It has been noted by several authors that General Relativistic frame dragging in rotating
neutron stars is a first order effect which has to be included in a self-consistent model of pulsar
magnetospheric structure and associated radiation and transport processes. To this end, I
undertook the present study with the aim of investigating the effect of General Relativity
(GR) on millisecond pulsar (MSP) visibility.
I developed a numerical code for simulating a pulsar magnetosphere, incorporating the
GR-corrected expressions for the electric potential and field. I included curvature radiation
(CR) due to primary electrons accelerated above the stellar surface, as well as inverse Compton
scattering (ICS) of thermal X-ray photons by these electrons. I then applied the model to
PSR J0437-4715, a prime candidate for testing the GR-Electrodynamic theory, and examined
its visibility for the H.E.S.S. telescope. I also considered the question of whether magnetic
photon absorption would take place for this particular pulsar. In addition, I developed a
classical model for comparison with the GR results.
I found that the typical electron energies and associated CR photon energies are functions
of position above the polar cap (PC). These energies are also quite smaller in the GR case
than in the classical case due to the different functional forms of the GR and classical electric
fields. I found the CR energy cut-off to be ~ 4 GeV compared to the well-known classical
value of ~ 100 GeV. Since the H.E.S.S. energy threshold is ~ 100 GeV, it seems as though
the CR component will not be visible, contrary to wide-held opinion. However, the ICS
component seems to be well in excess of the H.E.S.S. energy threshold and is expected to be
visible. I also found that no pair production will take place for PSR J0437-4715.
Hopefully, forthcoming H.E.S.S. observations will provide validation of these results.
KEY WORDS: General relativistic frame dragging, GR electrodynamics, millisecond pulsar
visibility, non-thermal radiation processes, pair production, H.E.S.S., individual pulsars:
PSR J0437-4715. / Thesis (M.Sc. (Physics))--North-West University, Potchefstroom Campus, 2004.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:nwu/oai:dspace.nwu.ac.za:10394/215 |
| Date | January 2004 |
| Creators | Venter, Christo |
| Publisher | North-West University |
| Source Sets | South African National ETD Portal |
| Detected Language | English |
| Type | Thesis |
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