Investigating the Baryon Cycle in Interacting Dwarfs with the Very Large Array and Pan-STARRS

TL;DR

This study uses high-resolution HI maps and optical imaging to analyze the effects of tidal interactions on dwarf galaxy systems, revealing gas dynamics, morphological distortions, and the preservation of gas during interactions.

Contribution

It provides detailed resolved HI kinematics and morphological analysis of interacting dwarf systems, offering new insights into the baryon cycle at low masses.

Findings

Detection of HI bridges and diffuse extensions indicating tidal interactions

Interacting dwarfs are not HI deficient, retaining their gas

Interactions significantly alter the kinematics of dwarf systems

Abstract

We present resolved HI synthesis maps from the Very Large Array (VLA) of three interacting dwarf systems: the NGC 3664 dwarf pair, the NGC 3264 dwarf pair, and the UGC 4638 dwarf triplet. All three dwarf systems are captured at various stages of interaction and span a range of environments. We detect clear hallmarks of tidal interactions through the presence of HI bridges, and diffuse HI extensions that surround the dwarfs. We overlay the HI data on Pan-STARRS r-band images and find further evidence of tidal interactions through coincident distorted HI and tidal stellar features in NGC 3264 and UGC 4638, and an unwound spiral arm pointing towards its smaller companion in NGC 3264. In UGC 4638, both the gas and diffuse stars are extended to similar radii east of the primary, which could indicate that the smaller dwarf in the system has already completed one pass through the primary. We additionally find that our three systems, and those from the Local Volume TiNy Titans survey, are not HI deficient and thus the interaction has not resulted in a loss of gas from the systems. A comparison with non-interacting dwarf galaxies shows that the interactions have a significant impact on the kinematics of the systems. Our new resolved HI kinematics, combined with detailed stellar and HI morphologies, provide crucial constraints for future dynamical modelling of hierarchical mergers and the baryon cycle at the low-mass scale.