Figure 2

 $v_{n}$ coefficients where $n=2,3,4$ in the range (a) $0.2 \leq |\Delta\eta| \leq 0.9$ and (c) $0.9 \leq |\Delta\eta| \leq 1.9$ obtained from the $P_2$ correlation function. The coefficients are compared with the expectations from the flow ansatz calculated in their respective $\Deta$ ranges in Pb-Pb collisions. Statistical errors are shown as vertical solid lines, whereas systematic errors are displayed as colored bands Ratios of the $v_{n}$ coefficients and their corresponding flow ansatz values are shown in (b) and (d). The errors on the ratios are only statistical.