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Astronomy Colloquium

Wednesday, March 9, 2016
4:00pm to 5:00pm
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Cahill, Hameetman Auditorium
Thinking Big (and Small) : Frontier Science in the Era of Wide Field Lensing Surveys
Alexie Leauthaud, Kavli IPMU, Tokyo,

A fundamental goal in observational cosmology is to understand the link between the luminous properties of galaxies and the dark matter halos in which they reside. A precise understanding of the key mechanisms that determine the growth, evolution, and global properties of galaxies has eluded astronomers for more than half a century. Dark matter is thought to play a key role in setting the conditions that determine galaxy properties but the exact details of how dark matter influences galaxy formation remains a topic of active debate. Weak lensing, which relies simply on the laws of gravity, is a unique method that can be used to directly probe the dark matter components of galaxies. While previous weak lensing surveys have been modest, reaching at most a few hundred square degrees, the state-of-the art in this field is changing dramatically with surveys such as the Hyper Suprime Cam (HSC) survey, an ambitious multi-wavelength (g,r,i,z,y) weak-lensing program to map out 1500 square degrees of the sky with the 8.2m Subaru Telescope to i∼26 mag. Euclid, WFIRST and LSST will follow in less than a decade.  In this talk, I will discuss new frontiers that are opening up with these expanded data-sets. New programs that will soon be within reach include detailed studies of the interconnected assembly histories of massive galaxies and dark matter, lensing-based constraints on the inner profiles of dark matter halos and possibly also of the stellar Initial Mass Function (IMF), and direct measurements of the halo masses of dwarf galaxies.

For more information, please contact Althea E. Keith by phone at 626-395-4973 or by email at [email protected].