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首页> 外文期刊>The Astrophysical journal >Metallicity Of The Intergalactic Medium Using Pixel Statistics. Iv. Oxygen
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Metallicity Of The Intergalactic Medium Using Pixel Statistics. Iv. Oxygen

机译：使用像素统计的星际介质的金属性。四氧

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We have studied the abundance of oxygen in the IGM by analyzing O Ⅵ, C Ⅳ, Si Ⅳ, and H I pixel optical depths derived from a set of high-quality VLT and Keck spectra of 17 QSOs at 2.1 ≤ z ≤ 3.6. Comparing ratios Τ_o Ⅵ /Τ_C Ⅳ(Τ_C Ⅳ) to those in realistic, synthetic spectra drawn from a hydrodynamical simulation and comparing to existing constraints on [Si/C] places strong constraints on the ultraviolet background (UVB) model using weak priors on allowed values of [Si/O]: for example, a quasar-only background yields [Si/O] ≈ 1.4, which is highly inconsistent with the [Si/O] ≈ 0 expected from nucleosynthetic yields and with observations of metal-poor stars. Assuming a fiducial quasar+galaxy UVB consistent with these constraints yields a primary result that [O/C] = 0.66 ± 0.06 ± 0.2; this result pertains to gas with overdensity δ≥2. Consistent results are obtained by similarly comparing t_O Ⅵ/t_(hi)(t_(hi)) and Τ_OⅥ/Τ_(Si)Ⅳ(Τ_(Si)Ⅳ) to simulation values, and also by directly ionization-correcting Τ_OⅥ/t_h i as a function of t_h I, into [O/H] as a function of density. Subdividing the sample reveals no evidence for evolution, but low- and high-Τ_H I, samples are inconsistent, suggesting either density dependence of [O/C] or-more likelu-prevalence of collisionally ionized gas at high density.
机译：我们通过分析OⅥ，CⅣ，SiⅣ和H I像素的光学深度，研究了IGM中氧的丰度，这些像素的光学深度是由一组高质量的VLT和在2.1≤z≤3.6的17个QSO的Keck光谱得出的。比较流体力学模拟中真实的合成光谱中的比率Τ_oⅥ/Τ_CⅣ（Τ_CⅣ），并与[Si / C]上的现有限制条件进行比较，在允许的条件下使用弱先验条件对紫外线背景（UVB）模型施加了强限制条件[Si / O]的值：例如，仅类星体的背景产生[Si / O]≈1.4，这与核合成产率和对金属贫乏的恒星的观测所期望的[Si / O]≈0高度不一致。假设符合这些约束的基准类星体+星系UVB产生的主要结果是[O / C] = 0.66±0.06±0.2；该结果与过密度δ≥2的气体有关。通过类似地比较t_OⅥ/ t_（hi）（t_（hi））和Τ_OⅥ/Τ_（Si）Ⅳ（Τ_（Si）Ⅳ）与模拟值，以及直接电离校正Τ_OⅥ/ t_h i，可以获得一致的结果。作为t_h I的函数，作为[O / H]作为密度的函数。将样品细分后，没有发现演化的证据，但是低和高T_HI样品不一致，表明[O / C]的密度依赖性或高密度碰撞离子化气体的似然率。

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