9 research outputs found
Cosmic coincidence problem and variable constants of physics
The standard model of cosmology is investigated using time dependent
cosmological constant and Newton's gravitational constant . The
total energy content is described by the modified Chaplygin gas equation of
state. It is found that the time dependent constants coupled with the modified
Chaplygin gas interpolate between the earlier matter to the later dark energy
dominated phase of the universe. We also achieve a convergence of parameter
, with minute fluctuations, showing an evolving . Thus our
model fairly alleviates the cosmic coincidence problem which demands
at present time.Comment: 27 pages, 15 figure
Combined constraints on modified Chaplygin gas model from cosmological observed data: Markov Chain Monte Carlo approach
We use the Markov Chain Monte Carlo method to investigate a global
constraints on the modified Chaplygin gas (MCG) model as the unification of
dark matter and dark energy from the latest observational data: the Union2
dataset of type supernovae Ia (SNIa), the observational Hubble data (OHD), the
cluster X-ray gas mass fraction, the baryon acoustic oscillation (BAO), and the
cosmic microwave background (CMB) data. In a flat universe, the constraint
results for MCG model are,
()
,
()
,
()
,
()
, and ()
.Comment: 12 pages, 1figur
Modified Chaplygin Gas as a Unified Dark Matter and Dark Energy Model and Cosmic Constraints
A modified Chaplygin gas model (MCG),
,
as a unified dark matter model and dark energy model is constrained by using
current available cosmic observational data points which include type Ia
supernovae, baryon acoustic oscillation and the seventh year full WMAP data
points. As a contrast to the consideration in the literatures, we {\it do not}
separate the MCG into two components, i.e. dark mater and dark energy
component, but we take it as a whole energy component-a unified dark sector. By
using Markov Chain Monte Carlo method, a tight constraint is obtained: , and .}Comment: 6 pages, 3 figure