Department of Relativistic Astrophysics and Cosmology
 
 
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55. Marek Szydlowski, Adam Krawiec, Wojciech Czaja
Phantom cosmology as a simple model with dynamical complexity
Phys. Rev., vol. E72, p. 036221 (2005).
[abstract] [preprint] [journal]

Abstract:
We study the Friedman-Robertson-Walker model with phantom fields modeled in terms of scalar fields. We apply the Ziglin theory of integrability and find that the flat model is nonintegrable. Then we cannot expect to determine simple analytical solutions of the Einstein equations. We demonstrate that there is only a discrete set of parameters where this model is integrable. For comparison we describe the phantoms fields in terms of the barotropic equation of state. It is shown that in contrast to the phantoms modeled as scalar fields, the dynamics is always integrable and phase portraits are contracted. In this case we find the duality relation.

56. Marek Szydlowski, Wojciech Czaja
Modified Friedmann cosmologies -Theory and observations
Annals Phys. , vol. 320, pp. 261-281 (2005).
[abstract] [preprint] [journal]

Abstract:
This paper shows the results of the investigation of a class of Cardassian scenarios of the evolution of the universe in the formulation of the qualitative theory of dynamical systems. That theory allowed us to analyze all solutions for all possible initial conditions on the phase plane. In the Cardassian models we find that big-rip singularities are present as a typical behavior in the future if $n < 0$. We were also able to find some exact solution for the flat Cardassian models as well as a duality relation. In turn for the statistical analysis of SNIa data, without any priors on the matter content in the model, we obtain that the big-rip scenario is favored. The potential function for the Hamiltonian description of dynamics was reconstructed from the SNIa data (inverse dynamical problem).

57. Rachel Mandelbaum, Christopher M. Hirata, Uros Seljak, Jacek Guzik, Nikhil Padmanabhan, Cullen Blake et al. (SDSS)
Systematic errors in weak lensing: application to SDSS galaxy-galaxy weak lensing
MNRAS, vol. 361, p. 1287 (2005).
[preprint] [journal]

Abstract:

58. Zdzisław A. Golda
Density Perturbations in Open Models of Early Universe with Positive Cosmological Constant
Acta Phys. Pol. , vol. B36, pp. 2149-2164 (2005).
[abstract] [journal]

Abstract:
The analytical solutions of the density perturbation equation in the Friedman--Lema\^{\i}tre--Robertson--Walker (FLRW) open cosmological models with radiation and positive cosmological constant are provided. The perturbations are of two types: the first propagating as acoustical waves, and the second of non-wave nature. It is shown that there occurs dispersion on curvature and cosmological constant for acoustical perturbations. The wave solutions have anomalous dispersion.

59. Zdzisław A. Golda, Andrzej Woszczyna, Karolina Zawada
Canonical gauge-invariant variables
Acta Phys. Pol., B , vol. B36, p. 2133 (2005).
[abstract] [preprint] [journal]

Abstract:
Under an appropriate change of the perturbation variable Lifshitz-Khalatnikov propagation equations for the scalar perturbation reduce to d'Alembert equation. The change of variables is based on the Darboux transform

60. Leszek M. Sokołowski
Elementy Kosmologii
(ZamKor 2005) ISBN: 83-88830-39-2 [opis]

Abstract:

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