Ultraviolet/Optical Emission of the Ionized Gas in AGN: Diagnostics of the Ionizing Source and Gas Properties

Abstract

Spectroscopic studies of active galactic nuclei (AGN) are powerful means of probing the physical properties of the ionized gas within them. In particular, near future observational facilities, such as the James Webb Space Telescope (JWST), will allow detailed statistical studies of rest-frame ultraviolet and optical spectral features of the very distant AGN with unprecedented accuracy. In this proceedings, we discuss the various ways of exploiting new dedicated photoionization models of the narrow-line emitting regions (NLR) of AGN for the interpretation of forthcoming revolutionary datasets.

Can nebular He II emission be explained by ultra-luminous X-ray sources?

“…This parameter is proportional to the ratio of ionising photons to total hydrogen density, and the range was chosen in order to span the observed range of the main relative line intensities, as commonly adopted in the literature (e.g. Feltre et al 2017;Ji et al 2020;Ramambason et al 2020). The models have a closed geometry and are ionisation bounded, that is to say the calculation stops when the hydrogen ionisation front is reached.…”

Can nebular HeII emission be explained by ultra-luminous X-ray sources?

“…This parameter is proportional to the ratio of ionising photons to total hydrogen density, and the range was chosen in order to span the observed range of the main relative line intensities, as commonly adopted in the literature (e.g. Feltre et al 2017;Ji et al 2020;Ramambason et al 2020). The models have a closed geometry and are ionisation bounded, i.e.…”