Apparent versus true value of the cosmological constant
  Supernovae observations strongly support the presence of a cosmological
constant, but its value, which we will call apparent, is normally determined
assuming that the universe can be accurately described by a homogeneous model.
Even in the presence of a cosmological constant we cannot exclude nevertheless
the presence of a small local inhomogeneity which could affect the apparent
value of the cosmological constant. Neglecting the presence of the
inhomogeneity can in fact introduce a systematic misinterpretation of
cosmological data, leading to the distinction between an apparent and the true
value of the cosmological constant. But is such a difference distinguishable?
Recently we set out to model the local inhomogeneity with a {\Lambda}LTB
solution and computed the relation between the apparent and the true value of
the cosmological constant. In this essay we reproduce the essence of our model
with the emphasis on its physical implications.
