We present JWST NIRSpec prism spectroscopy of lensed galaxies at z ≳ 9 found behind the massive galaxy cluster Abell 2744 in the UNCOVER Cycle 1 Treasury Program. We confirm the redshift via emission lines and/or the Lyα break for 10 galaxies at z = 8.50–13.08 down to MV = −17.3. We achieve a 100% confirmation rate for z > 9 candidates reported in H. Atek et al. Using six sources with multiple line detections, we find that offsets in redshift estimates between the lines and the Lyα break alone can be ±0.2, raising caution in designing future follow-up spectroscopy for the break-only sources with the Atacama Large Millimeter/submillimeter Array. With spec-z-confirmed sources in UNCOVER and the literature, we derive lower limits on the rest-frame ultraviolet (UV) luminosity function (LF) at z ≃ 9–12 and find that these lower limits agree with recent photometric measurements. We identify at least two unambiguous and several possible active galactic nucleus (AGN) systems based on X-ray, broad Hβ, high ionization lines, and excess in the UV LF. This requires the AGN LFs at z ≃ 9–10 to be comparable or even higher than the X-ray AGN LF estimated at z ∼ 6 and suggests a plausible cause of the high abundance of z > 9 galaxies claimed in the recent photometric measurements is AGNs. One UV-luminous source is confirmed at the same redshift as a broad-line AGN at z = 8.50 with a physical separation of 380 kpc in the source plane. These two sources show emission blueward of Lyα, indicating a giant ionized bubble enclosing them with a radius of 7.69 ± 0.18 pMpc. Our results imply that AGNs have a nonnegligible contribution to cosmic reionization.

中文翻译：

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揭秘：z = 8.50–13.08 的透镜星系的 NIRSpec 普查探测阴影中的高 AGN 分数和电离气泡


我们在 UNCOVER Cycle 1 Treasury Program 中展示了在大质量星系团 Abell 2744 后面发现的 z ≳ 9 透镜星系的 JWST NIRSpec 棱镜光谱。我们通过发射线和/或 Lyα 断裂确认 10 个星系在 z = 8.50–13.08 至 MV = −17.3 处的红移。我们对 H. Atek 等人报道的 z > 9 候选者实现了 100% 的确认率。使用具有多线检测的六个源，我们发现线和单独的 Lyα 断裂之间的红移估计偏移量可以±0.2，这提高了使用 Atacama 大型毫米/亚毫米阵列为仅断裂源设计未来后续光谱的谨慎程度。通过 UNCOVER 和文献中确认的 spec-z 来源，我们得出了 z ≃ 9-12 处静止帧紫外线 （UV） 光度函数 （LF） 的下限，并发现这些下限与最近的光度测量一致。我们根据 X 射线、宽 Hβ、高电离线和 UV LF 中的过量确定了至少两个明确的和几个可能的活跃星系核 （AGN） 系统。这要求 z ≃ 9-10 处的 AGN LF 与估计在 z ∼ 6 处估计的 X 射线 AGN LF 相当甚至更高，并表明最近光度测量中声称的 z > 9 星系丰度高的合理原因是 AGN。在 z = 8.50 处与宽带 AGN 具有相同的红移下确认一个紫外发光源，在源平面上的物理分离为 380 kpc。这两个源显示 Lyα 向蓝色发射，表明一个巨大的电离气泡包围着它们，半径为 7.69 ± 0.18 pMpc。我们的结果表明 AGNs 对宇宙再电离有不可忽视的贡献。