• gas kinematic
• Alma
• high-redshift
• galaxy

The aim of this thesis was to determine if galaxies in the first Gyrs of the Universe are
dynamically more chaotic than their local counterparts or not. Therefore, I investigated the
kinematical properties of a sample of high-redshift (z ∼5 −7) star-forming galaxies by using
observations of rest-frame far-infrared lines carried out with the telescope Atacama Large Millimeter/sub–Millimeter Array (ALMA). I performed a kinematical analysis by selecting a sample of 20 targets that is 2 times larger than the current sample in literature.
Based on the kinematics analysis of the selected galaxies studied through the [C II]
and [O III] emission lines, I found evidence for rotating disks already 1 Gyr after the Big
Bang. These disks have a gas velocity dispersion that is 5 times larger than
what is observed in the local Universe. This indicates that high-redshift galaxies are more
chaotic than local ones, as also predicted by recent galaxy evolution models and cosmological simulations.