The launch of the Large Area Telescope (LAT), on board the Fermi spacecraft, has led to an
astounding increase in the number of known y-ray pulsars. This wealth of new data has generated
renewed interest in the field of pulsar astrophysics, with many of the established geometric models
for y-ray emission coming under fresh scrutiny. In this work the outer gap (OG) and two-pole
caustic (TPC) geometric -ray models are employed alongside a simple empirical radio model to
obtain best-fit light curves by eye for six single-peak Fermi LAT pulsars first reported by Weltevrede
et al. (2010). These best-fit solutions aim to reproduce both the shapes of the radio and y-ray light
curves, and the radio-to- phase lag. A parameter study of the geometric models is also conducted,
and the increased qualitative understanding of these models thus gained is then employed to obtain
the best fits possible. The combination of radio and -ray models is found to be remarkably powerful
in constraining the values of the geometric parameters of the individual pulsars: the inclination
and observer angles. Generally the constraints implied by the radio model act perpendicularly
to those implied by the y-ray models, thus yielding smaller solution contours. The constraints
on the geometric parameters obtained for the six Fermi LAT pulsars in question agree quite well
with those obtained by Weltevrede et al. (2010). This agreement is remarkable considering that
the approach employed in this study is independent from the one employed by Weltevrede et al.
(2010). The errors obtained in this study on the values of the inclination angle for each pulsar are
generally smaller than those obtained by Weltevrede et al. (2010). As a secondary result, the value
of the flux correction factor, which is a measure of how well the observed y-ray energy flux of the
pulsar correlates with the overall y-ray energy flux, is constrained for each pulsar. / MSc (Space Physics), North-West University, Potchefstroom Campus, 2014
| Identifer | oai:union.ndltd.org:NWUBOLOKA1/oai:dspace.nwu.ac.za:10394/12260 |
| Date | January 2014 |
| Creators | Seyffert, Albertus Stefanus |
| Source Sets | North-West University |
| Language | English |
| Detected Language | English |
| Type | Thesis |
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