来自SPHEREx的经验近红外光谱模板：活动星系核与寄主星系辐射的解混
Empirical Near-Infrared Spectral Templates from SPHEREx: Disentangling AGN and Host-Galaxy Emission
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中文总结 AI 辅助
该研究基于SPHEREx巡天数据，开发含14个分量的近红外光谱模板，实现AGN与寄主星系辐射解混，相关系数达0.68，分类准确率最高81.3%，为AGN与寄主星系关联研究提供数据基础。
中文摘要 AI 辅助
SPHEREx开展了首个覆盖0.75-5.0微米的全天近红外光谱巡天，该波段范围涵盖了从寄主星系恒星光到活动星系核（AGN）加热的环面辐射的过渡，可实现活动星系核的光谱认证。我们开发了一种数据驱动框架，将加权非负矩阵分解与正向建模相结合，从北黄道极（NEP）天区的2777个正常星系和1064个AGN中推导经验静止帧模板。得到的14分量字典包含7个星系模板（涵盖恒星族连续谱和星云发射线）和7个AGN模板（捕获发射线以及温暖和炽热的环面连续谱），提供了一种可加的、可操作的分解方式。推导得到的近红外寄主星系占比与独立的SDSS光谱及HSC成像分解结果相关（皮尔逊相关系数r=0.68和r=0.59），与SDSS-HSC的相关性（r=0.66）相当，验证了AGN-寄主星系分离的可靠性。在NEP深场中，相同模板对93.0%的星系和93.5%的AGN的红移恢复精度满足|z_fit - z_spec| < 0.01，且以81.3%的准确率区分星系、窄线AGN和宽线AGN；在全天深度下，分类准确率仍保持72.9%。近红外系数还可标记DESI光谱分类和红移的可疑情况，展现了SPHEREx对光学光谱学的补充作用。该经验字典直接从巡天分光光度测量中学习，覆盖范围超出K波段，填补了近红外至中红外模板的长期空白，为SPHEREx全天巡天中AGN活动及其与寄主星系关联的种群规模研究提供了数据驱动的基础。
英文摘要
SPHEREx conducts the first all-sky near-infrared spectral survey over 0.75-5.0 $μ$m, spanning the transition from host-galaxy starlight to AGN-heated torus emission and enabling spectroscopic identification of active galactic nuclei (AGNs). We develop a data-driven framework combining weighted non-negative matrix factorization with forward modeling to learn empirical rest-frame templates from 2,777 normal galaxies and 1,064 AGNs in the North Ecliptic Pole (NEP) field. The resulting 14-component dictionary contains seven galaxy templates spanning stellar-population continua and nebular emission and seven AGN templates capturing emission lines and warm and hot torus continua, providing an additive, operational decomposition. Inferred near-infrared host fractions correlate with independent SDSS spectral and HSC imaging decompositions (at Pearson $r=0.68$ and $r=0.59$), comparable to the SDSS-HSC correlation ($r=0.66$) and supporting the reliability of the AGN-host separation. In the NEP deep field, the same templates recover redshifts with $|z_{\rm fit}-z_{\rm spec}| < 0.01$ for 93.0% of galaxies and 93.5% of AGNs and distinguish galaxies, narrow-line AGNs, and broad-line AGNs with 81.3% accuracy. At all-sky depth, classification retains 72.9% accuracy. The near-infrared coefficients also flag questionable DESI spectral classifications and redshifts, showing how SPHEREx complements optical spectroscopy. Learned directly from survey spectrophotometry and extending beyond the $K$ band, this empirical dictionary fills a long-standing gap in near-to-mid-infrared templates and provides a data-driven foundation for population-scale studies of AGN activity and its connection to host galaxies across the SPHEREx all-sky survey.
发表机构
- Shanghai Astronomical Observatory, Chinese Academy of Sciences（中国科学院上海天文台）
- University of Science and Technology of China（中国科学技术大学）
- Guizhou University（贵州大学）
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