Generation of a scale-invariant spectrum of adiabatic fluctuations in cosmological models with a contracting phase

被引:334
作者
Finelli, F [1 ]
Brandenberger, R
机构
[1] CERN, Div Theory, CH-1211 Geneva 23, Switzerland
[2] CNR, IASF, Sez Bologna, I-40129 Bologna, Italy
[3] Brown Univ, Dept Phys, Providence, RI 02912 USA
来源
PHYSICAL REVIEW D | 2002年 / 65卷 / 10期
关键词
D O I
10.1103/PhysRevD.65.103522
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
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.
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页数:8
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共 53 条
[1]   SINGULARITY-FREE COSMOLOGICAL SOLUTIONS OF THE SUPERSTRING EFFECTIVE ACTION [J].
ANTONIADIS, I ;
RIZOS, J ;
TAMVAKIS, K .
NUCLEAR PHYSICS B, 1994, 415 (02) :497-514
[2]   GAUGE-INVARIANT COSMOLOGICAL PERTURBATIONS [J].
BARDEEN, JM .
PHYSICAL REVIEW D, 1980, 22 (08) :1882-1905
[3]   SPONTANEOUS CREATION OF ALMOST SCALE-FREE DENSITY PERTURBATIONS IN AN INFLATIONARY UNIVERSE [J].
BARDEEN, JM ;
STEINHARDT, PJ ;
TURNER, MS .
PHYSICAL REVIEW D, 1983, 28 (04) :679-693
[4]  
BENEZIANO G, HEPTH0002094
[5]   On the spectrum of fluctuations in an effective field theory of the ekpyrotic universe [J].
Brandenberger, R ;
Finelli, F .
JOURNAL OF HIGH ENERGY PHYSICS, 2001, (11) :1-16
[6]   COSMOLOGICAL PERTURBATIONS IN INFLATIONARY-UNIVERSE MODELS [J].
BRANDENBERGER, R ;
KAHN, R .
PHYSICAL REVIEW D, 1984, 29 (10) :2172-2190
[7]   COSMOLOGICAL THEORY WITHOUT SINGULARITIES [J].
BRANDENBERGER, R ;
MUKHANOV, V ;
SORNBORGER, A .
PHYSICAL REVIEW D, 1993, 48 (04) :1629-1642
[8]  
Brandenberger RH, 1998, J HIGH ENERGY PHYS
[9]   METRIC PERTURBATIONS IN DILATON-DRIVEN INFLATION [J].
BRUSTEIN, R ;
GASPERINI, M ;
GIOVANNINI, M ;
MUKHANOV, VF ;
VENEZIANO, G .
PHYSICAL REVIEW D, 1995, 51 (12) :6744-6756
[10]   Model of graceful exit in string cosmology [J].
Brustein, R ;
Madden, R .
PHYSICAL REVIEW D, 1998, 57 (02) :712-724