Nonsingular bouncing cosmology: Consistency of the effective description
| Autor: | Jean-Luc Lehners, Michael Koehn, Burt A. Ovrut |
|---|---|
| Rok vydání: | 2016 |
| Předmět: |
High Energy Physics - Theory
Physics Cosmology and Nongalactic Astrophysics (astro-ph.CO) 010308 nuclear & particles physics Initial singularity FOS: Physical sciences Shape of the universe Curvature 01 natural sciences Cosmology Ekpyrotic universe Classical mechanics High Energy Physics - Theory (hep-th) 0103 physical sciences Energy condition Gravitational singularity 010306 general physics Entropy (arrow of time) Astrophysics - Cosmology and Nongalactic Astrophysics |
| Zdroj: | Physical Review D |
| ISSN: | 2470-0029 2470-0010 |
| DOI: | 10.1103/physrevd.93.103501 |
| Popis: | We explicitly confirm that spatially flat non-singular bouncing cosmologies make sense as effective theories. The presence of a non-singular bounce in a spatially flat universe implies a temporary violation of the null energy condition, which can be achieved through a phase of ghost condensation. We calculate the scale of strong coupling and demonstrate that the ghost-condensate bounce remains trustworthy throughout, and that all perturbation modes within the regime of validity of the effective description remain under control. For this purpose we require the perturbed action up to third order in perturbations, which we calculate in both flat and co-moving gauge -- since these two gauges allow us to highlight different physical aspects. Our conclusion is that there exist healthy descriptions of non-singular bouncing cosmologies providing a viable resolution of the big-bang singularities in cosmological models. Our results also suggest a variant of ekpyrotic cosmology, in which entropy perturbations are generated during the contracting phase, but are only converted into curvature perturbations after the bounce. Comment: 43 pages, 18 figures |
| Databáze: | OpenAIRE |
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