# Adiabatic and entropy perturbations propagation in a bouncing Universe

@article{Peter2003AdiabaticAE, title={Adiabatic and entropy perturbations propagation in a bouncing Universe}, author={Patrick Peter and N. Pinto-Neto and Diego Gonzalez}, journal={arXiv: High Energy Physics - Theory}, year={2003} }

By studying some bouncing universe models dominated by a specific class of hydrodynamical fluids, we show that the primordial cosmological perturbations may propagate smoothly through a general relativistic bounce. We also find that the purely adiabatic modes, although almost always fruitfully investigated in all other contexts in cosmology, are meaningless in the bounce or null energy condition (NEC) violation cases since the entropy modes can never be neglected in these situations: the…

## 12 Citations

Stochastic background of relic gravitons in a bouncing quantum cosmological model

- Physics
- 2012

The spectrum and amplitude of the stochastic background of relic gravitons produced in a bouncing universe is calculated. The matter content of the model consists of dust and radiation fluids, and…

Observational signatures of a non-singular bouncing cosmology

- Physics
- 2011

We study a cosmological scenario in which inflation is preceded by a bounce. In this scenario, the primordial singularity, one of the major shortcomings of inflation, is replaced by a non-singular…

Duality and scale invariant magnetic fields from bouncing universes

- Physics
- 2016

Recently, we had numerically shown that, for a non-minimal coupling that is a simple power of the scale factor, scale invariant magnetic fields arise in a class of bouncing universes. In this work,…

Cosmological Perturbations on a Bouncing Brane

- Physics
- 2007

The cosmological perturbations on a bouncing brane are studied. The brane is moving inside a Klebanov–Strassler throat where the infrared region of the geometry is smoothly cut off. For an observer…

Nonsingular cosmology with a scale-invariant spectrum of cosmological perturbations from Lee-Wick theory

- Physics
- 2009

We study the cosmology of a Lee-Wick type scalar field theory. First, we consider homogeneous and isotropic background solutions and find that they are nonsingular, leading to cosmological bounces.…

Cross-correlations between scalar perturbations and magnetic fields in bouncing universes

- PhysicsJournal of Cosmology and Astroparticle Physics
- 2019

Bouncing scenarios offer an alternative to the inflationary paradigm for the generation of perturbations in the early universe. Recently, there has been a surge in interest in examining the issue of…

Generation of scale invariant magnetic fields in bouncing universes

- Physics
- 2015

We consider the generation of primordial magnetic fields in a class of bouncing models when the electromagnetic action is coupled non-minimally to a scalar field that, say, drives the background…

Viable tensor-to-scalar ratio in a symmetric matter bounce

- Physics
- 2017

Matter bounces refer to scenarios wherein the universe contracts at early times as in a matter dominated epoch until the scale factor reaches a minimum, after which it starts expanding. While such…

The tensor bi-spectrum in a matter bounce

- Physics
- 2015

Matter bounces are bouncing scenarios wherein the universe contracts as in a matter dominated phase at early times. Such scenarios are known to lead to a scale invariant spectrum of tensor…

Bouncing alternatives to inflation

- Physics
- 2015

Abstract Although the inflationary paradigm is the most widely accepted explanation for the current cosmological observations, it does not necessarily correspond to what actually happened in the…

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