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arXiv 1909.07396astro-ph.GA
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莱曼连续逸出巡天-- II:电离辐射随[ OIII ]/[ OII ]谱线比的变化

The Lyman Continuum Escape Survey -- II: Ionizing Radiation as a Function of the [OIII]/[OII] Line Ratio

Kimihiko Nakajima, Richard S. Ellis, Brant E. Robertson, Mengtao Tang, Daniel P. Stark

摘要:

我们讨论了一个大的(~50)样品的z=3.1莱曼α发射体(LAEs)的物理性质表明,这样的来源是有前途的星系在再电离时代的类似物的休息帧光发射线光谱。现在已经确定了可靠的莱曼连续体逃逸分数,用于从莱曼连续体逃逸调查(LACES)中获得的大样本LAE,该调查是通过Fletcher等人(2019)报告的SSA 22调查区域中的深层HST成像进行的。使用新的措施[OII]发射固定从凯克MOSFIRE光谱,我们重新检查,对于一个更大的样本,早期的声称,莱曼连续泄漏可能与星云发射线比[OIII]/[OII]预期的密度约束HII地区。我们发现,一个大的[OIII]/[OII]线比确实是莱曼连续泄漏的必要条件,加强早期的索赔使用较小的样品在各种红移。然而,并不是所有的LAE与大[OIII]/[OII]线比的泄漏和泄漏的辐射似乎不与其他光谱诊断的差异。这表明泄漏辐射的检测受到附加属性的调制,可能是多孔HII区域的视角。我们讨论了我们的新结果的背景下,引人注目的双峰的LAE泄漏和非泄漏的LACES计划中发现的宇宙再电离源的影响。

英文摘要:

We discuss the rest-frame optical emission line spectra of a large (~50) sample of z=3.1 Lyman alpha emitters (LAEs) whose physical properties suggest such sources are promising analogs of galaxies in the reionization era. Reliable Lyman continuum escape fractions have now been determined for a large sample of such LAEs from the Lyman Continuum Escape Survey (LACES) undertaken via deep HST imaging in the SSA22 survey area reported in Fletcher et al. (2019). Using new measures of [OII] emission secured from Keck MOSFIRE spectra we re-examine, for a larger sample, earlier claims that Lyman continuum leakages may correlate with the nebular emission line ratio [OIII]/[OII] as expected for density-bound HII regions. We find that a large [OIII]/[OII] line ratio is indeed a necessary condition for Lyman continuum leakage, strengthening earlier claims made using smaller samples at various redshifts. However, not all LAEs with large [OIII]/[OII] line ratios are leakers and leaking radiation appears not to be associated with differences in other spectral diagnostics. This suggests the detection of leaking radiation is modulated by an additional property, possibly the viewing angle for porous HII regions. We discuss our new results in the context of the striking bimodality of LAE leakers and non-leakers found in the LACES program and the implications for the sources of cosmic reionization.

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