James Hinton, Stefan Funk, Robert Parsons, Stefan Ohm
Whilst the Vela pulsar and its associated nebula are often considered as the
archetype of a system powered by a \sim10^4 year old isolated neutron star,
many features of the spectral energy distribution of this pulsar wind nebula
are both puzzling and unusual. Here we develop a model that for the first time
relates the main structures in the system, the extended radio nebula (ERN) and
the X-ray cocoon through continuous injection of particles with a fixed
spectral shape. We argue that diffusive escape of particles from the ERN can
explain the steep Fermi-LAT spectrum. In this scenario Vela X should produce a
distinct feature in the locally-measured cosmic ray electron spectrum at very
high energies. This prediction can be tested in the future using the Cherenkov
Telescope Array (CTA). If particles are indeed released early in the evolution
of PWNe and can avoid severe adiabatic losses, PWN provide a natural
explanation for the rising positron fraction in the local CR spectrum.
View original:
http://arxiv.org/abs/1111.2036
No comments:
Post a Comment