This thesis presents results from three projects studying the structure and polarization of parsec-scale radio jets.
A numerical study of the radiation from superluminal jets . In this chapter, we use numerical method to solve the radiation transfer equations of all four Stokes parameters, I, Q, U, V in a conical or cylindrical jet for arbitrary optical depth and Faraday depth. This program is for a steady-state relativistic jet, with a pre-set magnetic field and velocity structure. We give a series of examples with different combinations of shape, magnetic field, velocity structure, optical depth, Faraday depth, etc. This program is useful to understanding the transfer of synchrotron radiation, especially in inhomogeneous jets.
Multi-epoch study of 3C X73 at four frequencies . We present 4 epochs VLBA observations of 3C 273 at 8, 15, 22 and 43 GHz in 1999, and compare them with 6 observations at 15 and 22 GHz in 1996. This enables us to derive detailed kinematic information on component velocities and accelerations. We derive rotation measure distributions at 4 epochs. We confirm the transverse rotation measure gradient that has been seen previously, but we also find large changes in rotation measure on a time scale of months. We discuss possible models that might exhibit these properties.
Multi-epoch six frequency VLBA and SVLBA study of 3C 454.3 . We present our VLBA and/or SVLBA observations of the quasar 3C 454.3 at 5 epochs from 1998.9 to 1999.9, at a total of 6 frequencies. The observations were designed to compare different wavelength images at similar resolution. We detected a series of stationary components and a single superluminal component in the core region. An 'S' shaped polarization pattern is detected in the extended jet, which we attribute to a helical magnetic field.
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