Star Formation in Isolated Dwarf Galaxies Hosting Tidal Debris: Extending the Dwarf-Dwarf Merger Sequence

TL;DR

This study investigates dwarf-dwarf galaxy mergers using imaging data, revealing that such mergers are linked to increased star formation activity and produce observable tidal debris, extending understanding of dwarf galaxy evolution.

Contribution

It provides the first large sample analysis of dwarf-dwarf mergers, showing that star formation is enhanced post-merger and tidal features are more common in highly star-forming dwarfs.

Findings

Tidal features detected in 3.29% of isolated dwarf galaxies.

Higher tidal feature detection in galaxies with intense star formation.

Merging dwarfs tend to be bluer than non-merging counterparts.

Abstract

Like massive galaxies, dwarf galaxies are expected to undergo major mergers with other dwarfs. However, the end state of these mergers and the role that merging plays in regulating dwarf star formation is uncertain. Using imaging from the Hyper Suprime-Cam Subaru Strategic program, we construct a sample of dwarf-dwarf mergers and examine the star formation and host properties of the merging systems. These galaxies are selected via an automated detection algorithm from a sample of 6875 spectroscopically selected isolated dwarf galaxies at $z<0.12$ and $\log(M_\star/M_\odot)<9.6$ from the Galaxy and Mass Assembly (GAMA) and Sloan Digital Sky Survey (SDSS) spectroscopic campaigns. We find a total tidal feature detection fraction of 3.29% (6.1% when considering only galaxies at $z<0.05$). The tidal feature detection fraction rises strongly as a function of star formation activity; 15%-20% of galaxies with extremely high H$\alpha$ equivalent width (H$\alpha$ EW > 250 Angstrom) show signs of tidal debris. Galaxies that host tidal debris are also systematically bluer than the average galaxy at fixed stellar mass. These findings extend the observed dwarf-dwarf merger sequence with a significant sample of dwarf galaxies, indicating that star formation triggered in mergers between dwarf galaxies continues after coalescence.