Absorption features of high-redshift galactic winds
Absorption features of high-redshift galactic winds
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DOI：
10.1111/j.1365-2966.2007.12220.x
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发表时间：
2007-04
影响因子：
4.8
通讯作者：
A. Fangano;A. Richter
中科院分区：
文献类型：
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作者：
A. Fangano;A. Richter
高红移星系的环境特征是由风驱动的流出气体和重力流入的气流。为了研究这种星系- igm的相互作用，我们在光滑粒子流体动力学模拟的z≈3输出中选择了Lyman-break星系的恒星爆发模拟体，生成了穿透周围体积的合成光学吸收谱线，包括对风的机械反馈的详细处理。通过对模拟结果的后处理，得到了几种可观测物种（HI、CIII、CIV、Si II、Si III、Si iv、O VI、O VII和O VIII）的分布。热风物质的特点是存在高电离物质，如0 vi、0 VII和0 VIII（后两者仅在x射线波段可见）；较冷（T < 10 5.5 K）的流入流可以通过Si II， Si III和ciii的光学吸收以及包围较冷气体团块的O VI的组合来识别。然而，合成光谱的线轮廓和像素光学深度分析表明，风吹星系所在的星系间灯丝产生的吸收特征与风环境的吸收特征非常相似。我们的结论是，仅基于观测到的离子吸收模式，在光学QSO吸收线光谱中可能难以清晰地识别高红移的风吹星系及其复杂的气体环境。
The environment of high-redshift galaxies is characterized by both wind-driven outflowing gas and gravitationally infalling streams. To investigate such galaxy-IGM interplay we have generated synthetic optical absorption line spectra piercing the volume surrounding a star-bursting analogue of a Lyman-break galaxy selected in a z ≈ 3 output from a smoothed particle hydrodynamics simulation, including a detailed treatment of mechanical feedback from winds. Distributions for several observable species (HI, CIII, CIV, Si II, Si III, Si iv, O VI, O VII and O VIII) have been derived by post-processing the simulation outputs. The hot-wind material is characterized by the presence of high-ionization species such as 0 vi, O VII and 0 VIII (the latter two observable only in X-ray bands); the colder (T < 10 5.5 K) infalling streams can be instead identified by the combined presence of Si II, Si III and C III optical absorption together with O VI that surrounds the cooler gas clumps. However, both line profile and pixel optical depth analysis of the synthetic spectra show that the intergalactic filament in which the wind-blowing galaxy is embedded produces absorption signatures that closely mimic those of the wind environment. We conclude that it may be difficult to clearly identify wind-blowing galaxies and their complex gaseous environment at high redshift in optical QSO absorption-line spectra based solely on the observed ion-absorption patterns.