Probing the role of self-gravity in clouds impacted by AGN-driven winds

TL;DR

This study uses hydrodynamic simulations to investigate how AGN-driven winds influence star-forming clouds, revealing complex interactions that can both suppress and trigger star formation depending on wind strength and properties.

Contribution

It provides new insights into the role of self-gravity in cloud survival and star formation regulation under AGN wind impact, highlighting the importance of wind power and type.

Findings

Self-gravity enhances cloudlet survival during wind interaction.

High-power winds disperse gas but can induce local collapse of cloudlets.

Kinetic winds are more effective than thermal winds in gas acceleration and dispersal.

Abstract

The impact of winds and jet-inflated bubbles driven by active galactic nuclei (AGN) are believed to significantly affect the host galaxy's interstellar medium (ISM) and regulate star formation. To explore this scenario, we perform a suite of hydrodynamic simulations to model the interaction between turbulent star-forming clouds and highly pressurised AGN-driven outflows, focusing on the effects of self-gravity. Our results demonstrate that the cloudlets fragmented by the wind can become gravitationally bound, significantly increasing their survival time. While external pressurisation leads to a global collapse of the clouds in cases of weaker winds ($10^{42}-10^{43}~{\rm erg~s^{-1}}$), higher-power winds ($10^{44}-10^{45}~{\rm erg~s^{-1}}$) disperse the gas and cause localised collapse of the cloudlets. We also demonstrate that a kinetic energy-dominated wind is more efficient in accelerating and dispersing the gas than a thermal wind with the same power. The interaction can give rise to multi-phase outflows with velocities ranging from a few 100 to several 1000~${\rm km\,s^{-1}}$. The mass outflow rates are tightly correlated with the wind power, which we explain by an ablation-based mass-loss model. Moreover, the velocity dispersion and the virial parameter of the cloud material can increase by up to one order of magnitude through the effect of the wind. Even though the wind can suppress or quench star formation for about 1 Myr during the initial interaction, a substantial number of gravitationally bound dense cloudlets manage to shield themselves from the wind's influence and subsequently undergo rapid gravitational collapse, leading to an enhanced star formation rate (SFR).