The interacting pair of galaxies Arp 82: Integral field spectroscopy and numerical simulations

TL;DR

This study combines integral field spectroscopy and numerical simulations to analyze the kinematics, metallicity distribution, and interaction history of the Arp 82 galaxy pair, revealing complex motions, metallicity gradients, and interaction dynamics.

Contribution

It provides new detailed spectroscopic data and a numerical model that reproduces observed features, elucidating the interaction history and effects on galaxy properties.

Findings

Detection of a bar in NGC 2536.

Identification of non-circular motions and kinematic misalignments.

Metallicity distribution shows a shallow gradient in NGC 2536 and a broken slope in NGC 2535.

Abstract

Spectral data cubes of the interacting pair of galaxies NGC 2535 and NGC 2536 (the Arp 82 system) targeting bright emission lines in the visible band, obtained with the imaging Fourier transform spectrometer (iFTS) SITELLE attached to the Canada-France-Hawaii Telescope (CFHT), are presented. Analysis of H$\upalpha$ velocity maps reveals a bar in $\rm NGC\,2536$. In $\rm NGC\,2535$, we find strong non-circular motions outside the ocular ring, in the elliptical arc and tidal tails of $\rm NGC\,2535$ and a misalignment between the kinematic and photometric position angles. We detect 155 HII region complexes in the interacting pair of galaxies and determine oxygen abundances for 66 of them using different calibrators. We find, regardless of the indicator used, that the oxygen abundance distribution in $\rm NGC\,2536$ is shallow whereas, in $\rm NGC\,2535$, it is best fitted by two slopes, the break occurring beyond the ocular ring. The inner slope is comparable to the one observed in isolated normal star-forming galaxies but the outer slope is shallow. We present a numerical simulation of the interaction that reproduces the observed tidal features, kinematics, and metallicity distribution, to investigate the effect of the interaction on the galaxies. The model indicates that the galaxies have undergone a close encounter, strongly prograde for the primary, and are half way in their course to a second close encounter.