Abstract
This talk will focus on the radiation mechanisms of non-thermal X-rays and soft gamma-rays from two types of young spin-down powered pulsars, the Crab-like pulsars and the soft gamma-ray pulsars.
The Crab-like pulsars have been regarded as typical very young pulsars for a long time, and the soft gamma-ray pulsars are a new class of young pulsars.
The simulations of the pulse profiles and spectra of seven pulsars will be shown. These seven pulsars, Crab pulsar, PSR B0540-69, PSR B1509-58, PSR J1846-0258, PSR J1811-1925, PSR J1617-5055 and PSR J1930+1852, fall into these two categories. The Crab pulsar and the Giant Crab PSR B0540-69 are the Crab-like pulsars, and the left five are the soft gamma-ray pulsars. The main difference between the two types of young pulsars is that the Crab-like pulsars' spectra peak at E<1 MeV while the soft gamma-ray pulsars' spectra peak at E~10 MeV. Their spectra also have different photon indices in X-ray band. The physics behind is two different pair creations, the photon-photon pair creation and the magnetic pair creation. The former happens when a high energy photon collides with a soft photon, and the latter happens when a high energy photon penetrates through a strong perpendicular magnetic field. In the outer gap of the pulsar, a large mount of pairs are generated around the null charge surface via photon-photon pair creation, and the electric field separates the two charges to move in opposite directions.
Therefore, there are outflow and inflow of particles in the magnetosphere, whose curvature photons are converted to pairs by photon-photon pair creation and magnetic pair creation respectively. For the Crab-like pulsar, the non-thermal X-rays and soft gamma-rays are emitted by the outgoing secondary pairs generated by photon-photon pair creation in the outer magnetosphere; for the soft gamma-ray pulsar, the radiating secondary pairs are generated below the null charge surface by the magnetic pair creation.