Speaker
Description
Modelling light-signals as shockwaves - that is, discontinuities in the first derivative of the Faraday-tensor - propagating through space-time results in a light cone condition defining the characteristic hypersurfaces of propagation. In non-linear electrodynamics, these can be given as null cones of an effective metric generally differing from the background metric representing gravity. Born—Infeld electrodynamics stands out as a non-linear theory without vacuum birefringence, allowing for only one such light cone. A known perturbative solution of the Einstein—Maxwell system is sufficient to integrate the null geodesics of the effective metric in Einstein—Born—Infeld theory along the equator of a compact object with electric and magnetic field to obtain the deflection angle up to first order. Substituting this into the exact lens equation results in a first order lensing polynomial, which is explored generally with focus on the interdependence of observable quantities on the ratio of magnifications and image positions, giving information about the parameters of the lensing object. Results are provided for known subcases and some mistakes in the literature are corrected.