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

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, $z\le 0.2$. We identify 17 close-companion galaxies with projected separations $r_p<30$ kpc, relative velocities $\hat{I}”v\le 300$ km s${}^{-1}$, and stellar-mass ratios $M_{BGG}/M_{CC}\le 4$ 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.

12 pages, 7 figures, Accepted for publication by ApJ