Strongly time-variable ultraviolet metal-line emission from the circum-galactic medium of high-redshift galaxies
Strongly time-variable ultraviolet metal-line emission from the circum-galactic medium of high-redshift galaxies
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高红移星系环星系介质的强时变紫外金属线发射
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发表时间：
2015
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通讯作者：
Cita
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作者：
N. Sravan;C. Faucher;F. Voort;D. Keres̆;A. Muratov;P. Hopkins;R. Feldmann;E. Quataert;N. M. Northwestern;Uc Berkeley;Asiaa;U. Diego;Caltech;Cita
我们使用宇宙学模拟的反馈在现实环境中的项目，实现了一套全面的恒星反馈过程，研究紫外线（UV）金属线发射从环星系介质的高红移（z = 2-4）星系。我们的模拟覆盖了z = 2处的晕质量范围M_h 2 × 10^（11）-8.5 × 10^（12）M_⊙，代表了莱曼破裂星系。在我们分析的跃迁中，低电离C iii（977 A）和Si iii（1207 A）发射线最明亮，C iv（1548 A）和Si iv（1394 A）也显示出有趣的空间扩展结构。质量越大的光晕平均紫外线亮度越高。在我们的模拟中，银河系晕的紫外金属线发射主要来自碰撞电离气体，并且具有很强的时变性，峰谷变化高达102 dex。紫外线金属线亮度的峰值密切对应于大规模和充满活力的质量外流事件，这遵循爆发的星星形成和注入足够的能量到星系晕的动力的金属线发射。强烈的时间变异性意味着即使是一些相对低质量的光环也可能被检测到。相反，通量有限的样本将偏向于其中央星系最近经历了强烈的星星形成爆发的晕。高红移星系周围空间延伸的紫外线金属线辐射应该可以被当前和即将到来的积分场摄谱仪探测到，比如超大望远镜上的多单元光谱探测器和凯克宇宙网络成像仪。
We use cosmological simulations from the Feedback In Realistic Environments project, which implement a comprehensive set of stellar feedback processes, to study ultraviolet (UV) metal-line emission from the circum-galactic medium of high-redshift (z = 2–4) galaxies. Our simulations cover the halo mass range M_h ∼ 2 × 10^(11)–8.5 × 10^(12) M_⊙ at z = 2, representative of Lyman break galaxies. Of the transitions we analyse, the low-ionization C iii (977 A) and Si iii (1207 A) emission lines are the most luminous, with C iv (1548 A) and Si iv (1394 A) also showing interesting spatially extended structures. The more massive haloes are on average more UV-luminous. The UV metal-line emission from galactic haloes in our simulations arises primarily from collisionally ionized gas and is strongly time variable, with peak-to-trough variations of up to ∼2 dex. The peaks of UV metal-line luminosity correspond closely to massive and energetic mass outflow events, which follow bursts of star formation and inject sufficient energy into galactic haloes to power the metal-line emission. The strong time variability implies that even some relatively low-mass haloes may be detectable. Conversely, flux-limited samples will be biased towards haloes whose central galaxy has recently experienced a strong burst of star formation. Spatially extended UV metal-line emission around high-redshift galaxies should be detectable by current and upcoming integral field spectrographs such as the Multi Unit Spectroscopic Explorer on the Very Large Telescope and Keck Cosmic Web Imager.