WALLABY Pre-Pilot Survey: The effects of tidal interaction on radial distribution of color in galaxies of the Eridanus supergroup

TL;DR

This study investigates how tidal interactions influence the radial color distribution in galaxies within the Eridanus supergroup, revealing mass-dependent effects on galaxy color gradients and disk sizes due to tidal perturbations.

Contribution

It provides new insights into the impact of tidal interactions on galaxy color gradients and disk sizes, especially in low-mass galaxies, using HI data from the WALLABY survey.

Findings

Low-mass galaxies show decreasing HI-to-optical disk size ratio with increased tidal strength.

Color gradients in low-mass galaxies become redder inward with stronger tidal perturbations.

High-mass galaxies exhibit marginal reddening but no significant change in color gradients with tidal strength.

Abstract

We study the tidal interaction of galaxies in the Eridanus supergroup, using HI data from the pre-pilot survey of WALLABY (Widefield ASKAP L-band Legacy All-sky Blind surveY). We obtain optical photometric measurements and quantify the strength of tidal perturbation using a tidal parameter $S_{sum}$. For low-mass galaxies of $M_* \lesssim 10^9 M_\odot$, we find a dependence of decreasing HI-to-optical disk size ratio with increasing $S_{sum}$, but no dependence of HI spectral line asymmetry with $S_{sum}$. This is consistent with the behavior expected under tidal stripping. We confirm that the color profile shape and color gradient depend on the stellar mass, but there is additional correlation of low-mass galaxies having their color gradients within $2R_{50}$ increasing with higher $S_{sum}$. For these low-mass galaxies, the dependence of color gradients on $S_{sum}$ is driven by color becoming progressively redder in the inner disk when tidal perturbations are stronger. For high-mass galaxies, there is no dependence of color gradients on $S_{sum}$, and we find a marginal reddening throughout the disks with increasing $S_{sum}$. Our result highlights tidal interaction as an important environmental effect in producing the faint end of the star formation suppressed sequence in galaxy groups.