Physics Magazine takes a look at the radiation surrounding those high-energy stars that zoot-zoot-zoot out in regularly recurring intervals (stars with a pulse, in other words, like the one that gave us one of the most famous album covers of all time). Based on observations from the High-Altitude Water Cherenkov (HAWC) Observatory, they’ve found that they might all be surrounded by angelic halos — of tera-electron-volt (TeV) gamma radiation:
…[B]y the time the pulsar has reached middle age—at about 10,000 years―this field has declined enough for the particles to escape into interstellar space. Astrophysicists believe that TeV halos are produced around such pulsars because these escaped particles repeatedly scatter off ambient photons from stars and the cosmic microwave background, boosting the photons to TeV energies via inverse Compton scattering.
This result could help to settle a debate regarding the diffusion of pulsar-emitted particles. The sizes of the TeV halos suggest that the accelerated particles diffuse more slowly than they would in a typical region of the interstellar medium. When only a handful of TeV halos were known, this difference could be explained by regions of anomalous relativistic electron transport. But the possible ubiquity and uniformity of the halos indicate that the unexpectedly slow diffusion is due to a yet-unknown particle-transport phenomenon inherent to all middle-aged pulsars.