Where does the antimatter in our galaxy come from?
We know there is antimatter within the Milky Way because of the telltale gamma radiation produced when electrons collide with their antiparticles. But where these particles, called positrons, come from is less well understood.
Now astronomer Gerry Skinner of the University of Maryland, College Park, and colleagues say that neutron stars and black holes might be leaking positrons into space (Nature, vol 451, p 159). They infer this from their observations of the telltale gamma-ray emissions, which turn out to be stronger on one side of the galaxy. This region…
