Cosmological consequences of a scalar field with oscillating equation of state. II. Oscillating scaling and chaotic accelerating solutions

TL;DR

This paper explores a dark energy model with oscillating behavior that leads to oscillating scaling solutions in the early universe and chaotic acceleration in the late universe, potentially addressing the coincidence problem.

Contribution

It introduces a novel oscillating dark energy model that exhibits a transition from oscillating scaling solutions to chaotic acceleration, linking early and late universe dynamics.

Findings

The model allows the universe to evolve as an oscillating scaling solution during radiation era.

It demonstrates a transition to chaotic accelerating solutions in the matter era.

The scenario aligns with cosmological constraints and explains late-time acceleration.

Abstract

Multiacceleration scenario can be used to solve the cosmological coincidence problem. In this paper, after considering the early radiation era, we revisit the cosmological dynamics of the oscillating dark energy model proposed in [https://doi.org/10.1103/PhysRevD.101.063531, Phys. Rev. D {\bf 101}, 063531 (2020)]. We find this model allows the Universe evolves as oscillating scaling solution (OSS) in the radiation era and as chaotic accelerating solution (CAS) in the matter era. Mathematically, the transition from OSS to CAS is a route of period-doubling bifurcation to chaos. Physically, there are two reasons convince us that this scenario can be a nice picture to describe the real Universe. One is the global cosmological parameter constraints are practicable if the Universe evolves as OSS in the radiation era. The other is the late-time Universe described by CAS can successfully explain the observed cosmic acceleration at low redshifts.