Friday.
1408.1476
Galaxy and mass assembly (GAMA): galaxy close-pairs, mergers, and the future fate of stellar mass
Robotham, et al
Use a highly complete subset of the GAMA-II redshift sample to fully describe the stellar mass dependence of close-pairs and mergers between 1e8 Msun and 1e12 Msun. Using the analytic form of this fit, investigate the total stellar mass accreting onto more massive galaxies across all mass ratios. Depending on how conservatively the merging system are selected, the fraction of mass merging onto more massive companions is 2.0-5.6%. Using the GAMA-II data, see no significant evidence for a change in the close-pair fraction between redshift z=0.05-0.2. However, find a systematically higher fraction of galaxies in similar mass close-pairs compared to published results over a similar redshift baseline. Using a compendium of data and the function gamma_M=A(1+z)m to predict the major close-pair fraction, find fitting parameters of A=0.021pm0.001 and m=1.53pm0.08, which represents a higher low-z normalization and shallower power-law slope than recent literature values. Find that the relative importance of in-situ SF versus galaxy merging is inversely correlated, with SF dominating the addition of stellar material below Mstar and merger accretion events dominating beyond M*. Find mergers to have measurable importance on the whole extend of the GSMF, manifest as a deepening of the dip in the GSMF over the next Gyr and an increase in Mstar by as much as 0.01-0.05 dex.
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