Alexie Leauthaud
Assistant Professor

Mailing address:
Kavli Institute for the Physics and Mathematics of the Universe
The University of Tokyo
5-1-5 Kashiwanoha
Kashiwa, 277-8583, Japan
Tel: +81 (0)4 7136-6570

Email: alexie.leauthaud at ipmu.jp

Affiliation: Kavli IPMU (WPI), UTIAS, The University of Tokyo, Kashiwa, Chiba 277-8583, Japan

If you are looking for data points or data compilations from my papers, check out SCIENCE PRODUCTS on the right.

RESEARCH INTERESTS: Weak Gravitational Lensing, Galaxy-Galaxy Lensing, Dark Matter, Galaxy Formation, Cosmology, Large-Scale Structure, Groups and Clusters of Galaxies.

RESEARCH DESCRIPTION: I probe the dark universe via measurements of weak gravitational lensing, the deflection of light from distant galaxies by intervening gravitational potentials. This is a purely geometrical effect, free from astrophysical biases and sensitive to all mass - regardless of its baryonic or dark form. Gravitational lensing techniques have a uniquely dual ability to probe both the growth of structure (which is dominated by the distribution of dark matter) as well as the geometrical distance-redshift relation (which traces the expansion history of the universe). Gravitational lensing is also powerful tool with which to probe the connection between galaxies and dark matter.


• I am involoved in the Hyper Suprime Cam (HSC) survey, an ambitious multiwavelength (g,r,i,z,y) weak-lensing program to map out 1500 square degrees of the sky with the Subaru Telescope to i~26 mag. The HSC survey began taking data in 2014.

• I am also working with the BOSS survey. In particular, I am interested in the physical mechanisms by which star formation is quenched in the most massive galaxies. As such, in collaboration with Shun Saito, we are using abundance matching techniques to model the lensing and clustering of BOSS galaxies at z=0.5.

• In collaboration with Jenny Greene we are targetting 100 BCGs with IFU spectroscopy via an ancillary program of the MaNGA SDSS IV survey. The goal of this program is to study the stellar populations of BCGs and to probe the relationship between galaxy assembly and halo assembly for the most massive galaxies in the universe.

• Further details on my work related to understanding and characterizing the formation of massive galaxies and BCGs can be found at the Massive Galaxies Project.


• In collaboration with Berekely graduate student Nick Hand we recently published the first measurement of the cross-correlation between CMB lensing and galaxy lensing. Details can be found here.

• In collaboration with Beth Reid, we published the first fit to the anisotropic clustering of Sloan Digital Sky Survey III "CMASS" galaxies on scales below 40 h-1 Mpc. Though model dependent, our measurement represents a 2.5 per cent measurement of the growth rate. Details can be found here.

• Using a combination of galaxy-galaxy lensing, galaxy clustering, and galaxy abundances, I measured the evolution of the stellar-to-halo mass relation in the COSMOS survey. Details can be found here.

• With former Berkeley graduate student Matt George, we produced a group membership catalog for a sample of ~160 X-ray selected groups in COSMOS. This catalog has been made public and you can find the details in George et al. 2011.

• I created the COSMOS ACS catalog - you can access this catalog via the link on the right hand side of this page. For more details on this catalog, please look at Leauthaud et al. 2007.




Selected publications

All publications

Curriculum Vitae

Seminars & Invited Conference Talks

The COSMOS ACS catalog

The COSMOS survey

The BOSS survey

The HSC survey

The MaNGA survey

Massive Galaxies Project