Are Mergers so Good at Triggering Starbursts?

Observations and simulations tell us that major galaxy interactions can lead to intense bursts of star formation. In order to constrain models and understand the fraction of stellar mass formed in mergers, it is of interest, however, to determine the average enhancement of star formation rate in major mergers. We apply two-point correlation function techniques, supplemented with morphlogical classifications to two deep cosmological surveys (ECDFS/GEMS and A901-2/STAGES) using COMBO-17 redshifts, colors and stellar masses plus IR-derived SFRs from Spitzer. For a sample of galaxies at 0.4<z<0.8 we find a mild average enhancement ɛ = 1.50±0.25 of the SFR of massive (M_* ≥ 10¹⁰ M_sun) star-forming galaxies caused by major merging out to projected distances of ∼40 kpc. Using these results, we find that less than 10% of star formation at z ∼ 0.6 is triggered directly by major mergers and interactions; star formation triggered by major mergers does not significantly impact the growth of stellar mass at z < 1.