Very-High-Energy Gamma Ray Emission from Blazar Jets

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The precise origin of gamma-ray emission form blazars remains elusive. Competing models propose that the emitting region might lie very close to the central black hole, or that it might lie upstream in the jet with localized high-energy events being the source of the gamma rays. The mechanisms proposed vary from self-Compton to external Compton, and even hadronic routes from high-energy protons entrained in the jet. One observational trend which is highly likely to be related to the emissions mechanisms, but which is not yet clearly understood, is the so-called blazar sequence. This is the apparent anti-correlation of peak gamma-ray energy at high energies (i.e. in the GeV range, less than VHE) from blazars with their luminosities. In this project we will develop new models, based on jets with a highly magnetised base, to determine if the VHE emission shows useful diagnostic signatures along the blazar sequence. The project will be theoretical/computational, with MHD modelling, and later comparison with existing data sets.