Rodr??guez et al. (2003b) used Very Large Array (VLA) in addition of Pie Town antenna (PT antenna) to observe the low mass protostellar system, L1551 IRS 5 at 3.5 cm. Their radio map showed two main results: a number of knots along the two extend radio jets driven from L1551 IRS 5 and the southern jet shows a peculiar bend at about 0.006 to the southwest of the driving source. To inves- tigate how the knots formed and what causes the bend in southern jet, I found three data sets reliable to make the maps from the VLA online data archive comprising 1994, 2002 and 2003. The 3.5 cm radio continuum maps of three epochs showed similar jets structure. I denoted the knots as RK A, B, C, D, E, F and G. For interpreting the nature of the knots seen in both jets and variations in the intensity/structure of the southern jet, I make the difference maps for multi-epoch comparison. There are no significant residuals (> 4_) for above-mentioned knots. We measure the velocities of the RKs relative to RK A: RK C (19 ± 13 kms?1), RK D (7.5 ± 4.7 kms?1 between epoch 1994 and 2002, 85 ± 20 kms?1 between epoch 2002 and 2003), RK E (72 ± 24 kms?1) and RK G (24 ± 32 kms?1). And the intrinsic velocity of RK B relative to southern protostar is 3.8 ± 2.8 kms?1. All of them are insignificant (< 4 _). However, I detected a positive residual with highly significant (> 6_) in all difference maps. I denoted it as RK H. And I obtained a significant proper motion of RK H (128 ± 18 kms?1). RK B, C, D, E, F and G are not likely formed by enhancement in mass loss or internal shock because their 4_ upper limit velocities are much slower than jet velocities of their corresponding jet. They can be interpreted by either the model of interaction of the binary jets or interaction with ambience cloudlets. Since the flux density of RK H is roughly constant within 1_ so that it is not likely formed by enhancement in mass loss but it can be explained by internal shock. / published_or_final_version / Physics / Master / Master of Philosophy

Thesis (Ph. D.)--University of Washington, 1998. / Vita. Includes bibliographical references (p. [143]-151).

Thesis (M.Sc.)--Saint Mary's University, 2008. / Includes abstract and appendix. Supervisor: David Clarke. Includes bibliographical references (leaves 88-90).

Thesis (PhD) -- McMaster University, 1996. / Includes bibliographical references (p.260-271). Also available via World Wide Web.

Presented here are observations, analysis and interpretation of five Fanaroff-Riley class I radio galaxies. Total intensity and polarised emission was observed in each source at 6 and 3 cm at angular resolutions of 16 to 2 arc seconds. These sources have a flux density greater than 1 Jy at 843 MHz, are 10-30 arc minutes in total angular extent, have redshifts between 0.011 and 0.035, are south of declination –43 degrees and have bright prominent jet structure. Images of the distribution of total intensity, polarised intensity and magnetic field configuration are presented and analysed. Physical properties in the jets and lobe are estimated using a number of different techniques. The observations have revealed a wide variety of structures, which imply many types of physical processes occurring in these sources, and different types of environments the jets travel through. The surface brightness distribution of some FR I radio galaxies with some characteristics of FR II galaxies are found to be consistent with the jets traveling through flat pressure gradients possibly caused by the presence of a cocoon surrounding the source. Analytical model imply jets with Mach numbers of 1-5, and jet velocities of approximately 1,000-20,000 km s-1 along most of the jets but mildly relativistic velocities 0.1-0.5c are indicated by Doppler boosting models at the base of most of the jets / Doctor of Philosophy (PhD)

Thesis (Ph. D.)--University of Texas at Austin, 2008. / Vita. Includes bibliographical references.

published_or_final_version / abstract / Physics / Master / Master of Philosophy

This thesis was motivated by the promise that some physical aspects of astrophysical jets and collimation processes can be scaled to laboratory parameters through hydrodynamic scaling laws. The simulation of astrophysical jet phenomena with laser-produced plasmas was attractive because the laser-target interaction can inject energetic, repeatable plasma into an external environment. Novel laboratory simulations of astrophysical jets involved constructing and using the YOGA laser, giving a 1064 nm, 8 ns pulse laser with energies up to 3:7 - 0:2 J. Laser-produced plasmas were characterized using Schlieren, interferometry and ICCD photography for their use in simulating jet and magnetosphere physics. The evolution of the laser-produced plasma in various conditions was compared with self-similar solutions and HYADES computer simulations. Millimeter-scale magnetized collimated out-flows were produced by a centimeter scale cylindrically symmetric electrode conguration triggered by a laser-produced plasma. A cavity with a flared nozzle surrounded the center electrode and the electrode ablation created supersonic uncollimated flows. This flow became collimated when the center electrode changed from an anode to a cathode. The plasma jets were in axially directed permanent magnetic fields with strengths up to 5000 Gauss. The collimated magnetized jets were 0.1-0.3 cm wide, up to 2.0 cm long, and had velocities of ~ 4:0 x 10⁶ cm/s. The dynamics of the evolution of the jet were compared qualitatively and quantitatively with fluxtube simulations from Bellan's formulation [6] giving a calculated estimate of ~ 2:6 x 10⁶ cm=s for jet evolution velocity and evidence for jet rotation. The density measured with interferometry was 1.9 ± .2 x 10¹⁷ cm⁻³ compared with 2.1 x10¹⁶ cm⁻³ calculated with Bellan's pressure balance formulation [6]. Kinks in the jet column were produced consistent with the Kruskal-Shafranov condition which allowed stable and symmetric jets to form with the background magnetic fields. The Euler number for the laboratory jet was 9 compared with an estimate of 40 for young stellar object jets [135] which demonstrated adequate scaling between the two frames. A second experiment was performed concerning laboratory simulations of magnetospheres with plasma winds impinging on permanent magnetic dipoles. The ratio of the magnetopause measured with ICCD photography to the calculated magnetopause standoff distance was ~2. / text

Thesis (M. Phil.)--University of Hong Kong, 2007. / Title proper from title frame. Also available in printed format.

<p dir="ltr">Understanding the acceleration of particles responsible for high-energy non-thermal phenomena in astrophysical jets is a ubiquitous pursuit. A possible culprit for non-thermal particle acceleration is turbulence. Specifically in this thesis, I investigate highly magne- tized or relativistic turbulence, where the magnetic energy to enthalpy ratio of the plasma is much greater than one, as a possible high-energy accelerator inside relativistic jets. I do this through three distinct projects. </p><p dir="ltr">My first project [1] (discussed in Section 3) was built upon a recent study of relativistic turbulence from [2], which found that a non-thermal particle equilibrium can be achieved when a plasma is heated via turbulence but allowed to cool radiatively. I extrapolated these results from PIC (Particle-in-Cell) simulations to larger scales and magnetizations, allowing me to encode key microphysical results of PIC simulations into a Fokker-Planck formalism. Combining these results with a single zone model for a blazar jet, I successfully define the underlying particle distribution with the global parameters of the emission region. To test this model, I fit data from 12 sources and successfully constrain key blazar parameters such as magnetization, bulk Lorentz factor, emission region size, and distance from the central engine. </p><p dir="ltr">My second project covers the development and testing of the open-source toolkit Tleco. This code base was used to evolve the Fokker-Planck equation and solve the resultant emission in my first project. Tleco offers efficient algorithms for evolving particle distributions and solving the resultant emission. It is meant to be user-friendly and easily customizable. </p><p dir="ltr">My third project attempts to enhance our understanding of coherent structures in relativistic turbulence. I employ intermittency analysis to establish a link between statistical fluctuations within the plasma and regions of high-energy dissipation. To achieve this, we used first-principle turbulent PIC simulations across a range of magnetizations and fluctuating magnetic field values. By utilizing the statistical fluctuations to determine the fractal dimension of the structures, I then examine their filling fraction and its dependence on magnetization and the fluctuating magnetic field.</p>