Zsolt Horváth, László Á. Gergely, David Hobill, Salvatore Capozziello, Mariafelicia De Laurentis
We discuss weak lensing characteristics for black holes in a fourth order f(R) gravity theory, characterized by a gravitational strength parameter $\sigma $ and a distance scale $r_{c}$. Above $r_{c}$ gravity is strengthened and as a consequence weak lensing features are modified compared to the Schwarzschild case. We find a critical impact parameter (depending upon $r_{c}$) for which the behavior of the deflection angle changes. Using the Virbhadra-Ellis lens equation we improve the computation of the image positions, Einstein ring radii, magnification factors and the magnification ratio. We demonstrate that the magnification ratio as function of image separation has a different power-law dependence for each parameter $\sigma $. As these are the lensing quantities most conveniently determined by direct measurements, future lensing surveys will be able to constrain the parameter $\sigma $ based on this prediction.
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http://arxiv.org/abs/1207.1823
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