Applications Of Gravitational Lensing: Unique Insights Into Galaxy Formation And Evolution.

Coordinators: Leon V. E. Koopmans, Chung-Pei Ma, Ben Moore, Peter Schneider, Tommaso Treu

In the quarter of a century since the discovery of the first gravitational lens, gravitational lensing has become a well established field of astrophysics and a powerful tool to tackle important cosmological problems. The program focuses on the study of phenomena at galactic and subgalactic scales, where other methods such as cosmic microwave background fluctuations or statistical properties of the large scales structure of the universe provide little insight. Examples of such applications include: i) direct detection and characterization of the properties of dark matter at sub-Mpc scales (substructure, cusps..); ii) use of lenses as gravitational telescopes to identify the most distant galaxies and the sources of cosmic hydrogen reionization beyond redshift seven; iii) study of supermassive black-holes at cosmological distances.

The proposed program aims at gathering theorists and observers in an effort to promote interaction between astrophysicists working on gravitational lensing and/or on galaxy formation. We will use this combined knowledge to address a range of questions such as: i) review the current contribution of gravitational lensing to our understanding of galaxy formation and evolution. Are there any ``crises'' challenging the standard picture of galaxy formation and the Lambda-CDM paradigm? How are they constrained by gravitational-lenses? ii) Assess future prospects. Are we asking the right questions and performing the most stringent tests on galaxy formation models and the dark matter properties? To what extent are lenses a unique tool in addressing these issues and how do they complement other methods? iii) Identify and propose a series of key (lensing-based) tests and measurements of galaxy formation models that will be feasible in the next decade.

A conference on the same topic will be held at KITP from Oct 3-6, 2006.
A separate announcement will be posted at a later date.