Do galaxy mergers increase star formation and turbulence at cosmic noon?

Abstract

Mergers and interactions can significantly affect the morphological and dynamical properties of galaxies, however the impact of mergers on turbulence at $z > 1$ has not been observationally constrained. In this work we use the interaction strength parameter $Q_P$ to identify likely interacting and isolated galaxies at cosmic noon ($z \sim 1-2$) within the KMOS\textsuperscript{3D} integral field spectroscopy survey, utilising redshifts from the 3D-HST, CANDELS and UVCANDELS surveys. For $186$ galaxies, we measure deconvolved H$\alpha$ kinematics, including velocity dispersion, using a spatially non-parametric approach to account for observational effects in the dynamically diverse range of galaxies. We compare offsets in H$\alpha$ flux, star formation rate (SFR), dust attenuations, and velocity dispersion of likely interacting galaxies to isolated control galaxies matched in mass and lookback time. We find increased H$\alpha$ fluxes and SFRs in the likely interacting sample at the level of $\sim 0.1$ dex, a similar enhancement to studies of local pairs. In contrast, we find no significant increase in the level of velocity dispersion in interacting galaxies compared to their controls. The lack of increase in dispersion may reflect a combination of physical and observational factors, including limits to increasing turbulent motions in an already turbulent medium and spectral resolution limits.