Q&A: Supernova Remnants and Neutron Stars

Q:
In Chandra Digest G54.1, reference is made to "a disc of matter and antimatter" surrounding SNR G54.1+ 03. How is mutual annihilation avoided?

A:
Mutual annihilation of matter and anti-matter almost certainly occurs, but further out in the nebula. The disk is a flow pattern that is continually resupplied with matter and antimatter electrons created near the surface of the neutron star by the interaction of photons with the extremely strong magnetic field there.