Current lookback time-redshift bounds on dark energy
  We investigate observational constraints on dark energy models from lookback
time (LT) estimates of 32 old passive galaxies distributed over the redshift
interval $0.11 \leq z \leq 1.84$. To build up our LT sample we combine the age
measurements for these 32 objects with estimates of the total age of the
Universe, as obtained from current CMB data. We show that LT data may provide
bounds on the cosmological parameters with accuracy competitive with type Ia
Supernova methods. In order to break possible degeneracies between models
parameters, we also discuss the bounds when our lookback time versus redshift
sample is combined with with the recent measurement of the baryonic acoustic
oscillation peak and the derived age of the Universe from current CMB
measurements.
