Scalar-Tensor Quintessence with a linear potential: Avoiding the Big Crunch cosmic doomsday

Understand

All quintessence potentials that are either monotonic with negative interval or have a minimum at negative values of the potential, generically predict a future collapse of the scale factor to a "doomsday" singularity.

• We show that this doomsday is generically avoided in models with a proper non-minimal coupling of the quintessence scalar field to the curvature scalar $R$.
• For simplicity we consider linear quintessence potential $V=-s\phi$ and linear non-minimal coupling $F=1-\lambda \phi$.
• However our result is generic and is due to the fact that the non-minimal coupling modifies the effective potential that determines the dynamics of the scalar field.