An investigation of star formation and dust attenuation in major mergers using ultraviolet and infrared data

TL;DR

This study examines how galaxy mergers influence dust attenuation and star formation rates using UV and IR data, revealing increased dust attenuation and central star formation in merging galaxies compared to isolated ones.

Contribution

It provides new insights into dust and star formation enhancements in major mergers by combining UV and IR observations, refining previous IR-only analyses.

Findings

Dust attenuation is higher in merger galaxies, especially in spiral-spiral pairs.

Specific star formation rates are elevated in mergers, influenced by stellar mass and companion morphology.

Nuclear star formation is more concentrated in pairs, resembling ULIRGs.

Abstract

Merger processes play an important role in galaxy formation and evolution. To study the influence of merger processes on the evolution of dust properties and cosmic star formation rate, we investigate a local sample of major merger galaxies and a control sample of isolated galaxies using GALEX ultraviolet (UV) and Spitzer infrared (IR) images. Through a statistical study, we find that dust attenuation in merger galaxies is enhanced with respect to isolated galaxies. We find this enhancement is contributed mainly by spiral galaxies in spiral-spiral (S-S) pairs, and increases with the increasing stellar mass of a galaxy. Combining the IR and UV parts of star formation rates (SFRs), we then calculated the total SFRs and specific star formation rates (SSFRs). We find the SSFRs to be enhanced in merger galaxies. This enhancement depends on galaxy stellar mass and the companion's morphology, but depends little on whether the galaxy is a primary or secondary component or on the separation between two components. These results are consistent with a previous study based only on IR images. In addition, we investigate the nuclear contributions to SFRs. SFRs in paired galaxies are more concentrated in the central part of the galaxies than in isolate galaxies. Our studies of dust attenuation show that the nuclear parts of pairs most resemble ULIRGs. Including UV data in the present work not only provides reliable information on dust attenuation, but also refines analyses of SFRs.