Measurement of two-particle correlations with respect to second- and third-order event planes in Au + Au collisions at $\\sqrt{s_{\\it NN}}=200$ GeV

We present measurements of azimuthal correlations of charged hadron pairs in $sqrt{s_{_{NN}}}=200$ GeV Au$+$Au collisions after subtracting an underlying event using a model that includes higher-order azimuthal anisotropy $v_2$, $v_3$, and $v_4$. After subtraction, the away-side ($Deltaphisimpi)$ of the highest transverse-momentum trigger ($p_Tu003e4$ GeV/$c$) correlations is suppressed compared to that of correlations measured in $p$$+$$p$ collisions. At the lowest associated particle $p_T$, the away-side shape and yield are modified. These observations are consistent with the scenario of radiative-jet energy loss. For the lowest-$p_T$ trigger correlations, an away-side yield exists and we explore the dependence of the shape of the away-side within the context of an underlying-event model. Correlations are also studied differentially versus event-plane angle $Psi_n$. The angular correlations show an asymmetry when selecting the sign of the trigger-particle azimuthal angle with respect to the $Psi_2$ event plane. This asymmetry and the measured suppression of the pair yield out of plane is consistent with a path-length-dependent energy loss. No $Psi_3$ dependence can be resolved within experimental uncertainties.