GA-NIFS: sRMS，一种用于分解积分场光谱中已分辨与未分辨发射的新方法及其在遥远类星体中的应用

中文摘要 AI 辅助

在1型活动星系核（AGN）中，对发射线轮廓的解释常因明亮、空间上未分辨的核连续谱和宽线区（BLR）发射主导了来自窄线区（NLR）和宿主星系的较窄且混合的成分而变得复杂。即使使用积分场光谱（IFS），这一挑战依然存在，因为相关的空间变化可能发生在比角分辨率更小的尺度上，尤其是在遥远AGN的致密宿主中。我们引入了空间均方根（sRMS）技术，这是一种分析单历元IFS的新方法，利用从部分重叠孔径提取的光谱的空间方差来隔离高红移BL-AGN的核外发射，并研究由此产生的运动学信息是否能够改善对其积分光谱的分解。我们构建了以未分辨核为中心的多个重叠孔径集合的sRMS光谱。在孔径探测的尺度上空间不变的发射因此被抑制，而空间变化的发射则被保留。我们将该过程应用于两个z~6.5类星体的JWST/NIRSpec数据。我们用多个高斯分量对所得的sRMS光谱进行建模，以确定空间变化发射的运动学，并利用这些运动学约束对积分光谱进行建模。sRMS技术识别出尺度比NIRSpec点扩散函数（PSF）小约5倍的空间变化窄线发射，并为各个运动学分量提供了稳健的运动学约束。将这些运动学约束施加于积分光谱拟合中，显著减少了多分量分解的简并性。模拟进一步展示了该方法探测紧密双BL-AGN中空间偏移BLR发射的潜力，在z~6.5时，对于BLR通量比约为10的双源，可探测到投影间距低至约200 pc的发射。

英文摘要

The interpretation of AGN emission-line profiles in type1 AGN is often complicated by the dominance of bright, spatially unresolved nuclear continuum and broad-line region (BLR) emission over narrower and blended components from the narrow-line region (NLR) and the host galaxy. This remains challenging even with integral-field spectroscopy (IFS), as the relevant spatial variations can occur on scales smaller than the angular resolution, particularly in the compact host of distant AGN. We introduce the spatial root-mean-square (sRMS) technique, a new approach to analyse single-epoch IFS that uses the spatial variance of spectra extracted from partially overlapping apertures to isolate off-nuclear emission of high-z BL-AGN, and investigate whether the resulting kinematic information can improve the decomposition of their integrated spectra. We construct sRMS spectra from ensembles of overlapping apertures centred on the unresolved nucleus. Emission that is spatially invariant on the scales probed by the apertures is consequently suppressed, whereas spatially varying emission is retained. We apply the procedure to JWST/NIRSpec data of two z~6.5 QSOs. We model the resulting sRMS spectra with multiple Gaussian components to determine the kinematics of the spatially varying emission, and use these kinematic constraints to model the integrated spectra. The sRMS technique identifies spatially varying narrow-line emission on scales up to ~5x smaller than the NIRSpec PSF and provides robust constraints on the kinematics of individual kinematic components. Imposing these kinematic constraints on the integrated-spectrum fit reduces significantly the degeneracy of multi-component decompositions. Simulations further demonstrate the potential of the method to detect spatially offset BLR emission from close dual BL-AGN, down to projected separations of ~200 pc at z~6.5 for a BLR flux ratio of ~10.

发表机构

• Centro de Astrobiología (CAB), CSIC–INTA（天体生物学中心（CAB），西班牙国家航空航天技术研究所-西班牙国家研究委员会）
• Departamento de Física de la Tierra y Astrofísica, Facultad de Ciencias Físicas, Universidad Complutense de Madrid（马德里康普顿斯大学物理科学学院地球与天体物理学系）
• Max-Planck-Institut für extraterrestrische Physik (MPE)（马克斯·普朗克地外物理研究所）
• INAF - Osservatorio Astrofisico di Arcetri（意大利国家天体物理研究所阿切特里天文台）
• European Space Agency（欧洲空间局）
• Department of Physics, University of Oxford（牛津大学物理系）

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