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arXiv 1906.11272astro-ph.GA
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混响映射分析是否提供了宽线区域的准确图像?

Do Reverberation Mapping Analyses Provide an Accurate Picture of the Broad Line Region?

S. W. Mangham, C. Knigge, P. Williams, Keith Horne, A. Pancoast, J. H. Matthews, K. S. Long, S. A. Sim, N. Higginbottom

摘要:

混响映射(RM)是确定活动星系核宽线区(BLR)性质的有效方法。然而,从观测到的光谱时间序列推断物理BLR属性是一个困难的逆问题。在这里,我们提出了两个广泛使用的RM方法:MEMEEcho(由Horne开发)和CARAMEL(由Pancoast及其合作者开发)的盲测。测试数据是模拟的光谱时间序列,其跟踪H $α$发射线对经验连续光曲线的响应。基本的BLR模型是一个旋转的,双锥吸积盘风,和合成光谱产生通过自洽电离和辐射转移模拟。我们生成两个模拟数据集,代表塞弗特星系和类星体。塞弗特模型产生了一个很大程度上是负面的反应,这两种方法都无法恢复。但是,两者均未通过$``gracefully''$,也不会产生虚假结果。对于类星体模型,CARAMEL和MEMEcho输出的专家解释都捕捉到了线形成区域的广泛环形,旋转主导的性质,尽管MEMEcho分析高估了其大小50%,但CARAMEL无法区分额外的流入和流出成分。尽管拟合个别光谱很好,CARAMEL速度延迟地图和RMS线轮廓是强烈不一致的输入数据。最后,由于H $α$线形成区域是旋转主导的,所以两种方法都不能恢复基本BLR模型的盘风性质。因此,在解释RM分析的结果时,需要相当小心的物理模型。

英文摘要:

Reverberation mapping (RM) is a powerful approach for determining the nature of the broad-line region (BLR) in active galactic nuclei. However, inferring physical BLR properties from an observed spectroscopic time series is a difficult inverse problem. Here, we present a blind test of two widely used RM methods: MEMEcho (developed by Horne) and CARAMEL (developed by Pancoast and collaborators). The test data are simulated spectroscopic time series that track the H$α$ emission line response to an empirical continuum light curve. The underlying BLR model is a rotating, biconical accretion disc wind, and the synthetic spectra are generated via self-consistent ionization and radiative transfer simulations. We generate two mock data sets, representing Seyfert galaxies and QSOs. The Seyfert model produces a largely *negative* response, which neither method can recover. However, both fail $``gracefully''$, neither generating spurious results. For the QSO model both CARAMEL and expert interpretation of MEMEcho's output both capture the broadly annular, rotation-dominated nature of the line-forming region, though MEMEcho analysis overestimates its size by 50%, but CARAMEL is unable to distinguish between additional inflow and outflow components. Despite fitting individual spectra well, the CARAMEL velocity-delay maps and RMS line profiles are strongly inconsistent with the input data. Finally, since the H$α$ line-forming region is rotation dominated, neither method recovers the disc wind nature of the underlying BLR model. Thus considerable care is required when interpreting the results of RM analyses in terms of physical models.

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