Cosmological data favor Galileon ghost condensate over $\Lambda$CDM
  We place observational constraints on the Galileon ghost condensate model, a
dark energy proposal in cubic-order Horndeski theories consistent with the
gravitational-wave event GW170817. The model extends the covariant Galileon by
taking an additional higher-order field derivative $X^2$ into account. This
allows for the dark energy equation of state $w_{\rm DE}$ to access the region
$-2<w_{\rm DE}<-1$ without ghosts. Indeed, this peculiar evolution of $w_{\rm
DE}$ is favored over that of the cosmological constant $\Lambda$ from the joint
data analysis of cosmic microwave background (CMB) radiation, baryonic acoustic
oscillations (BAOs), supernovae type Ia (SNIa) and redshift-space distortions
(RSDs). Furthermore, our model exhibits a better compatibility with the CMB
data over the $\Lambda$-cold-dark-matter ($\Lambda$CDM) model by suppressing
large-scale temperature anisotropies. The CMB temperature and polarization data
lead to an estimation for today's Hubble parameter $H_0$ consistent with its
direct measurements at 2$\sigma$. We perform a model selection analysis by
using several methods and find a statistically significant preference of the
Galileon ghost condensate model over $\Lambda$CDM.
