Do neutrinos push pulsars around?

17 Jun 2002

Many pulsars possess a proper motion across the sky, implying that the pulsars get kicked somehow in the act of being born in the violent explosion of a supernova. A new theory holds that these birth velocities might be caused by a non-symmetric shell of neutrinos rushing away from the supernova collapse.

According to Gino Segre of the Univ. of Pennsylvania (segre@dept.physics.upenn.edu), an asymmetry in the "neutrinosphere," the surface at which the neutrinos last scattered before emerging from the star, could be caused by neutrino oscillations-- such as the transformation of tau neutrinos into electron neutrinos under the bias of the star's magnetic field. A 1% anisotropy in the neutrino distribution could result in a "kick velocity" consistent with the measured average pulsar velocity of 450 km/sec.