AI 中文总结
研究289个低吸积FR I型射电星系样本，发现多数源吸积率低，标准ADAF机制下喷流功率预测值低于观测值。磁捕获盘情形可解释强大喷流，样本数据表明其在不同光度的FR I星系中常见，扩展了对MAD的认知。
AI 中文摘要
我们研究了从LOFAR两米天空调查（LoTSS）DR1中选出的289个Fanaroff-Riley I型（FR I）射电星系样本，通过其边缘变暗的射电形态识别。利用斯隆数字巡天（SDSS）DR17的光学测光和光谱，得出爱丁顿标度吸积率范围为-6.84 < log $\dot{m}$ < -0.87（中位数≈ -2.84）。绝大多数源低于$\dot{m}$ = 0.01，表明其中心引擎可用对流主导吸积流（ADAFs）很好描述。然而，即使对于a = 0.95的快速旋转黑洞，标准ADAF regime中 Blandford-Znajek机制预测的最大喷流功率仍低于约70%样本的观测喷流功率（由151 MHz射电光度估计）。我们证明磁捕获盘（MAD）情形，即大规模极向磁通量在事件视界附近积累，能完全解释这些低吸积系统中观测到的强大喷流。在MAD框架内，数据与a < 0.5的慢旋转黑洞一致。这个从LoTSS均匀选择的大样本扩展了先前为明亮 的3CR FR I群体建立的MAD要求，表明磁捕获盘在广泛光度范围内的FR I射电星系中很常见。
英文摘要
We study a sample of 289 Fanaroff-Riley type I (FR I) radio galaxies selected from the LOFAR Two-Metre Sky Survey (LoTSS) DR1, identified by their edge-darkened radio morphologies. Using Sloan Digital Sky Survey (SDSS) DR17 optical photometry and spectroscopy, we derive Eddington-scaled accretion rates spanning -6.84 < log $\dot{m}$ < -0.87 (median $\approx$ -2.84). The vast majority of sources lie below $\dot{m}$ = 0.01, indicating that their central engines are well described by advection-dominated accretion flows (ADAFs). However, even for a rapidly spinning black hole with a = 0.95, the maximum jet power predicted by the Blandford-Znajek mechanism in the standard ADAF regime is lower than the observed jet power (estimated from 151 MHz radio luminosity) for approximately 70% of the sample. We demonstrate that the magnetically arrested disc (MAD) scenario, in which large-scale poloidal magnetic flux accumulates near the event horizon, can fully account for the powerful jets observed in these low-accretion systems. Within the MAD framework, the data are consistent with slow-spinning black holes with $a < 0.5$. This large, uniformly selected LoTSS sample extends the MAD requirement previously established for the bright 3CR FR I population, indicating that magnetically arrested discs are common in FR I radio galaxies across a wide range of luminosities.
