From Voids to Clusters: Mergers and Evolutionary Pathways of Star-Forming and Quenched Low-Mass Galaxies

TL;DR

This study investigates how environment and mergers influence the evolution of low-mass galaxies, revealing the significance of different merger types in their star formation and growth across dense and under-dense regions.

Contribution

It provides the first statistical analysis of merger histories for low-mass galaxies in diverse environments using high-resolution simulations, distinguishing merger types and their effects.

Findings

Major mergers significantly impact star formation suppression.

Environmental density correlates with merger frequency and galaxy evolution.

Minor and mini mergers contribute to mass assembly and gas dynamics.

Abstract

The evolution of low-mass galaxies is shaped by both internal processes and environmental factors, yet the role of environment and mergers in regulating their growth and star formation rates remains poorly understood, especially in the low-density regime. This study aims to compare the evolutionary pathways and merger histories of star-forming and quenched galaxies in dense (cluster) and under-dense (void) environments, focusing on galaxies with stellar masses in the range $10^{8.5} \leq M_\star/M_\odot \leq 10^{10.5}$. It presents the first statistical analysis within this stellar mass range, explicitly distinguishing between mini, minor, and major mergers across varying environments. Using the high-resolution TNG300-1 simulation from the IllustrisTNG project, we classify galaxies as star-forming and quenched based on sSFR and UVJ criteria. We track their physical properties over the last $\sim 11.5$ Gyr ($z < 3$), follow their complete merger histories, distinguishing between major, minor, and mini mergers, and assess the statistical impact of these mergers on star formation, gas content, and the mass assembly of their supermassive black holes.