Steven Brett McArthur
Published: 2012
Total Pages: 302
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Observations of TeV gamma rays enable investigation of extreme, high-energy astrophysical environments. Of the identied TeV sources within the Galaxy, the largest number are pulsar wind nebulae (PWNe), formed by the shocked wind of relativistic leptons emitted by a pulsar and conned by the surrounding medium, with broadband emission arising from synchrotron and inverse Compton mechanisms. PWNe exhibit a wide range of morphologies as a result of a complex evolution, depending on the properties of the parent pulsar and conning medium. This work describes the discovery of gamma-ray emission from the PWN within the supernova remnant (SNR) CTA 1 by the VERITAS telescope array. By imaging the Cherenkov light from gamma-ray induced atmospheric showers, VERITAS revealed an extended TeV nebula surrounding the pulsar PSR J0007+7303. Comparison of the observed properties with known PWN, along with a one-zone model, suggests a recent interaction with the SNR reverse shock and allows for an estimate of the average nebular magnetic eld strength. No signicant energy-dependent morphology is seen. A multi-zone, cylindrically symmetric model is created to investigate tailed-out PWN morphology, accounting for multiple mechanisms for particle transport and cooling. The model is applied to the CTA 1 data, with a limited search of the parameter space performed to t the observed spectrum and extent. Possible improvements to the model performance are discussed.