Blazar jets imaged with Very Long Baseline Interferometry (VLBI) - kinematics of helical trajectories in 3C273 and 3C345

Doctoral thesis English OPEN
Porter, David Gareth Jon
  • Subject: QC

In this work a large collection of VLBI (Very Long Baseline Interferometry) maps are presented based upon data from the VLBA (Very Long Baseline Array) for 29 sources. The maps are the result of three epochs of imaging. A kinematic study was undertaken with a view to understanding some interesting structure seen in the quasars 3C273 and 3C345. Fortunately, these two sources present a large number of components and it was possible to perform model fitting to pinpoint their positions. In addition, model fitting was performed upon all of the sources that were successfully imaged. The aim of this was to eventually derive component velocities for as many blazars studied as possible. The outcomes of the work are presented in tables in the main thesis. In order to further understand the 3C273 and 3C345 jet structures seen a physical model was developed with A. Papageorgiou. With this kinematic model it was possible to trace out a variety of helical jet structures. The free parameters are the injection velocity for new components, the period of jet precession, the viewing angle and the jet half angle. Using the Levenberg- Marquardt algorithm (references given below) it was possible to fit jet trajectories to my model fitted component data. The algorithm produced quantitative output for some of the free parameters in my physical model. Therefore I report average jet half angles for 3C273 and 3C345 of 2.968 0.153 degrees and 2.519 0.573 degrees respectively. In ad dition, I find the precessional periods of 3C273 and 3C345 to be 71.161 19.066 years and 48.478 3.385 years respectively.
  • References (13)
    13 references, page 1 of 2

    Development of a Physical Model 253

    4.1 The C om ponent Injection A n g le .............................................................................. 253

    4.2 Com ponent Injection V e lo city ................................................................................ 256

    4.3 Com ponent Displacements ................................................................................... 257

    4.4 Plotting C om ponent Displacements .................................................................... 258

    4.5 Vector Transformation from Three Dim ensions to T w o ..................................... 258

    4.6 Obtaining 2D m ap or sky c o o r d in a te s ................................................................. 262

    6 Principle Results of Kinematic Study 275 6.1 Jet V elo cities............................................................................................................... 275 6.2 Application of a Physical Model to M odel Fitting R e s u lts ................................279

    Discussion, Conclusions and Further Work 281

    7.1 C om ponent Velocities................................................................................................281

  • Related Research Results (1)
    Inferred
    Physics and Astronomy (2012)
    41%
  • Metrics
    0
    views in OpenAIRE
    0
    views in local repository
    14
    downloads in local repository

    The information is available from the following content providers:

    From Number Of Views Number Of Downloads
    Online Research @ Cardiff - IRUS-UK 0 14
Share - Bookmark