Galaxy And Mass Assembly (GAMA) Survey: The Merging Potential of Brightest Group Galaxies

TL;DR

This study assesses the merging potential of Brightest Group Galaxies using GAMA data, finding limited growth from mergers, which is less than current galaxy evolution models predict.

Contribution

It provides the first direct estimate of BGG merger potential in a volume-limited sample, using spectroscopic data to identify close companions and quantify stellar mass growth.

Findings

Identified 17 close-companion galaxies indicating potential mergers.

Estimated BGGs can grow by about 2.2% per Gyr through mergers.

Observed growth rate is lower than predictions from galaxy evolution models.

Abstract

Using a volume-limited sample of 550 groups from the Galaxy And Mass Assembly (GAMA) Galaxy Group Catalogue spanning the halo mass range $12.8 < \log [M_{h}/M] < 14.2$, we investigate the merging potential of central Brightest Group Galaxies (BGGs). We use spectroscopically-confirmed close-companion galaxies as an indication of the potential stellar mass build-up of low-redshift BGGs, $z \leq 0.2$. We identify 17 close-companion galaxies with projected separations $r_{p} < 30$ kpc, relative velocities $\Delta v \leq 300$ km s$^{-1}$, and stellar-mass ratios $M_{BGG}/M_{CC} \leq 4$ relative to the BGG. These close-companion galaxies yield a total pair fraction of $0.03 \pm 0.01$. Overall, we find that BGGs in our sample have the potential to grow in stellar mass due to mergers by $2.2 \pm 1.5\%$ Gyr$^{-1}$. This is lower than the stellar mass growth predicted by current galaxy evolution models.