Pulsar Kick and Asymmetric Iron Velocity Distribution in SN 1987A

Abstract

We have investigated the relation among the directions of the momenta of matter, neutrinos, and the proto-neutron star in a collapse-driven supernova in order to discuss the pulsar kick. In particular, we have investigated the effects of the pulsar motion on the explosion, which were neglected in a previous study. As a result, it is suggested that the direction of the total momentum of the matter and neutrinos is opposite to that of the momentum of the proto-neutron star in the asymmetric explosion models. This is because the center of the explosion deviates from the center of the progenitor, due to the pulsar motion. This picture is common among the asymmetric explosion models. Hence if we assume that the pulsar motion is caused by an asymmetric supernova explosion, there should have been a neutron star born in SN 1987A (which has not yet been found) moving in the southern part of the remnant. In other words, the observation of one neutron star in SN 1987A on the south part of the remnant would support the asymmetric explosion models as opposed to the binary models.