\ Isolated-prompt $\gamma$--hadron correlations \ipqcd\ for central \PbPb collisions at \snnfive measured by the ALICE Collaboration, and \iaa\ for central \AuAu collisions at $\sqrt{s_{\rm NN}} = 200$ GeV measured by the PHENIX  and STAR  Collaborations at RHIC, also in central collisions. The boxes represent the systematic uncertainties, while the vertical bars indicate the statistical uncertainties. For ALICE, the blue-open boxes represent the $\mu$ scale uncertainty for the denominator NLO pQCD calculation for \pp collisions.