Cosmological perturbations through the big bang
| dc.creator | Wands, David | |
| dc.date | 2008-09-26 | |
| dc.date.accessioned | 2026-07-07T10:05:41Z | |
| dc.date.available | 2026-07-07T10:05:41Z | |
| dc.description | Several scenarios have been proposed in which primordial perturbations could originate from quantum vacuum fluctuations in a phase corresponding to a collapse phase (in an Einstein frame) preceding the Big Bang. I briefly review three models which could produce scale-invariant spectra during collapse: (1) curvature perturbations during pressureless collapse, (2) axion field perturbations in a pre big bang scenario, and (3) tachyonic fields during multiple-field ekpyrotic collapse. In the separate universes picture one can derive generalised perturbation equations to describe the evolution of large scale perturbations through a semi-classical bounce, assuming a large-scale limit in which inhomogeneous perturbations can be described by locally homogeneous patches. For adiabatic perturbations there exists a conserved curvature perturbation on large scales, but isocurvature perturbations can change the curvature perturbation through the non-adiabatic pressure perturbation on large scales. Different models for the origin of large scale structure lead to different observational predictions, including gravitational waves and non-Gaussianity. | |
| dc.description | 13 pages, latex, no figures. To appear in Adv Sci Lett, special issue on Quantum Gravity, Cosmology amd Black Holes | |
| dc.identifier | https://arxiv.org/abs/0809.4556 | |
| dc.identifier | http://arxiv.org/abs/0809.4556 | |
| dc.identifier.uri | http://salesiana.dossiersoluciones.com/handle/123456789/170078 | |
| dc.subject | Astrophysics | |
| dc.subject | General Relativity and Quantum Cosmology | |
| dc.subject | High Energy Physics - Theory | |
| dc.title | Cosmological perturbations through the big bang | |
| dc.type | text |