Lunch talk on Apr. 12, 2021

Photoionization modeling of line emiting/absorbing regions in Active Galactic Nuclei

Speaker: Tek Prasad Adhikari (IUCAA)

Venue: Video conference

Time: 12:30 PM, Monday, Apr. 12, 2021

Abstract: 

From the study of correlation between the continuum and lines variability in Active Galactic Nuclei (AGNs), it is widely accepted that the photoionization is the principal mechanism of emission and absorption lines production. This effect is observed in various AGN components: broad line region, narrow line region, warm absorber and dusty torus, where it is strongly believed that gas is photoionized by the AGN continuum radiation. So, modeling this process of photoionization allows us to constrain various physical properties of the ionized gas in the AGN environment. I will discuss that the photoionization modelling of the ionized gas can be potentially used as a density diagnostic of the absorbing and emitting plasma in AGNs. In particular, the observational properties of AGN: the absorption measure distributions (AMDs) and the line emissivity radial profiles are compared with that from simulations done with the photoionization codes TITAN and CLOUDY. Various aspects of photoionization modelling and its applications focused on AGN environment will be discussed.