EFFECTS OF ULTRAVIOLET BACKGROUND AND LOCAL STELLAR RADIATION ON THE H i COLUMN DENSITY DISTRIBUTION
EFFECTS OF ULTRAVIOLET BACKGROUND AND LOCAL STELLAR RADIATION ON THE H i COLUMN DENSITY DISTRIBUTION
复制标题
紫外线背景和局地恒星辐射对哈伊柱密度分布的影响
DOI：
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发表时间：
2010
期刊：
影响因子：
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通讯作者：
H. Yajima
中科院分区：
文献类型：
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作者：
K. Nagamine;Jun;H. Yajima
利用宇宙学光滑粒子流体动力学模拟研究了紫外线背景辐射场和局部恒星辐射对z = 3时阻尼Lyα系统（DLAs）和次DLAs的H i柱密度分布f（NH i）的影响。我们发现，在之前的光学薄近似模拟中，UVB沉入H i云的深度太深，因此与观测结果相比，我们低估了f（NH i）在19 < log NH i < 21.2。如果在高密度区域用ngas bbb6 × 10−3 cm−3关闭UVB，那么我们可以很好地再现在z = 3处观察到的f（NH i）。我们还利用辐射传输代码对模拟进行后处理，研究了局部恒星辐射的影响，发现局部恒星辐射对f（NH i）的影响不大。我们的研究结果表明，f（NH i）的形状主要由UVB决定，而局部恒星辐射的影响要弱得多，并且宇宙学模拟中经常使用的光学薄近似不足以正确处理DLAs内外的中性气体的电离结构。我们的结果还表明，DLA气体与暗物质晕内从光学厚的中性气体到光学薄的电离气体的过渡区密切相关。
We study the impact of ultraviolet background (UVB) radiation field and the local stellar radiation on the H i column density distribution f(NH i) of damped Lyα systems (DLAs) and sub-DLAs at z = 3 using cosmological smoothed particle hydrodynamics simulations. We find that, in the previous simulations with an optically thin approximation, the UVB was sinking into the H i cloud too deeply, and therefore we underestimated the f(NH i) at 19 < log NH i < 21.2 compared to the observations. If the UVB is shut off in the high-density regions with ngas>6 × 10−3 cm−3, then we reproduce the observed f(NH i) at z = 3 very well. We also investigate the effect of local stellar radiation by postprocessing our simulation with a radiative transfer code and find that the local stellar radiation does not change the f(NH i) very much. Our results show that the shape of f(NH i) is determined primarily by the UVB with a much weaker effect by the local stellar radiation and that the optically thin approximation often used in cosmological simulation is inadequate to properly treat the ionization structure of neutral gas in and out of DLAs. Our result also indicates that the DLA gas is closely related to the transition region from optically thick neutral gas to optically thin ionized gas within dark matter halos.
影响因子：
8.7
作者：
Komatsu, E.;Smith, K. M.;Wright, E. L.
通讯作者：
Wright, E. L.