2004ApJ...606L..49Q

The inner annular gap (IAG), a new type of inner gap whose magnetic field lines intersect the null charge surface (NCS), is proposed to explain γ-ray and radio emission from pulsars. The IAG can be an important source for high-energy particles. The particles can radiate between the NCS and the IAG. Some observational characteristics in both γ-ray and radio bands, such as the Crab-like, Vela-like, and Geminga-like γ-ray emission beams, can be reproduced by the numerical method. It is predicted that the view angle ζ should be larger than the inclination angle (ζ>α), otherwise the γ-ray radiation will have little possibility to be observed. Whether the IAG (or cap) is sparking (or free flow) depends on the surface binding energy of the pulsar. Instead of neutron star models, the scenario of the IAG is favorable for bare strange star models, because bare strange stars can easily satisfy the requisite condition to form an IAG for both pulsars ({b.Omega}⋅B<0) and antipulsars ({b.Omega}⋅B>0).