Turnaround overdensity as a cosmological observable: the case for a
  local measurement of $\Lambda$
  We demonstrate that, in the context of the $\Lambda$CDM model, it is in
principle possible to measure the value of the cosmological constant by
tracing, across cosmic time, the evolution of the turnaround radius of cosmic
structures. The novelty of the presented method is that it is local, in the
sense that it uses the effect of the cosmological constant on the relatively
short scales of cosmic structures and not on the dynamics of the Universe at
its largest scales. In this way, it can provide an important consistency check
for the standard cosmological model and can give signs of new physics, beyond
$\Lambda$CDM.
