Pulsar kick velocity induced by natal neutrino chirality flip: lower bound for the neutrino mangetic moment.

We show that neutrino quirality flip during the birth of a neutron star, with a strange quark matter core, is an efficient mechanism to allow neutrinos to anisotropically escape, thus providing a plausible explanation for the observed neutron star kick velocities. The mechanism is efficient provided the neutrino magnetic moment is not smaller than $2.5 \times 10^{-15}\mu_B$, where $\mu_B$ is the Bohr magneton. When this lower bound is combined with the most stringent upper bound, our results set a range for the neutrino magnetic moment given by $2.5 \times 10^{-15} \leq \mu_\nu/\mu_B \leq (0.1 - 0.4)\times 10^{-11}$. The obtained kick velocities for natal conditions are consistent with the observed ones and span the correct range of radii for typical magnetic field intensities.