Star Formation in CALIFA survey perturbed galaxies. II. Star Formation Histories and Oxygen Abundances

TL;DR

This study compares star formation histories and oxygen abundances in tidally perturbed versus non-perturbed galaxies, revealing that tidal interactions enhance recent star formation and induce metal-poor gas inflows, affecting galaxy evolution.

Contribution

It provides new evidence that tidal interactions lead to increased recent star formation and gas inflows, influencing chemical abundances and star formation regulation in galaxies.

Findings

Tidally perturbed regions show higher recent star formation rates.

Regions in perturbed galaxies have slightly lower oxygen abundances.

Gas inflows are more prevalent in tidally perturbed galaxies.

Abstract

Galaxy evolution is generally affected by tidal interactions. Firstly, in this series, we reported several effects which suggest that tidal interactions contribute to regulating star formation (SF). To confirm that so, we now compare stellar mass assembly histories and SF look-back time annular profiles between CALIFA survey tidally and non-tidally perturbed galaxies. We pair their respective star-forming regions at the closest stellar mass surface densities to reduce the influence of stellar mass. The assembly histories and annular profiles show statistically significant differences so that higher star formation rates characterize regions in tidally perturbed galaxies. These regions underwent a more intense (re)activation of SF in the last 1 Gyr. Varying shapes of the annular profiles also reflect fluctuations between suppression and (re)activation of SF. Since gas-phase abundances use to be lower in more actively than in less actively star-forming galaxies, we further explore the plausible presence of metal-poor gas inflows able to dilute such abundances. The resolved relations of oxygen (O) abundance, with stellar mass density and with total gas fraction, show slightly lower O abundances for regions in tidally perturbed galaxies. The single distributions of O abundances statistically validate that so. Moreover, from a metallicity model based on stellar feedback, the mass rate differentials (inflows$-$outflows) show statistically valid higher values for regions in tidally perturbed galaxies. These differentials, and the metal fractions from the population synthesis, suggest dominant gas inflows in these galaxies. This dominance, and the differences in SF through time, confirm the previously reported effects of tidal interactions on SF.