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arXiv 2012.15572astro-ph.GA
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变视活动星系核NGC 3516的混响映射

Reverberation Mapping of Changing-look Active Galactic Nucleus NGC 3516

Hai-Cheng. Feng, Chen. Hu, Sha-Sha. Li, H. T. Liu, J. M. Bai, Li-Feng. Xing, Wei-Yang. Wang, Zi-Xu. Yang, Ming. Xiao, Kai-Xing. Lu

摘要:

宽谱线的变化是理解变视活动星系核物理性质的关键。在这里,我们提出了一个密集的和均匀的6个月长的混响映射(RM)监测活动期间的CL-AGN塞弗特星系NGC 3516的低活动状态的结果。在2018- 2019年期间,使用丽江2.4米望远镜进行了光度和光谱监测。多数夜晚采样2天,平均采样$\sim$ 3天。H $α$和H $β$的静息帧时滞分别为$τ_{\rm{H}α}=7.56^{+4.42}_{-2.10}$天和$τ_{\rm{H}β}=7.50^{+2.05}_{-0.77}$天。根据RMS H $β$线色散$σ_{\rm{line}} = 1713.3 \pm 46.7$ $\rm{km}$ $\rm{s^{-1}}$和$f_σ$ = 5.5的维里因子,我们估计NGC 3516中心黑洞质量为$M_{\rm{BH}}= 2.4^{+0.7}_{-0.3} \times 10^{7} M_{\odot}$,这与以前的估计是一致的。速度分辨延迟表明,H $α$和H $β$的时间滞后增加向负速度。首次对H PDMATHAMN进行了速度分辨RM。这些RM结果与谱型变化前的观测结果一致,表明在谱型变化过程中,BLR结构基本不变。吸积率变化的CL模型似乎是有利于长期的H $β$可变性和RM观测的NGC 3516。

英文摘要:

The changes of broad emission lines should be a crucial issue to understanding the physical properties of changing-look active galactic nucleus (CL-AGN). Here, we present the results of an intensive and homogeneous 6-month long reverberation mapping (RM) monitoring campaign during a low-activity state of the CL-AGN Seyfert galaxy NGC 3516. Photometric and spectroscopic monitoring was carried out during 2018--2019 with the Lijiang 2.4 m telescope. The sampling is 2 days in most nights, and the average sampling is $\sim$3 days. The rest frame time lags of H$α$ and H$β$ are $τ_{\rm{H}α}=7.56^{+4.42}_{-2.10}$ days and $τ_{\rm{H}β}=7.50^{+2.05}_{-0.77}$ days, respectively. From a RMS H$β$ line dispersion of $σ_{\rm{line}} = 1713.3 \pm 46.7$ $\rm{km}$ $\rm{s^{-1}}$ and a virial factor of $f_σ$ = 5.5, the central black hole mass of NGC 3516 is estimated to be $M_{\rm{BH}}= 2.4^{+0.7}_{-0.3} \times 10^{7} M_{\odot}$, which is in agreement with previous estimates. The velocity-resolved delays show that the time lags increase towards negative velocity for both H$α$ and H$β$. The velocity-resolved RM of H$α$ is done for the first time. These RM results are consistent with other observations before the spectral type change, indicating a basically constant BLR structure during the changing-look process. The CL model of changes of accretion rate seems to be favored by long-term H$β$ variability and RM observations of NGC 3516.

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