A first look at the SMACS0723 JWST ERO: spectroscopic redshifts, stellar masses and star-formation histories
A first look at the SMACS0723 JWST ERO: spectroscopic redshifts, stellar masses and star-formation histories
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初看 SMACS0723 JWST ERO：光谱红移、恒星质量和恒星形成历史
DOI：
10.1093/mnrasl/slac136
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发表时间：
2022
影响因子：
6.5
通讯作者：
C. Pollock
中科院分区：
文献类型：
--
作者：
A. Carnall;R. Begley;D. McLeod;M. Hamadouche;C. T. Donnan;R. McLure;J. Dunlop;B. Milvang;C. L. Bondestam;F. Cullen;S. Jewell;C. Pollock
我们对 SMACS J0723.3-7327 簇字段中的 JWST ERO 数据进行了初步分析。我们首先报告 10 个新的光谱红移，从 ?观测值 = 1 。 8-5。 2 ? m NIRSpec 中等分辨率 ( ? = ? / Δ ? = 1000) 数据。这些都是通过多个高 SNR 发射线检测确定的，其中 5 个物体的 1 < ? < 3 显示多个静止框架近红外氢帕邢线，以及 5 个物体在 5 < ? < 9 显示静止框架光学氧气和氢气巴尔默线。对于 5 个较高红移的星系，我们提取 6 个 NIRCam 波段的通量，跨越 ?观测值 = 0 。 8 − 5 ? m 并使用这些数据结合现有的 HST 光度测量进行光谱能量分布拟合。 7 < ? < 9 个物体在 F277W、F356W 和 F444W 波段上呈现出 U 形图案，表明在发射中存在巴尔默断裂（巴尔默跳跃）和高当量宽度 [O iii] 发射。这表明恒星种群极其年轻，目前的大部分质量是在过去 10 密尔内形成的。我们根据光谱拟合报告了强大的恒星质量和平均恒星年龄，其中四个？ > 6 个星系表现出低恒星质量，从 log 10 ( ? ∗ / M (cid:12) ) = 7 开始。 4-8。 6 和相应的年轻平均恒星年龄只有几密尔。这项工作强调了将即将进行的大型 NIRCam 调查与 NIRSpec 后续行动相结合以测量严格限制物理参数所需的光谱红移的至关重要性。
We present a first-look analysis of the JWST ERO data in the SMACS J0723.3-7327 cluster field. We begin by reporting 10 new spectroscopic redshifts from ? obs = 1 . 8 − 5 . 2 ? m NIRSpec medium-resolution ( ? = ? / Δ ? = 1000) data. These are all determined via multiple high-SNR emission line detections, with 5 objects at 1 < ? < 3 displaying multiple rest-frame near-infrared Hydrogen Paschen lines, and 5 objects at 5 < ? < 9 displaying rest-frame optical Oxygen and Hydrogen Balmer lines. For the 5 higher-redshift galaxies we extract fluxes in 6 NIRCam bands spanning ? obs = 0 . 8 − 5 ? m and perform spectral energy distribution fitting using these data in combination with existing HST photometry. The 7 < ? < 9 objects exhibit a U-shaped pattern across the F277W, F356W and F444W bands, indicating the presence of a Balmer break seen in emission (Balmer jump) and high-equivalent-width [O iii] emission. This is indicative of an extremely young stellar population, with the bulk of the current mass having formed within the past 10 Myr. We report robust stellar masses and mean stellar ages from our spectral fitting, with the four ? > 6 galaxies exhibiting low stellar masses from log 10 ( ? ∗ / M (cid:12) ) = 7 . 4 − 8 . 6 and correspondingly young mean stellar ages of only a few Myr. This work highlights the critical importance of combining large upcoming NIRCam surveys with NIRSpec follow-up to measure the spectroscopic redshifts necessary to robustly constrain physical parameters.