Production of photons in a bouncing universe

Salim, J. M.; Bergliaffa, Santiago Esteban Pérez; Souza, Naiara Maria de

doi:10.1088/0264-9381/22/6/006

Cited by 6 publications

(13 citation statements)

References 39 publications

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“…84 Notice that mode-mixing is possible with ǫ = 1, as for instance in [344]. 85 See Sect.3.2.9 and [327] for an exact solution that has this feature. 86 The string pre-big-bang model without corrections furnishes a highly blue-tilted spectrum n s = 4 of scalar perturbations [385].…”

Section: Scalar Perturbationsmentioning

confidence: 99%

“…We have mentioned above that the the model must be improved by taking into account matter creation. A non-singular solution in WIST that incorporates the effect of the creation of matter on the geometry was studied in [327]. Friedman equation in conformal time is given by…”

Section: Solution With Matter Generationmentioning

confidence: 99%

“…A particular solution to these equations that describes creation of relativistic matter only around the bounce, and enters a radiation phase with a constant scalar field in a short time is given by the expression [327] a…”

Section: Solution With Matter Generationmentioning

confidence: 99%

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Bouncing cosmologies

Novello¹,

2008

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Section: Scalar Perturbationsmentioning

confidence: 99%

Section: Solution With Matter Generationmentioning

confidence: 99%

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Bouncing cosmologies

Novello¹,

2008

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“…The FRW universe undergoing a bounce instead of the big-bang is also an appealing idea in the context of quantum cosmology [22]. The attractiveness of bouncing models comes from the fact that they have no horizon problem and they explain quantum origin of structures in the Universe [23,24,25]. Molina-Paris and Visser and later Tippett [26,27] characterized the bouncing models by the minimal condition under which the present universe arises from a bounce from the previous collapse phase (the Tolman wormhole is different name for denoting such a type of evolution).…”

Section: The Bouncing Models: Basic Equationsmentioning

confidence: 99%

Can the initial singularity be detected by cosmological tests?

et al. 2005

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In the presented paper we raised the question whether initial cosmological singularity can be proved by cosmological tests. The classical general relativity theory predicts the existence of singularity in the past if only some energy conditions are satisfied. On the other hand the latest quantum gravity applications to cosmology suggest the possibility of avoiding the singularity and replacing it with a bounce. Bounce is the moment in the evolution of the Universe when the Universe's size has minimum. Therefore the existence of observationally detected bounce in past of Universe could indicate the validity of the loop quantum gravity hypothesis and nonexistence of initial singularity which is present in the classical ΛCDM. We investigated the bouncing model described by the generalized Friedmann-Robertson-Walker (FRW) equation in the context of the observations of the currently accelerating universe. The distant type Ia supernovae data are used to constraint on bouncing evolutional scenario where square of the Hubble function H 2 is given by formulaewhere Ω m,0 , Ω n,0 > 0 are density parameters and n > m > 0. In this paper are showed that the on the base of the SNIa data standard bouncing models can be ruled out on the 4σ confidence level. After adding the cosmological constant to the standard bouncing model (the extended bouncing model) we obtained as the best-fit that the parameter Ω n,0 is equal zero which means that the SNIa data do not support the bouncing term in the model. The bounce term is statistically insignificant on the present epoch. We also demonstrated that BBN offers the possibility of obtaining stringent constraints of the extra term Ω n,0 . The other observational test methods like CMB and the age of oldest objects in the Universe are also used. We use as well the Akaike informative criterion to select a model which fits data the best and we concluded that bouncing term should be ruled out by Occam's razor, which makes the big bang scenario more favorable then the bouncing scenario.

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“…The FRW universe undergoing a bounce instead of the big-bang is also an appealing idea in the context of quantum cosmology [61]. The attractiveness of bouncing models comes from the fact that they have no horizon problem and they explain quantum origin of structures in the Universe [62][63][64]. MolinaParis and Visser and later Tippett [47,48] characterised the bouncing models by the minimal condition under which the present universe arises from a bounce from the previous collapse phase (the Tolman wormhole is different name for denoting such a type of evolution).…”

Section: Equation Of State Parameter From Distant Supernovae Observatmentioning

confidence: 99%

Equation of state for the Universe from similarity symmetries

2006

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In this paper we proposed to use the group of analysis of symmetries of the dynamical system to describe the evolution of the Universe. This method is used in searching for the unknown equation of state. It is shown that group of symmetries enforce the form of the equation of state for noninteracting scaling multifluids. We showed that symmetries give rise to the equation of state in the form p = − + w 1 ρ(a) + w 2 a β + 0 and energy density ρ = + ρ 01 a −3(1+w) + ρ 02 a β + ρ 03 a −3 , which is commonly used in cosmology. The FRW model filled with scaling fluid (called homological) is confronted with the observations of distant type Ia supernovae. We found the class of model parameters admissible by the statistical analysis of SNIa data. We showed that the model with scaling fluid fits well to supernovae data. We found that m,0 0.4 and n −1 (β = −3n), which can correspond to (hyper) phantom fluid, and to a high density universe. However if we assume prior that m,0 = 0.3 then the favoured model is close to concordance CDM model. Our results predict that in the considered model with scaling fluids distant type Ia supernovae should be brighter than in the CDM model, while intermediate distant SNIa should be fainter than in the CDM model. We also investigate whether the model with scaling fluid is actually preferred by data over CDM model. As a result we find from the Akaike model selection criterion: it prefers the model with noninteracting scaling fluid.

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Production of photons in a bouncing universe

Cited by 6 publications

References 39 publications

Bouncing cosmologies

Bouncing cosmologies

Can the initial singularity be detected by cosmological tests?

Equation of state for the Universe from similarity symmetries

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