The nature of the X-ray filaments around bow shock pulsar wind nebulae

Vol. 683
2. Astrophysical processes

The nature of the X-ray filaments around bow shock pulsar wind nebulae

When a pulsar moves across the interstellar medium, it is likely to release energetic leptons. In some cases, they become visible as a linear, filamentary structure emitting X-rays. These structures could be as long as 15 pc, as in the Lighthouse Nebula, but with a very small cross section (1-10% of the length). In this Letter, Olmi and collaborators suggest that the X-ray emission of these filaments can be explained by the excitation of a non-resonant instability. For this to happen, tight conditions on the collimation of the released leptons must be satisfied, providing one of the best diagnostics to study the escape of particles from evolved pulsar wind nebulae. This is key to understanding cosmic ray transport around sources and it may link these systems to TeV halos.