Understanding the Origin of Bright Features

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Understanding the Origin of Bright Features

• Carrie Swift University of Michigan - Dearborn
• Philip A. Hughes University of Michigan - Ann
  Arbor
• Extragalactic Jets Theory and Observation from
  Radio to Gamma Ray
• May 24, 2007

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• Sophisticated simulations of relativistic flows
  lead to large, complex data sets.
• Typical data set 4-5 gigabytes per epoch of
  physical data.
• For time resolution similar to spatial resolution
  would require on the order of a terabyte of data
  to generate a simulated radio flux map.
• We want to know where and when in the flows
  history the bright radio features form.
• How do we find the needle in this very large
  haystack?

Alta Meadow Ranch - Montana
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Methodology

1. Perform a relativistic hydrodynamic simulation.
2. Generate simulated radio flux maps.
3. Select lines of sight corresponding to features
   of interest and examine the physical conditions
   that led to the formation of the radio features.

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1. Perform a relativistic hydrodynamic simulation.

• Simulation CF7
• Fully Relativistic
• Three Dimensional
• Precessing inlet that leads to filamentary
  structures over time.
• v 0.9798c
• 6 epochs last run at time 2.502e03
• Resulting data set is 14 gigabytes

Philip Hughes
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2. Generate simulated radio flux maps.
Angle of view 9º from direction of flow (within
1/?)
Static last epoch
Time-delay 6 epochs

• Emissivity Model Assume that the radiating
  particles are the result of shock-Fermi
  acceleration of the high energy tail of the
  particle distribution. The acceleration takes
  place in the region where the pressure is
  highest, so using pressure to model emissivity
  gives us a way to trace these particles.

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3. Select lines of sight corresponding to
features of interest and examine the physical
conditions that led to the formation of the radio
feature.
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Computational space of hydrodynamic simulation.
Rendered variable is momentum of flow
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Computational space of hydrodynamic simulation.
Rendered variable is momentum of flow
Boundary between epochs
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Computational space of hydrodynamic simulation.
Rendered variable is momentum of flow
Contours represent flux on plane of sky
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Computational space of hydrodynamic simulation.
Rendered variable is momentum of flow
Line of sight 7760 Color corresponds to total
flux as function of retarded time
Contours represent flux on plane of sky
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The flux of the line increases when it
encounters pressure enhancements due to
instabilities in the flow. Having an increase in
the boost in the region of the instabilities
results in a very bright line.
Flux range 0 to 1.2
Boost range 0 to 1.4 Pressure range 0 to 1.2
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The Effect of Angle of View and Differential
Beaming on the Radio Morphology
Within 1/?
Outside of 1/?
Map 7005 no inlet 10755 lines
Map 7004 no inlet 3375 lines
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Once outside the critical angle relativistic
effects no longer dominate the radio morphology.
Line 2537
Flux range 0 to 0.7
Boost range 0 to 1.2 Pressure range 0 to 1.0
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• Conclusions
• This methods highly visual nature allows for a
  straight forward analysis of radio features
  arising from a complex flow, leading to a better
  understanding of the relationship between the
  physical flow and the radio morphology of
  relativistic jets.

Anne-Marie Mineur

• Whats Next?
• Improved time resolution
• Apply to variety of simulations