Damped Lyman-Alpha and Lyman-Limit Absorbers in the Cold Dark Matter Model
Damped Lyman-Alpha and Lyman-Limit Absorbers in the Cold Dark Matter Model
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DOI：
10.1086/309900
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发表时间：
1995-09
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影响因子：
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通讯作者：
N. Katz;D. Weinberg;L. Hernquist;J. Miralda-Escudé
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文献类型：
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作者：
N. Katz;D. Weinberg;L. Hernquist;J. Miralda-Escudé
利用对Ω = 1冷暗物质宇宙的气体动力学模拟，研究了在等级成团的情况下阻尼Lyα和莱曼极限吸收体的形成.在模拟中，这些高柱密度系统与星系的形成有关。衰减的Lyα吸收，NH I沿着通过相对大质量、致密的原星系中心附近的视线出现。莱曼极限吸收，1017 cm-2 <$NH I <$1020.2 cm-2，在通过这些物体的外部或较小原星系中心附近的视线上形成。Lyman极限系统的数目比观测到的要少，而阻尼Lyα系统的数目与观测到的丰度相当接近。阻尼吸收体的半径通常约为10 kpc，但由于系统的数量比现在的L* 星系多得多，因此总体横截面很大。我们的研究结果表明，像那些观察到的高柱密度系统自然出现在星系形成的层次理论，现在可以直接从数值模拟研究这些吸收。
We study the formation of damped Lyα and Lyman-limit absorbers in a hierarchical clustering scenario using a gasdynamical simulation of an Ω = 1 cold dark matter universe. In the simulation, these high column density systems are associated with forming galaxies. Damped Lyα absorption, NH I ≳ 1020.2 cm-2, arises along lines of sight that pass near the centers of relatively massive, dense protogalaxies. Lyman-limit absorption, 1017 cm-2 ≲ NH I ≲ 1020.2 cm-2, develops on lines of sight that pass through the outer parts of such objects or near the centers of smaller protogalaxies. The number of Lyman-limit systems is less than observed, while the number of damped Lyα systems is quite close to the observed abundance. Damped absorbers are typically ~10 kpc in radius, but the population has a large total cross section because the systems are much more numerous than present-day L* galaxies. Our results demonstrate that high column density systems like those observed arise naturally in a hierarchical theory of galaxy formation and that it is now possible to study these absorbers directly from numerical simulations.