Pulsar Kicks With Modified URCA and Electrons in Landau Levels

TL;DR

This paper models how strong magnetic fields and modified URCA processes in proto-neutron stars can produce asymmetric neutrino emissions, resulting in pulsar kicks with predicted velocities up to 1000 km/s.

Contribution

It introduces a novel mechanism linking Landau level electron states in strong magnetic fields to pulsar velocity asymmetries during supernovae.

Findings

Pulsar kicks start around 10 seconds after supernova explosion.

Predicted pulsar velocities can reach up to 1000 km/s at high temperatures.

Neutrino emissions are correlated with magnetic field direction.

Abstract

We derive the energy asymmetry given the proto-neutron star during the time when the neutrino sphere is near the surface of the proto-neutron star, using the modified URCA process. The electrons produced with the anti-neutrinos are in Landau levels due to the strong magnetic field, and this leads to asymmetry in the neutrino momentum, and a pulsar kick. The magnetic field must be strong enough for a large fraction of the eletrons to be in the lowest Landau level, however, there is no direct dependence of our pulsar velocity on the strength of the magnetic field. Our main prediction is that the large pulsar kicks start at about 10 s and last for about 10 s, with the corresponding neutrinos correlated in the direction of the magnetic field. We predict a pulsar velocity of 1.03 $\times 10^{-4} (T/10^{10}K)^7$ km/s, which reaches 1000 km/s if T $\simeq 9.96 \times 10^{10}$ K.