通过光谱比对，发现遥远与近处类星体有相似特征，或可互为代理研究宇宙演化。
Identifying Doppelganger Active Galactic Nuclei across redshifts from spectroscopic surveys
- 从斯隆巡天数据中筛选出光谱高度相似的类星体对，寻找跨红移的‘双生’现象。
- 在135nm~510nm波段及多条发射线（如C IV、Mg II）上发现多组光谱匹配样本。
- 为研究高红移类星体提供本地观测代理，适合星系演化与活动星系核研究者。
活动星系核（AGN）是宇宙中最明亮的天体之一，是研究星系演化的关键探针。然而，理解其性质随宇宙时间的演化仍是重大挑战。本研究探讨低红移（近处）类星体能否作为高红移（遥远）类星体的代理，通过识别光谱‘双生子’——即虽相隔巨大宇宙距离但发射线特性极为相似的类星体。我们基于斯隆数字巡天数据发布16版（SDSS DR16），分析了真实类星体的关键光谱特征，包括连续谱及氮（N V）、碳（C IV）、镁（Mg II）、氢-beta（Hβ）和铁（Fe II，光学与紫外波段）等发射线。纳入参数包括等效宽度、速度弥散（以半高全宽FWHM表示）以及135nm、300nm、510nm波段的连续谱光度。初步结果显示存在多组光谱高度相似的类星体，暗示本地类星体可能与高红移类星体具有相似的内在属性。本文展示了一组分析结果中的较优候选双生类星体对。
原文摘要 · Abstract (English)
Active Galactic Nuclei (AGNs) are among the most luminous objects in the universe, making them valuable probes for studying galaxy evolution. However, understanding how AGN properties evolve over cosmic time remains a fundamental challenge. This study investigates whether AGNs at low redshift (nearby) can serve as proxies for their high-redshift (distant) counterparts by identifying spectral 'doppelgängers', AGNs with remarkably similar emission line properties despite being separated by vast cosmic distances. We analyze key spectral features of bona fide AGNs using the Sloan Digital Sky Survey's Data Release 16, including continuum and emission lines: Nitrogen (N V), Carbon (C IV), Magnesium (Mg II), Hydrogen-beta (H$β$), and Iron (Fe II - optical and UV) emission lines. We incorporated properties such as equivalent width, velocity dispersion in the form of full width at half maximum (FWHM), and continuum luminosities (135nm, 300nm, and 510nm) closest to these prominent lines. Our initial findings suggest the existence of multiple AGNs with highly similar spectra, hinting at the possibility that local AGNs may indeed share intrinsic properties with high-redshift ones. We showcase here one of the better candidate pairs of AGNs resulting from our analyses.
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