Satellites and central galaxies in SDSS: the influence of interactions on their properties

TL;DR

This study examines galaxy systems in SDSS-DR14, revealing that interactions influence star formation and stellar populations differently in central and satellite galaxies, with effects depending on mass and proximity.

Contribution

It provides a detailed analysis of how galaxy interactions affect star formation and stellar populations in central and satellite galaxies using SDSS data.

Findings

Interacting central galaxies show increased star formation and younger stars.

Satellite galaxies in interactions tend to have older stellar populations.

Effects of interactions depend on galaxy mass and distance between members.

Abstract

We use SDSS-DR14 to construct a sample of galaxy systems consisting of a central object and two satellites. We adopt projected distance and radial velocity difference criteria and impose an isolation criterion to avoid membership in larger structures. We also classify the interaction between the members of each system through a visual inspection of galaxy images, finding $\sim80\%$ of the systems lack evidence of interactions whilst the remaining $\sim20\%$ involve some kind of interaction, as inferred from their observed distorted morphology. We have considered separately, samples of satellites and central galaxies, and each of these samples were tested against suitable control sets to analyse the results. We find that central galaxies showing signs of interactions present evidence of enhanced star formation activity and younger stellar populations. As a counterpart, satellite samples show these galaxies presenting older stellar populations with a lower star formation rate than the control sample. The observed trends correlate with the stellar mass content of the galaxies and with the projected distance between the members involved in the interaction. The most massive systems are less affected since they show no star formation excess, possibly due to their more evolved stage and less gas available to form new stars. Our results suggest that it is arguable a transfer of material during interactions, with satellites acting as donors to the central galaxy. As a consequence of the interactions, satellite stellar population ages rapidly and new bursts of star formation may frequently occur in the central galaxy.