Azimuthal correlation distributions in the 30$-$50% centrality class of Pb$-$Pb collisions at $\sqrt{s_{\rm NN}} = 5.02$ $\mathrm{TeV}$ for the intervals $0.20< z_{\rm T}< 0.30$ and $20< p_{\rm T}^{\rm trig}< 25$ GeV/$c$. Each marker corresponds to a different trigger: isolated-narrow clusters (blue-full circles), also shown in Fig. 1; isolated-wide clusters (violet-open squares), scaled by $1-P$, where $P$ is the purity; isolated-photon triggers (orange-empty crosses), calculated using the equation in the text. The vertical bars indicate the statistical uncertainties. The dashed-green line at $|\Delta \varphi|=3/5\pi$ indicates the lower limit of the integration used in the $D(z_{\rm T})$ calculation.