I have used custom techniques to reduce IFU data collected with the K-band Multi Object Spectrograph (KMOS) on the VLT. The reduced data provides spatially-resolved insights into the dynamical structure of roughly 50 z~3.5 galaxies, which is the largest kinematics sample at this epoch to date. The galaxies are modelled as rotating disks, using information from HST imaging to constrain some of the fitting parameters a-priori. From these models, the physical properties of the galaxies are extracted. Of particular interest is the V/sigma ratio, (that is the ratio of the circular velocity to the intrinsic velocity dispersion) which gives some indication of the extent to which the disk is supported by rotation or by random particle motions. Previous work has shown a declining trend of this ratio over cosmic time, when compared with values extracted from stable disks observed in the local universe. Understanding these trends is crucial to understanding the evolution of galaxy structure over time, from turbulence at early times to local stability.
I will present my results and discuss the difficulties in measuring the intrinsic velocity dispersion of galaxies using seeing-limited data.