Substructures in Minor Mergers’ Tidal Streams

Abstract

ABSTRACT: In this work, we explore the idea that stellar and/or gaseous substructures like stellar clusters could be formed from the tidal stream material produced in galactic minor mergers. We use two sets of N-body simulations of satellite galaxies interacting with a larger host galaxy. The first set used satellites devoid of gas while the second set used satellites with a gaseous component including star-formation and supernova feed- back. We estimated the spatial distribution of mass to identify overdensity regions in which a substructure could be formed. As a first conclusion, we found that without gas, no substructure formed as none of the overdensities show a definite morphology or dynamical stability over time. Conversely, including gas resulted in a remarkably different behavior, several clumps appear and they proved to be real physical struc- tures that remained for a considerable time ( 1 Gyr). Furthermore, the study of the orbital structure, ages and masses of the overdensities lead us to conclude that substructures (star clusters or high-velocity clouds) can be formed in tidal streams of gas-rich satellites. Also, evidence was found favoring the presence of dark matter in the substructures after the formation process, adding to the discussion about the forma- tion of star clusters and providing an observational mechanism to verify the reliability of the model.