The environmental dependence of neutral hydrogen content in spiral galaxies

TL;DR

This study examines how the neutral hydrogen content in spiral galaxies decreases more significantly at high galaxy densities, indicating environmental effects like galaxy interactions and intra-cluster medium influence galaxy evolution.

Contribution

It reveals the density-dependent behavior of HI deficiency in spiral galaxies and links it to the morphology-density relation, highlighting environmental impacts on galaxy properties.

Findings

HI deficiency increases sharply at high densities

The density threshold for HI deficiency matches that for morphological changes

Environmental interactions likely drive both HI loss and morphological transformation

Abstract

We present a study of the relationship between the deficiency of neutral hydrogen and the local three-dimensional number density of spiral galaxies in the Arecibo catalog of global HI measurements (Springob et al. 2005). We find that the dependence on density of the HI content is weak at low densities, but increases sharply at high densities where interactions between galaxies and the intra-cluster medium become important. This behavior is reminiscent of the morphology-density relation (Dressler 1980) in that the effect manifests itself only at cluster-type densities, and indeed when we plot both the HI deficiency-density and morphology-density relations, we see that the densities at which they "turn up" are similar. This suggests that the physical mechanisms responsible for the increase in early types in clusters are also responsible for the decrease in HI content.