论文标题
估计活性银河核的连续体和宽线区域的红色：NGC 5548的平均红色和积聚盘的大小
Estimating reddening of the continuum and broad-line region of active galactic nuclei: the mean reddening of NGC 5548 and the size of the accretion disc
论文作者
论文摘要
We use seven different methods to estimate broad-line and continuum reddenings of NGC 5548. We investigate two possible reddening curves considered for active galactic nuclei (AGNs): the mean AGN reddening curve of Gaskell & Benker (2007) which is relatively flat in the ultraviolet, and a curve that rises strongly into the ultraviolet like a Small Magellanic Cloud (SMC) reddening curve.我们还考虑了标准的银河系曲线。无论采用哪种曲线，我们发现由于太阳能社区中的灰尘而导致的少量变红量大约14倍。紫外线比率排除了NGC 5548的陡峭SMC状红色曲线。银河系和Gaskell＆Benker曲线给出了E（B-V）的平均红色（B-V）= 0.25 +/- 0.02。四个非氢行线变红指标表明，内在的氢线比与贝克 - 墨西尔病例B值一致。未固定的光光谱能量分布与外部释放的吸积盘的预测分布一致。我们针对NGC 5548得出的红色是1型AGN的先前估计值的典型代表。忽略内部灭绝会导致低估了1200埃的亮度七倍。因此，增生光盘的尺寸尺度被低估了约2.6倍。这类似于2013年Agnstorm运动中发现的积聚盘大小的差异，因此支持Gaskell（2017）提出的提议，即增生盘大小的差异主要是由于忽略了红色。
We use seven different methods to estimate broad-line and continuum reddenings of NGC 5548. We investigate two possible reddening curves considered for active galactic nuclei (AGNs): the mean AGN reddening curve of Gaskell & Benker (2007) which is relatively flat in the ultraviolet, and a curve that rises strongly into the ultraviolet like a Small Magellanic Cloud (SMC) reddening curve. We also consider a standard Milky Way curve. Regardless of the curve adopted, we find a total reddening ~14 times greater than the small amount of reddening due to dust in the solar neighbourhood. The UV-to-optical ratios rule out a steep SMC-like reddening curve for NGC 5548. The Milky Way and Gaskell & Benker curves give a mean reddening of E(B-V) = 0.25 +/- 0.02. The four non-hydrogen-line reddening indicators imply that the intrinsic hydrogen line ratios are consistent with Baker-Menzel case B values. The unreddened optical-to-UV spectral energy distribution is consistent with the predicted distribution for an externally-illuminated accretion disc. The reddening we derive for NGC 5548 is typical of previous estimates for type-1 AGNs. Neglecting internal extinction leads to an underestimate of the luminosity at 1200 Angstroms by a factor of seven. The size scale of the accretion disc has therefore been underestimated by a factor of ~2.6. This is similar to the accretion disc size discrepancy found in the 2013 AGNSTORM campaign and thus supports the proposal by Gaskell (2017) that the accretion disc size discrepancy is primarily due to the neglect of reddening.
