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arXiv 1204.3233astro-ph.CO
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Subaru FOCAS对z=7-7.1 Lyα辐射源的测量:z >~ 7 Lyα光度学光度函数的检验

Subaru FOCAS survey of z=7-7.1 Lyα emitters: a test for z >~ 7 Lyα photometric luminosity functions

Kazuaki Ota, Masanori Iye

摘要:

最近对z >~ 7的Lyα发射体(LAEs)的观测,导出了各种Lyα光度函数(LFs),其结果相互矛盾,从z <~ 6(再电离后的历元)开始演化或不演化。这可能是因为大多数z >~ 7 LF包括光度候选物并且可能包括一些污染物。我们用Subaru望远镜的窄带NB 980(λc ~ 9800 A,FWHM ~ 100 A)暗天体照相机和光谱仪对z=7-7.1的LAEs进行了成像和光谱测量,将其“无污染”的结果与以前导出的z > 7的光度Lyα LF进行了比较。我们对斯巴鲁深空和MS 1520.1+3002星系团周围的天空进行了成像,发现了一个LAE候选者,但是光谱学没有发现Lyα,尽管它足够深,可以探测到它。我们使用最近调查中的5个z=7和3个z=7.7的Lyα LF计算了我们调查中LAE的预期数量。其中7个在泊松统计和宇宙方差的误差范围内与零检测一致(0.1^{+1.8}_{-0.1}-1.1 ^{+2.2}_{-1.0} LAEs),但从其中一个z=7和两个z=7.7的LF预测的平均值(0.7-1.1 LAEs)表明几乎是一个单一的检测。剩余的一个z=7 LF预测3.0^{+3.2}_{-2.0} LAE。对于z=7,差异可能来自不同的LAE选择标准。对于z=7.7,有两种可能:(1)如果z=7.7的LAEs在Lyα光度上比低红移的LAEs更亮,那么即使被中性氢衰减,观测到z=7.7的LF也类似于或高于低红移的LF。(2)所有/大多数z=7.7候选者不是LAE。这支持了LF从z ~ 6下降到7.7以及在z ~ 6-7.7处的再电离。

英文摘要:

Recent observations of z >~ 7 Lyα emitters (LAEs) have derived a variety of Lyα luminosity functions (LFs) with contradictory results, evolution or non-evolution from z <~ 6, the epoch after reionization. This could be because most of z >~ 7 LFs comprise photometric candidates and might include some contaminations. We conducted the Subaru Telescope Faint Object Camera And Spectrograph narrowband NB980 (λc ~ 9800A, FWHM ~ 100A) imaging and spectroscopy survey of z=7-7.1 LAEs to compare its "contamination-free" result with z >~ 7 photometric Lyα LFs previously derived. We imaged the Subaru Deep Field and the sky around a cluster MS 1520.1+3002 and found one LAE candidate, but spectroscopy did not reveal Lyα though deep enough to detect it. We calculated the expected number of LAEs in our survey, using five z=7 and three z=7.7 Lyα LFs from recent surveys. Seven of them are consistent with null detection (0.1^{+1.8}_{-0.1}-1.1^{+2.2}_{-1.0} LAEs) within errors including Poisson statistics and cosmic variance, but average values (0.7-1.1 LAEs) predicted from one z=7 and two z=7.7 LFs among the seven indicate nearly a single detection. The remaining one z=7 LF predicts 3.0^{+3.2}_{-2.0} LAEs. As to z=7, the discrepancy likely comes from different LAE selection criteria. For z=7.7, there are two possibilities; (1) If z=7.7 LAEs are somehow brighter in Lyα luminosity than lower redshift LAEs, z=7.7 LF is observed to be similar to or higher than lower redshift LFs even if attenuated by neutral hydrogen. (2) All/most of the z=7.7 candidates are not LAEs. This supports the decline of LF from z ~ 6 to 7.7 and reionization at z ~ 6-7.7.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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