High Energy Physics Seminars

Dark energy, responsible for the apparent acceleration of the Universe, is typically considered to be represented by a cosmological constant. However, according to the latest results from WMAP 9 and Planck, the measured 2-sigma range for the equation-of-state parameter lies below -1, which is indicative of a dark energy density that increases over time, i.e., phantom dark energy. I discuss the full categorization of dark energy models with monotonically increasing dark energy densities, introducing two new categories described by what we have dubbed the "little rip" and the "pseudo-rip." I present example parameterizations for each type and discuss the implications for bound structures and the Universe itself in the future.