Origin and Evolution of High-Redshift Ultraluminous and Luminous Infrared Galaxies

Abstract

The most dust-obscured galaxies dominate the star formation activities of the universe at its peak epoch 10-11 billion years ago. However, it remains highly debated whether these distant, vigorously star-forming galaxies are triggered via violent interactions like their local counterparts or driven by an elevated gas supply in the early universe. The primary goal of this dissertation is to understand the origin and evolution of ultraluminous and luminous infrared galaxies ((U)LIRGs) at high—z via characterizing their morphological and kinematic properties, and comparing them with local well-studied systems and hydrodynamic simulations. By characterizing the optical morphologies of >2000 Herschel-selected galaxies at 0:2 < z < 1:5, I have concluded that the abundance of interacting galaxies increases with the increase of infrared luminosity and the deviation from the starforming galaxy main sequence. Although the merger fraction of ULIRGs decreases from > 85% to only 50% from z 0 to z > 1, I have demonstrated that this difference can be in part explained by systematic biases in the datasets based on a careful comparison between local and z 1 (U)LIRGs, and an artificially redshifted dataset constructed from local (U)LIRGs. Spatially resolved kinematics from integral field spectrograph and millimeter interferometer observations have been used to determine dynamical status of star-forming galaxies with ambiguous morphologies. Using wide-field integral field spectrograph observations of 24 local (U)LIRGs and a series of hydrodynamic simulations of galaxy mergers, I have demonstrated that the reliability of kinematic classifications shows a strong trend with the galaxy interaction stages. Mergers in the strong interaction phases have the most distinct kinematic properties compared to isolated disks, whereas a significant population of the interacting disks in the earlier stage and merger remnants are indistinguishable from isolated disk systems.