Supermassive black holes ( SMBHs ) in galactic nuclei can eject hypervelocity stars ( HVSs ) .
Using restricted three-body integrations , we study the properties of stars ejected by circular , binary SMBHs as a function of their mass ratios q = M _ { 2 } / M _ { 1 } and separations a , focusing on the stellar velocity and angular distributions .
We find that the ejection probability is an increasing function of q and a , and that the mean ejected velocity scales with q and a similar to previous work but with modified scaling constants .
Binary SMBHs tend to eject their fastest stars toward the binary orbital plane .
We calculate the ejection rates as the binary SMBHs inspiral , and find that they eject stars with velocities v _ { \infty } > 1000 km/s at rates of \sim 4 \times 10 ^ { -2 } -2 \times 10 ^ { -1 } yr ^ { -1 } for q = 1 ( \sim 10 ^ { -4 } -10 ^ { -3 } yr ^ { -1 } for q = 0.01 ) over their lifetimes , and can emit a burst of HVSs with v _ { \infty } > 3000 km/s as they coalesce .
We integrate the stellar distributions over the binary SMBH inspiral and compare them to those produced by the ‘ ‘ Hills mechanism ’ ’ ( in which a single SMBH ejects a star after tidally separating a binary star system ) , and find that N \sim 100 HVS velocity samples with v _ { \infty } \gtrsim 200 km/s are needed to confidently distinguish between a binary and single SMBH origin .