The Mean Ultraviolet Spectrum of a Representative Sample of Faint z ? 3 Lyman Alpha Emitters
The Mean Ultraviolet Spectrum of a Representative Sample of Faint z ? 3 Lyman Alpha Emitters
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微弱 z 的代表性样品的平均紫外线光谱？
DOI：
10.1093/mnras/sty750
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发表时间：
2018
影响因子：
4.8
通讯作者：
Iwata Ikuru
中科院分区：
文献类型：
--
作者：
Nakajima Kimihiko;Fletcher Thomas;Ellis Richard S;Robertson Brant E;Iwata Ikuru
我们讨论了一个大的（1000）样品的低光度红移Z 3.1莱曼α发射体（LAEs）的休息帧紫外（UV）发射线光谱从斯巴鲁成像调查在SSA 22调查领域。我们早期基于较小样本的工作表明，此类源具有高的[Oiii]/[Oii]线比，可能源于硬电离光谱，这可能是再电离时代类似源的典型特征。利用从VLT/VIMOS获得的光谱，我们利用Ciii]λ1909，Civλ1549，Heiiλ1640和Oiii]λλ1661，1666 λ的高电离诊断发射线在各种堆叠子集中的强度，重新检查了较大样品中电离辐射的性质。我们的分析证实了早期的建议之间的相关性Ly α和Ciii]发射，我们发现类似的趋势与宽带紫外光度和静止帧紫外颜色。使用不同的诊断线比和我们的恒星光电离模型，我们确定气相金属丰度和硬度的电离光谱的特点是，莱曼连续光子数每紫外光度。我们证实了我们早先的建议，LAEs的比连续选择的莱曼破裂星系，特别是对于那些LAEs与最微弱的紫外光度显着更大。我们简要地讨论了宇宙再电离的影响，如果贫金属强烈的恒星形成系统研究这里是那些在高得多的红移的代表性例子。
We discuss the rest-frame ultraviolet (UV) emission line spectra of a large (∼100) sample of low luminosity redshiftz∼ 3.1 Lyman alpha emitters (LAEs) drawn from a Subaru imaging survey in the SSA22 survey field. Our earlier work based on smaller samples indicated that such sources have high [Oiii]/[Oii] line ratios possibly arising from a hard ionizing spectrum that may be typical of similar sources in the reionization era. With optical spectra secured from VLT/VIMOS, we re-examine the nature of the ionizing radiation in a larger sample using the strength of the high ionization diagnostic emission lines ofCiii]λ1909,Civλ1549,Heiiλ1640, and Oiii]λλ1661, 1666 Å in various stacked subsets. Our analysis confirms earlier suggestions of a correlation between the strength of Ly α andCiii] emission and we find similar trends with broad-band UV luminosity and rest-frame UV colour. Using various diagnostic line ratios and our stellar photoionization models, we determine both the gas phase metallicity and hardness of the ionization spectrum characterized by ξion– the number of Lyman continuum photons per UV luminosity. We confirm our earlier suggestion that ξionis significantly larger for LAEs than for continuum-selected Lyman break galaxies, particularly for those LAEs with the faintest UV luminosities. We briefly discuss the implications for cosmic reionization if the metal-poor intensely star-forming systems studied here are representative examples of those at much higher redshift.