The Hubble parameter in the early universe with viscous QCD matter and finite cosmological constant
Version of Record online: 21 APR 2011
Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Annalen der Physik
Volume 523, Issue 5, pages 423–434, May 2011
How to Cite
Tawfik, A. (2011), The Hubble parameter in the early universe with viscous QCD matter and finite cosmological constant. Ann. Phys., 523: 423–434. doi: 10.1002/andp.201100038
- Issue online: 21 APR 2011
- Version of Record online: 21 APR 2011
- Manuscript Accepted: 4 APR 2011
- Manuscript Revised: 2 APR 2011
- Manuscript Received: 15 FEB 2011
- Astrophysical aspects;
- classical general relativity;
- classical general relativity.
The evolution of a flat, isotropic and homogeneous universe is studied. The background geometry in the early phases of the universe is conjectured to be filled with causal bulk viscous fluid and dark energy. The energy density relations obtained from the assumption of covariant conservation of energy-momentum tensor of the background matter in the early universe are used to derive the basic equation for the Hubble parameter H. The viscous properties described by ultra-relativistic equations of state and bulk viscosity taken from recent heavy-ion collisions and lattice QCD calculations have been utilized to give an approximate solution of the field equations. The cosmological constant is conjectured to be related to the energy density of the vacuum. In this treatment, there is a clear evidence for singularity at vanishing cosmic time t indicating the dominant contribution from the dark energy. The time evolution of H seems to last for much longer time than the ideal case, where both cosmological constant and viscosity coefficient are entirely vanishing.