Lyman continuum leaking AGN in the SSA22 field
Lyman continuum leaking AGN in the SSA22 field
复制标题
SSA22 场中的莱曼连续介质泄漏 AGN
DOI：
10.1093/mnras/stw1329
复制
发表时间：
2017
期刊：
影响因子：
--
通讯作者：
A. K. Inoue
中科院分区：
文献类型：
--
作者：
G. Micheva;I. Iwata;A. K. Inoue
Subaru/SuprimeCam窄带测光的SSA 22领域揭示了存在四个莱曼连续体（LyC）的候选人之间的样本14活动星系核。两个显示偏移，可能有恒星LyC的性质或前景污染物。剩下的两个LyC候选者是I型活动星系核。我们认为，平均LyC逃逸分数的高红移低光度活动星系核是不可能的，因为往往假设在文献中。从直接测量，我们得到的平均LyC-紫外线通量密度比和电离辐射率的AGN类的数量，并发现它至少有两个因素低于assumingfesc= 1得到的值。与最近的Lyα森林测量结果相比，红移3的活动星系核最多只占总电离收支的12%，最少只占15%。我们的研究结果表明，活动星系核不太可能主导宇宙的电离预算在高红移。
Subaru/SuprimeCam narrowband photometry of the SSA22 field reveals the presence of four Lyman continuum (LyC) candidates among a sample of 14 AGN. Two show offsets and likely have stellar LyC in nature or are foreground contaminants. The remaining two LyC candidates are Type I AGN. We argue that the average LyC escape fraction of high redshift low luminosity AGN is not likely to be unity, as often assumed in the literature. From direct measurement we obtain the average LyC-to-UV flux density ratio and ionizing emissivity for a number of AGN classes and find it at least a factor of two lower than values obtained assumingfesc= 1. Comparing to recent Lyα forest measurements, AGNs at redshiftz∼ 3 make up at most ∼12% and as little as ∼5% of the total ionizing budget. Our results suggest that AGNs are unlikely to dominate the ionization budget of the Universe at high redshifts.