11 research outputs found
Constraints on Exotic Matter for An Emergent Universe
We study a composition of normal and exotic matter which is required for a
flat Emergent Universe scenario permitted by the equation of state
(EOS)() and predict the range of the permissible values
for the parameters and to explore a physically viable cosmological
model. The permitted values of the parameters are determined taking into
account the data obtained from observations, a model independent BAO
peak parameter and CMB shift parameter (WMAP7 data). It is found that although
can be very close to zero, most of the observations favours a small and
negative . As a consequence, the effective Equation of State parameter for
this class of Emergent Universe solutions remains negative always. We also
compared the magnitude () vs. redshift() curve obtained in the
model with that obtained from the union compilation data. According to our
analysis the class of Emergent Universe solutions considered here is not ruled
out by the observations.Comment: 6 pages, 7 figures, 1 tabl
Observational Constraints of Modified Chaplygin Gas in Loop Quantum Cosmology
We have considered the FRW universe in loop quantum cosmology (LQC) model
filled with the dark matter (perfect fluid with negligible pressure) and the
modified Chaplygin gas (MCG) type dark energy. We present the Hubble parameter
in terms of the observable parameters , and
with the redshift and the other parameters like , , and .
From Stern data set (12 points), we have obtained the bounds of the arbitrary
parameters by minimizing the test. The best-fit values of the
parameters are obtained by 66%, 90% and 99% confidence levels. Next due to
joint analysis with BAO and CMB observations, we have also obtained the bounds
of the parameters () by fixing some other parameters and .
From the best fit of distance modulus for our theoretical MCG model in
LQC, we concluded that our model is in agreement with the union2 sample data.Comment: 14 pages, 10 figures, Accepted in EPJC. arXiv admin note: text
overlap with arXiv:astro-ph/0311622 by other author