Spectroscopy of CASSOWARY gravitationally lensed galaxies in SDSS: characterization of an extremely bright reionization-era analogue at z = 1.42
Spectroscopy of CASSOWARY gravitationally lensed galaxies in SDSS: characterization of an extremely bright reionization-era analogue at z = 1.42
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SDSS 中食火鸡引力透镜星系的光谱：z = 1.42 处极其明亮的再电离时代类似物的表征
DOI：
10.1093/mnras/stad387
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发表时间：
2023
影响因子：
4.8
通讯作者：
Rigby, Jane R.
中科院分区：
文献类型：
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作者：
Mainali, Ramesh;Stark, Daniel P.;Jones, Tucker;Ellis, Richard S.;Hezaveh, Yashar D.;Rigby, Jane R.
我们提出了从食火鸡巡天中选出的 16 个明亮（r= 19-21）引力透镜星系 atz≃ 1-3 的新观测结果。我们的样本中包括 z= 1.42 星系 CSWA-141，它是已知最亮的高红移 (g = 20.5) 的再电离时代类似物之一，具有较大的特定恒星形成率 (31.2 Gyr−1) 和 [Oiii]+Hβ 等效宽度 (EW[Oiii] + H β= 730 Å)，几乎与 atz≃ 预期平均值相同7-8。在本文中，我们研究了样品中的静止帧紫外星云线发射，目的是了解调节强 Ciii] 发射的因素。尽管我们样本中的大多数光源都显示出较弱的紫外线发射，但我们发现 CSWA-141 光谱中的 Ciii] 升高 (EWCiii]= 4.6 ± 1.9 Å)，并检测到其他突出的发射线 (Oiii]、Siiii]、Feii⋆、Mgii)。我们比较了具有强和弱 Ciii] 发射的高红移星系的其余光学线特性，发现具有最强紫外线发射的系统往往具有年轻的恒星群体和中度贫金属和高度电离的星云气体，这与低红移和高红移的趋势一致。 CSWA-141 的亮度使得能够对常见 atz> 6 的极端发射线星系进行详细研究。我们发现 Ciii] 双峰追踪的气体可能探测到比 [Oii] 和 [Sii] 追踪的气体更高的密度。光谱解析的 Mgi 发射线和几条低电离吸收线的表征表明，年轻恒星周围的中性气体可能在光学上很薄，可能有助于电离辐射的逃逸。
We present new observations of 16 bright (r= 19–21) gravitationally lensed galaxies atz≃ 1–3 selected from the CASSOWARY survey. Included in our sample is thez= 1.42 galaxy CSWA-141, one of the brightest known reionization-era analogues at high redshift (g = 20.5), with a large specific star formation rate (31.2 Gyr−1) and an [Oiii]+Hβ equivalent width (EW[Oiii] + H β= 730 Å) that is nearly identical to the average value expected atz≃ 7–8. In this paper, we investigate the rest-frame UV nebular line emission in our sample with the goal of understanding the factors that regulate strong Ciii] emission. Although most of the sources in our sample show weak UV line emission, we find elevated Ciii] in the spectrum of CSWA-141 (EWCiii]= 4.6 ± 1.9 Å) together with detections of other prominent emission lines (Oiii], Siiii], Feii⋆, Mgii). We compare the rest-optical line properties of high-redshift galaxies with strong and weak Ciii] emission, and find that systems with the strongest UV line emission tend to have young stellar populations and nebular gas that is moderately metal-poor and highly ionized, consistent with trends seen at low and high redshift. The brightness of CSWA-141 enables detailed investigation of the extreme emission line galaxies which become common atz> 6. We find that gas traced by the Ciii] doublet likely probes higher densities than that traced by [Oii] and [Sii]. Characterization of the spectrally resolved Mgiiemission line and several low-ionization absorption lines suggests neutral gas around the young stars is likely optically thin, potentially facilitating the escape of ionizing radiation.