Observational constraints on new generalized Chaplygin gas model
  We use the latest data to investigate observational constraints on the new
generalized Chaplygin gas (NGCG) model. Using the Markov Chain Monte Carlo
(MCMC) method, we constrain the NGCG model with the type Ia supernovae (SNe Ia)
from Union2 set (557 data), the usual baryonic acoustic oscillation (BAO)
observation from the spectroscopic Sloan Digital Sky Survey (SDSS) data release
7 (DR7) galaxy sample, the cosmic microwave background (CMB) observation from
the 7-year Wilkinson Microwave Anisotropy Probe (WMAP7) results, the newly
revised $H(z)$ data, as well as a value of $\theta_{BAO} (z=0.55) = (3.90 \pm
0.38)^{\circ}$ for the angular BAO scale. The constraint results for NGCG model
are $\omega_X =
-1.0510_{-0.1685}^{+0.1563}(1\sigma)_{-0.2398}^{+0.2226}(2\sigma)$, $\eta =
1.0117_{-0.0502}^{+0.0469}(1\sigma)_{-0.0716}^{+0.0693}(2\sigma)$, and
$\Omega_X = 0.7297_{-0.0276}^{+0.0229}(1\sigma)_{-0.0402}^{+0.0329}(2\sigma)$,
which give a rather stringent constraint. From the results, we can see a
phantom model is slightly favored and the probability that energy transfers
from dark matter to dark energy is a little larger than the inverse.
