A FUV and optical study of star formation in closely interacting galaxies: star forming rings, tidal arms and nuclear outflows

TL;DR

This study uses FUV, optical, and infrared observations to analyze star formation and nuclear activity in eight interacting galaxies at different stages, revealing recent star formation in tidal features and nuclear outflows, with no significant difference between barred and unbarred galaxies.

Contribution

It provides a detailed spatially and spectrally resolved analysis of star formation, metallicity, and AGN activity in interacting galaxies using UVIT, VLT/MUSE, and IRSF data, highlighting the effects of interactions.

Findings

Most galaxies show recent star formation in tidal tails and rings.

Barred and unbarred galaxies do not differ significantly in star formation rates.

Extended nuclear outflows are observed in two galaxies.

Abstract

We present a study of the morphology of star formation and the associated nuclear activity in a sample of 8 closely interacting southern galaxies, which are in different stages of interaction, starting with nearly merged nuclei that have one prominent bulge to more widely spaced interacting galaxies. We have used Far-Ultraviolet (FUV) observations from the Ultraviolet Imaging telescope (UVIT), near-Infrared observations from the infrared survey facility telescope (IRSF) and archival optical data from the VLT/MUSE integral field spectrograph. Analysing resolved stellar populations across the disk of the interacting galaxies can provide unique insights into how interactions affect galaxy properties, such as morphology, star formation rates and chemical composition. We take advantage of the unprecedented capabilities of MUSE and UVIT to carry out a highly detailed spatially and spectrally resolved study of star formation rate, star formation histories, metallicity and AGN activity in the sample of eight interacting galaxies which are in different stages of interaction. Most of our sample galaxies are gas-rich and show evidence of recent, massive star formation in tidal tails, rings and spiral arms. This is evident from their FUV and H$\alpha$ emissions, which trace young, massive star-forming regions. We compared the star formation rate in the barred and unbarred galaxies in our sample and found that the barred galaxies do not show significant enhancement in star formation rate or large-scale difference in star formation morphology compared to unbarred galaxies. IC5250 and NGC7733N, show extended nuclear outflows of size $\sim$ 5 kpc and 8 kpc respectively.