Power-law bounces in gravity: Analysis of the ekpyrosis and accelerating regimes
Phys. Rev. D 112, 104059 – Published 21 November, 2025
DOI: https://doi.org/10.1103/rrnm-z3qy
Abstract
We investigate the dynamics of the Friedmann-Lemaître-Robertson-Walker spacetime within the framework of gravity using a compact, model-independent dynamical systems approach. By assuming a power-law scale factor, we explore ekpyrotic and accelerating solutions to address the big bang singularity. Our analysis demonstrates that a cosmological bounce, characterized by a transition from contraction to expansion, possibly avoids the singularity without directly using the Raychaudhuri equation, unlike previous approaches using specific forms. We identify a key fixed point in the phase space corresponding to the bounce, supported by perturbation analysis and qualitative description of trajectories in the phase space. The results suggest that gravity provides a robust framework for nonsingular cosmologies.