Inferences on the timeline of reionization at z ∼ 8 from the KMOS Lens-Amplified Spectroscopic Survey
Inferences on the timeline of reionization at z ∼ 8 from the KMOS Lens-Amplified Spectroscopic Survey
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DOI：
10.1093/mnras/stz632
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发表时间：
2019-01
影响因子：
4.8
通讯作者：
C. Mason;A. Fontana;T. Treu;K. Schmidt;A. Hoag;L. Abramson;R. Amorín;M. Bradač;L. Guaita
中科院分区：
文献类型：
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作者：
C. Mason;A. Fontana;T. Treu;K. Schmidt;A. Hoag;L. Abramson;R. Amorín;M. Bradač;L. Guaita
探测到和未探测到来自z>；6星系(7)的莱曼α(Lyα)辐射，其中Lyα红移到近红外波长。在这里，我们给出了在KMOS透镜放大光谱调查(KLASS)中，在被大质量星系团引力透镜作用下的53个内在微弱的Lyman Break星系候选星系中寻找z>；7.2Lyα辐射。在∼积分时间为7-10h的情况下，我们的样品中没有检测到信噪比(S/N)和GT；5的Lyα发射。我们确定我们对5σ空间和光谱未分辨的发射线的观测完成了80%，其中积分线通量>；5.7×10−18erg S−1 cm−2。我们定义了一个由29个目标组成的光度选择的子样本，z=7.90±0.6，中位数5σLyαEW极限为58？我们使用它们的光谱对星系间介质(IGM)的平均中性氢分数进行贝叶斯推断。我们的推论考虑了我们观测的波长敏感性和不完全红移覆盖，以及每个目标的光度红移概率分布。这些观察，结合文献中的样本，使我们能够对z∼8的免疫球蛋白中性氢平均分数下限为0.76，(68{RM%})，(95{RMPERCENT})$，提供了在z∼6-8时快速再电离的进一步证据。我们表明这与将星系光度函数扩展到$M_rm{\Small UV}\Lesssim-12$的再电离历史模型是一致的，具有低电离光子逃逸分数$f_\tExtrm{Esc}\Lesssim 15{{\\Rm PERCENT}}$。
Detections and non-detections of Lyman alpha (Lyα) emission from z > 6 galaxies ( 7, where Lyα redshifts to near infra-red wavelengths. Here we present a search for z > 7.2 Lyα emission in 53 intrinsically faint Lyman Break Galaxy candidates, gravitationally lensed by massive galaxy clusters, in the KMOS Lens-Amplified Spectroscopic Survey (KLASS). With integration times of ∼7–10 h, we detect no Lyα emission with signal-to-noise ratio (S/N) > 5 in our sample. We determine our observations to be 80 per cent complete for 5σ spatially and spectrally unresolved emission lines with integrated line flux >5.7 × 10−18 erg s−1 cm−2. We define a photometrically selected sub-sample of 29 targets at z = 7.9 ± 0.6, with a median 5σ Lyα EW limit of 58 Å. We perform a Bayesian inference of the average intergalactic medium (IGM) neutral hydrogen fraction using their spectra. Our inference accounts for the wavelength sensitivity and incomplete redshift coverage of our observations, and the photometric redshift probability distribution of each target. These observations, combined with samples from the literature, enable us to place a lower limit on the average IGM neutral hydrogen fraction of $\gt 0.76 \,\, (68{{\ \rm per\ cent}}), \,\, \gt 0.46 \,\, (95{{\ \rm per\ cent}})$ at z ∼ 8, providing further evidence of rapid reionization at z ∼ 6–8. We show that this is consistent with reionization history models extending the galaxy luminosity function to $M_ \rm {\small UV}\lesssim -12$, with low ionizing photon escape fractions, $f_\textrm{esc} \lesssim 15{{\ \rm per\ cent}}$.