ABERRATION AND ANGLE-DEPENDENT
DOPPLER EFFECTS ON THE
SPECTRA OF TWO COMPONENT ACCRETION COLUMN X-RAY PULSARS
by Jesse Davila Jr.
M.S. Thesis in Physics
Miami University
Several x-ray pulsars exhibit line structures in their spectra that have been
traditionally interpreted as originating from
cyclotron processes in the accreting plasma.
A few of these objects also show evidence of a second spectral feature that,
traditionally, has been thought to be the second cyclotron harmonic.
Detailed calculations of the emitted flux spectra are presented
that incorporate a two-component model of the accretion cap. The two
components are modeled as slabs separated by a shock wave where the
post-shock slab is the subsonic high density and temperature plasma that
creates the radiation via free-free or bremsstrahlung processes and the
pre-shock material is represented by a relatively cool low density plasma
that is moving near the free-fall velocity. Results show that two spectral features
are easily produced; one representing the fundamental cyclotron harmonic
of the post-shock plasma; and another that is a Doppler shifted line produced
by scattering in the pre-shock plasma.
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