Cosmic Steps in Modeling Dark Energy

Abstract

The past and recent data analyses gave some hints of steps in dark energy. Considering the dark energy as a dynamical scalar field, we investigate several models with various steps: a step in the scalar potential, a step in the kinetic term, a step in the energy density and a step in the equation-of-state parameter w. These toy models provide a workable mechanism to generate steps and features of dark energy. Remarkably, a single real scalar can cross w=-1 dynamically with a step in the kinetic term.Comment: 6 pages, 5 figures, structure improved, reference added, results unchange