A study of interacting galaxies from the Arp-Madore catalog

Triggering of star formation and nuclear activity

¹ Instituto de Astrofísica de Canarias, Calle Vía Láctea, s/n, 38205 La Laguna, Tenerife, Spain
² Departamento de Astrofísica, Universidad de La Laguna, 38206 La Laguna, Tenerife, Spain
³ Departamento de Astronomia, Universidade Federal do Rio Grande do Sul, IF, CP 15051, Porto Alegre, 91501-970 RS, Brazil
⁴ Departamento de Astronomia, Instituto de Astronomia, Geofísica e Ciências Atmosféricas da USP, Cidade Universitária, 05508-900 São Paulo, SP, Brazil
⁵ Departamento de Física, CCNE, Universidade Federal de Santa Maria, 97105-900 Santa Maria, RS, Brazil

Received: 26 January 2024
Accepted: 31 May 2024

Abstract

We present Gemini Multi-Object Spectrograph (GMOS) spectroscopic observations of 95 galaxies from the Arp & Madore (1987) catalog of peculiar galaxies. These galaxies have been selected because they appear to be in pairs and small groups. These observations have enabled us to confirm that 60 galaxies are indeed interacting systems. For the confirmed interacting sample, we have built a matched control sample of isolated galaxies. We present an analysis of the stellar populations and nuclear activity in the interacting galaxies and compare them with the isolated galaxies. We find a median light (mass) fraction of 55% (10%) in the interacting galaxies coming from stellar populations younger than 2 Gyr and 28% (3%) in the case of the isolated galaxies. More than half of the interacting galaxies are dominated by this young stellar population, while in the isolated ones most of the light comes from older stellar populations. We used a combination of diagnostic diagrams (BPTs and WHAN) to classify the main ionization mechanisms of the gas. The interacting galaxies in our sample consistently show a higher fraction of active galactic nuclei (AGN) relative to the control sample, which ranges between 1.6 and 4 depending on the combination of diagnostic diagrams employed to classify the galaxies and the number of galaxies considered. Our study provides further observational evidence that interactions drive star formation and nuclear activity in galaxies and can have a significant impact on galaxy evolution.