  PHENIX and STAR data on the intercept parameter of the two-pion Bose-Einstein
correlation functions in sqrt(s_{NN}) = 200 GeV Au+Au collisions are analyzed
in terms of different models of hadronic multiplicities. To describe this
combined PHENIX and STAR dataset, an in-medium eta' mass reduction of at least
200 MeV is needed, at the 99.9 % confidence level in the considered model
class. Such a significant eta' mass modification may indicate the restoration
of the U_A(1) symmetry in a hot and dense hadronic matter and the return of the
9th "prodigal" Goldstone boson.
