A gauge invariant prescription to avoid $\gamma$-crossing instability in Galileon bounce

Abstract

We revisit the evolutions of scalar perturbations in a non-singular Galileon bounce. It is known that the second order differential equation governing the perturbations is numerically unstable at a point called $\gamma$-crossing. This instability is usually circumvented using certain gauge choices. We show that the perturbations can be evolved across this point by solving the first order differential equations governing suitable gauge invariant quantities without any instabilities. We demonstrate this method in a matter bounce scenario described by the Galileon action.

6 pages, 3 figures. Comments are welcome; v2: minor changes, published in Physical Review D

References in corpus (3)

• A Critical Review of Classical Bouncing Cosmologies
• Cosmological Perturbations Through a Non-Singular Ghost-Condensate/Galileon Bounce
• The Matter Bounce Alternative to Inflationary Cosmology

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• Negative non-Gaussianity as a salvager for PBHs with PTAs in bounce
• Conserved cosmological perturbations in USR inflation and bouncing scenarios