Speaker
Giuseppe Fanizza
(Universita di Bari, Italy)
Description
We present a new method to compute the deflection of light rays in a perturbed FLRW
geometry. By using the properties of the Geodesic Light Cone (GLC) gauge where null rays
propagate at constant angular coordinates irrespectively of the given (inhomogeneous and/or
anisotropic) geometry, the gravitational deflection of null geodesics can then be obtained
in any other gauge. This connection can be done by expressing the angular coordinates of the given gauge in terms
of the GLC angular coordinates. We apply this method to the standard Poisson gauge,
including scalar perturbations, and give the full result for the deflection effect in terms of
the direction of observation and observed redshift up to second order, and up to third order
for the leading lensing terms. Furthermore, we also discuss the connection with literature and estimate the effects of lensing on the CMB temperature.
