Quarkonium in A-A collisions with the ALICE experiment

Quarkonia, i.e. bound states of heavy quarks (charm/bottom), provide remarkable probes of the hot and strongly-interacting medium, the quark gluon plasma (QGP), which is created during heavy-ion collisions. Heavy quarks are produced during initial hard-scattering processes prior to the QGP formation and their number is conserved throughout the partonic and hadronic phases of the collision. At LHC, experimental observations of quarkonium states in A-A collisions are reproduced through two antagonist mechanisms: the sequential suppression and quarkonium production by (re)combination of deconfined quarks. Recent measurements of a significant J/psi elliptic flow (v(2)) in Pb-Pb collisions at root s(NN) = 5.02 TeV suggest a participation of the charm quarks to the collectivity of the medium. However, quarkonium interactions in the medium are not yet fully understood and several points should still be clarified. The ALICE experiment at the LHC measures quarkonia at mid-rapidity in the dielectron decay channel and at forward rapidity in the dimuon one, both down to zero transverse momentum. Latest measurements of quarkonium nuclear modification factor and elliptic flow in Pb-Pb collisions will be presented and compared to lower energy results and theoretical predictions.