A. Sheykhi, M. Sadegh Movahed
A new dark energy model called "ghost dark energy" was recently suggested to
explain the observed accelerating expansion of the universe. This model
originates from the Veneziano ghost of QCD. The dark energy density is
proportional to Hubble parameter, $\rho_D=\alpha H$, where $\alpha$ is a
constant of order $\Lambda_{\rm QCD}^3$ and $\Lambda_{\rm QCD}\sim 100 MeV$ is
QCD mass scale. In this paper, we extend the ghost dark energy model to the
universe with spatial curvature in the presence of interaction between dark
matter and dark energy. We study cosmological implications of this model in
detail. In the absence of interaction the equation of state parameter of ghost
dark energy is always $w_D > -1 $ and mimics a cosmological constant in the
late time, while it is possible to have $w_D < -1 $ provided the interaction is
taken into account. When $k = 0$, all previous results of ghost dark energy in
flat universe are recovered. To check the observational consistency, we use
Supernova type Ia (SNIa) Gold sample, shift parameter of Cosmic Microwave
Background radiation (CMB) and the Baryonic Acoustic Oscillation peak from
Sloan Digital Sky Survey (SDSS). The best fit values of free parameter at
$1\sigma$ confidence interval are: $\Omega_m^0= 0.35^{+0.02}_{-0.03}$,
$\Omega_D^0=0.75_{-0.04}^{+0.01}$ and $b^2=0.08^{+0.03}_{-0.03}$. Consequently
the total energy density of universe at present time in this model at 68% level
equates to $\Omega_{\rm tot}^0=1.10^{+0.02}_{-0.05}$.
View original:
http://arxiv.org/abs/1104.4713
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