Recoil velocities of Binary Neutron Star Remnants

Binary neutron stars are among the most intriguing astrophysical events in the Universe. When two neutron stars merge, the resultant remnant object can get recoiled due to asymmetric gravitational wave emission and the dynamical ejection of matter around it. This has important implications for their retention in hierarchical mergers of low-mass binaries in dense star clusters. High recoils may also affect the evolution of post-merger accretion disk and jet emission from the remnant. In this work, we present, for the first time, estimates for the recoil velocity of binary neutron star merger remnants using the Computational Relativity database of numerical simulations. Using gravitational waveforms as well as distribution of ejected matter, we obtain an upper bound for kick velocities of the order of a few tens of kilometers per second, and going as high as 180 km/s in some cases.