Evidence for Higher Black Hole Spin in Radio-loud Quasars
Evidence for Higher Black Hole Spin in Radio-loud Quasars
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DOI：
10.3847/1538-4357/aa9181
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发表时间：
2017-10
期刊：
影响因子：
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通讯作者：
A. Schulze;C. Done;Youjun Lu;Fu-Wen Zhang;Y. Inoue
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文献类型：
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作者：
A. Schulze;C. Done;Youjun Lu;Fu-Wen Zhang;Y. Inoue
关于了解活动星系核群的主要未解决的问题之一是无线电安静和无线电响亮类星体之间二分法的起源。最有希望的解释是由自旋范式提供的，该范式表明，射电响亮的类星体具有更高的黑洞自旋。然而，黑洞自旋的测量仍然极具挑战性。我们在这里的目的是比较在0.3 < z < 0.8的情况下，无线电大声和无线电安静的斯隆数字巡天（SDSS）类星体仔细匹配样本的平均辐射效率。我们使用[O iii]光度作为极紫外区电离连续体的间接平均示踪剂，其中由于黑洞自旋导致的光谱能量分布（SED）差异最为明显。我们发现，与红移、黑洞质量、光学连续光度或吸积率相匹配的无线电静音样本相比，无线电大声样本的[O iii]谱线强度增强了至少1.5倍。我们认为这种增强是由SED的差异引起的，这表明在固定的吸积速率下，在射电大声群体中平均辐射光度更高。这表明，相对于射电安静类星体群而言，射电吵闹类星体群的平均系统辐射效率更高，因此黑洞自旋也更高，这为黑洞自旋范式提供了观测支持。
One of the major unsolved questions concerning the understanding of the active galactic nucleus population is the origin of the dichotomy between radio-quiet and radio-loud quasars. The most promising explanation is provided by the spin paradigm, which suggests that radio-loud quasars have a higher black hole spin. However, the measurement of black hole spin remains extremely challenging. We here aim at comparing the mean radiative efficiencies of carefully matched samples of radio-loud and radio-quiet Sloan Digital Sky Survey (SDSS) quasars at 0.3 < z < 0.8 . We use the [O iii] luminosity as an indirect average tracer of the ionizing continuum in the extreme-UV regime where the differences in the spectral energy distribution (SED) due to black hole spin are most pronounced. We find that the radio-loud sample shows an enhancement in [O iii] line strength by a factor of at least 1.5 compared to a radio-quiet sample matched in redshift, black hole mass, and optical continuum luminosity or accretion rate. We argue that this enhancement is caused by differences in the SED, suggesting higher average bolometric luminosities at fixed accretion rate in the radio-loud population. This suggests that the radio-loud quasar population has on average systematically higher radiative efficiencies and therefore higher black hole spin than the radio-quiet population, providing observational support for the black hole spin paradigm.