A joint model for the emission and absorption properties of damped Lya absorption systems
A joint model for the emission and absorption properties of damped Lya absorption systems
复制标题
阻尼 Lya 吸收系统发射和吸收特性的联合模型
DOI：
10.1111/j.1365-2966.2009.14972.x
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发表时间：
2009
影响因子：
4.8
通讯作者：
Barnes L
中科院分区：
文献类型：
--
作者：
Barnes L
最近发现的超微弱延长线发光体，其通量为10−18erg S−1 cm−2atz∼3，如果将该发射线解释为Lyα，则可以解释这个红移时的大部分受阻Lyα系统(DLA)的发生率。在结构形成的Λ冷暗物质模型的背景下，我们展示了一个类似于所提出的模型，它再现了DLA的入射率和运动学，也为合理的参数再现了新的微弱Lyα发射体的尺寸分布。这进一步支持了将发射解释为Lyα，以及将发射源与迄今难以捉摸的Dla宿主星系的数量进行识别。观测到的DLA入射率以及观测到的发射体的空间密度和大小分布表明，DLA宿主星系的Ly∼辐射的占空比为0.20.4。我们进一步表明，对于大多数发射体来说，Lyα冷却对Lyα排放的贡献很小。这使得中心集中的恒星形成速度为十分之几M⊙yr−1，周围环绕着半径高达30-50kpc的扩展Lyα晕，这是对发射来源最合理的解释。Lyα发射的光度函数和低电离吸收的速度宽度分布都要求暗物质晕内部的维里速度为≲50-70 km的星系S−1对∼3的DLA入射率贡献很小，这表明恒星形成的能量和动量输入可以有效地从这些晕中移除气体。具有Dm晕、维里速度为100-150公里的星系S−1似乎占DLA宿主星系的大多数。因此，位于∼3的DLA宿主星系应该成为像我们的银河系这样典型的当今星系的基石。
The recently discovered population of ultra-faint extended line emitters, with fluxes of a few times 10−18erg s−1cm−2atz∼ 3, can account for the majority of the incidence rate of damped Lyα systems (DLAs) at this redshift if the line emission is interpreted as Lyα. We show here that a model similar to that proposed by , which reproduces the incidence rate and kinematics of DLAs in the context of Λ cold dark matter models for structure formation, also reproduces the size distribution of the new population of faint Lyα emitters for plausible parameters. This lends further support to the interpretation of the emission as Lyα, as well as the identification of the emitters with the hitherto elusive population of DLA host galaxies. The observed incidence rate of DLAs together with the observed space density and size distribution of the emitters suggest a duty cycle of ∼0.2–0.4 for the Lyα emission from DLA host galaxies. We further show that Lyα cooling is expected to contribute little to the Lyα emission for the majority of emitters. This leaves centrally concentrated star formation at a rate of a few tenths M⊙yr−1, surrounded by extended Lyα haloes with radii up to 30–50 kpc, as the most plausible explanation for the origin of the emission. Both the luminosity function of Lyα emission and the velocity width distribution of low ionization absorption require that galaxies inside dark matter (DM) haloes with virial velocities ≲50–70 km s−1contribute little to the incidence rate of DLAs atz∼ 3, suggesting that energy and momentum input due to star formation efficiently removes gas from these haloes. Galaxies with DM haloes with virial velocities of 100–150 km s−1appear to account for the majority of DLA host galaxies. DLA host galaxies atz∼ 3 should thus become the building blocks of typical present-day galaxies like our Milky Way.