发表机构
Centro de Estudios de Física del Cosmos de Aragón; Instituto de Astrofísica de Canarias; Universidad de La Laguna（阿拉贡宇宙物理研究中心; 加那利天体物理研究所; 拉帕鲁纳大学）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
利用GTC望远镜上的EMIR光谱仪在Ks波段观测Lyα团块SHARDS20018464，确认其[OIII]双线发射，红移z=3.59±0.01，流量比接近理论值，证实其为新型致密Lyα发射体，支持年轻大质量恒星团光电离情景。
AI 中文摘要
利用位于10.4米GTC望远镜上、配备新升级的H2RG焦平面阵列探测器的红外光谱仪EMIR（Espectrógrafo Multiobjeto Infra-Rojo），对Lyα团块SHARDS20018464进行了光谱后续观测。我们在Ks波段观测了该团块，在文献给出的光度红移z=3.49处，该波段对应静止系可见光部分。得益于EMIR的灵敏度，我们在团块和伴星系的位置上识别出了[OIII]发射双线。探测到的谱线流量约为10^{-17} erg s^{-1} cm^{-2}，通过4小时曝光获得。分别分析两条谱线得到的平均红移为z=3.59±0.01，略高于光度红移，但在不确定度范围内一致。我们还估算了这两条谱线的流量及其比值，发现R=2.92，非常接近理论预测值2.98。这是观测到的发射对应[OIII]双线的有力分析确认。在不确定度范围内，该团块的红移证实了文献中报告的光度红移，以及为其推断的物理性质。其异常小的尺寸（5-8 kpc，而典型样本约为100 kpc）及其位于伴星系一侧的位置，也证实了先前提出的观点：该天体可能是新型致密Lyα发射体的首个例子。此外，数据支持由年轻大质量恒星团引起的光电离情景。
英文摘要
A spectroscopic follow-up of the Ly$α$ blob SHARDS20018464 was performed using the infrared spectrograph EMIR (Espectrógrafo Multiobjeto Infra-Rojo) at the 10.4 m GTC telescope, equipped with its newly upgraded H2RG focal plane array detector. We observed the blob in the Ks band, which corresponds, at the photometric redshift of $z=3.49$ presented in the literature, to the rest-frame visible part of the spectrum. Thanks to the sensitivity of EMIR, we were able to identify the [OIII] emission doublet at the position of the blob and the companion galaxy. The flux of the detected lines is of the order of $10^{-17}$ erg s$^{-1}$ cm$^{-2}$, obtained with 4-hour exposure. The mean redshift derived by analysing the two lines individually is $z=3.59\pm0.01$, slightly higher than the photometric one, although in agreement within the uncertainties. We also estimated the flux of the two lines and their ratio, which was found to be $R = 2.92$, very close to the theoretical prediction of 2.98. This is a strong analytical confirmation that the observed emissions correspond to the [OIII] doublet. Within uncertainties, the redshift of the blob confirms the photometric one reported in the literature, as well as the physical properties inferred for it. Its remarkably small size (5-8 kpc vs. $\sim 100$ kpc for typical samples) and its position aside the companion galaxy also confirm the previously-proposed idea that this object could be the first of a new class of compact Ly$α$ emitters. Moreover, the data support the scenario of photo-ionisation due to a cluster of young and massive stars.
CommentsLetter accepted for publications on A&A. Four pages, four figures and one table
