宇宙黎明时期的射电类星体：来自DESI巡天的光谱样本
Radio Quasars in the Cosmic Dawn: A Spectroscopic Sample from the DESI Survey
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中文总结 AI 辅助
基于DESI巡天数据，构建了4.7<z<6.7最大的射电类星体光谱样本，识别出83个高红移射电类星体，其中26个为射电噪，其射电发射由喷流主导，与射电未探测类星体在光谱特性上总体相似，表明强大的射电喷流在z~5时已充分形成。
中文摘要 AI 辅助
我们呈现了迄今为止最大的4.7<z<6.7射电类星体统计光谱样本。这些天体选自一个专门的暗能量光谱仪（DESI）目标项目，为研究射电喷流对早期类星体演化的影响提供了可靠的样本。利用来自LOFAR两米巡天第三期数据发布（LoTSS-DR3）在144 MHz的低频射电数据，我们识别出83个高红移射电类星体，其中26个被归类为射电噪（占646个确认高红移类星体的5-15%，定义为$R = F_{5\text{GHz}}/F_{4400A} >10$）。这些类星体的射电光度约为$\sim10^{25-28}$ W/Hz，其射电发射预计由喷流主导，而非恒星形成活动。对其静止系紫外（UV）光谱的分析显示，与射电未探测到的类星体相比，其复合光谱特性和CIV速度偏移总体相似。射电探测和射电噪类星体平均表现出略小的Ly$\alpha$和CIV等值宽度，然而，我们没有发现显著证据（$\sim1.3σ$）表明弱线类星体（WLQs）的比例更高（射电噪类星体约10±4%，而射电未探测类星体约4±1%）。我们进一步发现，宽吸收线（BAL）类星体主要为射电静，且吸收指数与射电噪度之间未观察到相关性，这表明射电发射并非由BAL外流本身产生，两者是物理上不同的现象。我们的结果表明，强大的射电喷流在z~5时已经充分形成。
英文摘要
We present the largest statistical spectroscopic sample of radio quasars at 4.7<z<6.7 to date. These have been selected from a dedicated Dark Energy Survey Instrument (DESI) target program and provide a robust sample to study the influence of radio jets on early quasar evolution. Using low-frequency radio data from the LOFAR Two Metre Sky Survey Data Release 3 (LoTSS-DR3) at 144 MHz, we identify 83 high-z radio quasars, 26 of which are classified as radio-loud (5-15% of 646 confirmed high-z quasars, defined as $R = F_{5\text{GHz}}/F_{4400A} >10$). With radio luminosities of $\sim10^{25-28}$ W/Hz, the radio emission in all 83 quasars is expected to be jet-dominated rather than powered by star formation. Analysis of their rest-frame ultra-violet (UV) spectra reveals broadly similar composite spectral properties and CIV velocity shifts compared to radio non-detected quasars. The radio-detected and radio-loud quasars exhibit slightly smaller Ly$α$ and CIV equivalent widths on average, however, we find no significant evidence ($\sim1.3σ$) for a higher fraction of weak-line quasars (WLQs; ~10+/-4% versus ~4+/-1% for radio non-detected quasars). We further find that the broad absorption line (BAL) quasars are predominantly radio-quiet, and no correlation is observed between absorption index and radio-loudness, suggesting that radio emission is not produced by the BAL outflows themselves and are physically distinct phenomena. Our results demonstrate that powerful radio jets were already well-established by z~5.
发表机构
- NSF NOIRLab, Gemini Observatory（美国国家光学-红外天文研究实验室，双子座天文台）
- Department of Astronomy, University of Michigan（密歇根大学天文学系）
- Centre for Extragalactic Astronomy, Department of Physics, Durham University（杜伦大学物理系河外天文中心）
- NSF NOIRLab（美国国家光学-红外天文研究实验室）
- Steward Observatory, University of Arizona（亚利桑那大学斯图尔德天文台）
- European Southern Observatory (ESO)（欧洲南方天文台）
- School of Mathematics, Statistics and Physics, Newcastle University（纽卡斯尔大学数学、统计与物理学院）
- Centre for Astrophysics Research, Department of Physics, Astronomy and Mathematics, University of Hertfordshire（赫特福德大学物理、天文与数学学院天体物理研究中心）
- Leiden Observatory, Leiden University（莱顿大学莱顿天文台）
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