Galaxy evolution in compact groups I: Revealing a transitional galaxy population through a multiwavelength approach

TL;DR

This study investigates how compact galaxy groups influence galaxy evolution, revealing a unique population of transitional, more compact galaxies and environmental effects that promote morphological and star formation changes.

Contribution

It introduces a multiwavelength approach to identify a transitional galaxy population and demonstrates environmental impacts on galaxy morphology and star formation in compact groups.

Findings

Discovery of a peculiar, compact galaxy population in CGs not seen in field galaxies.

Higher fraction of quenched and low sSFR galaxies in CGs compared to control.

Evidence of morphological transformation driven by dense environments.

Abstract

Compact groups of galaxies (CGs) show members with morphological disturbances, mainly products of galaxy-galaxy interactions, thus making them ideal systems to study galaxy evolution, in high-density environment. To understand how this environment affects the properties of galaxies, we select a sample of 340 CGs in the Stripe 82 region, for a total of 1083 galaxies, and a sample of 2281 field galaxies as a control sample. By performing a multi-wavelength morphological fitting process using S-PLUS data, we divide our sample into early-type (ETG), late-type (LTG), and transition galaxies using the r-band S\'ersic index and the colour (u-r). We find a bimodal distribution in the plane of the effective radius-S\'ersic index, where a secondary "peculiar" galaxy population of smaller and more compact galaxies is found in CGs, which is not observed in the control sample. This indicates that galaxies are undergoing a morphological transformation in CGs. In addition, we find significant statistical differences in the distribution of specific Star Formation Rate (sSFR) when we compare both environments for LTGs and ETGs. We also find a higher fraction of quenched galaxies and a lower median sSFR in CGs than in the control sample, suggesting the existence of environmental effects favoring the cessation of star formation, regardless of galaxy type. Our results support the notion that CGs promote morphological and physical transformations, highlighting their potential as ideal systems for galaxy pre-processing.