Major mergers are not significant drivers of star formation or morphological transformation around the epoch of peak cosmic star formation
Galaxy evolution at high redshift: the legacy of deep near-infrared surveys
Emma K Lofthouse
S. Kaviraj (Hertfordshire), C. J. Conselice (Nottingham), A. Mortlock (Edinburgh). W. Hartley (ETH Zurich)
University of Hertfordshire
We investigate the contribution of major mergers (mass ratios >1:5) to stellar mass growth and morphological transformations around the epoch of peak cosmic star formation (z~2). We visually classify a complete sample of massive (M>10^10 solar masses ) galaxies at this epoch, drawn from the CANDELS survey, into spheroids, late-type galaxies and major mergers. The spheroids are further split into disturbed systems, which show morphological disturbances and relaxed systems which have no features. Given recent simulation work, which indicates that recent (ain drivers of this process. We then use the rest-frame U-band luminosity as a proxy for star formation activity to show that only a small fraction of the U-band luminosity budget (~6%) is actually hosted by major mergers at this epoch. Taken together, our results show that major mergers are not significant drivers of galaxy evolution at z~2.


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