HI debris in the IC 1459 galaxy group

TL;DR

This study uses HI synthesis imaging to reveal extensive, irregular HI debris around the elliptical galaxy IC 1459, indicating tidal interactions and contributing significantly to the group's intergalactic medium.

Contribution

First detailed HI imaging of IC 1459's surroundings showing large-scale debris from tidal interactions, expanding understanding of galaxy group dynamics.

Findings

Detected ~10^9 solar masses of HI debris over 250 kpc.

HI debris shows irregular morphology and kinematics.

Debris constitutes a significant part of the group's intergalactic medium.

Abstract

We present HI synthesis imaging of the giant elliptical galaxy IC 1459 and its surroundings with the Australia Telescope Compact Array (ATCA). Our search for extended HI emission revealed a large complex of HI clouds near IC 1459, likely the debris from tidal interactions with neighbouring galaxies. The total HI mass ($\sim 10^9$\Msun) in the detected clouds spans 250 kpc from the north-east of the gas-rich spiral NGC 7418A to the south-east of IC 1459. The extent and mass of the HI debris, which shows rather irregular morphology and kinematics, are similar to those in other nearby groups. Together with HI clouds recently detected near two other IC 1459 group members, namely IC 5270 and NGC 7418, using Phased-Array Feeds (PAFs) on the Australian Square Kilometer Array Pathfinder (ASKAP), the detected debris make up a significant fraction of the group's intergalactic medium.