The quasar main sequence appears to be an incredibly powerful tool to organize the diversity in large samples of type-1 quasars but the most important physical parameters governing it are still unclear. Here, we investigate the origin of the broadening and of a defining feature of Population B sources: a strong redward asymmetry of the Balmer emission lines. We focus on a prototypical source, Fairall 9. Spectropolarimetric data of the Fairall 9 broad H β and H α profiles allowed for a view of the geometric and dynamical complexity of the line emitting regions. Measurements (1) provided evidence of rotational motion; (2) were helpful to test the presence of polar and equatorial scatterers, and their association with non-virial motions. However, we suggest that the polarization properties appear to be more consistent with a warped disc geometry induced by Lense–Thirring precession.

中文翻译：

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使用 VLT/FORS2 对 fairall 9 进行线性光谱偏振分析

类星体主序列似乎是一个非常强大的工具，可以组织大型 1 型类星体样本的多样性，但控制它的最重要的物理参数仍不清楚。在这里，我们研究了人口 B 源的扩展和定义特征的起源：巴尔默发射线的强烈的红向不对称。我们专注于一个原型源，Fairall 9。Fairall 9 宽 H β 和 H α 轮廓的光谱极化数据允许查看线发射区域的几何和动态复杂性。测量 (1) 提供了旋转运动的证据；(2) 有助于测试极地和赤道散射体的存在，以及它们与非维里运动的关联。然而，