Figure 1

Corrected per-trigger pair yield for $4 < {p_{\rm t, assoc}} < 6GeV/c$ for central Pb--Pb events (histogram), peripheral Pb--Pb events (red circles) and pp events (blue squares) a) azimuthal correlation; b) zoom on the region where the pedestal values (horizontal lines) and the $v_2$ component ($\cos 2 {\Delta\varphi}$) are indicated. Solid lines are used in the yield extraction while the dashed lines are used for the estimation of the uncertainty of the pedestal calculation; c) background-subtracted distributions using the flat pedestal Error bars indicate statistical uncertainties only.