The Prevalence of Gas Outflows in Type 2 AGNs. II. 3D Biconical Outflow Models

TL;DR

This study develops 3D biconical outflow models with dust to analyze ionized gas kinematics in type 2 AGNs, constraining outflow velocities and geometries by comparing simulations with observations.

Contribution

The paper introduces a comprehensive 3D modeling approach that links outflow parameters with observed gas kinematics in a large AGN sample, advancing understanding of AGN-driven outflows.

Findings

Intrinsic outflow velocities range from ~500 to 2000 km/s.

Velocity dispersion increases with intrinsic velocity and bicone inclination.

Wider outflow opening angles are associated with higher intrinsic velocities.

Abstract

We present 3D models of biconical outflows combined with a thin dust plane for investigating the physical properties of the ionized gas outflows and their effect on the observed gas kinematics in type 2 active galactic nuclei (AGNs). Using a set of input parameters, we construct a number of models in 3D and calculate the spatially integrated velocity and velocity dispersion for each model. We find that three primary parameters, i.e., intrinsic velocity, bicone inclination, and the amount of dust extinction, mainly determine the simulated velocity and velocity dispersion. Velocity dispersion increases as the intrinsic velocity or the bicone inclination increases, while velocity (i.e., velocity shifts with respect to systemic velocity) increases as the amount of dust extinction increases. Simulated emission-line profiles well reproduce the observed [O III] line profiles, e.g., a narrow core and a broad wing components. By comparing model grids and Monte Carlo simulations with the observed [O III] velocity-velocity dispersion (VVD) distribution of ~39,000 type 2 AGNs, we constrain the intrinsic velocity of gas outflows ranging from ~500 km/s to ~1000 km/s for the majority of AGNs, and up to ~1500-2000 km/s for extreme cases. The Monte Carlo simulations show that the number ratio of AGNs with negative [O III] velocity to AGNs with positive [O III] velocity correlates with the outflow opening angle, suggesting that outflows with higher intrinsic velocity tend to have wider opening angles. These results demonstrate the potential of our 3D models for studying the physical properties of gas outflows, applicable to various observations, including spatially integrated and resolved gas kinematics.