The Perpendicularity of Dust Lanes and Radio Jets in Early-Type Galaxies: Implications for AGN Feedback

TL;DR

This study uses Hubble imaging to analyze dust and jet orientations in early-type galaxies, revealing that dust lanes are perpendicular to jets, implying mergers influence jet directions and AGN feedback.

Contribution

It introduces an automated method for measuring dust and jet orientations, providing new insights into the connection between mergers, dust features, and jet alignment in galaxies.

Findings

Dust lanes are perpendicular to jets.

Dust disks and rings align with galaxy axes.

Merger-driven dust infall influences jet orientation.

Abstract

The orientation of radio jets relative to their host galaxies offers an interesting avenue for probing the connection between active galactic nuclei (AGN) and their surroundings. Several studies have also investigated the orientation of nuclear dust features. We follow up on this previous work with newer Hubble Space Telescope imaging of early-type radio galaxies, and a largely automated process for measuring position angles. We classify the dust features as lanes, disks, or rings. Lanes are irregular structures that likely form from gas-rich minor mergers, while disks and rings are more well-defined and may form from settling lanes or internal mechanisms. We find that dust lanes do not have a preferred alignment relative to their host galaxies, but are preferentially perpendicular to the jets. In contrast, dust disks and rings tend to be closely aligned with the major axes of their host galaxies, but have varying orientations relative to the jets. Our results suggest that infalling dusty material from mergers can influence the angle of the radio jet. This would allow the jet orientation to change over time, and may help explain the role of AGN feedback in maintaining quiescence in massive galaxies.