Results from a few decades of reverberation mapping (RM) studies have revealed a correlation between the radius of the broad-line emitting region (BLR) and the continuum luminosity of active galactic nuclei. This "radius-luminosity" relation enables survey-scale black-hole mass estimates across cosmic time, using relatively inexpensive single-epoch spectroscopy, rather than intensive RM time monitoring. However, recent results from newer reverberation mapping campaigns challenge this widely used paradigm, reporting quasar BLR sizes that differ significantly from the previously established radius-luminosity relation. Using simulations of the radius--luminosity relation with the observational parameters of SDSS-RM, we find that this difference is not likely due to observational biases. Instead, it appears that previous RM samples were biased to a subset of quasar properties, and the broader parameter space occupied by the SDSS-RM quasar sample has a genuinely wider range of BLR sizes. We examine the correlation between the deviations from the radius-luminosity relation and several quasar parameters; the most significant correlations indicate that the deviations depend on UV/optical SED and the relative amount of ionizing radiation. Our results indicate that single-epoch black-hole mass estimates that do not account for the diversity of quasars in the radius-luminosity relation could be overestimated by an average of ~0.3 dex.

中文翻译：

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斯隆数字巡天混响映射项目：Hβ 半径-光度关系

几十年的混响映射 (RM) 研究结果表明，宽线发射区 (BLR) 的半径与活动星系核的连续光度之间存在相关性。这种“半径-光度”关系可以使用相对便宜的单历元光谱学，而不是密集的 RM 时间监测，在整个宇宙时间内进行调查尺度的黑洞质量估计。然而，较新的混响映射活动的最新结果挑战了这种广泛使用的范式，报告的类星体 BLR 大小与之前建立的半径-亮度关系有很大不同。使用SDSS-RM 观测参数与半径-光度关系的模拟，我们发现这种差异不太可能是由于观测偏差造成的。反而，看来以前的 RM 样本偏向于类星体特性的一个子集，而 SDSS-RM 类星体样本占据的更广泛的参数空间具有真正更广泛的 BLR 大小范围。我们检查了半径-光度关系的偏差与几个类星体参数之间的相关性；最显着的相关性表明偏差取决于紫外线/光学 SED 和电离辐射的相对量。我们的结果表明，不考虑半径-光度关系中类星体多样性的单纪黑洞质量估计可能被平均高估~0.3 dex。我们检查了半径-光度关系的偏差与几个类星体参数之间的相关性；最显着的相关性表明偏差取决于紫外线/光学 SED 和电离辐射的相对量。我们的结果表明，不考虑半径-光度关系中类星体多样性的单纪黑洞质量估计可能被平均高估~0.3 dex。我们检查了半径-光度关系的偏差与几个类星体参数之间的相关性；最显着的相关性表明偏差取决于紫外线/光学 SED 和电离辐射的相对量。我们的结果表明，不考虑半径-光度关系中类星体多样性的单纪黑洞质量估计可能被平均高估~0.3 dex。