HI-deficient galaxies in intermediate density environments

TL;DR

This study investigates the causes of HI deficiency in galaxies within intermediate density environments, revealing that ram pressure stripping and tidal interactions contribute to gas removal in these settings.

Contribution

It provides new high-resolution HI observations of six HI-deficient galaxies in groups and analyzes the mechanisms behind their gas loss.

Findings

Galaxies exhibit truncated HI disks and lopsided gas distributions.

Both ram pressure stripping and tidal interactions are key in gas removal.

HI deficiency is present in galaxies outside dense clusters, in groups and triplets.

Abstract

Observations show that spiral galaxies in galaxy clusters tend to have on average less neutral hydrogen (HI) than galaxies of the same type and size in the field. There is accumulating evidence that such HI-deficient galaxies are also relatively frequent in galaxy groups. An important question is, which mechanisms are responsible for the gas deficiency in galaxy groups. To gain a better understanding of how environment affects the gas content of galaxies, we identified a sample of six HI-deficient galaxies from the HI Parkes All Sky Survey (HIPASS) using HI-optical scaling relations. One of the galaxies is located in the outskirts of the Fornax cluster, four are in loose galaxy groups and one is in a galaxy triplet. We present new high resolution HI observations with the Australia Telescope Compact Array (ATCA) of these galaxies. We discuss the possible cause of HI-deficiency in these galaxies based on HI observations and various multi-wavelength data. We find that the galaxies have truncated HI disks, lopsided gas distribution and some show asymmetries in their stellar disks. We conclude that both ram pressure stripping and tidal interactions are important gas removal mechanisms in low density environments.