Is Centaurus A special? A neutral hydrogen perspective

TL;DR

This study uses high-resolution neutral hydrogen observations of Centaurus A to analyze its morphology and kinematics, comparing it with other early-type and radio galaxies to understand its evolution and typicality.

Contribution

It provides a detailed HI analysis of Centaurus A, demonstrating its properties are typical for its class and challenging the link between mergers and AGN activity.

Findings

Centaurus A's HI morphology and kinematics are typical for early-type galaxies.

Recent merger in Centaurus A is not linked to current AGN activity.

Centaurus A can be considered a typical early-type/radio galaxy from an HI perspective.

Abstract

Due to the proximity, the neutral hydrogen belonging to Centaurus A can be observed at high resolution with good sensitivity. This allows to study the morphology and kinematics in detail in order to understand the evolution of this radio-loud source (e.g. merger history, AGN activity). At the same time, it is important to compare the results to other sources of the same class (i.e. early-type galaxies in general and radio galaxies in particular) to see how Centaurus A fits into the global picture of early-type/radio galaxy evolution. The amount of HI, the morphology of a warped disk with HI clouds surrounding the disk and the regular kinematics of the inner part of the HI disk are not unusual for early-type galaxies. The growing evidence that mergers are not necessarily responsible for AGN activity fits with the observational result that the recent merger event in Centaurus A is not connected to the current phase of activity. Based on these results, we conclude that Centaurus A has typical neutral hydrogen properties for an early-type and radio galaxy and it can therefore - from an HI perspective - be seen as a typical example of its class.