Measurements of High pT $\pi^0$ Azimuthal Anisotropy in Au+Au Collisions at $\sqrt{s_{NN}}$ = 200 GeV at PHENIX

The phenomena of jet suppression has been well established via separate measurements of the nuclear modification factor $R_{AA}$, azimuthal anisotropy and di-hadron correlations. The current challenge is to quantitatively understand the underlying suppression mechanism, as well as to understand the interplay between jet suppression, collective flow and coalescence as function $p_T$. Meeting this challenge requires new measurements which extend the current experimental $p_T$ reach and combine the constraining power of $R_{AA}$ and anisotropy. In a recent experimental run (Year-2007), the PHENIX experiment collected over 800 $\mu b^{-1}$ in integrated luminosity of Au+Au collisions. Augmented with newly installed high resolution reaction plane detectors, this wealth of high statistics data allows detailed measurements of $R_{AA}$ relative to the reaction plane. The results using $\pi^0$s will be presented and compared with various energy loss model calculations. We will also study the $v_2$ results in different $p_T$ regions, and compare them using reaction plane determined in various $\eta$ windows. The former can shed light on the interplay between jet suppression, collective flow and coalesces, the later can help us to quantify the non-flow effects due to jets.