Abstract:
An estimate of the effect of light bending and redshift on pulsar beam
characteristics has been made using a weak Kerr metric for the case of a
1.4 M/subΘ neutron star with a radius in the range 6-10 Km and
rotation periods of 1.36ms and 33ms, respectively. Assuming that the
pulsar emission has the form of a narrow conical beam directed away from
the surface and is located within two stellar radii, the beam is found to
be widened by a factor of ≤2 and to suffer a reduction in the
intensity (flattening of the profile) by an order of magnitude or less.
The effect is largest for the most rapidly rotating the neutron stars. For
an emission region located beyond 2Okm, the flattening is generally
insignificant. The pulse profile is slightly asymmetrical due to dragging
of the inertial frames. For millisecond periods, aberration tends to
reverse the flattening effect of space-time curvature by narrowing the
pulse and can completely overcome it for emission from a location beyond
≈30km. Although the pulse must slightly brighten up, a large
redshift factor overcomes this effect to keep the pulse flattened for all
neutron' star radii considered here.
