyα和O Iλ1302与Hα的偏移量，这与膨胀壳层模型和莱曼破裂星系的观测结果一致。吸波体的偏移量几乎与静态介质一致。我们没有发现Lyα发射与年龄、金属丰度或变红之间的一一对应关系。因此，我们证实了Lyα受到外流的增强，并受热星周围的尘埃和H I柱密度的调节。
The usefulness of H i Lyα photons for characterizing star formation in the distant universe is limited by our understanding of the astrophysical processes that regulate their escape from galaxies. These processes can only be observed in detail out to a few × 100 Mpc. Past nearby (z < 0.3) spectroscopic studies are based on small samples and/or kinematically unresolved data. Taking advantage of the high sensitivity of Hubble Space Telescope's Cosmic Origins Spectrograph (COS), we observed the Lyα lines of 20 Hα-selected galaxies located at =0.03. The galaxies cover a broad range of luminosity, oxygen abundance, and reddening. In this paper, we characterize the observed Lyα lines and establish correlations with fundamental galaxy properties. We find seven emitters. These host young (⩽10 Myr) stellar populations have rest-frame equivalent widths in the range 1–12 Å, and have Lyα escape fractions within the COS aperture in the range 1%–12%. One emitter has a double-peaked Lyα with peaks 370 km s−1 apart and a stronger blue peak. Excluding this object, the emitters have Lyα and O i λ1302 offsets from Hα in agreement with expanding-shell models and Lyman break galaxies observations. The absorbers have offsets that are almost consistent with a static medium. We find no one-to-one correspondence between Lyα emission and age, metallicity, or reddening. Thus, we confirm that Lyα is enhanced by outflows and is regulated by the dust and H i column density surrounding the hot stars.