Fermi Gamma-ray Space Telescope

Modeling of the Gamma-ray Emission of Pulsar Magnetospheres in the Fermi Era

Constantinos Kalapotharakos
Alice K. Harding, Demosthenes Kazanas


I will present patterns of gamma-ray emission due to curvature radiation in dissipative pulsar magnetospheres. These state-of-the-art solutions, by their nature, provide, besides the field geometry, also the necessary particle accelerating electric fields. Using these solutions, we generate model gamma-ray light curves by calculating the trajectories and the Lorentz factors of the radiating particles, under the influence of both the accelerating electric components and curvature radiation-reaction. I will show how this study leads to the construction of model magnetospheres that successfully reproduce the observed light-curve phenomenology as depicted in the radio-lag vs peak-separation diagram obtained by Fermi. These models employ a hybrid form of conductivity; specifically, infinite conductivity interior to the light-cylinder and high but finite conductivity on the outside. In these models the gamma-ray emission is produced in regions near the equatorial current sheet. The model allows the calculation of phase-averaged and phase-resolved spectra and the total gamma-ray luminosities as well. I will show that the corresponding photon cut-off energies and total gamma-ray luminosities are within the observed ranges. Of particular interest are our model phase-resolved spectra, since there is a small number of bright pulsars for which the spectral parameters have been measured across the phase of the gamma-ray pulse. I will present model parameters that best match these particular pulsars.