Stars within 0.1 pc of the supermassive black hole Sgr A* at the Galactic centre are expected to encounter a cluster of stellar-mass black holes ( BHs ) that have segregated to that region .
Some of these stars will scatter off an orbiting BH and be kicked out of the Galactic centre with velocities up to \sim 2000 { km s } ^ { -1 } .
We calculate the resulting ejection rate of hypervelocity stars ( HVSs ) by this process under a variety of assumptions , and find it to be comparable to the tidal disruption rate of binary stars by Sgr A* , first discussed by Hills ( 28 ) .
Under some conditions , this novel process is sufficient to account for all of the hypervelocity B-stars observed in the halo , and may dominate the production rate of all HVSs with lifetimes much less than the relaxation time-scale at a distance \sim 2 pc from Sgr A* ( \gtrsim 2 Gyr ) .
Since HVSs are produced by at least two unavoidable processes , the statistics of HVSs could reveal bimodal velocity and mass distributions , and can constrain the distribution of BHs and stars in the innermost 0.1 pc around Sgr A* .