Time Coordinate: 3:30 pm 7th Oct. 2016 (Friday)

Space Coordinate: NTHU General Building II, R521

Speaker: Dr. Po-Chieh Yu (NCU)

Title: Investigations of AGNs: From Seyfert to QSOs

Abstract:
The reason of non-detection of polarized broad-line regions (BLRs) in some Seyfert 2 galaxies (non-HBLR) remains a mystery. Using integral field unit OSIRIS of Keck plus adaptive optics, we probe local Seyfert 2 galaxies down to scales of 5-30 parsecs. With these K-band data, we can study nuclear stellar populations, molecular gas, and ionized gas within the central few hundred parsecs of the HBLR and non-HBLR Seyfert2 galaxies.

Furthermore, some QSOs have the similar phenomena; the BLRs disappear in changing-look QSOs with the decreasing of continuum flux. The mechanisms causing the disappearance of BLRs are still unclear. To extend the sample, we have searched for changing-look QSOs using photometric data of Palomar Transient Factory (PTF), Sloan Digital Sky Survey (SDSS), and Pan-STARRS, along with the spectra of SDSS and LAMOST. I will also present preliminary results of our survey.