Shooting for the stars: Jet-mode feedback and AGN jet deceleration from stellar mass-loading

TL;DR

This paper models how stellar mass-loss causes deceleration of AGN jets, quantifying the energy available for galaxy feedback and exploring how stellar populations influence jet dynamics.

Contribution

It introduces a simple model linking stellar mass-loss to AGN jet deceleration, providing new insights into the energy budget of jet feedback in the local Universe.

Findings

Over 25% of jet power is decelerated and available for feedback.

Most jets are decelerated within their host galaxies.

Stellar mass-loss rates decrease over time, affecting jet deceleration.

Abstract

AGN jets are thought to be vital ingredients in galaxy evolution through the action of kinetic feedback; however, how narrow, relativistic outflows couple to galaxies remains an open question. Jet deceleration, which is often attributed to the entrainment of material, such as stellar winds, is thought to be necessary for efficient coupling. We present a simple model of jet deceleration due to stellar mass-loading to investigate the energy budget of direct jet feedback in the local Universe. To this end, we produce models of stellar mass-loss, including deriving a prescription for main sequence mass-loss rates as a function of stellar population age. We pair this mass-loss data with a parametric fit for radio AGN incidence, predicting that a majority of jets are decelerated within their hosts, and generally replicate the expected FR-II fraction in LERGs. We calculate that $\gtrsim$25\% of the jet power in the local Universe is efficiently decelerated and available for direct feedback within galaxies for any stellar population age. This fraction is largely invariant to the shape of the radio AGN incidence function at low jet Eddington fractions. The stellar mass-loss rate evolves significantly over time, approximately following $\tau^{-1.1}$, leading to corresponding decreases in decelerated jet power in older stellar populations. Although asymptotic giant branch (AGB) stars dominate mass-loss at all ages, we find that their stochasticity is important in low-mass galaxies, and derive a critical jet power below which main sequence stars alone are sufficient to decelerate the jet.