Spatially-dependent multi-wavelength modeling of pulsar wind nebulae

Abstract

The next era of ground-based Cherenkov telescope development will see a great increase in both quantity and quality of γ-ray morphological data. This initiated the development of a spatio-temporal leptonic transport code to model pulsar wind nebulae. In this thesis I present the development and implementation of this code that predicts the evolution of the leptonic particle spectrum and radiation at different radii in a spherically-symmetric source. I show how the code is calibrated using the models of previous authors and then indicate how we simultaneously fit the overall broadband spectral energy distribution, the surface brightness profile and the X-ray photon index vs. radius for PWN 3C 58, PWN G21.5−0.9 and PWN G0.9+0.1. Such concurrent fitting of disparate data sets is non-trivial and we thus investigate the utility of different goodness-of-fit statistics, specifically the traditional χ 2 test statistic and a newly developed scaled-flux-normalised test statistic to obtain best-fit parameters. We find reasonable fits to the spatial and spectral data of all three sources, but note some remaining degeneracies that motivate further model development and will have to be broken by future observations