Looking inside the nest: the hidden structure of the merger galaxy NGC 1316 (Fornax A)

TL;DR

This paper investigates the complex nuclear structures of galaxy NGC 1316 using imaging and stellar kinematics, revealing a gaseous spiral, a stellar disc, and evidence of recent galaxy accretion.

Contribution

It uncovers previously undetected nuclear structures and links them to recent accretion events, providing new insights into galaxy evolution processes.

Findings

Detection of inner gaseous spiral arms.

Identification of a kinematically cold stellar disc.

Evidence of recent galaxy accretion.

Abstract

We present an analysis of the circumnuclear structure of NGC 1316 using both near-infrared imaging and stellar kinematics. 2D decomposition of the images suggests the presence of a structure that resembles inner gaseous spiral arms, at about 5 to 15" from the center (500 to 1500 pc). We also find a disc-like stellar structure with radius less than 200 pc. Analysis of previously published SINFONI integral field kinematics data indicates a kinematically decoupled core in the same spatial scale, further evidence that indeed the nuclear stellar structure found is a kinematically cold stellar disc. We suggest that both newly-found structural components are the result of a recent accretion of a companion galaxy.