2023-04-07 Abstract

Title: Changing-State AGNs: Accretion Driven Event?
Speaker:  Arghajit Jana
Date: April 7 at 14:30
Location: R521, General Building II
Changing state active galactic nuclei (CS-AGNs) are a new subset of AGN that challenge our current understanding of the unification model of AGN. They switch between type-1 and type-2 AGN, characterized by the appearance and/or disappearance of the broad emission lines in their optical spectra. Although the exact reasons for the CS behavior is highly debated, various models are proposed to explain the CS event, such as tidal disruption event, changes in accretion rate, obscuration in the line of sight etc. To put constraints on the various models proposed for the CS behavior, we carried out a systematic investigation on a sample of CS-AGNs in the local universe, using optical and X-ray observations. We find that the change in the accretion rate could explain the CS-AGNs in most cases.