Research
| Intro | |
| Jet 1: 15°. Sound Speed Model At epoch 156 the radio jet is a diffuse, rather featureless, but elongated structure with no discernible core. The radio core, caused by pressure enhancements due to Kelvin-Helmholtz instabilities arising along the axis of flow, begins to emerge by epoch 196, and is clearly visible by epoch 216. At epoch 236 the jet is still a simple pear-shaped structure, but there are small projections on the leading and trailing edges of the core. Twenty epochs later the extended emission has enlarged noticeably, and the projections on both sides of the core have brightened and enlarged. The brightest part of the core remains small. These trends - namely that the core remains small, the extended emission enlarges and grows more complex, continue over time. By epoch 336, the core is not substantially larger than it was at epoch 236, but the extended emission is much larger, growing from 12 jet radii to 18 jet radii in length, and from 9.7 jet radii to 11.5 jet radii in width. By epoch 336 the extended emission is very complex - there are projections, rings and arches throughout. |
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| Jet 1: 25°. Sound Speed Model At 25° we see changes in morphology over time similar to those seen at 15°, but these changes are exaggerated. The jet starts out at epoch 156 as a faint elongated diffuse structure. As time passes, the diffuse structure seen at epoch 156 further elongates, and brightens. By epoch 256 clear substructure can be seen, with extended emission surrounding the core, which appears as a circle of bright emission with small projections from the leading edge. By epoch 276 the core appears rectangular and the extended emission has developed a figure-8 outline. The extended emission has both projections and ring-like structures. One can make out the cylindrical shape of the jet system in this and later images. The structure continues to evolve into more complex forms. By epoch 336 these are overlapping rings, projections and trailing bright spots in the core. Note that the radio cores in both the 15° and 25° sequences overlap in the plane of the sky - they are the same feature seen at different angles. The complex structure of the extended emission reflects the position and shape of the bow shock over time. As the bow shock's properties change over time different parts of it will be subject to beaming at different times. This leads to the projections and rings. At 25° less smearing occurs, so more structure is visible than in the 15° maps. |
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Jet 1: 85°. Sound Speed Model At 85° smearing is not an important factor. The jet begins at epoch 156 as a faint tube of emission with a leading bright spot. This bright spot corresponds to the location of the bow shock. At epoch 156 the jet has traversed about 45% of the computational space, but is still very faint, emphasizing that the jet is slow to evolve and slow to brighten. In the next several images one can perceive the shape of the jet in the trailing emission. Other bright spots develop behind the bow, and appear to remain stationery over time. These stationary bright spots correspond to the location Kelvin-Helmholtz instabilities that occur along the axis of flow. These instabilities are confined to a small region of the flow, so while they last for many epochs, they appear stationary. Over time the bow shock brightens and moves forward, but the jet does not change appearance radically from epoch 216 to 336. |
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| Jet 2: 4°. Pressure Model Jet 2 does not change form much over time. It starts out at epoch 248 as a bright circle, which over time elongates and brightens. By epoch 264 some very simple substructure is seen in the core, which has projections on the leading edge. However, by epoch 272 these projections have filled in and the jet appears as a simple elongated bright spot. The transient projections from the core between epochs 264 and 268 are caused by a slight dip in pressure in the bow shock around epoch 260. This transient feature disappears as the pressure of the bow again rises, and by epoch 272 all the lines of sight in that part of the sky are passing through the same region of the bow. |
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| Jet 2: 15°. Pressure Model The jet first appears as a small circle, which brightens and then extends over time. It is interesting that the area of the core decreases over time. Jet 2 is highly relativistic, so at 15°, little of its emission is subject to beaming. The beamed region is decreasing at late times as the brightest emission will be from the region of the bow shock near the axis. As the bow approaches the observer, the portion of the bow that is subject to beaming deceases, so the radio core contracts. |
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| Jet 2: 85°. Pressure Model At 85° Jet 2 displays almost no evolution. One can clearly make out the shape of the bow, and follow its course across the computational space, but there are no changes of consequence in form. |