Major Merger Galaxy Pairs at z=0: Dust Properties and Companion Morphology

TL;DR

This study analyzes dust properties in close major-merger galaxy pairs, revealing differences based on companion morphology and challenging standard models of gas redistribution during mergers.

Contribution

It provides the first detailed dust property comparison between spiral-spiral and spiral-elliptical galaxy pairs using multi-wavelength data and advanced modeling.

Findings

S+S and S+E pairs differ in dust composition and star formation enhancement.

Spirals in S+E pairs do not show increased interstellar radiation fields.

Dust properties are significantly influenced by companion morphology.

Abstract

We present an analysis of dust properties of a sample of close major-merger galaxy pairs selected by K_s magnitude and redshift. The pairs represent the two populations of spiral-spiral (S+S) and mixed morphology spiral-elliptical (S+E). The CIGALE (Code Investigating GALaxy Emission) is used to fit dust models to the 2MASS, WISE and Herschel flux density measurements and derive the parameters describing the PAH contribution, interstellar radiation field (ISRF) and photo-dissociation regions (PDRs). Model fits verify our previous Spitzer Space Telescope analysis that S+S and S+E pairs do not have the same level of enhancement of star formation and differ in dust composition. The spirals of mixed morphology galaxy pairs do not exhibit the enhancements in interstellar radiation field and therefore dust temperature for spirals in S+S pairs in contrast to what would be expected according to standard models of gas redistribution due to encounter torques. This suggests the importance of the companion environment/morphology in determining the dust properties of a spiral galaxy in a close major-merger pair.