Invited Presentation

Detection of gas between the broad and narrow emission line region in partially obscured quasars

Author(s): Zhenzhen Li (Shanghai Astronomical Observatory) Lei Hao (Shanghai Astronomical Observatory) Hongyan Zhou (University of Science and Technology of China)

Presenter: Zhenzhen Li (Shanghai Astronomical Observatory)

Emission Lines of active galactic nuclei (AGNs) are important probes for detecting gas around the central supermassive black holes. Using these emission lines, two emission line regions have been detected: the broad emission line region (BELR) close to the central black hole and the narrow emission line region (NELR) further away. In contrast, so far detection of emission lines from gas located between these two regions remains uncertain. Some researchers suggest that AGNs may also contain an intermediate-width emission line region (IELR). A consensus, however, is yet to be arrived at due to the lack of convincing evidence for the detection. Partially obscured quasars may provide an effective way to detect the IELR. Using the dusty torus as a natural “coronagraph” to obscure the central BELR, we successfully detected prominent intermediate-width emission lines (IELs) in a partially obscured quasar OI 287. This provides observational basis for the method of detecting IELRs using partially obscured quasars. Futhermore, using larger sky survey data, we have built a sample of similar objects with prominent IELs, which are useful for us to explore the physical properties of the poorly understood IELR.