Elliptic flow of direct photons, \vtwogammadir, in the 0--20\% (left) and 20--40\% (right) centrality classes for \PbPb\ collisions at \sqrtSnn = 2.76 TeV . The vertical bars and the boxes indicate the statistical and the total uncertainties on the data, respectively. ALICE data are compared to model calculations  and PHENIX data  in the same respective centrality classes.