On time variability and other complications in studying the UV broad absorption lines of quasars: results from numerical simulations of radiation driven disk winds

TL;DR

This paper reviews axisymmetric, time-dependent hydrodynamical simulations of radiation-driven disk winds in AGN, demonstrating their ability to replicate observed UV broad absorption lines, variability, and complex wind geometries.

Contribution

It provides new insights into the physical and geometrical properties of AGN disk winds through detailed simulations that match observational features.

Findings

Simulated line profiles resemble observed quasar broad absorption lines.

Time-dependent simulations explain observed UV line variability.

Predicted intensity maps support partial, inhomogeneous wind coverage.

Abstract

We review the main results from axisymmetric, time-dependent hydrodynamical simulations of radiation driven disk winds in AGN. We illustrate the capability of such simulations to provide useful insights into the three domains of observational astronomy: spectroscopy, time-variability, and imaging. Specifically, the synthetic line profiles predicted by the simulations resemble the broad absorption lines observed in quasars. The intrinsically time dependent nature of radiation driven disk winds that have been predicted by the simulations can be supported by a growing number of the observed dramatic variability in the UV absorption lines. And finally, the intensity maps predicted by the simulations give physical and geometrical justification to the phenomenologically deduced fact that a proper interpretation of the observed line absorption requires the wind covering factor to be considered as being partial, inhomogeneous, and velocity dependent.