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Rigorous theoretical constraint on constant negative EoS parameter [Formula: see text] and its effect for the late
Alvina Burgazli1, Maxim Eingorn2,3,4, Alexander Zhuk2
1Department of Theoretical Physics, Odessa National University, Dvoryanskaya st. 2, Odessa, 65082 Ukraine.
The European Physical Journal. C, Particles and Fields
|May 22, 2015
Summary
A specific cosmic fluid with an equation of state parameter w = -2/3 is required for scalar perturbations in the late Universe. This clustered fluid screens gravitational potential around structures like galaxies.
Area of Science:
- Cosmology
- Astrophysics
- Theoretical Physics
Background:
- The late-stage Universe contains inhomogeneously distributed structures like galaxies.
- Cosmological models often include a cosmological constant and a perfect fluid with negative equation of state (EoS) parameter w.
Purpose of the Study:
- To investigate scalar perturbations in Friedmann-Robertson-Walker metrics due to inhomogeneities.
- To determine the constraints on the EoS parameter (w) of a perfect fluid in the late Universe.
Main Methods:
- Analysis of scalar perturbations of Friedmann-Robertson-Walker metrics.
- Investigating the behavior of a perfect fluid with a negative constant EoS parameter (w).
Main Results:
- The perfect fluid must be clustered and have an EoS parameter w = -2/3 to be compatible with scalar perturbation theory.
- This specific EoS parameter (w = -2/3) corresponds to a frustrated network of cosmic strings.
- A perfect fluid with w = -2/3 neither accelerates nor decelerates the Universe and screens gravitational potential around inhomogeneities.
Conclusions:
- The frustrated network of domain walls (w = -1/3) is ruled out.
- Physically reasonable solutions for flat, open, and closed Universes are obtained with a perfect fluid having w = -2/3.
- This clustered fluid concentrates around inhomogeneities, leading to gravitational potential screening.
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