Oral Presentation
Updated AGN Picture with Dusty/Dust-free Gas Structures and Effects of the Radiation Pressure
Presenter: Shoichiro Mizukoshi (the University of Tokyo)
We investigate the properties of two gas structures of active galactic nuclei (AGNs), i.e., dusty and dust-free gas components, by separating them with the line-of-sight dust extinction (Av) and the neutral gas column density (NH). We find that the typical column density of the dusty and dust-free gas is different depending on the Seyfert type, indicating that both structures have anisotropic column density distributions. The number of targets with the dusty gas column density (NH,d) of log(NH,d) [cm−2] > 23 is much smaller than that with the same column density of the dust-free gas. This result indicates that the optically-thick part of the dusty gas structure is very thin. There are very few targets with a larger Eddington ratio ( f_Edd) than the effective Eddington limit of the dusty gas and the covering factor of the dusty gas with 22 ≤ log(NH,d) [cm−2] < 24 shows a clear drop at the effective Eddington limit. These results support the scenario in which the covering factor of the dusty torus decreases in a high Eddington ratio due to the radiation-driven dusty gas outflow. The covering factor of the dust-free gas with the column density (NH,df) of 22 ≤ log(NH,df) [cm−2] < 24 similarly shows the decrease in high Eddington ratio, while it might be due to the dust-free gas outflow driven by some other mechanisms than the radiation pressure. Finally, we propose an updated picture of the AGN gas structure based on our results and Ricci et al. (2017).
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