Dark energy: Theory and observational prospects.

다국어 초록 (Multilingual Abstract)

The question of late-time cosmological acceleration remains one of the most pressing issues for both contemporary cosmology and theoretical physics in general. In three separate papers, this thesis investigates a range of questions raised by the current cosmological evidence for such an acceleration. We first consider new mechanisms in the underlying physics, investigating the possibility that a hidden Lorentz-violating vector field is the source of this effect and describing hitherto unknown mechanisms for the production of a "phantom" behavior. In a second, more observational section, we then consider what bounds may be placed on both astrophysical parameters such as those describing the large-scale behavior of gas, and the time evolution of the dark energy, through a study of the kinetic Sunyaev-Zel'dovich (kSZ) effect as a tracer of the growth of peculiar velocities in the low-redshift universe. We expand and refine prior methods for doing so, considering a cross-correlation between a galaxy survey such as one from the Southern African Large Telescope (SALT) and a CMB experiment such as the Atacama Cosmology Telescope (ACT). Finally, we propose a new method, velocity field reconstruction, for the extraction of the kSZ from a combination of a wide galaxy survey, such as the Dark Energy Survey, and a narrow and deep CMB experiment such as ACT. In this final section, we discuss both the mathematical tools, and the experimental methods, for taking advantage of the rich sources of information that can be mined from near-future observatories.