Uplifting, Depressing, and Tilting Dark Energy
Abstract
Current data in the form of baryon acoustic oscillation, supernova, and cosmic microwave background distances prefer a cosmology that accelerates more strongly than at z≈0.5-1.5, and more weakly at z0.5. We examine dark energy physics that can accommodate this, showing that interactions (decays, coupling to matter, nonminimal coupling to gravity) fairly generically tend not to give a satisfactory solution (in terms of fitting both distances and growth) even if they enable the effective dark energy equation of state to cross w=-1. To fit the cosmological data it appears the dark energy by itself must cross w=-1, a highly unusual physical behavior.
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