Integral field spectroscopy and numerical simulations of the NGC 2207/IC 2163 system

TL;DR

This study combines integral field spectroscopy and numerical simulations to analyze the NGC 2207/IC 2163 galaxy system, revealing detailed chemical, kinematic, and star formation properties influenced by their interaction.

Contribution

It provides a comprehensive analysis of the system's chemical gradients, star formation alterations, and kinematic disturbances, supported by numerical modeling of the collision.

Findings

Negative oxygen abundance gradients in both galaxies

Altered star formation in IC 2163's eyelids due to interaction

Disturbed gas kinematics and AGN-like features in NGC 2207

Abstract

We present integral field spectroscopy of the interacting galaxy system NGC 2207/IC 2163 obtained with the imaging Fourier Transform Spectrometer SITELLE. Approximately 1000 HII region complexes are detected in both galaxies and analyzed using their strong optical emission lines. Their properties were studied via BPT diagrams and their luminosity function. We conducted a detailed study of the distribution of oxygen abundance across the system using a series of strong-line O/H indicators and calibrations. Both galaxies exhibit negative galactocentric abundance gradients with a slope -0.015 dex kpc$^{-1}$. There are marginal signs of discontinuities in the O/H gradients with some indicators while no significant azimuthal variations are seen. A shallower slope in the HII region luminosity function between the arm and inter-arm regions in IC 2163 is observed, supporting previous conclusion that the star formation process in this galaxy eyelids has been altered during the interaction. The kinematics of the ionised gas reveal disturbed velocity fields, AGN-like features in the nucleus of NGC 2207, and elevated velocity dispersion in turbulent or feedback-driven regions. To interpret these findings, we modeled the collision using the numerical algorithm GCD+. The simulation reproduces key features of the system and demonstrates how close passages drive enhanced star formation and localized chemical enrichment. Finally, two dwarf galaxies in the field are found to have very similar systemic velocities as their larger counterparts, and could well play a minor role in the global interaction based on their morphology and position.