Abstract
This thesis presents a radio study accompanied by X-ray comparison of pulsar wind nebulae (PWNe) across different evolutionary stages. We utilize radio interferometers—the Australian Telescope Compact Array and the Very Large Array to observe a sample of PWNe. The research aims to investigate the morphological evolution, magnetic fields, and spectral properties of these objects with high-resolution radio imaging. For young PWNe, we confirm the presence of X-ray jets in these PWNe, which are often absent in radio images. While the equatorial torus is often morphologically distinct in radio and X-ray. We study the magnetic fields of these PWNe that mostly align the main structure of the PWN that reflects the interaction of gas inside these PWNe. In the intermediate-stage PWN MSH 15-52, we observe complex structures shaped by reverse shock interactions, including radio filaments and X-ray features such as the jet and the prominent fingers like structures with no radio counterparts. For older bow-shock PWNe, we observe cometary morphologies with long tails. Magnetic field mapping shows that the field in the tail is generally aligned with the direction of pulsar's motion, though notable exceptions exist such as the lighthouse. Spectral steepening along the tail is observed and attributed to synchrotron cooling. We also notice the difference in the emission peak at different wavebands. We also found the correlation between the length or size of the PWN and the pulsar properties such as the rotation period, characteristic age and so on. The findings highlight the need for future deep polarization observations, broader spectral coverage, and detailed magnetohydrodynamic simulations to fully understand the physics governing PWNe.
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