Department of Relativistic Astrophysics and Cosmology
Selected publications
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61. 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]

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.

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

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

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


64. Christopher M. Hirata, Rachel Mandelbaum, Uros Seljak, Jacek Guzik, Nikhil Padmanabhan, Cullen Blake et al. (SDSS)
Galaxy-galaxy weak lensing in the Sloan Digital Sky Survey: intrinsic alignments and shear calibration errors
MNRAS, vol. 353, p. 529 (2004).
[preprint] [journal]


65. G. Siemieniec-Ozieblo, A. Woszczyna
Acoustic instabilities at the transition from the radiation-dominated to the matter-dominated universe
Astron. Astrophys. , vol. 419, pp. 801-810 (2004).
[abstract] [preprint] [journal]

The transition from acoustic noise in the radiation-dominated universe to the density structures in the matter dominated epoch is considered. The initial state is a stochastic field of sound waves moving in different directions. The construction of the initial state is compatible with the hyperbolic type of propagation equation for density perturbations, and parallel to the theory of stochastic background of gravitational waves. Instantaneous transition between the cosmological epochs is assumed, and Darmois-Israel joining conditions are applied to match solutions for sound waves with growing or decaying modes at the decoupling. As a result a substantial amplification of the low scale structures is obtained.

66. G. Siemieniec-Oziębło, Z. A. Golda
Magnetic amplification in cylindrical cosmological structure
Astron. Astrophys., vol. 422, pp. 23-27 (2004).
[abstract] [preprint] [journal]

We derive the amplification of the cosmological magnetic field associated with forming gravitational structure. The self-similar solutions of magnetohydrodynamic equations are computed both in linear and nonlinear regimes. We find that the relatively fast magnetic field enhancement becomes substantial in the nonlinear phase.

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