Oral Presentation

Probing the origin of broad line region by reverberation mapping of an extremely variable

Author(s): Shumpei Nagoshi (Kyoto University)

Presenter: Shumpei Nagoshi (Kyoto University)

We performed reverberation mapping to J1258 with optical spectroscopy to investigate the structure of the broad line region and to measure the black hole mass. We also measured the time-lag between the WISE light curve and the optical light curve to estimate the size of the dust torus. In addition, we compared optical to X-ray spectral indices ($\alpha_{\rm{ox}}$) before and after the state transition to investigate the structure difference of the accretion disk.
The results of the reverberation mapping show that the Eddington ratio crossed the value of 0.01 before and after state transition for the black hole mass of $10^{9.46^{+0.15}_{-0.19}}\rm{M_\odot}$. The variations in $\alpha_{\rm{ox}}$ and the Eddington ratio were consistent with those predicted from the instability of the accretion disk caused by hydrogen ionization. From the viewpoint of the broad line region, we confirmed the existence of two distinct rotating/inflowing components located near the dust torus. After we discuss the origin of these line-emitting regions, we suggest that these components originate from rotating/inflowing gases located near the dust torus generated by different processes.