Measurement of elliptic and higher-order harmonics at 2.76 TeV Pb+Pb collisions with the ATLAS detector.

Anisotropy coefficients $v_n$ are important observables for studying the hot, dense medium created in heavy ion collisions. They not only probe the collective flow of the bulk medium (at $p_T$<3-4 GeV), but also probe the path-length dependent energy loss (at higher $p_T$), both are associated with the asymmetries in the initial geometry. However, auto-correlations not related to initial geometry, commonly referred to as non-flow effects, can contribute to these coefficients, hence need to be systematically suppressed. We present comprehensive measurements of coefficients $v_2$-$v_6$ using the event plane method and two-particle correlations method in broad $p_T$, eta and centrality ranges using the Pb-Pb data from the ATLAS experiment.