Bibcode
Goicoechea, L. J.; Mediavilla, E.; Buitrago, J.; Atrio, F.
Bibliographical reference
Monthly Notices of the Royal Astronomical Society (ISSN 0035-8711), vol. 259, no. 2, p. 281-292.
Advertised on:
11
1992
Citations
14
Refereed citations
14
Description
We present a second-order analytical expansion of null equatorial
geodesics in the Kerr metric. The equations developed are applied to the
study of light transit in compact binary systems. We show that the
effects arising from path bending have a significant influence on the
computed time delays, even at first order of approximation in the
Schwarzschild metric, reducing by about 50 percent the lags expected
when rectilinear propagation is assumed. We calculate the time delays in
the second-order approximation, including the effects derived from light
deflection. For systems in which the central object is a rotating black
hole, the time lag could even be of the order of minutes. The duration
of the eclipse and the amplitude of the lensing effect are also studied
and we find a coverage for the lensing effect of almost 180 deg for
neutron stars. The influence of the spin of the central object is
manifested in the asymmetry of the curve representing time delay versus
orbital phase, which is very enhanced in the part affected by lensing.