暗能量光谱仪中的氮强发射类星体。I. 样本选择与基本性质
Nitrogen-Loud Quasars from the Dark Energy Spectroscopic Instrument. I. Sample Selection and Basic Properties
- National Astronomical Observatories, Chinese Academy of Sciences（中国科学院国家天文台）
- Technology and Engineering Center for Space Utilization, Chinese Academy of Sciences（中国科学院空间应用工程与技术中心）
- School of Physics and Technology, Nanjing Normal University（南京师范大学物理与电子工程学院）
- School of Astronomy and Space Science, University of Chinese Academy of Sciences（中国科学院大学天文与空间科学学院）
- Institute of High Energy Physics, Chinese Academy of Sciences（中国科学院高能物理研究所）
机构由 AI 辅助整理，请以论文原文为准。
AI总结：
利用DESI数据构建了包含1,993个氮强发射类星体的最大样本，发现其具有更窄的发射线、更低黑洞质量和更高爱丁顿比率，可能处于快速吸积阶段。
AI中文摘要：
我们展示了迄今为止最大的氮强发射（N-loud）类星体样本，这些类星体在红移范围 $1.6 < z < 4.3$ 内具有强的宽 N IV] $\lambda1486$ 和/或 N III] $\lambda1750$ 发射线，样本选自暗能量光谱仪（DESI）第一版数据发布。最终样本包含 1,993 个氮强发射类星体，约占母类星体样本的 1.2%。氮强发射类星体的 $L_{1450}$ 分布与 DESI 母样本大致相似，但其红移分布不同，在 $z \sim 2.5$--3 附近有更强的集中。它们的复合光谱显示出与母类星体大致相似的紫外连续谱形状，同时表现出显著增强的宽氮发射特征，包括 N V、N IV] 和 N III]。其他金属发射特征也显示出中等程度的增强。相对于在红移和紫外连续谱光度上匹配的对照样本，氮强发射类星体表现出系统性地更窄的宽 C IV 和 Mg II 发射线、更低的单历元维里黑洞质量以及更高的爱丁顿比率，这表明氮强发射类星体可能优先出现在相对快速的黑洞吸积阶段。射电强比例为 10.1%，其中同时表现出 N III] 和 N IV] 发射的天体比例最高。该星表为未来研究氮增强及其物理起源提供了统计基线。
英文摘要：
We present the largest sample to date of nitrogen-loud (N-loud) quasars with strong broad N IV] $\lambda1486$ and/or N III] $\lambda1750$ emission lines over the redshift range $1.6 < z < 4.3$, selected from the Dark Energy Spectroscopic Instrument (DESI) Data Release 1. The final sample contains 1,993 N-loud quasars, corresponding to about 1.2% of the parent quasar sample. The $L_{1450}$ distribution of the N-loud quasars is broadly similar to that of the DESI parent sample, but their redshift distribution is distinct, with a stronger concentration around $z \sim 2.5$--3. Their composite spectrum displays a broadly similar UV continuum shape to that of the parent quasars, while showing significantly enhanced broad nitrogen emission features, including N V, N IV], and N III]. Other metal emission features also show a moderate enhancement. Relative to a control sample matched in redshift and UV continuum luminosity, the N-loud quasars show systematically narrower broad C IV and Mg II emission lines, lower single-epoch virial black hole masses, and higher Eddington ratios, suggesting that N-loud quasars may preferentially appear during a relatively rapid black hole accretion phase. The radio-loud fraction is 10.1%, with the highest fraction among objects exhibiting both N III] and N IV] emission. The catalog provides a statistical baseline for future studies of nitrogen enhancement and its physical origin.
