General-relativistic pulsar radio and high-energy emission. (arXiv:1910.01555v1 [astro-ph.HE])
<a href="http://arxiv.org/find/astro-ph/1/au:+Giraud_Q/0/1/0/all/0/1">Quentin Giraud</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Petri_J/0/1/0/all/0/1">Jérôme Pétri</a>
According to current pulsar emission models, photons are produced within
their magnetosphere or inside the current sheet outside the light-cylinder.
Radio emission is favoured in the vicinity of the polar caps whereas the
high-energy counterpart is presumably enhanced in regions around the
light-cylinder, magnetosphere or/and wind. However, gravitational impacts on
light-curves and their spectral properties have only been sparsely touched. In
this paper, we present a new method to simulate the influence of the neutron
star gravitational field on its emission according to general relativity. We
numerically compute photon trajectories assuming a background Schwarzschild
metric, applying our method to neutron star radiation mechanisms, like thermal
emission from hot spots and non-thermal magnetospheric emission by curvature
radiation. We detail the general-relativistic impacts onto observations made by
a distant observer. Sky maps are computed using the vacuum electromagnetic
field of a general-relativistic rotating dipole. We compare Newtonian results
to their general-relativistic counterpart. For magnetospheric emission, we show
that, more importantly than the aberration and the curvature of the trajectory
of the photons, the Shapiro time delay significantly affected the phase delay
between radio and high-energy light curves although the characteristic pulse
profile that defines pulsar emission is kept.
According to current pulsar emission models, photons are produced within
their magnetosphere or inside the current sheet outside the light-cylinder.
Radio emission is favoured in the vicinity of the polar caps whereas the
high-energy counterpart is presumably enhanced in regions around the
light-cylinder, magnetosphere or/and wind. However, gravitational impacts on
light-curves and their spectral properties have only been sparsely touched. In
this paper, we present a new method to simulate the influence of the neutron
star gravitational field on its emission according to general relativity. We
numerically compute photon trajectories assuming a background Schwarzschild
metric, applying our method to neutron star radiation mechanisms, like thermal
emission from hot spots and non-thermal magnetospheric emission by curvature
radiation. We detail the general-relativistic impacts onto observations made by
a distant observer. Sky maps are computed using the vacuum electromagnetic
field of a general-relativistic rotating dipole. We compare Newtonian results
to their general-relativistic counterpart. For magnetospheric emission, we show
that, more importantly than the aberration and the curvature of the trajectory
of the photons, the Shapiro time delay significantly affected the phase delay
between radio and high-energy light curves although the characteristic pulse
profile that defines pulsar emission is kept.
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