  We argue that "ridge" in 2-particle correlation function associated with hard
trigger at RHIC heavy ion collisions is naturally explained by an interrelation
of jet quenching and hydrodynamical transverse flow. The excess particles
forming the ridge are produced by QCD bremsstrahlung along the beam (and thus
have wide rapidity distribution) and then boosted by transverse flow.
Nontrivial correlation between directions of the jet and the radial flow is
provided by jet quenching: our straightforward and basically
parameter-independent calculation reproduces the angular shape, width and other
properties of the "ridge".
