The KMOS3D survey: design, first results, and the evolution of galaxy kinematics from 0.7 ≤ z ≤ 2.7

We present the KMOS3D survey, a new integral field survey of over 600 galaxies at 0.7 1, implying that the star-forming main sequence is primarily composed of rotating galaxies at both redshift regimes. When considering additional stricter criteria, the Hα kinematic maps indicate that at least ~70% of the resolved galaxies are disk-like systems. Our high-quality KMOS data confirm the elevated velocity dispersions reported in previous integral field spectroscopy studies at z 0.7. For rotation-dominated disks, the average intrinsic velocity dispersion decreases by a factor of two from 50 km s–1at z ~ 2.3 to 25 km s–1at z ~ 0.9. Combined with existing results spanning z ~ 0-3, we show that disk velocity dispersions follow an evolution that is consistent with the dependence of velocity dispersion on gas fractions predicted by marginally stable disk theory.