Abstract
Pulsar is a kind of neutron star that emits a beam of electromagnetic radiation. When the beam of emission is pointing toward the earth, we can observe it. To explain the characteristic of pulsars, different pulsar models were developed, for example, the polar cap model, the outer gap model and TPC/slot gap model. The mainly differences between these models are the different acceleration regions for high-energy particles and relative emission mechanisms to radiate γ rays.
Fermi satellite was launched in 2008, since then it has collected many useful data for studying pulsars. By using the data collected by Fermi, we reanalyze the spectrum of geminga pulsar, and find the outer gap model is more suitable.