Closing the cosmological loop with the redshift drift
  The redshift drift (also known as the Sandage Test) is a model-independent
probe of fundamental cosmology, enabling us to watch the universe expand in
real time, and thereby to confirm (or not) the recent acceleration of the
universe without any model-dependent assumptions. On the other hand, by
choosing a fiducial model one can also use it to constrain the model
parameters, thereby providing a consistency test for results obtained with
other probes. The drift can be measured by the Extremely Large Telescope and
also by the full SKA. Recently two alternative measurement methods have been
proposed: the cosmic accelerometer, and the differential redshift drift. Here
we summarize a comparative analysis of the various methods and their possible
outcomes, using both Fisher Matrix and MCMC techniques. We find that no single
method is uniformly better than the others. Instead, their comparative
performance depends both on experimental parameters (including the experiment
time and redshift at which the measurement is made) and also on the scientific
goal (e.g., detecting the drift signal with high statistical significance,
constraining the matter density, or constraining the dark energy properties).
In other words, the experiment should be optimized for the preferred scientific
goal.
