Cosmological dynamics of multifield dark energy

Abstract

We numerically and analytically explore the background cosmological dynamics of multifield dark energy with highly nongeodesic or “spinning” field-space trajectories. These extensions of standard single-field quintessence possess appealing theoretical features and observable differences from the cosmological standard model. At the level of the cosmological background, we perform a phase-space analysis and identify approximate attractors with late-time acceleration for a wide range of initial conditions. Focusing on two classes of field-space geometry, we derive bounds on parameter space by demanding viable late-time acceleration and the absence of gradient instabilities, as well as from the de Sitter swampland conjecture.