Electron-Positron Pair Production by Ultrarelativistic Electrons in a Soft Photon Field

Citation:

Mastichiadis A. Electron-Positron Pair Production by Ultrarelativistic Electrons in a Soft Photon Field. [Internet]. 1985.

Abstract:

The fully differential cross section for photon -electron pair production is integrated numerically over phase space. We obtain results for the astrophysically interesting case in which the interaction between an ultrarelativistic electron and a soft photon results in e('-) - e('+) pair production. The positron spectrum is a function of the energies of both the photon and the electron, as well as the angle of interaction. We integrate over solid angle by assuming an isotropic distribution of photons. We find that the energy at which the positron distribution peaks is inversely proportional to the photon energy and independent of the electron energy. The positron spectrum is integrated once more over initial electron energies for a power law energy distribution of primary electrons. The same procedure is repeated for the recoil particle; it is shown that the peak of the recoil energy distribution depends linearly on the energy of the primary electron. Finally, semi-analytical expressions are obtained for the energy losses of the primary electrons. Triplet pair production turns out to be important in the magnetospheres of hot (T (TURNEQ) 10('7) K), young (t (LESSTHEQ) 200 yrs) neutron stars. Interactions between thermal photons and highly relativistic electrons accelerated in the pulsar magnetosphere can initiate intense electromagnetic cascades. The development of such cascades is followed and some conclusions for the properties of young neutron stars are drawn. Finally, the possibility of a young pulsar (presumably arising from a recent supernova explosion) in the galactic center region is considered; it is shown that it can explain the intense positron production observed from this region, without conflicting other observations.

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