Megan E. DeCesar, Alice K. Harding, M. Coleman Miller, Ioannis Contopoulos, Constantinos Kalapotharakos, Damien Parent
The high-quality Fermi LAT observations of gamma-ray pulsars have opened a
new window to understanding the generation mechanisms of high-energy emission
from these systems. The high statistics allow for careful modeling of the light
curve features as well as for phase resolved spectral modeling. We modeled the
LAT light curves of the Vela and CTA 1 pulsars with simulated high-energy light
curves generated from geometrical representations of the outer gap and slot gap
emission models, within the vacuum retarded dipole and force-free fields. A
Markov Chain Monte Carlo maximum likelihood method was used to explore the
phase space of the magnetic inclination angle, viewing angle, maximum emission
radius, and gap width. We also used the measured spectral cutoff energies to
estimate the accelerating parallel electric field dependence on radius, under
the assumptions that the high-energy emission is dominated by curvature
radiation and the geometry (radius of emission and minimum radius of curvature
of the magnetic field lines) is determined by the best fitting light curves for
each model. We find that light curves from the vacuum field more closely match
the observed light curves and multiwavelength constraints, and that the
calculated parallel electric field can place additional constraints on the
emission geometry.
View original:
http://arxiv.org/abs/1111.0325
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