27208 - Gravitational Lensing

Learning outcomes

At the end of the course, the student acquires the basic knowledge of the theory of gravitational lensing, and is able to discuss the applications of lensing in different astrophysical branches. In particular, the student is able to distinguish between different regimes of lensing (strong, weak, etc) and he can discuss the observational requirements.

Course contents

1 Introduction to lensing 1.1 History of gravitational lensing 1.2 Fermat principle e light deflection 2 The general lens 2.1 deflection angle for the general lens 2.2 Lens equation 2.3 Lensing potential 2.4 magnification and distortion 2.5 Second order lensing 2.6 Time delay surface 3 Lens models 3.1 Point lens 3.2 Axially symmetric lenses 3.2.1 Singular Isothermal Sphere 3.2.2 Softened Isothermal Sphere 3.2.3 NFW model 3.3.1 External shear 3.3.2 Elliptical lenses 4 Microlensing 4.1 Lensing of stars by stars 4.2 MACHO searches  4.2.1 Method 4.2.2 Observational results 4.3 Binary lenses 4.4 Extrasolar planet searches 4.5 Extragalactic microlensing 5 Lensing by galaxies and galaxy clusters 5.1 Strong lensing 5.1.1 Generalities 5.1.2 Observables 5.1.3 Parametric reconstructions 5.1.4 SL by galaxies: observational results 5.15 SL by galaxy clusters: observational results 5.2 Weak lensing by galaxy clusters 5.2.1 Shear measurements 5.2.2 Kaiser & Squires inversion 5.2.3 Mass-sheet degeneracy 5.2.4 Methods to measure masses with weak lensing

Assessment methods

Oral examination. The student must show to have well understood the theoretical background and to be able to discuss the astrophysical applications.

Teaching tools

Lecture notes and presentations can be downloaded from the teacher website.

Links to further information

http://pico.bo.astro.it/~massimo/pico/Teaching.html

Office hours

See the website of Massimo Meneghetti