Major mergers with small galaxies - the discovery of a Magellanic-type galaxy at z=0.12

TL;DR

This paper reports the discovery of a Magellanic-type galaxy at z=0.12 showing signs of an ongoing merger, with detailed analysis of its properties supporting the occurrence of major mergers at dwarf galaxy scales.

Contribution

The study presents the first evidence of a Magellanic-type galaxy undergoing a major merger at low redshift, with detailed spectroscopic and photometric analysis.

Findings

Discovered a galaxy with LMC-like mass at z=0.12 showing merger features.

Spectroscopy indicates low star formation and high metallicity.

Supports the occurrence of major mergers among dwarf galaxies.

Abstract

We report on the serendipitous discovery of a star-forming galaxy at redshift z=0.116 with morphological features that indicate an ongoing merger. This object exhibits two clearly separated components with significantly different colors, plus a possible tidal stream. Follow-up spectroscopy of the bluer component revealed a low star-forming activity of 0.09 M$_{\odot}$/year and a high metallicity of 12+log(O/H)=8.6. Based on comparison with mass-star-formation-rate and mass-metallicity relations, and on fitting of spectral energy distributions, we obtain a stellar mass of 3x10$^9$ M$_{\odot}$, which renders this object comparable to the Large Magellanic Cloud (LMC). Thus our finding provides a further piece of evidence of a major merger already acting on small, dwarf galaxy-like scales.