Dynamic and Radiative Implications of Jet-Star Interactions in AGN Jets

TL;DR

This study investigates how interactions between AGN jets and stellar environments, especially mass loading from stellar winds, influence jet dynamics, emission features, and observed radio-optical offsets, using synthetic mapping to match observations.

Contribution

It introduces detailed simulations incorporating mass loading effects to explain jet deceleration, emission structures, and positional offsets in FR I galaxies, advancing understanding of jet-environment interactions.

Findings

Mass entrainment is crucial for replicating observed jet emissions.

Synthetic maps reproduce typical radio-optical offsets.

Offsets depend on galaxy properties and observational biases.

Abstract

The interactions between jets from active galactic nuclei (AGN) and their stellar environments significantly influence jet dynamics and emission characteristics. In low-power jets, such as those in Fanaroff-Riley I (FR I) galaxies, the jet-star interactions can notably affect jet deceleration and energy dissipation. Recent numerical studies suggest that mass loading from stellar winds is a key factor in decelerating jets, accounting for many observed characteristics in FR I jets. Additionally, a radio-optical positional offset has been observed, with optical emission detected further down the jet than radio emission. This observation may challenge traditional explanations based solely on recollimation shocks and instabilities. This work utilizes the radiative transfer code RIPTIDE to generate synthetic synchrotron maps, from a population of re-accelerated electrons, in both radio and optical bands from jet simulations incorporating various mass-loading profiles and distributions of gas and stars within the ambient medium. Our findings emphasize the importance of mass entrainment in replicating the extended and diffuse radio/optical emissions observed in FR I jets and explaining the radio-optical offsets. These offsets are influenced by the galaxy's physical properties, the surrounding stellar populations, and observational biases. We successfully reproduce typical radio-optical offsets by considering a mass-load equivalent to $10^{-9}~M_\odot \cdot \rm{yr}^{-1} \cdot \rm{pc}^{-3}$. Overall, our results demonstrate that positive offset measurements are a promising tool for revealing the fundamental properties of galaxies and potentially their stellar populations, particularly in the context of FR I jets.