Faint extended Lya emission due to star formation at the centre of high column density QSO absorption systems Extended Lya emission from DLAs
Faint extended Lya emission due to star formation at the centre of high column density QSO absorption systems Extended Lya emission from DLAs
复制标题
由于高柱密度 QSO 吸收系统中心的恒星形成而产生微弱的扩展 Lya 发射 DLA 的扩展 Lya 发射
DOI：
10.1111/j.1365-2966.2009.16172.x
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发表时间：
2010
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
我们使用详细的Lyα辐射传输计算来进一步验证Rauch等人的声明，即他们在最近的超深光谱调查中从阻尼Lyα吸收系统（DLAs）的难以捉摸的宿主种群中检测到空间扩展的微弱Lyα发射。我们研究了由于在DLAs中心形成星星而引起的Lyα辐射的空间和光谱分布，以及它与气体空间和速度结构的依赖关系。我们的模型同时再现了DLAs和微弱Lyα发射体的观测性质，包括DLAs的速度宽度和柱密度分布以及微弱发射体的大空间范围发射。我们的模型证实了以前的建议，DLAs主要是由暗物质（DM）晕在质量范围109.5- 1012 M的，因此显着低于推断为L * 莱曼断裂星系（LBG）的质量。我们的模型表明，承载DLA的DM晕以中性氢的形式保留了高达20%的宇宙重子部分，并且晕中心的星星形成是微弱的Lyα发射的原因。Lyα辐射的很大一部分散射到观测到的半径上，可以达到50 kpc或更大，这要求晕中心气体的整体运动幅度适中。观测到的发射体的空间密度和尺寸分布以及DLAs的入射率表明，由于星星形成而产生的Lyα发射的占空比为25%。
We use detailed Lyα radiative transfer calculations to further test the claim of Rauch et al. that they have detected spatially extended faint Lyα emission from the elusive host population of damped Lyα absorption systems (DLAs) in their recent ultra-deep spectroscopic survey. We investigate the spatial and spectral distribution of Lyα emission due to star formation at the centre of DLAs, and its dependence on the spatial and velocity structure of the gas. Our model simultaneously reproduces the observed properties of DLAs and the faint Lyα emitters, including the velocity width and column density distribution of DLAs and the large spatial extent of the emission of the faint emitters. Our modelling confirms previous suggestions that DLAs are predominately hosted by dark matter (DM) haloes in the mass range 109.5–1012M⊙, and are thus of significantly lower mass than those inferred forL*Lyman Break Galaxies (LBGs). Our modelling suggests that DM haloes hosting DLAs retain up to 20 per cent of the cosmic baryon fraction in the form of neutral hydrogen, and that star formation at the centre of the haloes is responsible for the faint Lyα emission. The scattering of a significant fraction of the Lyα emission to the observed radii, which can be as large as 50 kpc or more, requires the amplitude of the bulk motions of the gas at the centre of the haloes to be moderate. The observed space density and size distribution of the emitters together with the incidence rate of DLAs suggests that the Lyα emission due to star formation has a duty cycle of ∼25 per cent.