# Enhanced HI profile asymmetries in close galaxy pairs

## TL;DR

This study investigates how galaxy mergers influence HI profile asymmetries by comparing close pair and isolated galaxies, finding that mergers significantly increase asymmetry levels, thus linking HI asymmetries to galaxy evolution.

## Contribution

It provides the first quantitative comparison of HI profile asymmetries in close pairs versus isolated galaxies, highlighting merger activity's role in shaping HI profiles.

## Key findings

- Merger activity increases HI profile asymmetry.
- Close pair galaxies show higher asymmetry than isolated ones.
- HI asymmetry can trace galaxy merger history.

## Abstract

Analysing the quantified HI profile asymmetries of galaxies in different environments, we explore not only the prevalence of asymmetry in HI profiles, but also the possibility of using HI profile asymmetries to trace merger activity. We construct close pair and isolated galaxy catalogues of HI profiles from the Arecibo Legacy Fast ALFA (ALFALFA) survey, and using a simple HI flux ratio, quantify and compare the profile asymmetries between the two catalogues. In this way, we investigate the popular proposition that merger activity causes HI profiles to become asymmetric, and thereby probe the role of mergers in galaxy evolution. We find small but significant differences between the asymmetry distributions of the two samples, indicating that merger activity does indeed enhance asymmetry in the global HI profile.