The outer filament of Centaurus A as seen by MUSE

TL;DR

This study uses MUSE observations to analyze the complex morphology and kinematics of the outer filament near Centaurus A, revealing evidence of jet-ISM interactions and the impact of low-power radio jets on the host galaxy's gas.

Contribution

It provides new integral-field spectroscopic evidence of jet-ISM interactions in the outer filament of Centaurus A, highlighting the influence of low-power jets on the surrounding gas.

Findings

Ionized gas shows complex morphology with blobs and arc-like structures.

The jet influences the morphology and kinematics of the gas.

Even low-power jets can significantly impact the ISM.

Abstract

We investigate signatures of a jet-interstellar medium (ISM) interaction using optical integral-field observations of the so-called outer filament near Centaurus A, expanding on previous results obtained on a more limited area. Using the Multi Unit Spectroscopic Explorer (MUSE) on the VLT during science verification, we observed a significant fraction of the brighter emitting gas across the outer filament. The ionized gas shows complex morphology with compact blobs, arc-like structures and diffuse emission. Based on the kinematics, we identified three main components. The more collimated component is oriented along the direction of the radio jet. The other two components exhibit diffuse morphology together with arc-like structures also oriented along the radio jet direction. Furthermore, the ionization level of the gas is found to decrease from the more collimated component to the more diffuse components. The morphology and velocities of the more collimated component confirm our earlier results that the outer filament and the nearby HI cloud are likely partially shaped by the lateral expansion of the jet. The arc-like structures embedded within the two remaining components are the clearest evidence of a smooth jet-ISM interaction along the jet direction. This suggests that, although poorly collimated, the radio jet is still active and has an impact on the surrounding gas. This result indicates that the effect on the ISM of even low-power radio jets should be considered when studying the influence Active Galactic Nuclei can have on their host galaxy.