FEASTS: The Fate of Gas and Star Formation in Interacting Galaxies

TL;DR

This study uses HI data from FEASTS to analyze how galaxy interactions affect gas distribution and star formation, revealing increased HI disorder and complex gas dynamics in interacting systems.

Contribution

It introduces a detailed parameterization of HI disorder in interacting galaxies and links these parameters to gas and star formation properties, providing new insights into interaction effects.

Findings

Interacting galaxies show higher HI disorder across most parameters.

Secondary galaxies with similar mass and low velocity have more HI expansion and clumpiness.

Gas deficiency correlates with HI piling at system edges, affecting star formation.

Abstract

We use HI data from the FAST Extended Atlas of Selected Targets Survey (FEASTS) to study the interplay between gas and star formation of galaxies in interacting systems. We build control and mock HI disks and parameterize HI disorder by a series of disorder parameters, describing the piling, clumpiness and expansion of HI. We find that interacting galaxies have higher HI disorder described by almost all disorder parameters. Systems with comparable stellar masses and small relative velocities tend to have stronger expansion and clumpiness of HI. At a given stellar mass, decreased HI and total neutral gas mass and suppressed star formation rate of secondary galaxies are correlated with most disorder parameters. For primary galaxies, HI and total neutral gas deficiency correlate with more HI piling at two ends of the system outside HI disks but not with the expansion or clumpiness of HI. We also find that the HI surface densities of both primary and secondary galaxies are lower within the HI disks and higher outside compared to the control galaxies. Our results suggest that while all the disorder parameters quantify the interaction strength almost equally well, they have different sensitivities in tracing star formation rate and gas mass enhancements. They also imply that while gas removal likely dominates the tidal effects on secondary galaxies, primary galaxies experience more complex situation that are possibly related to gas depletion and accretion happening at different interaction stages.