  Measurements of di-hadron azimuthal correlations at different centralities
for Au+Au collisions at 200 AGeV were reported by the PHENIX Collaboration. The
data were presented for different ranges of transverse momentum. In particular,
it was observed that the away-side correlation evolves from double- to a
single-peak structure when the centrality decreases. In this work, we show that
these features naturally appear as due to an interplay between the
centrality-dependent smooth background elliptic flow and the one produced by
event-by-event fluctuating peripheral tubes. To compare with the PHENIX data,
we also carry out numerical simulations by using a hydrodynamical code
NeXSPheRIO, and calculate the correlations by both cumulant and the ZYAM method
employed by PHENIX Collaboration. It is shown that our results are in
reasonable agreement with the data. A brief discussion on the physical content
of the present model and its difference from other viewpoint is also presented.
