ANISOTROPIC LYMAN-ALPHA EMISSION
ANISOTROPIC LYMAN-ALPHA EMISSION
复制标题
各向异性莱曼阿尔法发射
DOI：
10.1088/0004-637x/794/2/116
复制
发表时间：
2013
期刊：
影响因子：
--
通讯作者：
J. Wallace
中科院分区：
文献类型：
--
作者：
Zheng Zheng;J. Wallace
作为氢原子共振散射的结果，恒星形成星系的Lyα辐射提供了对周围（几乎各向同性）中性气体环境的探测。通过对中性氢云模型进行辐射传输计算，研究了环境各向异性对观测到的Lyα辐射的影响。环境的各向异性导致Lyα通量和光谱特性的各向异性，并导致它们之间的相关性。Lyα通量（或观测到的光度）取决于视角，并显示出与初始Lyα光学深度的近似相关性。来自一组随机方向的云的Lyα通量的分布偏向于高值，为观测中看到的Lyα等效宽度（EW）分布提供了自然贡献。在Lyα线较大的峰距处，EW分布较窄，与观测结果一致。峰值偏移似乎与线的形状（半峰全宽和不对称性）相关，指出单独使用Lyα线特征来确定星系的系统红移的可能性。这项研究表明，中性氢的空间和运动学分布的各向异性可能是塑造恒星形成星系Lyα发射观测特性的重要因素。讨论了利用Lyα辐射探测星系环星系和星系际环境的意义。
As a result of resonant scatterings off hydrogen atoms, Lyα emission from star-forming galaxies provides a probe of the (hardly isotropic) neutral gas environment around them. We study the effect of the environmental anisotropy on the observed Lyα emission by performing radiative transfer calculations for models of neutral hydrogen clouds with prescriptions of spatial and kinematic anisotropies. The environmental anisotropy leads to corresponding anisotropy in the Lyα flux and spectral properties and induces correlations among them. The Lyα flux (or observed luminosity) depends on the viewing angle and shows an approximate correlation with the initial Lyα optical depth in the viewing direction relative to those in all other directions. The distribution of Lyα flux from a set of randomly oriented clouds is skewed to high values, providing a natural contribution to the Lyα equivalent width (EW) distribution seen in observation. A narrower EW distribution is found at a larger peak offset of the Lyα line, similar to the trend suggested in observation. The peak offset appears to correlate with the line shape (full width at half-maximum and asymmetry), pointing to a possibility of using Lyα line features alone to determine the systemic redshifts of galaxies. The study suggests that anisotropies in the spatial and kinematic distributions of neutral hydrogen can be an important ingredient in shaping the observed properties of Lyα emission from star-forming galaxies. We discuss the implications of using Lyα emission to probe the circumgalactic and intergalactic environments of galaxies.
通过流出驱动腔进行光束 Lyα 发射
影响因子：
6.5
作者：
Behrens;Dijkstra;Niemeyer
通讯作者：
Niemeyer