Large light deflection angles are produced in the strong gravitational field
regions around neutron stars and black holes. In the case of binary systems,
part of the photons emitted from the companion star towards the collapsed
object are expected to be deflected in the direction of the earth. Based on a
semi-classical approach we calculate the characteristic time delays and
frequency shifts of these photons as a function of the binary orbital phase.
The intensity of the strongly deflected light rays is reduced by many orders of
magnitude, therefore making the observations of this phenomenon extremely
difficult. Relativistic binary systems containing a radio pulsar and a
collapsed object are the best available candidates for the detection of the
strongly deflected photons. Based on the accurate knowledge of their orbital
parameters, these systems allow to predict accurately the delays of the pulses
along the highly deflected path, such that the sensitivity to very weak signals
can be substantially improved through coherent summation over long time
intervals. We discuss in detail the cases of PSR 1913+16 and PSR 1534+12 and
find that the system geometry is far more promising for the latter. The
observation of the highly deflected photons can provide a test of general
relativity in an unprecedented strong field regime as well as a tight
constraint on the radius of the collapsed object.Comment: 7 pages, uuencoded, gzip'ed, postscript file with figures included.
Accepted for pubblication in MNRA
