Tidal Tales of Minor Mergers: Star Formation in the Tidal Debris of Minor Mergers

TL;DR

This study investigates star formation in the tidal debris of minor galaxy mergers, revealing that such mergers, though less dramatic than major ones, are common and contribute to galactic and intergalactic structures through in situ star formation.

Contribution

It provides the first comprehensive survey of star formation in the tidal debris of minor mergers, demonstrating in situ formation of young star clusters in all observed cases.

Findings

Young star clusters are present in all six surveyed minor mergers.

Star clusters formed in situ within tidal debris, not from pre-existing stars.

Minor mergers, despite less debris per event, are frequent and influential.

Abstract

How does the tidal debris of minor galaxy mergers contribute to structures in spiral galaxies or in the intergalactic medium? While major mergers are known to create structures such as tidal dwarf galaxies and star clusters within their tidal debris, less is known about minor mergers (mass ratios between a dwarf galaxy and disk galaxy of less than one-third) and their tidal debris. This work surveys 6 nearby minor mergers using optical broad-band and H-alpha narrow-band imaging to characterize star formation in their tidal debris. Young star clusters with ages less than the dynamical age of the tidal tails are found in all 6 mergers, indicating that the star clusters formed in situ. Even if minor mergers contribute less tidal debris per interaction than major mergers, they are more common and possibly contribute structure to all types of galaxies and to the intergalactic medium throughout the history of the universe.