A NonRadial Oscillation Model for Radio Pulsars

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A Non-Radial Oscillation Model for Radio Pulsars
In collaboration with Dr. J. Christopher
Clemens University of North Carolina at Chapel
Hill
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Average Pulse Shapes
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Polarization Properties
Stinebring, D. R., Cordes, J. M., Rankin, J. M.,
Weisberg, J. M., Boriakoff, V. 1984, ApJS, 55,
247
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Drifting Subpulses
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Vacuum Gap, Drifting Spark Model
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Phase Shifts
PSR 032039
Rapidly oscillating Ap star HR 3831
Edwards, R. T., Stappers, B. W., van Leeuwen,
A. G. J. 2003, AA, 401, 321
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Intensity and Velocity Variations
The displacement (intensity) variations are
described as
The velocity variations are described as
Where are spherical coordinates
aligned to the magnetic axis of the star
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Intensity Variations in WDs
l 2, m 0
l 1, m 0
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Polarization Geometry
Displacements and velocities are aligned to
magnetic pole Induced electric field (E?) due
to E? v x B(0) is orthogonal to E? Result two
orthogonal electric fields
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Our Model
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Single Pulse Behavior
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PSR 094310 Data
The
Single pulses
Fourier Transform
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PSR 094310 Dual Frequencies
Two possibilities for a split subpulse
frequency 1. Two closely spaced independent
frequencies 2. Combined frequency and amplitude
or phase modulation of a single frequency
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PSR B094310
Pulsational and geometrical parameters are
largely independent
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Conclusions and Future Work

• Developed a physical model for pulsar morphology
  based on asteroseismological principles
• Conducted quantitative fitting of model to data
• Next step fit more complex pulsar behavior,
  acquire data for definitive tests
• Subpulse phase correlation between both magnetic
  poles
• Subpulse frequency independent of observational
  radio frequency