Cosmological Evolution of Modified Chaplygin Gas with the Sign-Changeable Interactions
Abstract
The cosmological evolution of modified Chaplygin Gas (MCG) model with the sign-changeable interactions is studied. The key point of the new interaction is the deceleration parameter qequiv-ddot{a}a/dot{a}2 in the interaction term Q. This new feature gives the possibility that interaction Q can change its sign when the universe changes from deceleration ( q>0) to acceleration ( q<0) and brings different evolution to cosmology. We find that there exist some stable scaling attractors, which can alleviate the coincidence problem. The equation of state (EoS) of MCG approaches the attractor phase from either w g >-1 or w g <-1 depending on the choice of its initial cosmic density parameter and the ratio of pressure to critical energy density. So, the phantom divide is crossed. Furthermore, we show numerically the evolution of 2kappa2/9H3Q with the proper parameters and find the new interaction Q has a transition from Q<0 to Q>0 as the universe expands, which is different from the usual interaction. The numerical calculation shows that a heteroclinic orbit (solution of dynamical system) can interpolate between MCG matter-dominated phase (an unstable critical point) and MCG vacuum-energy-dominated attractor.
- Publication:
-
International Journal of Theoretical Physics
- Pub Date:
- November 2012
- DOI:
- 10.1007/s10773-012-1224-5
- Bibcode:
- 2012IJTP...51.3432X
- Keywords:
-
- Dark energy;
- Modified Chaplygin gas;
- Sign-changeable interaction