The student is assumed to have a working knowledge of geometrical optics and gravitational potential theory. Basic familiarity with astronomical objects (stars, galaxies, clusters of galaxies, large-scale structure) is assumed. Some knowledge of cosmology and general relativity is useful, but not essential. In terms of the Leiden curriculum, the astronomy BSc provides a good preparation.
Light rays are deflected by gravitational fields, which makes massive bodies act like lenses. Although the effect is incredibly weak in terrestrial settings, in astronomical and cosmological settings it becomes observable. This course describes the phenomenon quantitatively, and introduces the various ways in which astronomers use it as a tool to interpret observations.
Topics that will be covered include
- light deflection by gravitational fields in Newtonian Gravity and General Relativy
- the lensing equation and sample solutions (including multiple imaging)
- the Fermat potential and time delays
- shear, convergence and magnification
- the mass-sheet degeneracy
strong lensing and its applications:
- the gravitational telescope
- galaxy and galaxy cluster masses
- milli-lensing and halo substructure
- time delay cosmography
microlensing and its applications:
- MACHOs in the haloes of galaxies
- stellar populations
- binary lenses and the lensing effect of planets
weak lensing and its applications
- shape noise and measuring weak lensing
- tangential shear and mass distributions of galaxies and galaxy clusters
- mass mapping
- cosmic shear and large-scale structure
Upon completion of this course you will be able to measure and interpret gravitational lensing in astronomical data, in the context of strong, micro- and weak lensing.
This is course is not designed to develop soft skills per se.
Basics of lensing, Kuijken: https://arxiv.org/pdf/astro-ph/0304438.pdf
As reference we will use the 33rd Saas-Fee Advanced course on Gravitational lensing.
Strong lensing, C.Kochanek: https://arxiv.org/abs/astro-ph/0407232
Microlensing, J. Wambsganss: https://arxiv.org/abs/astro-ph/0604278
Weak lensing, P. Schneider: https://arxiv.org/abs/astro-ph/0509252