MUSE-ings on AM1354-250: Collisions, Shocks and Rings

TL;DR

This study uses MUSE observations to analyze the collisional ring galaxy AM1354-250, revealing gas expansion, star formation in the ring, shock excitation, and kinematic disturbances caused by a recent galaxy collision.

Contribution

First detailed spectroscopic analysis of AM1354-250 confirming its collisional origin and providing insights into gas dynamics and star formation triggered by the interaction.

Findings

Gaseous ring expanding at ~70 km/s

Star formation mainly in HII regions of the ring

Evidence of shocks and LINER-like emission

Abstract

We present MUSE observations of AM1354-250, confirming its status as a collisional ring galaxy which has recently undergone an interaction, creating its distinctive shape. We analyse the stellar and gaseous emission throughout the galaxy finding direct evidence that the gaseous ring is expanding with a velocity of $\sim$70km.s$^{-1}$ and that star formation is occurring primarily in HII regions associated with the ring. This star formation activity is likely triggered by the interaction. We find evidence for several excitation mechanisms in the gas, including emission consistent with shocked gas in the expanding ring and a region of LINER-like emission in the central core of the galaxy. Evidence of kinematic disturbance in both the stars and gas, possibly also triggered by the interaction, can be seen in all of the velocity maps. The ring galaxy retains weak spiral structure, strongly suggesting the progenitor galaxy was a massive spiral prior to the collision with its companion an estimated $140 \pm 12$ Myr ago.