  Investigation of femtoscopic correlation functions in relativistic heavy ion
reactions is an important tool to access the space-time structure of particle
production in the sQGP. The shape of the correlation functions is often assumed
to be Gaussian, but a detailed analysis reveals that the statistically correct
assumption could be the so-called L\'evy distribution. The detailed analysis of
correlation functions in various systems may shed light on the location of the
critical endpoint on the QCD phase diagram. It could also reveal if there is
partially coherent pion production or could indicate the possible in-medium
mass modification of the $\eta'$ meson due to the (partial) restoration of the
$U_A(1)$ axial symmetry. In this paper we present the status of the centrality
dependent measurements of two-pion L\'evy Bose-Einstein correlation functions
in Au+Au collisions at PHENIX.
