PERTURBATIONS IN THE KERR-NEWMAN DILATONIC BLACK-HOLE BACKGROUND - MAXWELL WAVES, THE DILATON BACKGROUND, AND GRAVITATIONAL LENSING - ART. NO. 044015

In this paper we continue the analysis of one of our previous papers a nd study the affect of the existence of a non-trivial dilaton backgrou nd on the propagation of electromagnetic waves in the Kerr-Newman dila tonic black hole space-time. For this purpose we again employ the doub le expansion in both the background electric charge and the wave param eters of the relevant quantities in the Newman-Penrose formalism and t hen identify the first order at which the dilaton background enters Ma xwell equations. We then assume that gravitational and dilatonic waves are negligible (at that order in the charge parameter) with respect t o electromagnetic waves and argue that this condition is consistent wi th the solutions already found in the previous paper. Explicit express ions are given for the asymptotic behavior of scattered waves, and a s imple physical model is proposed in order to test the effects. An expr ession for the relative intensity is obtained for Reissner-Nordstrom d ilaton black holes using geometrical optics. A comparison with the app roximation of geometrical optics for Kerr-Newman dilaton black holes s hows that at the order to which the calculations are carried out gravi tational lensing of optical images cannot probe the dilaton background . [S0556-2821(98)07316-0].