Shuta

The broadband emission of Pulsar Wind Nebulae (PWNe) is well described by non-thermal emissions from accelerated electrons and positrons.
However, the difference of spectral indices at radio and X-rays are not reproduced by the standard shock particle acceleration and cooling processes, and then, for example, the broken power-law spectrum for the particle energy distribution at the injection has been groundlessly adopted.
Here, we propose a possible resolution for the particle distribution; the radio emitting particles are not accelerated at the pulsar wind termination shock but are stochastically accelerated by a turbulence inside PWNe.
The turbulence may be induced by the interaction of the pulsar wind with the supernova ejecta.
We upgrade our one-zone spectral evolution model including the stochastic acceleration and apply to the Crab Nebula.
We consider the both continuous and impulsive injections of particles to the stochastic acceleration process.
The radio emission in the Crab Nebula is reproduced by our stochastic acceleration model.
The required forms of the momentum diffusion coefficient will be discussed.