http://www.cnr.it/ontology/cnr/individuo/prodotto/ID5510
On the generation of a scale invariant spectrum of adiabatic fluctuations in cosmological models with a contracting phase (Articolo in rivista)
- Type
- Label
- On the generation of a scale invariant spectrum of adiabatic fluctuations in cosmological models with a contracting phase (Articolo in rivista) (literal)
- Anno
- 2002-01-01T00:00:00+01:00 (literal)
- Alternative label
- Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#autori
- Finelli F., Brandenberger R. (literal)
- Pagina inizio
- Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#numeroVolume
- Note
- ISI Web of Science (WOS) (literal)
- Titolo
- On the generation of a scale invariant spectrum of adiabatic fluctuations in cosmological models with a contracting phase (literal)
- Abstract
- In Pre-Big-Bang and in Ekpyrotic Cosmology, perturbations on cosmological
scales today are generated from quantum vacuum fluctuations during a phase
when the Universe is contracting (viewed in the Einstein frame). The
backgrounds studied to date do not yield a scale invariant spectrum of
adiabatic fluctuations. Here, we present a new contracting background model
(neither of Pre-Big-Bang nor of the Ekpyrotic form) involving a single
scalar field coupled to gravity in which a scale-invariant spectrum of
curvature fluctuations and gravitational waves results. The equation of
state of this scalar field corresponds to cold matter. We demonstrate that
if this contracting phase can be matched via a nonsingular bounce to an
expanding Friedmann cosmology, the scale-invariance of the curvature
fluctuations is maintained. We also find new background solutions for
Pre-Big-Bang and for Ekpyrotic cosmology, which involve two scalar fields
with exponential potentials with background values which are evolving in
time. We comment on the difficulty of obtaining a scale-invariant spectrum
of adiabatic fluctuations with background solutions which have been studied
in the past. (literal)
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