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 X2 into account. This allows for the dark energy equation of state wDE to access the region -2 <wDE<-1 without ghosts. Indeed, this peculiar evolution of wDE is favored over that of the cosmological constant Λ 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 Λ -cold-dark-matter (Λ CDM ) model by suppressing large-scale temperature anisotropies. The CMB temperature and polarization data lead to an estimation for today's Hubble parameter H0 consistent with its direct measurements at 2 σ . We perform a model selection analysis by using several methods and find a statistically significant preference of the Galileon ghost condensate model over Λ CDM .
Physical Review D
- Pub Date:
- September 2019
- Astrophysics - Cosmology and Nongalactic Astrophysics;
- General Relativity and Quantum Cosmology
- 6 pages, 4 figures, accepted version by PRD