$p_{\rm T}^{\rm norm}$ as a function of $\langle {\rm d}N/{\rm d}\eta \rangle^{\rm norm}$. Results are shown for two centrality estimators: one based on transverse energy (black diamonds) and the other based on charged-particle multiplicity (red crosses). For the \nch-based centrality estimator, two values of $c_s^2$ are extracted using non-overlapping fit ranges (dashed-lines). The $p_{\rm T}^{\rm norm}$ versus $\langle {\rm d}N/{\rm d}\eta \rangle^{\rm norm}$ correlation for the $\eta$-based centrality estimator corresponds to the centrality definition labeled as IV in Table.1.